Dipsacus and Scabiosa Species—The Source of Specialized Metabolites with High Biological Relevance: A Review

The genera Dipsacus L. and Scabiosa L. of the Caprifoliaceae family are widely distributed in Europe, Asia, and Africa. This work reviews the available literature on the phytochemical profiles, ethnomedicinal uses, and biological activities of the most popular species. These plants are rich sources of many valuable specialized metabolites with beneficial medicinal properties, such as triterpenoid derivatives, iridoids, phenolic acids, and flavonoids. They are also sources of essential oils. The genus Dipsacus has been used for centuries in Chinese and Korean folk medicines to treat bone (osteoporosis) and joint problems (rheumatic arthritis). The Korean Herbal Pharmacopoeia and Chinese Pharmacopoeia include Dipsaci radix, the dried roots of D. asperoides C.Y.Cheng & T.M.Ai. In addition, S. comosa Fisch. ex Roem & Schult. and S. tschiliiensis Grunning are used in traditional Mongolian medicine to treat liver diseases. The current scientific literature data indicate that these plants and their constituents have various biological properties, including inter alia antiarthritic, anti-neurodegenerative, anti-inflammatory, antioxidant, anticancer, and antimicrobial activities; they have also been found to strengthen tendon and bone tissue and protect the liver, heart, and kidney. The essential oils possess antibacterial, antifungal, and insecticidal properties. This paper reviews the key biological values of Dipsacus and Scabiosa species, as identified by in vitro and in vivo studies, and presents their potential pharmacological applications.


Introduction
Fruits, vegetables, and herbs provide the body with many valuable specialized metabolites, often with pro-health properties. These include polyphenols, alkaloids, terpenoids, and essential oils, all of which display specific biological activities. Plants have been utilized in folk medicine in many countries for centuries because of their long-known therapeutic benefits. Not only have the beneficial medicinal properties of plants have been known for thousands of years, consumer interest in phytotherapy/herbal medicines and natural food supplements continues to grow, and in many countries, traditional medicine is the only mode of treatment for many diseases.
Although herbal materials have many ethnomedicinal benefits, their toxicity or potential side effects remain relatively unexplored, and their medical potential frequently lacks a scientific basis. By determining the chemical composition of plant extracts, it is possible to estimate their safety and biological activities and hence their potential as natural drugs. The use of medicinal plants as natural sources of compounds with inter alia antioxidant, anti-inflammatory, and anti-diabetic properties has drawn the attention of many researchers. Oxidative stress and the inflammatory response are associated with many neurological diseases (Alzheimer's disease, Parkinson's disease, amyotrophic lateral S. tschiliensis Grüning [8,9] (synonymous name of S. comosa Fisch. ex Roem & Schult. [8,9]) Meng Gu Shan Luo Bo (in Chinese) [51] Inner Mongolia autonomy district and China (the west of Hebei Province) [52] Mountainous regions (300-1500 m) [52,53] The genera Dipsacus and Scabiosa currently belong to the Caprifoliaceae Juss. family (honeysuckle family) [7,8]. They were previously classified taxonomically in the Dipsaceae [7]. According to Plants of the World Online database [9], the Caprifoliaceae includes 33 accepted genera. This family has been divided into six subfamilies and one genus. Both genera Dipsacus and Scabiosa are classified into the subfamily Dipsacoideae and order Dipsacales [8,54]. The genus Dipsacus is widely distributed in Europe, North Africa, and Asia in North Myanmar and comprises 21 accepted species [9]. The native range of the genus Scabiosa includes Eurasia, Macaronesia to North Africa, Eritrea, and South Africa, with 66 accepted species [9]. In particular, numerous representatives of European Scabiosa species appear in the Mediterranean region [55,56]. Table S1 (Supplementary Material) presents accepted species of the genera Dipsacus and Scabiosa. Dipsacus includes various ornamental plants used in floristry for their decorative dried inflorescences. The dried inflorescences were previously used in the textile industry to clean and lift the nap on woolen fabrics [57,58]. The name dipsacus itself is believed to be derived from the Greek word for dipsa or thirst [9]. The genus name scabiosa is derived from the Latin word scabies or itch [9]. According to Akar [59], Scabiosa plants were traditionally used to treat scabies, skin sores, and other skin infections.

Traditional Medicinal Uses and Pharmacopoeial Monographs
Many Dipsacus and Scabiosa species are known in various traditional medicines, including traditional Chinese medicine. So far, among over 20 species of the genus Dipsacus and 60 species of Scabiosa, the phytochemical profiles and biological properties of only a few species are known. As such, there is a need to better understand the chemical composition of these genera and their potential medicinal value.

Dipsacus spp.
Numerous, recent reports have examined the potential therapeutic effects of Dipsacus genera. However, most phytochemical and biological studies have focused on the biological activities and health-promoting factors of D. asperoides C.Y.Cheng et T.M.Ai (=D. asper Wall. ex C.B.Clarke) [6]. The oldest report on Dipsacus genus can be found in Shen Nong's Herbal Classic (Shen Nong Ben Cao Jing in Chinese) [6,11,18]. D. asper is widespread in the southern and northern regions of China such as the Hunan, Yunnan, Gansu, and Shanxi Provinces [12,19]. The growing demand for this species and its mass harvesting has significantly weakened its population in a natural state [19,60]. D. asperoides is cultivated on a large scale, mainly in Hefeng City, Hubei Province. This species is also cultivated in other Chinese cities, including Xichang, Sichuan, Xifeng, Guizhou, Jianchuan, and Yunnan Provinces as well as Jiangxi and Guangxi Provinces in China [18,60].
Dipsaci radix can be subjected to diaphoretic-, salt-, and wine-processing methods [6]. Some researchers suggest that the procedure of herb processing may result in differences in specialized metabolite content and biological effects. Some studies indicate that wine processing yields higher levels of key compounds (e.g., asperosaponin V and VI, dipsacoside A and B, dipsacussaponin B, loganic acid, and chlorogenic acid) than crude Dipsaci radix [65,66]. Materials processed by rice wine may promote anti-osteoporosis, anti-inflammatory, anti-coagulant, and analgesic activities or have a beneficial effect on blood circulation [6,67,68].
Dipsaci radix is commonly available in the Chinese herbal medicine market. This herb is mainly produced in China, in the Provinces of Sichuan, Yunnan, Hubei, Hunan, Xizang, Jiangxi, Guizhou, and Guangxi [18,20]. Dipsaci radix has a pharmacopeial monograph in the Korean Herbal Pharmacopoeia (Korea Food and Drug Administration 2007) and the 10th Chinese Pharmacopoeia, 2015 edition. The raw material is standardized to contain akebia saponin D whose level should be above 2% [69]. Chun et al. [30] indicate that the traditional use of D. asperoides is associated with its analgesic and anti-inflammatory properties for treating inter alia rheumatoid arthritis and bone fractures. The Chinese Pharmacopoeia, 2015 edition, recommends 9-15 g as the daily dose of D. asper for humans [15].
In the Korean herbal medicine markets, Phlomidis radix from Phlomis umbrosa Turczaninow is often sold instead of Dipsaci radix or both raw materials are mixed [70]. This mistake results from the morphological similarity of these two dried raw materials and their names [69,70]. Both species have been used in the Korean medicine Sok-dan for the treatment of bone-and arthritis-related diseases and are listed in the Korean Herbal Pharmacopoeia [70].
HPLC  [69]. Akebia saponin D (a quality indicator of Dipsaci radix) predominated, with a content range of 0.73-10.96% (w/w) [69]. Both herbs showed anti-osteoarthritis ability in a Sprague-Dawley rat model induced by monosodium iodoacetate intra-articular knee injections [70]. However, Phlomidis radix was found to be more effective, suggesting that it may be used as an alternative to Dipsaci radix. It was found that the 70% ethanol extract (200 mg/kg/day) administered as oral gavage for 21 days restored the weight-bearing ability of the hind paw, suppressed histopathological changes of the osteoarthritic knee, inhibited the serum levels of inflammation mediators tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β), and inhibited the over-expression of the gene encoding matrix-degrading metalloproteinases MMP-9 and MMP-13 in the knee joint tissue [70]. In addition, the ethanol extract of Dipsaci radix displayed a protective effect against the destruction of articular cartilage, elevated myeloperoxidase (MPO) and down-regulated dystonin gene expression, modulated WNT/β-catenin signaling pathway, suppressed gene expression of Adamts4, and increased the expression of cartilage collagen genes (e.g., Col2A1, Col9A1, and Col11A1) and SOX5, SOX9, and Frzb genes [30].
Another species of Dipsacus is D. fullonum L., commonly known as teasel or wild teasel [33,34]. Traditionally, D. fullonum has been used to treat Lyme disease [35] and eye infections in cattle [36]. D. fullonum is distributed naturally in Europe to the Caucasus and North-Western Africa [9]. A rich source of valuable ingredients used in the traditional medicine of the Kashmir Himalayas is D. inermis Wall., also known as Wopal haakh/Wopal Hak in the Kashmiri language. It is used in treating cold, fever, cough, sore throat, general fatigue, and body pain and has demonstrated stomachic and carminative properties [37][38][39]71]. The roots of D. japonicus Miq., commonly known as Tuc doan in Vietnam, show tonic, anodyne, and demulcent activities. The recommended daily dose is 10-20 g as a decoction, alcoholic maceration, powder, or pill [41]. Decoction of D. japonicus roots has been used in the traditional medicine of China and Vietnam for rheumatism, sprains, trauma, fractures, relieving joint pain and ostealgia, and hepatic and renal hypofunction [40,41]. D. japonicus is widespread in central and northern China, Korea, Japan, and Vietnam [9,40]. The leaves of D. sativus (L.) Honck. are used as an infusion for the treatment of cardiovascular diseases. This species was originally cultured in Europe and was introduced from Japan to China in 1929 [42].
In Tunisia, species from Scabiosa were commonly applied for skin treatment [56]. In the Iberian Peninsula, an infusion of S. atropurpurea L. inflorescence is used externally on the skin as an anti-acne treatment and orally for measles, rubeola, and scarlet fever [44,84]. In northern Peru, the aerial parts have been used for menstrual regulation and in Iberia, as a veterinary diuretic [46]. S. atropurpurea is distributed throughout the Mediterranean, Europe, Asia, and southern Africa [46]. Genetic investigations show that S. atropurpurea has 97% similarity with S. tschiliensis and thus is also called Japanese scabiosa [46]. This species is known as Mor uyuzotu orŞeytanotu in Turkey, Ambarina in Northern Peru, and Escabiosa in the Iberian Peninsula [45]. The leaves and flowers of S. stellata L. were used in the traditional medicine of Morocco to treat heel cracks [46,48]. S. stellata is an endemic plant in North Africa and is commonly known as starflower pincushions [75]. Another endemic species in North Africa (Algeria, Egypt, Libya, Morocco, and Tunisia) is S. arenaria Forssk. [9,72]. In traditional Mongolian medicine, the inflorescences of S. comosa Fisch. ex Roem. et Schult. and S. tschilliensis Grunning (known as Lanpenhua in Chinese) are used for liver diseases [74,79]. S. tschiliensis is widespread in China (in Hebei Province) and the Inner Mongolia autonomy district [51,53] and is locally called Meng Gu Shan Luo Bo [51]. Qingganjiuwei powder (composed of nine herbal materials including S. comosa) is commonly used as an anti-fibrosis drug in patients with chronic hepatic disease in Inner Mongolia [85,86]. This drug is accepted by the Inner Mongolia Region Drug Administration [86]. The flowers of S. comosa (Scabiosae flos) are also an ingredient of Gurigumu-7 used in traditional Mongolian and Tibetan medicine to treat liver diseases. This preparation is in the form of a bitter and astringent powder [87].
The indicator of the quality of Dipsaci radix is akebia saponin D (asperosaponin VI) [65]. It is known that environmental conditions, geographic location, the growth stage of the plants, or the year of harvest affect the content of the specialized metabolites in plants. Jin et al. [60] demonstrated that the content of akebia saponin D varied in D. asperoides roots collected from different geographical regions of China (i.e., Guizhou, Hubei, Sichuan, and Yunnan Provinces). The highest akebia saponin D content (about 6% of dry weight) was noted in roots collected from Hubei. A similar observation was noted by Du et al. [95]. The level of akebia saponin D ranged from 1.61% to 15.19% in samples of different origin. 2.
The levels of the main iridoids in Dipsaci radix, e.g., loganic acid, loganin, sweroside, and dipsanosides A and B, varied according to location and collection time. The highest level of loganic acid was 31.223 mg/g; loganin, 4.411 mg/g; sweroside, 8.364 mg/g; dipsanoside A, 4.513 mg/g; and dipsanoside B, 7.426 mg/g [99]. Du et al. [95] also demonstrated that the content of loganic acid (0.71-1.10%) and loganin (0.29-0.61%) varied between samples from different origins in China. In addition, the level of some iridoids in the leaves and roots including loganic acid, loganin, sweroside, sylvestroside III, and cantleyoside detected in D. fullonum varied according to the time of year of harvesting [33]. The leaves of the plants collected in the first year of vegetation contained a higher total iridoid content than the roots and leaves harvested in the second year. The most abundant iridoids were sylvestroside III in the leaves and cantleyoside in the roots. Moreover, sweroside (0.67 mg/g dry weight) and sylvestroside III (34.8 mg/g d.w.) were present in higher amounts in leaves, while the levels of loganic acid (5.27 mg/g d.w.), loganin (3.02 mg/g d.w.), and cantleyoside (21.41 mg/g d.w.) were higher in the roots [33]. Table 3. Iridoids identified in Dipsacus and Scabiosa species.

No.
Compound Name Species (Part of Plant)
The phenolic acid content in Dipsaci radix varied according to the geographical region of China [95,99]. The total level of phenolic acids ranged from 0.98 mg/g to 49.55 mg/g, with the highest level observed in plant material collected from Guizhou Province [99]. The predominant phenolic acid was chlorogenic acid (0.186-19.174 mg/g; 2.02-8.28%) [95,99], which was also an abundant phenolic in D. fullonum [33]. However, qualitative differences were reported between the leaves and the roots, with the highest level being found in the leaves obtained from plants in the second year of vegetation (28.44 mg/g d.w.). Wang et al. [53] also found differences in the content of chlorogenic acid in plants of S. tschiliensis between the pre-flowering, flowering, and fruiting stages. The level was also dependent on the extraction solvent; the richest source of chlorogenic acid, 45.35 mg/g d.w., was found in the ethyl acetate fraction from plants at the pre-flowering stage.

No.
Compound Name Species (Part of Plant)

Essential Oils
Essential oils are present in some species of Dipsacus and Scabiosa (Table 7) [35,83,102]. The essential oils isolated by hydrodistillation from dried and fresh roots and leaves of D. fullonum were rich in many components; however, quantitative and qualitative differences were noted. The dominant compound in the essential oils from leaves, regardless of fresh or dried materials, was phytol (branched-chain unsaturated diterpene alcohol; precursor for vitamins E and K1), whose content ranged from 61.08% to 72.31%. It was not detected in root essential oil. In addition, the main components in fresh leaf essential oil, i.e., with a level above 5%, were 9,12,15-octadecatrienoic acid methyl ester and cyclohexane, cyclopropylidene. On the other hand, in the essential oils from the dry and fresh roots, the main component was n-hexadecanoic acid, especially in the dried material (16.00%), which was also rich in 11,14,17-eicosatrienoic acid, methyl ester (15.86%). n-hexadecanoic acid was also identified in the essential oils from dried and fresh leaves but at much lower levels (2.01-2.34%) [35]. In the essential oil from the flowering aerial parts of D. japonicus, linalool (11.78%), trans-geraniol (8.58%), and 1,8-cineole (7.91%) predominated. The other main ingredients present at above 5% were β-caryophyllene (5.58%), α-terpineol (5.32%), β-selinene (5.15%), and spathulenol (5.04%) [102].

Fatty Acids
The presence of fatty acids has only been investigated in S. stellata aerial parts and D. asper roots [6,49] (Table 8). Thirteen fatty acids including saturated and unsaturated acids have been identified. The fatty acids present in the hexane extract of S. stellata aerial parts accounted for 87% of the total content with linolenic acid, palmitic acids, and linoleic acids predominating [49].

Safety of Use
The use of traditional medicines, herbs, and supplements of plant origin is becoming more popular. However, it is necessary to determine the side effects that they may cause or their toxicity to use safely.
An in vitro study showed that the extract of D. asperoides was not toxic for normal cells at a concentration up to 500 µg/mL [26,112]. The viability of RAW 264.7 macrophages and periodontal ligament stem cells after treatment with water or ethanol extracts for 24 h was about 90-100% [26,112]. However, the periodontal ligament stem cells treated for 7-21 days with 500 µg/mL of D. asper ethanol extract showed morphology changes [112]. The cell viability of J774A.1 murine macrophage was also not affected by the methanol extract of D. inermis at a concentration up to 100 µg/mL [39]. The concentration above 300 µg/mL decreased the cell viability below 80%. In addition, Dipsaci radix stimulated the proliferation of MC3T3-E1 and primary osteoblastic cells in the concentration range of 3-300 µg/mL after 24 h and 48 h [113]. It should be also noted that akebia saponin D, a quality indicator of Dipsaci radix, at a concentration of 25-200 µM has no cytotoxic effect in mouse primary chondrocytes after 24 h [25]. In addition, saponin favored the proliferation of rat bone marrow stomal cells on days 4 and 7 in a dose-dependent manner (0.01-10 µM) [64] and enhanced the proliferation of human mesenchymal stem cells at a concentration up to 1 mg/L after 3 and 5 days [114].
The toxicity of Dipsacus or Scabiosa plants has been tested not only in vitro but also in vivo. According to Zhou et al. [115], the clinical safety of D. asper has been evaluated by Zhan et al. [116]. The total saponin extract (0.28 g/tablet) was administered to volunteers for six months, resulting in only mild side effects such as abdominal discomfort, constipation, swollen gums, raised level of blood alanine aminotransferase (ALT), and dysphoria.
A study using F344 rats which were orally treated with the aqueous extract of Dipsaci radix at doses of 0.125, 0.25, 0.5, 1, or 2 g/kg body weight (b.w.)/day for 13 weeks resulted in no deaths or pathophysiological changes [20]. On the other hand, Xiao et al. [117] found that an extract of D. asper roots may have an adverse effect at a concentration of 2-32 g/kg/day. Dipsaci radix enhanced fetal malformation in a dose-dependent manner in pregnant ICR mice. In addition, the extract at a dosage of 32 g/kg/day, i.e., 17-times higher than recommended for an adult human, was toxic to the fetus; it led to abnormalities of fetal skeletal development including malformed limbs (polydactylia) and sternum (hypoplasia and split) as well as inhibited mineralization cartilaginous tissue and osteogenesis. It is worth emphasizing that the extract also inhibited the mouse embryogenic stem cells and 3T3 cells growth in a dose-dependent manner (0.1-125 mg/mL) with IC 50 values of 6.83 mg/mL and 5.13 mg/mL, respectively [117].
The ethyl acetate extract of S. stellata whole plants orally administered for 14 days at a concentration of 0.5-2 g/kg in a single dose was not toxic for albino Wistar rats and did not induce animal mortality [50]. Moreover, no changes in respiration and urination or in hematological and serum biochemical parameters such as ALT, aspartate aminotransferase (AST), total bilirubin, urea, creatinine, cholesterol, triglycerides, and glucose levels were observed in comparison to those in the control animals [50]. Mouffouk et al. [77] estimated the cytotoxicity of the hydroethanolic extract, petroleum ether, ethyl acetate, and n-butanolic fractions of S. stellata whole plants in larvae of brine shrimp lethality method. A dosedependent pattern (at a concentration of 10-100 µg/mL) in the mortality rate of the brine shrimp nauplii was noted. Only the n-butanolic extract caused mortality above 50% at a concentration of above 80 µg/mL. The 70% ethanol extract of aerial parts of S. atropurpurea possessed an LD 50 value for adult male albino rats of 5 g/kg b.w. [43].

Pharmacokinetic and Bioavailability of Some Specialized Metabolites of Dipsaci radix
The synergistic effect of numerous, various specialized metabolites of plants is responsible for the medicinal properties of plants. Therefore, knowing the chemical composition of herbal materials is the basis for understanding the mechanisms of their action [118]. It is important to know the pharmacokinetics of drugs to understand the toxicity of their preparations or their therapeutic potential. The therapeutic effectiveness of the preparations/compounds is related to their bioavailability. The bioavailability of compounds depends on many different parameters, such as digestion, absorption, or metabolism [119]. Akebia saponin D, the main ingredient of Dipsaci radix, shows low absorption. Therefore, its therapeutic effect is limited [119]. Wang et al. [119] suggested that the microcrystalline form of akebia saponin D obtained by antisolvent precipitation may enhance the bioavailability of akebia saponin D.
A few specialized metabolites identified in the roots of D. asper, e.g., 4-O-caffeoylquinic acid, 3-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, loganic acid, loganin, sweroside, dipsacoside B, and asperosaponin VI, showed rapid absorption after intragastric administration to Sprague-Dawley rats at a concentration of 75.6 g/kg; these ingredients reached the maximum plasma concentration in an hour [15]. In addition, it was shown that sauteing with rice wine of D. asper roots enhanced the bioavailability of these specialized metabolites, indicated by a significant increase in maximum plasma concentration and area under the curve for the plasma concentration from zero to the last quantifiable time-point as well as an increase in the level of bioactive compounds in rat liver and kidney tissues compared with those in the crude material (aqueous extract) [15,120].
6. Biological Activities of Dipsacus and Scabiosa Species 6.1. Strengthening the Bone Tissue and Antiarthritic Activity The roots of D. asperoides, known in Chinese as Xu Duan, means "connects broken bones" [26]. Until now, numerous in vitro and in vivo studies have demonstrated that Dipsaci radix or the pure compounds isolated from this plant material can be potential agents for promoting osteoblast formation and may have an anabolic systemic skeletal effect. Dipsaci radix can improve bone density and affect bone histomorphology. Dipsaci radix has also shown osteoprotective properties in ovariectomized animals [6,18,23,25,68,[110][111][112][113]115,[121][122][123][124][125][126][127][128]. In healthy BALB/c mice, an increase in the bone trabeculae density, bone volume/tissue volume ratio, bone surface/tissue volume, and trabecular number and the depletion in the trabecular separation on the proximal tibia after drinking water extract of Dipsaci radix were observed [61].
Osteoporosis is characterized by an increase in bone fragility. Osteoporosis can usually occur with aging and after menopause due to estrogen deficiency, which contributes to the reduction of bone density and bone mass and degradation of the microstructure [129]. The hormone replacement therapy that is used in osteoporosis treatment increases bone density. However, the use of hormone replacement therapy for a long time should be limited due to the serious side effects of its use [126]. Modern therapies enhance bone metabolism by promoting osteoblast activity and by inhibiting the effects of osteoclasts [126]. The ethanol extract of D. asperoides roots showed concentration-dependent progestogenic activity (40-100 µg/mL) in the T47D progesterone receptor-positive human mammary adenocarcinoma cell line; 100 µg/mL of extract demonstrated the equivalent of 31.45 ng/mL of progesterone treatment. These results indicate that D. asperoides roots can be used as an option for progestins [130]. Moreover, asperosaponin D may promote the osteogenic differentiation of human mesenchymal stem cells through the estrogen signaling pathway [131].
Liu et al. [18,122] reported that Dipsaci radix decoction has anti-osteoporosis properties in ovariectomized Wistar or Sprague-Dawley rats (oral treatment at a dose of 100-500 mg/kg b.w./day) by increasing trabecular bone formation and bone mineral density and preventing bone mass loss and trabecular structure changes; it also decreases the serum alkaline phosphatase (ALP) level and the level of bone turnover markers, e.g., serum osteocalcin and urinary deoxypyridinoline/creatinine ratio, and receptor activator for nuclear factor κB ligand (RANKL) in osteoblasts and bone marrow stromal cells of the tibia. A recent study showed that Dipsaci radix may be able to control osteoblast differentiation, osteoclast proliferation, and mineralization via regulating mitogen-activated protein kinases (MAPK), nuclear-kappa B factor (NF-κb), TNF-α, and Toll-like receptor (TLR4) signaling pathways [127]. Intragastric treatment of bilaterally ovariectomized Wistar rats with wine processed Dipsaci radix (with a dose of 75.6 g/kg/day) resulted in protection from an increase in urine Ca/creatinine and P/creatinine levels and serum ALP and osteocalcin concentrations and increased the femur bone mineral density. These effects were comparable to that observed in rats treated with 17β-estradiol [68].
In traditional Chinese medicine, Xian-Ling-Gu-Bao capsules have been used to prevent and treat osteoporosis, osteoarthritis, aseptic bone necrosis, or climacteric syndrome. Xian-Ling-Gu-Bao was officially approved in 2002 by the China Food and Drug Administration as an over-the-counter drug for the treatment of osteoporosis [132,133]. This product is composed of the raw material of six plant species: Epimedii herba (70%), Dipsaci asperoidis radix (10%), Anemarrhenae rhizoma (5%), Psoraleae fructus (5%), Rehmanniae radix (5%), and Salviae miltiorrhizae radix (5%) [133]. Xian-Ling-Gu-Bao administered to ovariectomized C57/BL6 mice for six weeks displayed anti-osteoporosis effects by enhancing bone mineral density and bone strength and by decreasing the serum level of the bone formation marker procollagen type I N-terminal propeptide (PINP) and the bone resorption marker C-terminal telopeptide of type I collagen (CTX) [125]. Wu et al. [132] also reported that Xian-Ling-Gu-Bao showed the ability to prevent osteoporosis in two osteoporosis models, prednisolone-treated zebrafish (Danio rerio) and ovariectomized Sprague-Dawley rats. Xian-Ling-Gu-Bao altered the protein levels of osteoprotegerin and RANKL. An increase in the OPG/RANKL ratio may suppress bone loss. It is worth mentioning that a dose of 1800 mg/kg (a concentration of six-times the recommended daily dose) did not cause toxicity or adverse effects in the heart, kidney, liver, stomach, or small intestine [132].
Another formulation containing Dipsaci radix used in traditional Chinese medicine for treating kidney disease, osteoporosis, strengthening bones, and bone fractures is Du-Zhong-Wan. This preparation is composed of Eucommiae cortex (salted bark of Eucommia ulmoides Oliv.) and Dipsaci radix in an equal weight ratio (1:1) [23]. It was shown that Du-Zhong-Wan displayed anti-osteoporotic activity in the Sprague-Dawley rat osteopenia model. After treatment with Du-Zhong-Wan at a dose of 2-6 g/kg/day for 12 weeks, an increase in the bone mineral density of the femur was observed, together with an improvement of trabecular bone mass and microarchitecture, reduction of the bone resorption and tartrateresistant acid phosphatase 5b (TRACP-5b) level, and higher serum level of osteocalein, and serum and endometrium level of estrogen [23]. Tian et al. [134] reported that Du-Zhong-Wan favored fractured callus formation and improved osteoblastogenesis and angiogenesis by increasing the level of the H-type vessel endothelium markers (CD31 and endomucin) and proangiogenic factor SLIT3 in C57BL/6 mice after ovariectomy with the open transverse femoral fracture.
Niu et al. [113,123] showed that the 60% ethanolic extract and total saponins of Dipsaci radix at a concentration of 50-500 mg/kg/day may have anti-osteoporotic properties in Sprague-Dawley female rats after bilateral ovariectomy or hindlimb unloading Sprague-Dawley rat model by preventing a decrease in bone mass and by improving bone mineral density, biomechanical strength, and trabecular bone architecture. In addition, Dipsaci radix suppressed osteoclastogenesis through a reduction of the serum level of bone turnover marker (osteocalcin) and urine concentration of phosphorus, calcium, and deoxypyridinoline/creatinine ratio.
Akebia saponin D was also found to have a potential application in osteoarthritis therapy. Gu et al. [25] demonstrated that it showed anti-inflammatory activity in mouse primary chondrocytes and alleviated osteoarthritis following the surgical destabilization of a medial meniscus model of osteoarthritis in C57BL/6 male wild-type mice. Akebia saponin D was able to inhibit the production of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), nitric oxide (NO), prostaglandin E2 (PGE2), IL-6, TNF-α, and NF-κB; it also activated the nuclear factor erythroid-2-related factor 2 (Nrf2)/Heme oxygenase 1 (HO-1) pathway and suppressed the expression of matrix synthesis degradation-related proteins such as disintegrin, metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), as well as MMP13 in IL-1β treated chondrocytes. It was also found to enhance the expression of Aggrecan and Collagen II [25]. A recent study found it to also enhance the proliferation and differentiation of human mesenchymal stem cells into nucleus pulposuslike cells through p-ERK1/2 and p-Smad2/3 activation, which may prevent intervertebral disc degeneration [114]. Akebia saponin D also favored the proliferation and osteogenic differentiation of rat bone marrow stromal cells through the phosphatidylinositol-3 kinase/AKT signaling pathway, thus inhibiting osteoporosis. This active compound elevated osteogenic differentiation markers such as ALP activity and calcium deposit formation and mRNA level of osteogenic-related genes (ALP, osteocalcin, type 1 collagen (COL 1), and RUNX2) [64].
Another terpenoid compound, hederagenin, also alleviated the progression of osteoarthritis and inhibited inflammation and cartilage degradation. In an in vitro study, hederagenin exerted chondroprotective and anti-inflammatory effects by suppressing the JAK2/STAT3/MAPK pathway, inhibited extracellular matrix degradation, elevated Aggrecan and Collagen II levels, and reduced levels of MMPs and ADAMTS5. In addition, this pentacyclic triterpenoid saponin inhibited cartilage destruction in rats induced by monosodium iodoacetate [137]. Hederagenin 3-O-(2-O-acetyl)-α-L-arabinopyranoside and the dichloromethane fraction of Dipsaci radix also improved osteoblastic differentiation of human alveolar bone marrow-derived mesenchymal stem cells. This specialized metabolite caused the formation of calcified nodules and enhanced the level of bone differentiation protein expression such as sialoprotein and osteocalcin similar to dexamethasone [121].
Moreover, the main iridoid glycoside isolated from Dipsaci radix, sweroside (at a concentration of 1 µM), enhanced rat osteoblast-like UMR 106 cell proliferation, while loganic acid, loganin, and sweroside favored mineralization. Loganin and sweroside suppressed the formation of adipocytes in 3T3-L1 cells [125]. The anti-osteoporotic property of sweroside was also confirmed by Wu et al. [128]. This compound enhanced mineralization of MC3T3-E1 cells by increasing the protein expression of the membrane estrogen receptor-α and G protein-coupled receptor 30 (GPR30), which activate the p38 signaling pathway.
MC3T3-E1 mouse embryonic osteoblast proliferation and differentiation were also promoted by various concentrations (25, 50, or 100 µg/mL) of a 17 kDa polysaccharide (DAI-1) isolated from D. asperoides in high glucose concentrations; this appeared to act via the stimulation of the bone morphogenetic protein 2 (BMP-2)/Smad/runt-related transcription factor 2 (Runx2)/Osterix signaling pathway. The polysaccharide also enhanced osteocalcin level and the mRNA and protein levels of BMP-2 and Runx2 [110]. A homogenous polysaccharide with a molecular weight of 26.1 kDa isolated from the roots of D. asper (at a dose of 50 or 200 mg/kg b.w.) was also able to enhance mRNA and protein levels of VEGF and osteoprotegin, suppress mRNA and protein expression levels of RANKL, and activate the PI3K/Akt/eNOS signaling pathway in ovariectomized rats [111]. The water-soluble polysaccharide (ADAPW), with an average molecular weight of 16 kDa, inhibited the viability of the human osteosarcoma HOS cells by induction of apoptosis cells and inhibition of the PI3K/Akt signaling pathway [11].
An increase in bone resorption may also lead to osteo-or rheumatoid arthritis. Rheumatoid arthritis is a chronic autoimmune and inflammatory disease of the connective tissue [17]. Dipsaci radix has been also applied for many years in traditional Chinese medicine to treat other bone diseases such as rheumatic arthritis [6]. The aqueous extract of D. asperoides roots at a concentration of 50 mg/kg and 100 mg/kg, administered orally once a day for 21 days, displayed antiarthritic effects in collagen-induced rheumatoid arthritis in male DBA/1 mice by enhancement of the ankle joint architecture and suppression of arthritis score (synovitis, pannus, and bone erosion scores) and serum levels of anti-CII IgG2a antibody and the inflammatory mediators (TNF-α, IL-1β, and IL-6). These effects were comparable or stronger to those after treatment with 1 mg/kg of the anti-rheumatoid drug indomethacin [138].
Akebia saponin D at a concentration of 10 or 20 mg/kg/day also showed antiosteoclastogenic activity in the arthritic joints of male BALB/c and DBA/1 with collagen-induced arthritis. The saponin reduced mRNA expression of osteoclastogenesis markers such as TRAP, CtsK, MMP-9, and β3-integrin. In addition, akebia saponin D also inhibited phosphorylation of Akt, p38, and JNK and mRNA and protein levels of osteoclastogenesis markers in RANKL-induced osteoclastogenesis bone marrow-derived monocytes [17]. Dipsaus saponins also inhibited chondrocyte apoptosis in a rat model of osteoarthritis in a dose-dependent pattern by decreasing expression of Bax, caspase-3, and caspase-9 and by increasing expression of Bcl-2 [139]. Cantleyoside, an iridoid identified in D. asper roots, inhibited proliferation of human rheumatoid arthritis fibroblast synovial cells (HFLS-RA) and induced cell apoptosis through AMPK/Sirt 1/NF-κB pathway activation [140]. Moreover, the protective effect of sweroside was observed in IL-1β-induced inflammation in rat articular chondrocytes. The anti-inflammatory effect of this iridoid was mediated by the inhibition of NF-κB and mTORC1 signaling pathways [141].
These above findings suggest that Dipsaci radix may have a beneficial therapeutic effect in the treatment of postmenopausal osteoporosis and may protect against arthritis.

Anti-Neurodegenerative Activity
Alzheimer's disease is a neurodegenerative disease that destroys memory and deteriorates cognitive function [142].
Five-month administration of 4 g/kg ethanol extract of D. asper roots improved neurocognitive dysfunction in the passive avoidance task and diminished expression of hippocampal β-amyloid protein (Aβ) positive cells in aluminum chloride-treated male Sprague-Dawley rats. This effect increased with the time of treatment (1-5 months). It may be important in the treatment of Alzheimer's disease and memory system dysfunction [31]. Akebia saponin D, at a dose of 30-270 mg/kg administered for four weeks, also showed a preventive effect against memory cognitive impairment in ibotenic acid-exposed male Sprague-Dawley rats [143]. Moreover, it was shown that the saponin can protect against learning and memory dysfunction in rats induced by bilateral intracerebroventricular injections of Aβ1-42 in the Y-maze and Morris water-maze tests. Akebia saponin D attenuated the activation of microglia and astroglia and protein expression level of IL-1, COX-2, TNF-α, NF-κB, and Akt phosphorylation in the rat brain [143]. The total saponin of D. asperoides also possessed neuroprotective properties in rat cortical and hippocampal neurons against damage induced with β-amyloid protein, ameliorated cell viability, and decreased lactate dehydrogenase (LDH) release and lipid peroxidation at a concentration of 150-300 mg/L [144]. Other triterpene compounds, such as oleanolic acid, ursolic acid, and hederagenin, also showed neuroprotective activity in multiple brain disorders [145,146]. For example, hederagenin diminished Aβ deposition in the head area of Caenorhabditis elegans, ameliorated cognitive impairment or pathological changes in APP/PS1 mice, and induced PPARα/TFEB-dependent autophagy of BV2 cells [145]. Moreover, treatment with sweroside, a secoiridoid glycoside, alleviated memory deficits in scopolamine-induced Zebrafish (Danio rerio) in behavioral tests such as the tank diving test, the Y-maze, and the novel object recognition test [147]. The flavonoid apigenin also suppressed neurotoxicity and cognitive function in LPS-induced mice. The compound protected against neuronal degenerative changes in mice hippocampi [148].

Hepatoprotective Activity
Liver fibrosis is a chronic liver disease caused by many agents such as hepatitis B virus (HBV), hepatitis C virus (HCV), non-alcoholic steatohepatitis, or alcoholic fatty liver disease [150].
The flavonoids and phenolic acids from Scabiosa spp. have demonstrated anti-hepatic fibrosis potential in male Wistar or male Sprague-Dawley rats treated intraperitoneally with carbon tetrachloride (CCl 4 ) (a selective hepatotoxic drug); similar effects were also noted for drugs used in Mongolian medicine, such as Qingganjiuwei and Gurigumu-7 (composed of various herbs including S. comosa flowers) [43,47,86,87].
Qingganjiuwei, a drug commonly used in Inner Mongolia in patients with chronic hepatic disease, improved liver morphology and structure in CCl 4 -treated SD rats when administered at 1.575-4.725 g/kg/day for eight weeks. The drug reduced hepatocyte necrosis, lymphocytic infiltration, and pseudolobuli and lowered COL1, tissue inhibitor of metalloproteinase1 (TIMP1), and α-smooth muscle actin (α-SMA) expression. The drug also activated the MAPK pathway in the liver through the suppression of extracellular signal-regulated kinase (ERK), C-Jun amino-terminal kinases (JNKs), and stress-activated protein kinase-2 (p38 proteins) [86]. Qingganjiuwei also increased mRNA and protein expressions of MMP2 and MMP9 and inhibited the levels of the serum aminotransferases (ALT and AST) [86].
The methanol-eluted fraction of Gurigumu-7 extract (0.264 g/kg) displayed a more potent hepatoprotective effect in mice with CCl 4 -induced liver damage compared to crude Gurigumu-7 extract, even when applied at a four-times higher concentration (1.084 mg/kg). The methanol fraction alleviated histopathological changes in the liver and serum ALT, ASP, and liver malonyldialdehyde (MDA) levels and enhanced the liver superoxide dismutase (SOD) level in a dose-dependent manner (66, 132, and 264 mg/kg) [87].
Anti-hepatic fibrosis was also reported for S. comosa and S. tschilliensis [79,80]. Some specialized metabolites inhibited the viability of hepatic stellate LX-2 cells at concentrations of 12.5-200 µM; this included those belonging to flavonoids, which accounted for about 60% of the total identified compounds in the inflorescences of Scabiosa plants. The flavonoids enhanced the expression of Stat1, Pparg, Hsp90aa1 genes, signal transduction and transcriptional activator 1 (STAT1), and peroxisome proliferator-activated receptor G (PPARG) proteins, which play key roles in the pathogenesis of liver fibrosis [79]. Apigenin exhibited the strongest ability to inhibit cell proliferation [79]. The flavonoid-rich extract of S. comosa inflorescences at concentrations of 100 and 200 mg/kg also suppressed hepatic fibrosis in Wistar rats pre-treated with CCl 4 ; the extract inhibited the level of biochemical parameters in blood serum (ALT, AST, ALP, and hyaluronic acid), the markers of liver fibrosis (laminin, amino-terminal propeptide of type III procollagen (PIIINP), collagen IV, collagen deposition in the liver tissues), and expression of α-SMA, collagen I, and fibronectin [47]. Moreover, the extract attenuated phosphorylation of Smad3 in liver tissue and TGF-β1pre-treatment primary mouse hepatic stellate cells. In the latter, it was observed that the expression of the fibrotic genes (α-SMA, collagen I, and fibronectin) was suppressed in a dose-dependent manner [47]. Ethanol extract of aerial parts of S. atropurpurea and hexane, ethyl acetate, n-butanolic, and chloroform fractions were able to decrease the levels of serum ALT, AST, and ALP in CCl 4 -induced liver damage in albino rats after treatment with a dose of 100 mg/kg [43].
In addition, some triterpenoid derivatives isolated from the whole plants of S. tschiliensis, such as scabiosaponins E, F, G, I, and J; hookerosides A and B; and prosapogenin 1b, showed strong inhibition of pancreatic lipase. Moreover, 0.12 mg/mL prosapogenin 1b exerted similar inhibitory properties as the lipase inhibitor orlistat at a concentration of 0.005 mg/mL [51]. Akebia saponin D reduced lipid droplet accumulation in BRL cells, attenuated hepatic steatosis, and elevated the expression of Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNip3) and phospho-AMPP; it also improved mitochondrial function and autophagy modulation, inhibited rotenone-induced BRL cell apoptosis, elevated Bcl-2/Bax ratio, and suppressed the level of intracellular reactive oxygen species (ROS) and mitochondrial membrane potential loss in rotenone-treated BRL cells and rat liver mitochondria [154,155].

Cardioprotective Activity
Cardiovascular diseases are one of the leading causes of death worldwide [156]. The anti-atherosclerotic effect of akebia saponin D was studied in vitro in H 2 O 2 -treated human umbilical vein endothelial cells (HUVECs) and in vivo in ApoE −/− mice [157]. It was shown that this saponin protected against H 2 O 2 -induced cytotoxicity in HUVEC, inhibited ROS level, the mitochondrial membrane potential disruption, and apoptosis in oxidative stress-induced endothelial cells in a dose-dependent manner (50-200 µM); the mechanism was believed to involve increasing Bcl-2 family protein levels and decreasing caspase-3 and Bax activation. Moreover, doses of 150 mg/kg/day and 450 mg/kg/day reduced aortic plaque formation in mice as well as aortic and liver apoptosis, serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and lipid deposition in the liver, as well as atherosclerotic lesion size; it also enhanced the expression of antioxidant enzymes (SOD, catalase (CAT), and glutathione (GSH)) in vascular tissue and liver [157]. Li et al. [158] demonstrated that sweroside has a protective effect on ischemia-reperfusion-induced myocardial injury by inhibiting oxidative stress and pyroptosis partially via modulation of the Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 pathway. The iridoid also suppressed aconitine-induced cardiac toxicity in the H9c2 cardiomyoblast cell line [159]. Long-term gavage (for six weeks) of akebia saponin D protected against fibrosis myocardial ischemia injury, inhibited cardiac dysfunction, and reduced infarct size in a Sprague-Dawley rat model with chronic myocardial infarction induced by permanent ligation of the left coronary artery. Treatment with this saponin decreased hydroxyproline level and changed the activity of the oxidative stress enzymes by elevating SOD and DSH-peroxidase (GSH-Px) levels and by reducing MDA content. Moreover, akebia saponin D regulated inflammatory mediators by diminishing the levels of TNF-a and IL-6 and by elevating the level of IL-10 [160]. Several in vitro and in vivo studies found flavonoids detected in Scabiosa spp., such as apigenin and luteolin, to have cardioprotective properties [161][162][163].
However, Song et al. [164] demonstrated that D. asper roots, drunk widely as a tea for beneficial health effects, or dipsacus saponin D may have an undesirable effect on platelets and may increase the risk of thrombosis. D. asper roots were found to be an herb with procoagulant activities on platelets and prothrombotic properties. Dipsacus saponin C elevated procoagulant activity in a dose-and time-dependent manner, elevated intracellular calcium level, and decreased ATP. In addition, it caused translocation of Bax and Bak, cytochrome c release, caspase-3 activation, and the disruption of mitochondrial membrane potential. The oral administration of 10 mg/kg and 25 mg/kg dipsacus saponin C also resulted in an increase in thrombus formation in a rat venous thrombosis model [164].

Renal and Gastritis Protection
A 61 kDa polysaccharide (WDRAP-1) isolated from D. asperoides roots showed protective activity against oxidative stress generated in renal ischemia-reperfusion injury in male Wistar rats and displayed strong superoxide and hydroxyl radical scavenging activities in vitro. It was shown that oral pre-treatment of rats with the polysaccharide at a concentration of 50-200 mg/kg b.w. for 14 days before ischemia-reperfusion may improve renal injury (especially at the highest dose); treatment suppressed the level of renal injury indicators including creatinine, blood urea nitrogen, lactate dehydrogenase (LDH), and serum MDA and enhanced serum SOD and some renal tissue antioxidant enzyme activities (SOD, GSH-Px, and CAT) [63]. Hederagenin was also found to protect against renal fibrosis. This terpenoid compound attenuated the proliferation and fibrosis of TGF-β-treated NRK-49 F cells by targeting the muscarinic acetylcholine receptor [165].
Dipsacus saponin C, a saponin isolated from the roots of D. asper, was found to have a protective effect against HCl·ethanol-induced gastritis and indomethacin-induced gastric ulcers in male Sprague-Dawley rats. It was shown that treatment with dipsacus saponin C caused a decrease in gastric secretion volume and gastric acid production in pylorus-ligated rats. It was found that this compound had a moderate effect on colonization and growth inhibition of Helicobacter pylori at a concentration of 50-100 µM. In addition, dipsacus saponin C also showed a cytotoxic effect for SNU638 and AGS human gastric cancer cells with an IC 50 at 54.6 mM and 37.3 mM, respectively [91].
Moreover, akebia saponin D may exert a therapeutic role by regulating the intestinal microbiome and protecting intestinal epithelial cells from external damage. It was found to achieve this by inhibiting oxidative damage to the intestinal barrier by downregulating PPAR-γ/FABP4 in the human intestinal cell line FHs74 Int [166].
Luteolin was also found to have therapeutic effects against interstitial fibrosis-induced renal anemia in vitro and in vivo. This activity was mediated via the SIRT1/forkhead box O3 (FOXO3) pathway [167].

Anti-Asthmatic Effect
Dipsaci radix alleviated the asthmatic response in BALB/c mice with allergic asthma induced by an ovalbumin. Dipsaci radix treatment at a dose of 20 m/kg or 40 mg/kg resulted in attenuation of the methacholine response, inflammatory cell infiltration, and mucus secretion in the bronchial airway and a decrease in the levels of pro-inflammatory cytokines (IL-5 and IL-13) in bronchoalveolar lavage fluid, eotaxin, serum total IgE, expression of iNOS, and NF-κB phosphorylation in lungs [27]. Similarly, apigenin, one of the flavonoids identified in Scabiosa spp., was found to inhibit inflammatory mediators and eosinophilia in lung and airway tissues in in vivo acute lung injury and asthma models [163].

Anti-Diabetic Activity
A polysaccharide (DAP) isolated from D. asper roots demonstrated beneficial effects on renal function and renal pathological changes as well as antihyperglycemic, hypolipidemic, and antioxidant activities in streptozotocin-induced diabetic Wistar rats [16]. Four weeks of intragastric administration (100 mg/kg and 300 mg/kg per day) in type 2 diabetic rat model resulted in a reduction of glycosylated, fasting blood glucose, serum creatinine, blood urea nitrogen, urine protein, and urinary albumin excretion. Moreover, oral administration of the polysaccharide (300 mg/kg) suppressed the serum level of TC, TG, LDL, and renal AGE-RAGE formation (advanced glycation end products-receptor for advanced glycation end products) and enhanced SOD, CAT, and GSH activities in the kidney of rats with diabetic nephropathy [16]. Similar antilipemic effects were also observed for hederagenin. This pentacyclic triterpene exerts its potential through the p38MAPK pathway in oleic acid-induced HepG2 cells and in hyperlipidemic Sprague-Dawley rats [168].
The ethanol extract and the hexane, ethyl acetate, n-butanolic, and chloroform fractions of the aerial parts of S. atropurpurea demonstrated anti-hyperglycemic activity by decreasing the blood glucose level in albino rats with alloxan-induced hyperglycemia [43]. The methanol extract of S. atropurpurea subsp. maritima whole plants demonstrated αglucosidase inhibitory activity with an IC 50 value = 100 µg/mL. This effect was higher than that found for the positive control, the anti-diabetic drug acarbose (IC 50 = 196 µg/mL) [78]. Methanolic extracts from the fresh leaves and roots of D. fullonum also inhibited porcine pancreatic α-amylase activity [35]. These extracts demonstrated low effectiveness in this study, with the strongest activity being found to be IC 50 = 86.01 µg/mL for the dried leaf extract. This activity was more than 100-times lower compared to that of acarbose (IC 50 = 0.69 µg/mL).

Anti-Inflammatory Activity
Several plant species of Dipsacus and Scabiosa or some specialized metabolites isolated from them can be valuable, new anti-inflammatory agents [26,32,39,50,92,169].
The water extract of D. asper roots demonstrated anti-inflammatory properties in the lipopolysaccharide (LPS)-activated murine macrophage cell line RAW 264.7 by suppressing NO production with an IC 50 = 45.1 µg/mL [92]. In a later study [26], an aqueous extract of D. asperoides roots at a dose of 50-500 µg/mL showed inhibitory potential on inflammation and oxidative stress in RAW 264.7 macrophages exposed to LPS; it was found to act by lowering NF-κB and ERK1/2 phosphorylation, nuclear translocation of NF-κB, and activation of Nrf2/HO-1. The extract reduced the levels of inflammatory mediators (iNOS, COX-2, and cytokines IL-6 and IL-1β) as well as ROS levels [26]. The methanol extract of D. inermis leaves also showed the ability to inhibit the production of NO, COX-2, PGE2, pro-inflammatory mediators (IL-1β and IL-6, and TNF-α), intracellular ROS level, and phosphorylation of NF-κBp65 and IκBα in a dose-dependent manner (25-100 µg/mL) in the LPS-induced murine macrophage cell line J774A.1 [39]. The anti-inflammatory potential of D. inermis leaf extract was also confirmed in vivo in Wistar albino rats; it protected against vascular permeability (caused by acetic acid) and paw oedema (induced by carrageenan) in a concentration-and time-dependent manner. In addition, the serum levels of TNF-α, IL-1β, and IL-6 were significantly reduced while IL-10 level was enhanced after oral administration of the extract at a concentration of 50-100 mg/kg b.w. [39]. Antiinflammatory properties in a Wistar rat model of carrageenan-induced paw oedema also demonstrated the ethyl acetate extract of S. stellata whole plants. The highest activity was observed in the first hour after treatment with the extract at a concentration of 50 mg/kg (72.73% of inhibition). This effect was stronger than that of diclofenac (about 45% of inhibition). In addition, the anti-inflammatory effect of the plant extract lasted up to 24 h [50].
Some compounds belonging to iridoids, saponins, or phenolic acids (for example, dipsasperoside A, dipsanoside A and B, dipsacus saponin A, akebia saponin D, or caffeic acid) isolated from the roots of D. asper also were able to reduce the production of NO in RAW 264.7 cells. The potent activity was demonstrated by akebia saponin D and dipasperoside A, with IC 50 values of 12.7 µM and 15.2 µM, respectively; these values were higher than those for the positive control, a nonselective NOS inhibitor, N G -monomethyl-L-arginine (IC 50 = 22.6 µM) [92]. Reduced NO levels and iNOS expression have also been observed in LPS-induced RAW 264.7 cells after treatment with akebia saponin D (at a concentration of 25-100 µM) [32]. Akebia saponin D also suppressed the expression of DNA methyltransferase (DNMT) 3b, the levels of PGE2 and p-STAT3, as well as the protein and mRNA levels of IL-6 and TNF-α [169]. The levels of the inflammatory indicators, prostaglandin E2, i-NOS, COX-2, TNF-α, IL-1β, and IL-6, were also decreased after treatment with 40 and 80 µM sweroside in LPS-induced RAW264.7 cells. In addition, sweroside suppressed inflammation through the sirtulin 1 (SIRT1)/NF-κB and SIRT1/Forkhead transcription factor O1 signaling pathways [170].
Akebia saponin D also showed anti-inflammatory activity in vivo by reducing paw oedema in carrageenan-induced Sprague Dawley rats and by inhibiting xylene-induced ear swelling in mice. It also lowered the level of NO in rat plasma in a carrageenan-induced rat paw oedema model [32].
Anti-inflammatory potential was also demonstrated by apigenin, which was believed to act by the modulation of the p38/MAPK, PI3K/Akt and NF-κB pathways [163].
The antioxidant activity of the methanolic extract from D. asper roots was confirmed in DPPH and Cu 2+ -mediated LDL oxidation with IC 50 values of 90.2 and 134.4 µg/mL, respectively. This activity may be attributed to caffeoylquinic acid derivatives identified in root extract such as 3,4-di-O-caffeoylquinic acid, 4,5-di-O-caffeoylquinic acid, 3,5-di-Ocaffeoylquinic acid, and their methyl derivatives. These specialized metabolites showed potent antioxidant activity against DPPH radical formation and Cu 2+ -mediated LDL oxidation with IC 50 values of 10.4-18.2 µM and 1.8-2.3 µM, respectively [24]. The content of the total polyphenols in the acetone/water extract (7:3) of D. fullonum whole plant was 19.52 mg GAE (gallic acid equivalents)/g d.w. of plant material; it displayed an antioxidant capacity lower than 5 mmol TEAC (Trolox equivalent antioxidant capacity)/100 g d.w. plant material in the DPPH and ABTS assays [171]. The antioxidant properties were also demonstrated in 50% methanolic extract of leaves and roots (ultrasound assisted extraction) in the ORAC assay with values of 14.78 mmol TEAC/100 g d.w. and 10.87 mmol TEAC/100 g d.w. for the leaf and root extracts, respectively [33]. A similar observation was found by Saar-Reismaa et al. [34]. The crude 70% ethanol extract of D. fullonum leaves showed antioxidant activity in the ORAC assay (10.8 mmol TEAC/100 mL). The fraction NP7 of crude leaf extract that was rich in two chlorogenic acid derivatives, saponarin and isoorientin, also displayed antioxidant activity (12.5 mmol TEAC/100 mL), while the fraction NP2 containing bis-iridoids was ineffective (0.78 mmol TEAC/100 mL) [34].
On the other hand, the aqueous extract of D. fullonum leaves obtained by ultrasound assisted extraction (extraction time, four hours) showed high radical scavenging activity (RSA) (73.81%) in DPPH [172]. The procedure extraction with the aqueous solution of amino acid ionic liquids, viz., triethanolammonium salts of two amino acids methionine  [172]. Antioxidant effect was also observed for the extract of D. sativus leaf. The extract at a dose of 300 mg/kg/day in ICR mice pre-treated with D-galactose to induce oxidative stress resulted in an increase in the level of SOD and a decrease in the level of MDA in the peripheral blood plasma [42].
S. stellata whole plants are a rich source of polyphenolic compounds. The ethyl acetate and n-butanolic fractions have moderate antioxidant activity in simple, chemical, antioxidant tests such as DPPH, ABTS assays, and FRAP test. The n-butanolic fraction displayed stronger potential in the DPPH assay, i.e., FRS 50 (free radical scavenge) = 64.46 µg/mL, compared to ascorbic acid FRS 50 = 8.21 µg/mL [76]. The dichloromethane fraction did not possess significant activity in antioxidant assays, which may be related to the low content (below 1 mg of gallic acid/g dry extract) of phenolic compounds [76]. A 70% ethanol extract of S. stellata whole plants in DPPH also displayed antioxidant activity, with an IC 50 value of 86 µg/mL [75]. The petroleum ether, ethyl acetate, and n-butanolic fractions from S. stellata whole plants showed various antioxidant potential in different chemical models such as DPPH and ABTS, FRAP, CUPRAC, β-carotene, phosphomolybdate assay, ferrous ions, and metal chelating assays [50]. The strongest effect was demonstrated by the n-butanolic fraction in DPPH (IC 50 = 21.22 µg/mL) and chelation in ferrous iron assay (EC 50 = 1.65 mg/mL), while the ethyl acetate fraction was most active in ABTS (IC 50 at 14 µg/mL), CUPRAC (A 0 . 50 = 28.5 µg/mL), and β-carotene assays (IC 50 = 10.34 µg/mL). In addition, the n-butanolic fraction in DPPH had a higher reducing power than butylated hydroxyl toluene (BHT) (22.32 µg/mL) but lower than α-tocopherol (13.02 µg/mL), butylated hydroxy anisole (BHA) (6.82 µg/mL), and ascorbic acid (3.1 µg/mL) [50]. The highest protein denaturation inhibition was found for the ethyl acetate extract, which showed 78.86% inhibition at the maximal tested concentration (1 mg/mL). Ibuprofen (standard drug) at the same concentration caused 100% inhibition [77]. Antioxidant activity was also reported for 70% ethanol extracts of S. comosa and S. tschilliensis inflorescences. S. tschilliensis had a stronger antioxidant activity than S. comosa in DPPH, ABTS, and FRAP assays. For example, the IC 50 values in DPPH were 272.8 µg/mL and 331.1 µg/mL, respectively [74]. Wang et al. [52] reported that the 90% ethanol extract of S. tschilliensis at a concentration of 26.5 µg/mL scavenged 50% of DPPH free radicals (IC 50 value for ascorbic acid was 5.41 µg/mL). The crude extract (95% ethanol) and four solvent partitioned fractions (water, n-butanol, ethyl acetate, and petroleum ether) from S. tschiliensis whole plants at various growing stages (pre-flowering, flowering, and fruiting stage) showed different antioxidant activities in DPPH, ABTS, inhibition of lipid peroxidation, or OH scavenging activity [53]. The IC 50 values for the crude extract were in the range of 25.65-86.79 µg/mL while the ethyl acetate fraction from the pre-flowering stage of plants had the highest antioxidant capacity (IC 50 8.47 µg/mL) in DPPH. This value was comparable to that of vitamin C (7.6 µg/mL). The ethyl acetate fraction from the pre-flowering stage of plants also possessed the highest ABTS (58.76 µg/mL), hydroxyl radical scavenging ability (67.64 µg/mL), and lipid-peroxidation-inhibition activity [53]. The n-butanolic and ethyl acetate fractions of S. arenaria roots also displayed strong antioxidant activity in four assays: DPPH, ABTS, reducing power, and β-carotene bleaching inhibition activity.
The n-butanolic fraction demonstrated excellent ability, mainly in the β-carotene bleaching inhibition assay (IC 50 = 0.018 mg/mL). This effect was stronger than that obtained for BHT (IC 50 = 0.04 mg/mL). In the DPPH and ABTS assays, the IC 50 values for both fractions were comparable to BHT [73]. The ethyl acetate fractions of the roots, flowers, fruits, and aerial parts (stems and leaves) of S. arenaria showed the beneficial antioxidant ability in DPPH, with IC 50 values of 0.017-0.019 mg/mL; the best properties were observed for the flowers [72,73]. Other species of Scabiosa, S. artropurpurea and S. atropurpurea subsp. maritima, also demonstrated antioxidant properties. In comparison to ascorbic acid (IC 50 = 0.084 mg/mL), among four tested extracts, the ethanol extract of S. artropurpurea stems exhibited the best antioxidant capacity, with IC 50 = 0.1383 mg/mL in DPPH assay. In addition, the hexanoic volatile fraction (VF1) and ethyl acetate extract displayed similar effects with IC 50 values of 0.4798 mg/mL and 0.4806 mg/mL, respectively [46]. The antioxidant activity of 70% ethanol extract of aerial parts of S. atropurpurea and hexane, ethyl acetate, n-butanol, and chloroform fractions were also demonstrated by increasing blood glutathione in diabetic albino rats [43]. Silver nanoparticles with S. atropurpurea subsp. maritima water fruit extract also was found as a promising antioxidant agent in DPPH and FRAP assays. The IC 50 values were 0.112 mg/mL and 0.036 mg ascorbic acid equivalent antioxidant capacity/g d.w., respectively, and were comparable to that for ascorbic acid [56].
The pure compounds isolated from D. asper roots, i.e., six dicaffeoylquinic acid derivatives (3,4- and displayed inhibitory activity against Cu 2+ -mediated LDL oxidation (1.8-2.3 µM), stronger than those obtained for the positive controls, BHT and caffeic acid [24]. In another study, 3,5-di-O-caffeoylquinic acid also demonstrated significant antioxidant properties in the DPPH assay, with an IC 50 value of 3.63 µg/mL [74]. Two secoiridoid glucosides, eustomoruside and eustomoside, and one flavonoid, isoorientin, isolated from the whole plant S. stellata Cav. also displayed strong radical scavenging activities in DPPH with an IC 50 value of 7.1-8.5 µg/mL compared to that for ascorbic acid (IC 50 = 6.3 µg/mL) [75]. The polysaccharide fraction from the roots of D. asperoides also demonstrated antioxidant effects in DPPH and ABTS assays but with little potency; the EC 50 value was 0.355 mg/mL in DPPH free radical scavenging activity and 5.867 mg/mL in ABT [14].

Anticancer Activity
The synthetic drugs used in chemotherapy not only have strong toxic effects on cancer cells, but they also have strong adverse side effects in chemotherapy. Many plant specialized metabolites are used in cancer therapies and new substances, and new plant species with potential anti-cancer activity are being sought.

Leaves
Iridoid glycosides fraction of 80% methanol extract  An aqueous extract of D. asperoides roots inhibited the viability of human mammary carcinoma-derived triple negative MDA-MB-231 cells (with IC 50 = 15 µg/mL) and arrested the cell cycle in the G 2 /M phase; it also induced apoptosis by increasing pro-apoptotic caspase 3/7 activity and by suppressing the expression of BRAF, p-ERK, MEK, pPI3K, pAKT, and cyclin-dependent kinase 4/6 in a dose-dependent manner [175]. The cytotoxic activity of bis-iridoid glycosides fraction of D. fullonum leaf methanol extract (with sylvestroside III and IV as the main compounds) was evaluated against human breast cancer cell lines MCF7 and MDB-MB-231 and human cervical cancer HeLa cell line [174]. The two breast cancer cell lines were most sensitive to the fraction, resulting in a viability of 64.0% for MCF7 cells and 69.5% for MDB-MD-231 cells [174]. In addition, the ethanolic extracts of the aerial parts and flowers of D. fullonum have antiproliferative activity on the human hepatocellular carcinoma Hep3B cell line with an IC 50 value above 100 µg/mL [176]. The methanol extract of S. atropurpurea subsp. maritima leaves at a concentration of IC 10 , IC 20 , or IC 30 enhanced the toxicity of doxorubicin in human epithelial colorectal adenocarcinoma Caco-2 cells with IC 50 = 1.04 µg/mL (vs. 2.41 µg/mL when the cells were treated only with doxorubicin) [81]. In addition, the combination of doxorubicin with S. atropurpurea extracts at a concentration of IC 50 and IC 10 , respectively, increased the percentage of apoptotic cells, the percentage of caspase-activated cells, mRNA levels of the apoptosis related-genes (Bax, caspase-3, p21), and decreased the expression level of anti-apoptotic genes (Bcl-2). It was a stronger effect than that obtained for doxorubicin or S. atropurpurea extract alone. The plant methanol extract also reversed P-glycoprotein or multidrug resistance-associated protein in Caco-2 cells [81]. The use of silver nanoparticles with S. atropurpurea subsp. maritima water fruit extract was found to be promising anticancer agents with cytotoxic activity against the human multiple myeloma U266 cell line and the human breast cancer cell line MDA-MB-231. The silver nanoparticles inhibited the growth of cells in a concentration-dependent manner with IC 50 values of 10 and 12 µg/mL, respectively [56].
The 16 kDa water-soluble polysaccharide (ADAPW) isolated from D. asperoides roots had the ability to inhibit the growth of human osteosarcoma cell line HOS and induce apoptosis in a concentration-dependent manner (100,200, and 400 µg/mL) after 24 h. It was also found to down-regulate PI3K and pAkt protein levels, reduce mitochondrial membrane potential, and increase intracellular ROS level [11].
Taken together, these above results indicated that some Dipsacus and Scabiosa plants or some specialized metabolites may display anticancer activity and may be useful as chemopreventive agents.

Antimicrobial and Anti-Insecticidal Activity
An increase in bacterial resistance to antibiotics has caused researchers to look for alternative solutions, which may be natural antibiotics [177].
Recent studies confirmed that extracts or essential oils from Dipsacus or Scabiosa spp. such as D. asper, D. fullonum, D. japonicus, S. stellata, S. arenaria, or S. atropurpurea subsp. maritima have antimicrobial activity [21,33,34,56,75,77,82,83,102]. Traditionally, D. fullonum is known as the remedy for Lyme disease caused by Borrelia burgdorferi whose vectors are ticks. The anti-Borrelia activity of D. fullonum/D. sylvestris extracts were evaluated in only a few studies in the recent ten years [34,178,179]. A 70% ethanol extract of D. fullonum leaves and its fractions showed significant anti-Borrelia activity against the stationary phase of B. burgdorferi strain B31 [34]. The strongest growth inhibition was found for a crude ethanol extract, which suppressed the cell viability by about 80% at a concentration of 305.5 mg/L. The NP5 fraction, containing loganic acid, and NP7, rich in saponarin, isoorientin, and two chlorogenic acid derivatives, were also effective, with a residual viability of 23.4-29.8% at a concentration of 332.8 mg/L and 340.2 mg/L, respectively; these values were comparable to that of the positive control, the triple antibiotic combination (doxycylin, cefoperazone, and daptomycin at a dose of 22.2 mg/L, 33.4 mg/L, and 80.1 mg/L, respectively) [34]. In contrast, Feng et al. [179] found that the 45% ethanolic extract of D. fullonum (accidentally mixed with a sample of D. asper) at a concentration of 0.25-1% was not active against either the non-growing stationary phase or growing B. burgdorferi, with residual viability of 84-90% and MIC > 2%. Among three tested extracts (70% ethanolic, ethyl acetate, and dichloromethane extracts) from D. sylvestris roots, only the ethanol extract was inactive against B. burgdorferi while the ethyl acetate extract showed the strongest ability [178]. A 50% methanolic extracts of D. fullonum leaves and roots were also tested against other microorganisms, including bacteria (Bacillus subtilis B5, Escherichia coli ATCC 10536, Pseudomonas aeruginosa DSM 939, P. fluorescens W1, and Staphylococcus aureus DSM 799) and yeasts (Candida famata AII4b, C. tropicalis ATCC 60557, C. sphaerica FII7A, Saccharomyces cerevisiae SV30, and Yarrowia lipolytica PII6a). It was found that the cell growth inhibitory activity differed among plant materials and bacteria strains. The greatest effect of growth inhibition zones was observed for the root extract against E. coli ATCC 10536 and S. aureus DSM 799 [33].
The antibacterial potential was also found for S. arenaria [82]. Various degree of antibacterial activity was related to the type of plant material (stems and leaves, roots, flowers, and fruits) and solvent used (crude extract and its fractions such as ethyl acetate, n-butanol, and aqueous). It was found that the highest antibacterial effect was noted for the n-butanolic fraction of fruits. In this case, MIC values for two Escherichia coli strains and two Pseudomonas aeruginosa strains were 0.019 mg/mL and 0.156 mg/mL, respectively. The butanolic fractions of the aerial parts and flowers were active against only E. coli strains with MIC values of 0.078 mg/mL and 0.156 mg/mL, respectively. In addition, Staphylococcus aureus ATCC 25923 and S. saprophyticus were sensitive to the butanolic fraction of fruits (MIC = 0.625 mg/mL). Among four tested strains of Candida spp. (C. albicans ATCC 90028, C. glabrata ATCC 90030, C. parapsilosis ATCC 22019, and C. krusei ATCC 6258), the most sensitive was C. albicans ATCC 90028 with MIC = 0.0195 mg/mL. E. coli ATCC 25922 and C. albicans ATCC 90028 were also sensitive to eleven subfractions from the butanolic fraction of the aerial part (MIC = 0.0195 mg/mL) [82]. A 70% ethanol extract of the whole plant S. stellata showed the highest antibacterial activity against Streptococcus pyogenes with MIC = 1.2 mg/mL (in comparison to gentamicin MIC = 2 µg/mL). For other strains of Grampositive bacteria (Bacillus subtilis, Enterococcus faecalis ATCC 1034, Staphylococcus aureus 8325-4, S. aureus CIP 53.154, S. epidermidis, Micrococcus luteus, and Listeria innocua), Gramnegative bacteria (Escherichia coli CIP 54.127, Enterobacter cloacae, Salmonella enterica, Serratia marcescens, Proteus vulgaris, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa ATCC 9027, and Shigella sonnei) and five yeasts (Candida albicans, C. glabrata, C. tropicalis, C. kefyr, and Cryptococcus neoformans), MIC ranged from 2.5 mg/mL to above 10 mg/mL [75]. The highest antimicrobial activity was found for fractions B and C obtained after eluting from a Diaion HP-20 column with 25% and 50% methanol. Staphylococcus spp., Candida spp. (C. albicans, C. tropicalis, and C. kefyr), and Cryptococcus neoformans were the most sensitive microorganisms to both fractions with MIC values of 0.6-1.5 mg/mL, while E. faecalis ATCC 1034, M. luteus, and S. pyogenes were also sensitive to fraction B [75]. The ethyl acetate, n-butanol, and the petroleum ether extracts from S. stellata whole plants were also tested for antibacterial activity in the agar disk diffusion assay against ten bacterial strains including four Gram-positive (Staphylococcus aureus ATCC 25923, S. albus, Enterococcus spp., and Streptococcus D) and six Gram-negative bacteria (Escherichia coli ATCC 35218, Pseudomonas aeruginosa ATCC 15442, Acinetobacter baumannii, Proteus mirabilis, Salmonella typhimurium, and Enterobacter sakazaki) [77]. Three bacterial strains, S. albus, P. aregionosa ATCC 15442, and S. typhimurium, were the most resistant strains to all extracts. The highest activity was exhibited by the ethyl acetate extract against the clinical strain of P. mirabilis (16-20 mm of the growth inhibition zones at a concentration of 0.0625-1 mg/mL). In addition, this extract also was active against five other bacterial strains, including S. aureus ATCC 25923, A. baumannii, E. coli ATCC 35218, Enterococcus sp., and Streptococcus D. The petroleum ether extract showed inhibitory activity against S. aureus (ATCC 25923) and E. coli (ATCC 35218) while the n-buthanol extract against A. baumannii and E. sakazaki [77]. In another study, the antibacterial and antifungal activities of the silver nanoparticles with S. atropurpurea subsp. maritima water extract from fruit against bacteria (Escherichia coli, Micrococcus luteus, Staphylococcus aureus, and Klebsiella pneumoniae) and fungal pathogens including Candida clinical strains (C. albicans, C. tropicalis, and C. glabrata), Microsporum canis, Trichophytom rubrum, and Trichophytom interdigitale were also reported. The silver nanoparticles inhibited the cell growth of bacteria and Candida sp., as evidenced by the zone inhibition (19.3-28 mm) and the MIC value (3.9-15.62 µg/mL). The lowest MIC value was found for two dermatophyte species, T. rubrum and T. interdigitale. In addition, the antifungal potential of the silver nanoparticles was associated with the disruption of membrane integrity and attenuation of the biofilm and hyphae formation [56]. D. asper crude extract from the roots also displayed antifungal activity in vivo in a whole-plant assay. This property was evaluated against seven plant pathogenic fungi such as Magnaporthe grisea causing rice blast, Rhizoctonia solani causing rice sheath blight, Botrytis cinerea causing tomato gray mold, Phytophthora infestans causing tomato late blight, Puccinia recondita causing wheat leaf rust, Blumeria graminis f. sp. hordei causing barley powdery mildew, and Colletotrichum coccodes causing red pepper anthracnose. It was shown that the activity was dependent on the fungal pathogens and the solvent used (n-hexane, ethyl acetate, acetone, methylene chloride, and methanol) for extraction. The fungi causing the tomato late blight and the tomato gray mold were the most sensitive to Dipsacus root extract. The greatest anti-fungal effect was demonstrated by the ethyl acetate and acetone extracts at a concentration of 1-2 mg/mL that inhibited tomato diseases by 90% [21].
It is well known that essential oils and their ingredients have potent antimicrobial properties [177]. The essential oil isolated from flowers of S. arenaria showed a strong ability (stronger than the positive control, thymol; MIC = 0.2 mg/mL) to inhibit the growth of cells of two Staphylococcus aureus strains with an MIC = 0.1562 mg/mL [83]. Notably, the essential oil isolated from fruits was found to be an anticandidal agent against Candida albicans ATCC 90028, C. parapsilosis ATCC 27853, C. kreusei ATCC 6258, and C. glabrata ATCC 90030 (MIC = 0.625 mg/mL) [83]. The essential oil isolated from D. japonicus flowering aerial parts can be used as a promising, natural insecticidal agent against stored-product insects such as adult red flour beetles (Tribolium castaneum) and maize weevils (Sitophilus zeamais), and they displayed contact toxicity with LD 50 values of 13.45 µg/adult and 18.32 µg/adult, respectively. This essential oil also had fumigant activity against adult insects with LC 50 5.26 mg/l air for T. castaneum and 10.11 mg/l air for S. zeamais. The strongest fumigant toxicity was possessed by one of the abundant ingredients in D. japonicus essential oil, i.e., 1,8-cineole [102].

Others
Akebia saponin D was also found to be a potential antidepressant agent. Intraperitoneal injection (40 mg/kg/d) alleviated LPS-induced microglia-mediated neuroinflammatory response in mice by inhibiting the TLR4/NF-κB signaling pathway in the hippocampus and prefrontal cortex [180]. It also ameliorated chronic mild stress-induced depressive-like behaviors in C57BL/6 mice by inducing a neuroprotective microglial phenotype in the hippocampus through the PPAR-γ pathway [181]. A similar antidepressant effect was also found for apigenin in a mouse model of chronic mild stress [182].
Gong et al. [32] found akebia saponin D to be effective against pain. It displayed an anti-nociceptive effect in SPF KM mice by shortening the licking time in the formalin test, increasing the reaction time to heat stimuli, and inhibiting acetic acid-induced writhing in mice.
Akebia saponin D activated the expression of the progesterone receptor in primary decidual cells and the Notch signaling pathway. Gao et al. [62] proposed that Dipsaci radix and its main ingredient, akebia saponin D, may promote decidualization in pregnant women. Bushen Antai, a Chinese herbal medicine preparation containing Dipsaci radix, was found to reduce the pregnancy loss caused by mifepristone administration [183]. This preparation may stimulate estrogen and progesterone receptors through Akt and Erk1/2 signaling pathways in the maternal-fetal interface of pregnant rats.

Conclusions
The present review broadens the knowledge of the phytochemistry of some species of Dipsacus and Scabiosa genera as well as their biological properties. The phytochemical analyses showed qualitative similarities in some specialized metabolites, especially iridoids, between species of both genera. Some species of Dipsacus and Scabiosa contain above 200 different compounds belonging to iridoids, triterpenoids derivatives, flavonoids, or phenolic acids with caffeoylquinic acid derivatives. Dipsacus spp. were predominated by terpenoid saponins while Scabiosa spp. were rich sources of iridoids and flavonoids. Apigenin, luteolin, and their derivatives were particularly common. Hederagenin and its related saponins are the main group of triterpenoids identified in Dipsacus. The oleananetype triterpenoids were also common in Scabiosa genus. The wine-processing method has a beneficial effect on the biological activity of Dipsaci radix and the level of some specialized metabolites with its quality indicator, akebia saponin D. Dipsacus, and Scabiosa species and their constituent compounds possess beneficial biological activities. Many in vitro and in vivo studies confirmed their traditional medicinal uses. Dipsaci radix and akebia saponin D demonstrated anti-osteoporosis and antiarthritic properties. Scabiosa spp. showed anti-hepatic fibrosis potential. In addition, akebia saponin D displayed cardioprotective activity. Antioxidant, antimicrobial, and anti-inflammatory activities of both genera were also confirmed. Some newly identified specialized metabolites such as polysaccharides displayed promising biological properties. Thus, in the future, it is worth paying more attention to their pharmacological activities. The varied biological activities of extracts from Dipsacus and Scabiosa as well as the pure compounds isolated from them indicate their potential use in the future as effective, natural herbal drugs in the treatment of various diseases in official medical applications.
Supplementary Materials: The following supporting information can be downloaded at: https://www. mdpi.com/article/10.3390/molecules28093754/s1, Table S1. The list of accepted species in the genera Dipsacus and Scabiosa according to Plants of the World Online database [9].
Author Contributions: Conceptualization, data collection, design of the study, interpretation of the data, drafting the manuscript, visualization, reviewing, and editing, E.S.; critical revision of the manuscript, E.S. and A.S.; supervision, E.S. and A.S. The authors declare no conflict of interest. All authors have read and agreed to the published version of the manuscript.