Salvia verticillata (L.)—Biological Activity, Chemical Profile, and Future Perspectives

Species belonging to the genus Salvia, Lamiaceae, have been deeply involved in the folk medicine of different nations since ancient times. Lilac sage, or Salvia verticillata L. (S. verticillata) is a less studied species from the genus. However, it seems to have a prominent potential for the future drug discovery strategies of novel phytopharmaceuticals. This review aims to summarise the data on the biological activity and the phytochemical profile of extracts and essential oils derived from S. verticillata. This review is based on data from 57 in vitro and in vivo studies. The chemical profile of S. verticillata includes different synergic compounds like phenolic acids, flavonoids, terpenes, and salvianolic acids. Although some small amounts of salvianolic acid B were found in S. verticillata extracts, the major compound among the salvianolic acids is salvianolic acid C, a compound associated with the potential for improving liver fibrosis, cardio- and hepatoprotection, and the inhibition of SARS-CoV-2 infection. The cannabinoid type 2 receptor agonist β-caryophyllene is one of the major compounds in S. verticillata essential oils. It is a compound with a prominent potential in regenerative medicine, neurology, immunology, and other medical fields. The in vivo and the in vitro studies, regarding S. verticillata highlighted good antioxidant potential, anti-inflammatory, antibacterial, and antifungal activity. S.verticillata was also reported as a potential source of drug candidates for the treatment of neurodegenerative diseases such as Alzheimer’s disease, because of the inhibitory activity on the acetylcholinesterase. However, the number of studies in this direction is limited.


Introduction
The Lamiaceae family is one of the most widespread and diverse families in the plant world.It includes about 200 genera and over 3000 species of aromatic herbaceous plants, with a significant application in traditional medicine, cosmetics, the food industry, and the pharmaceutical industry as well.
The genus Salvia consists of over 900 species.The name of the genus comes from the Latin word "salvare", meaning "to save" or "to heal" [1].Species belonging to this genus have been used since ancient times as spices, repellents, diuretics, anti-inflammatory agents, and to improve fertility [2,3].Nowadays, the Salvia species are commonly associated with anti-inflammatory, antibacterial, antifungal, antidiabetic, antioxidant, spasmolytic, and cytotoxic activity [4].Several studies suggested that Salvia officinalis L. could affect Alzheimer's disease.However, more detailed future studies are needed.
Salvia verticillata L. (S. verticillata), also known as lilac sage, is a worldwide perennial herbaceous plant that is native to western Asia and eastern and central Europe.S. verticillata grows in a continental climate characterised by a moderate amount of rainfall [5].It is a drought-tolerant plant that grows in warmer temperatures and its development is Rosmarinic acid is one of the major compounds found in most of the S. verticillata extracts.In general, the levels of rosmarinic acid are highly variable and normally are between 0.15 and 41.53 mg/g [23].The compound is associated with diverse biological activity like antibacterial, antifungal, antiviral, antioxidant, anticancer, anti-inflammatory [25], hepatoprotective, cardioprotective, nephroprotective, antidiabetic, antiallergic, anti-ageing, and antidepressant activity [26].
Salvianolic acids, which were identified in extracts from Serbia, Iran, and Turkey, are regarded as compounds with significant antioxidant and neuroprotective activity.Recently, it has been discussed the potential benefits of these compounds in the management of neurodegenerative diseases such as Parkinson's disease [27].In vitro, hepatoprotective activity was also established [28].
The flavone apigenin, which is also regarded as one of the main compounds of Salvia extracts, is associated with antidiabetic activity, anticancer activity [29], anti-inflammatory activity, neuroprotective activity, and antioxidant effects.The compound is studied as a potential agent to slow the progression of Alzheimer's disease [29].

Serbia
Aerial parts (flowers, leaves) Comparison between 3 populations of EOs.
For example, the natural bicyclic sesquiterpene β-caryophyllene, which was found in the samples from Italy, Iran, and Romania (in concentrations between 11.9% and 31.5%), has a significant potential to be used in the prevention and treatment of different neuroinflammatory and neurodegenerative pathologies [48].In general, the compound is safe.According to the Organization for Economic Cooperation and Development guidelines, β-caryophyllene is regarded as toxic at doses greater than 2000 mg/kg [48,49].Studies on acute toxicity reported that oral administration of 2000 mg/kg of β-caryophyllene in female mice induced no toxic effects [48].In general, S. verticillata EOs seem to be one of the best sources of β-caryophyllene.Although the compound could be isolated from the EOs of a wide variety of plants, its concentrations in S. verticillata EOs are one of the highest.Other plants which are considered rich sources of the compound are Cinnamomum tamala (concentration of about 25.3% in the EO) and Cannabis sativa (concentration in the EOs between 3.8 and 37.5%) [13].
The compound is regarded as a dietary cannabinoid.More precisely, it is a cannabinoid type 2 receptor agonist [11].
Many in vivo studies reported that β-caryophyllene (Figure 1) reduced/inhibited the activity of nitric oxide synthase and improved the activity of the antioxidant enzymes, affecting lipid peroxidation, as well as glutathione levels [50,51].
Studies on acute toxicity reported that oral administration of 2000 mg/kg of β-caryophyllene in female mice induced no toxic effects [48].In general, S. verticillata EOs seem to be one of the best sources of β-caryophyllene.Although the compound could be isolated from the EOs of a wide variety of plants, its concentrations in S. verticillata EOs are one of the highest.Other plants which are considered rich sources of the compound are Cinnamomum tamala (concentration of about 25.3% in the EO) and Cannabis sativa (concentration in the EOs between 3.8 and 37.5%) [13].
The compound is regarded as a dietary cannabinoid.More precisely, it is a cannabinoid type 2 receptor agonist [11].
Many in vivo studies reported that β-caryophyllene (Figure 1) reduced/inhibited the activity of nitric oxide synthase and improved the activity of the antioxidant enzymes, affecting lipid peroxidation, as well as glutathione levels [50,51].β-Caryophyllene is also associated with inhibition of the expression of IL-6 and IL-1β, which are also related to the inflammatory process, by stimulating cytokine production [13].At concentrations of 10, 25, and 50 μM, β-caryophyllene was reported to reduce the levels of nitric oxide and prostaglandin E2, as well as suppress the nuclear factor kappa B (NF-κB) activation on BV2 mouse cell lines, reducing neuroinflammation [48].Neuroprotection seems to be one of the target directions for this molecule.It was reported that at doses of 5 mg/kg, β-caryophyllene exerts nonpsychoactive anti-inflammatory effects [13].It was established that emulgel formulation containing 1% β-caryophyllene promotes the wound healing processes in animals [52].The authors reported that the treatment with β-caryophyllene enhanced the re-epithelialisation and increased laminin-γ2 and desmoglein-3 immunolabeling [52].
A recent study reported that supplementation with β-caryophyllene may have beneficial effects on obese individuals [11].Animal studies reported that the intake of the molecule had significant effects on weight reduction (including a significant reduction in body fat %), improvement of dyslipidaemia, improved steatosis and ballooning of liver cells, and reduced adipogenesis [53,54].
Although S. verticillata EOs were not yet tested for wound healing activity, it seems that S. verticillata EOs could provide many benefits in skin recovery.Both β-caryophyllene β-Caryophyllene is also associated with inhibition of the expression of IL-6 and IL-1β, which are also related to the inflammatory process, by stimulating cytokine production [13].At concentrations of 10, 25, and 50 µM, β-caryophyllene was reported to reduce the levels of nitric oxide and prostaglandin E2, as well as suppress the nuclear factor kappa B (NF-κB) activation on BV2 mouse cell lines, reducing neuroinflammation [48].Neuroprotection seems to be one of the target directions for this molecule.It was reported that at doses of 5 mg/kg, β-caryophyllene exerts nonpsychoactive anti-inflammatory effects [13].It was established that emulgel formulation containing 1% β-caryophyllene promotes the wound healing processes in animals [52].The authors reported that the treatment with βcaryophyllene enhanced the re-epithelialisation and increased laminin-γ2 and desmoglein-3 immunolabeling [52].
A recent study reported that supplementation with β-caryophyllene may have beneficial effects on obese individuals [11].Animal studies reported that the intake of the molecule had significant effects on weight reduction (including a significant reduction in body fat %), improvement of dyslipidaemia, improved steatosis and ballooning of liver cells, and reduced adipogenesis [53,54].
Although S. verticillata EOs were not yet tested for wound healing activity, it seems that S. verticillata EOs could provide many benefits in skin recovery.Both β-caryophyllene and its isomer α-humulene are widely distributed in the composition of EOs of various plants including S. verticillata.α-Humulene, also known as α-caryophyllene, is a monocyclic sesquiterpene primarily isolated from the essential oil of Humulus lupulus.Experimental studies on α-humulene and its isomers highlighted significant anti-tumour potential and cytotoxic activity against cancer cells, effectiveness against a wide range of microorganisms, and anti-inflammatory and analgesic activity.These compounds were reported to provide good gastroprotective and antioxidant activity as well [55].The sesquiterpenes α-humulene and β-caryophyllene were found to be synergistic with doxorubicin and at the same time do not have cytotoxic effects on normal cells [55].One of the mechanisms is related to Pharmaceuticals 2024, 17, 859 9 of 25 the elevation of the level of reactive oxygen species (ROS) in the mitochondria, which leads to a decreased membrane potential.Calcium is released into the cytosol, and this can lead to cellular imbalance and cell death [56][57][58].On the other hand, cell apoptosis can be induced by increasing the activity of enzymes caspase 3 and caspase 8 (which can be triggered by TNF), as well as by the elevation of ROS levels, which stimulate receptors on the surface of cells (DR4/DR5) [59][60][61][62].It also has anti-inflammatory activity due to influencing factors of the inflammation process, such as NF-κB, which controls cytokine production.A study demonstrated the antibacterial activity of α-humulene at a dose of 2 µg/mL on strains WT-ETBF, rETBF, and WT-NTBF of Bacteroides fragilis, as well as inhibiting biofilm formation [63].The antibacterial activity of α-humulene and germacrene D is due to an effect to a lesser extent on Gram-positive and to a greater extent on Gram-negative microorganisms.α-Humulene has potential analgesic, antioxidant, and gastroprotective effects [55,64].
The monoterpenes αand β-pinene are other major constituents of S. verticillata EOs.These bicyclic structural isomers, widely present in the composition of many other plants, are associated with diverse biological effects, such as antimicrobial, antiviral, analgesic, anti-inflammatory, antioxidant, and fungicidal activity [65].It was established in vitro that α-pinene reduces the synthesis of thromboxane A2 and suppresses the platelet aggregation [66].α-Pinene was also reported to provide good anticancer activity on human cell lines from liver cancer, ovarian cancer, and neuroblastoma.A significant synergism was observed between αand β-pinene and Paclitaxel in non-small-cell lung cancer cells [65,67].Neuroprotection, suppression of the formation of ROS, and enhancement of the expression of enzymatic antioxidants were also reported [65,68].αand β-pinene were also found to exhibit anti-epileptic activity.In a study with mice, α-pinene, β-pinene, and a mixture containing both of the compounds were administered in doses of 100-400 mg/kg, as well as diazepam in a dose of 2 mg/kg.After 1 h, the mice were injected with pentylenetetrazole to induce convulsions, and a significant reduction in seizure intensity was observed [65,69].
Other major compounds found in S. verticillata EOs are the germacrenes and sesquiterpenes, which are involved in the synthesis of other sesquiterpenes.It is considered that the name "germacrene" origins from "germacrone", a compound isolated for the first time from Geranium macrorrhizum oil [70].The germacrenes are associated with antioxidant, anti-inflammatory, antifungal, anticancer, and insecticidal activity [70,71].
β-Phellandrene, a monocyclic monoterpene, is present in S. verticillata EOs from Iran, Serbia, Turkey, and Italy.It is known as an insecticide of natural origin, with such activity proven by some studies.One of the in vivo studies performed with β-phellandrene demonstrated significant genotoxicity at a dose of 1425-2850 mg/kg.Other studies do not prove such but still consider possible damage to the DNA strands [72].
The monoterpene 1,8-cineole, or eucalyptol, which can be isolated from the EOs of Eucalyptus, as well as from Salvia and Melaleuca quinquenervia, is widely used in the cosmetic and perfume industry.The compound is included in the composition of repellents.Eucalyptus has demonstrated significant antioxidant and anti-inflammatory activity, inhibiting the synthesis of ROS and inflammatory cytokines [73,74].The compound has a therapeutic potential for the management of some cardiovascular, respiratory, and digestive diseases.It was studied in the treatment of bronchitis, asthma, rhino sinusitis, pneumonia, flu, and other conditions.The intake of the compound is associated with anti-inflammatory effects and muscle relaxation and affects mucus hypersecretion by affecting interleukin-1b and tumour necrosis factor-a (TNF-a).It is considered that the anti-inflammatory effect might be a result of binding to the NF-jB [73].In vitro and in vivo anticancer activity studies demonstrate the potential for the use of 1,8-cineole in the treatment of breast, ovarian, liver, skin, and colon cancer.It was established that the compound induces tumour cell apoptosis through tumour suppressor protein p53 [75].COX-2-induced expression of the aryl hydrocarbon receptor (AhR) was also reported to be suppressed [76].Moreover, 1,8-cineole exhibits analgesic, anaesthetic, sedative, antifungal, and antimicrobial effects, affecting Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis.
The target of 1,8-cineole is L-asparaginase, yet its antimicrobial activity alone is relatively low.This activity is enhanced when applying oil, due to the synergism of the compounds in the composition.Synergism has also been observed between chemical agents with antibacterial activity, such as mupirocin and 1,8-cineole, but the mechanisms of action are not fully established [73].
The levels of spathulenol, in S. verticillata EOs could reach about 17%.In general, the concentrations of this tricyclic sesquiterpenoid are between 5 and 9%.Currently, spathulenol is regarded as a compound with significant antioxidant potential and antibacterial, antifungal, antiseptic, anti-nociceptive, and antitumour activities.It is used in the management of diabetes, rheumatoid arthritis, and wound healing.An in vitro study demonstrated the protective activity of spathulenol on 6-hydroxydopamine-treated neuroblastoma cells.6-OHDA (6-hydroxydopamine) stimulates the formation of catecholamine quinones and ROS, which induce oxidative stress and cell death [77].The combination of 6-OHDA and spathulenol resulted in a dose-dependent recovery of damaged cells.Therefore, it can be used in the treatment of neurodegenerative diseases [77].In an in vitro study, spathulenol demonstrated activity on mice lymphoma cell lines.It has been proven that spathulenol can be used as an adjuvant in anticancer therapy, but in vivo studies are also needed [78].
The composition of extracts differs not only by region and country but also by the solvents used in the process.Sometimes variations in the concentration of a substance in the composition are obtained precisely because of this.Other factors are the time of picking, cultivation, and conditions for nourishing the plant.
A significant number of in vitro and less in vivo studies on S. verticillata reported activities and highlighted the therapeutic potential of the plant.However, more in vivo studies are needed.

Biological Activity
The biological activity of S. verticillata is mainly due to two main groups of secondary metabolites from the chemical composition of the plant: phenolic compounds (phenolic acids, flavonoids) and terpenes (monoterpenes and diterpenes).A high percentage of the phytochemical composition is represented by terpenoids such as caryophyllene, camphor, and α-thujone; and polyphenols such as caffeic acid, rosmarinic acid, and their metabolites, yunnaneic and salvianolic acids.Also, flavonoids like luteolin, apigenin and its 7-Oderivatives, cirismaritin, and quercetin were reported [1].Salvia species roots mainly contain diterpenes, while the aerial parts-flowers and leaves-contain monoterpenes, triterpenoids, and flavonoids.These metabolites are responsible for antioxidant, antiinflammatory, antibacterial, cytotoxic activity, etc. (Figure 2) [21].
The high levels of rosmarinic acid in the composition of S. verticillata extracts are responsible for the significant antibacterial activity and milder antifungal activity.Other compounds, such as luteolin, apigenin, quercetin, and diterpenoids such as carnosic acid and carnosol, contain in their molecules several hydroxyl (OH) groups, which bind to the enzymatic active centre of microorganisms and suppress their growth [1].EOs from S. verticillata have higher antibacterial activity as they contain substances such as limonene, α-pinene, β-pinene, α-thujene, and myrcene [1].
The antibacterial activity of S. verticillata has been demonstrated by several in vitro studies on both extracts and EOs.
enzymatic active centre of microorganisms and suppress their growth [1].EOs from S. verticillata have higher antibacterial activity as they contain substances such as limonene, α-pinene, β-pinene, α-thujene, and myrcene [1].The antibacterial activity of S. verticillata has been demonstrated by several in vitro studies on both extracts and EOs.

S. verticillata, aerial parts, methanol extracts
Study on the antimicrobial activity evaluated on 8 bacterial strains and 8 fungal strains, using Müller-Hinton Broth.Study on the antioxidant effects using green phosphate/Mo (V) complex, diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ABTS radical cation scavenging activity, nitric oxide (NO) radical scavenging activity, a measurement of inhibitory activity toward lipid peroxidation, and a measurement of ferrous ion chelating ability.
It was established that the antioxidant activity of S. verticillata crude extract is based on the flavone chrysoeriol. [81]

S. verticillata subsp. amasiaca, essential oils and extracts
Study on the antioxidant activity, using DPPH radical scavenging; anticancer activity on cancer prostate (PC-3) and human glioblastoma U-87 MG cell lines and anticholinesterase activity, using Ellman's colorimetric procedure.

Study on the antioxidant activity of 10
Salvia species from Germany.The QUENCHER method was used.
The results indicate that the ethanolic extracts of S. verticillata and S. forsskaolii had antioxidant activity comparable to S. officinalis.

Study Objectives Study Design Main Results References
S. verticillata L., methanol extract In vitro examination of S. verticillata antibacterial activity and antioxidant activity, using DPPH scavenging assay.

S. verticillata, S. trichoclada, S. fruticosa
In vitro investigation of the antioxidant activity, using DPPH scavenging assay, and the inhibitory ability of S. verticillata, S. trichoclada, and S. fruticosa extracts on acetylcholinesterase, using the Ellman method.
The antioxidant activity of S. verticillata extracts is comparable to that of Salvia officinalis (Table 3) [22,87,91,93].These data point out the use of S. verticillata as a natural antioxidant in the food industry.The antioxidant capacity of Salvia extracts is mainly due to phenolic compounds, and especially rosmarinic acid.These compounds act as donors of hydrogen atoms and affect free radicals in different phases, for example, the distribution, initiation, and activation of enzymes with antioxidant activity [1].The antioxidant capacity of S. verticillata extracts is comparable to that of the essential oil.
S. verticillata extracts are also sources of salvianolic acid C, which reduces the free radical levels.Currently more than 10 different salvianolic acids were identified: salvianolic acid A, B, C, D, E, F, G, etc.These water-soluble compounds are specific for the Salvia species [101].Salvianolic acids are associated with different biological activities, including multiple mechanisms for cardiovascular protection [101], anticancer activity [102], etc.
In 2020, it was reported that salvianolic acid C could inhibit SARS-CoV-2 infection by blocking the formation of the six-helix bundle of the core of the spike protein [103].The compound is also associated with being a cardioprotector [101] and hepatoprotector [104] and as a compound with a potential for improving liver fibrosis [102] (Figure 3).
Pharmaceuticals 2024, 17, x FOR PEER REVIEW 22 including multiple mechanisms for cardiovascular protection [101], anticancer ac [102], etc.In 2020, it was reported that salvianolic acid C could inhibit SARS-CoV-2 infe by blocking the formation of the six-helix bundle of the core of the spike protein The compound is also associated with being a cardioprotector [101] and hepatopro [104] and as a compound with a potential for improving liver fibrosis [102] (Figure 3 The hepatoprotective activity of salvianolic acid C was tested in acetamino overdose in mice [104].It was reported that salvianolic acid C can prevent the elevat the serum biochemical parameters and the lipid profile including aspartate aminot ferase, alanine aminotransferase, and total bilirubin.The study provided significan dence that salvianolic acid C can protect the hepatocytes from acetaminophen-ind damage by mitigating mitochondrial oxidative stress and the inflammatory respons can be mediated by the caspase anti-apoptotic effect through the inhibition o Kelch-like ECH-associated protein 1/erythroid 2-related factor 2/heme oxygenasenalling axis [104].
Recently, the compound gained attention as a potential molecule that could b volved in the therapy of the early phase of ischemic stroke [105].Wenbo Guo and leagues reported that treatment with salvianolic acid C can significantly reduce th farct volume, improve the neurological deficits, and reverse the pathological chang the transient middle cerebral artery occlusion in mouse models [105].Salvianolic a was isolated also from other Salvia species, such as Salvia miltiorrhiza.
The therapeutic potential of salvianolic acid C could be quite diverse.Moreo synergism exists between the beneficial effects of salvianolic acid C and the other pounds found in the composition of S. verticillata extracts.In the next decades, it is h likely for this compound to be included in the composition of novel drug candidates target oncology, neurology, cardiology, and gastroenterology.
In vitro studies reported that the EO affects both Gram-positive and Gram-neg microorganisms [106,107], affecting mainly Escherichia coli, with almost no activi Pseudomonas aeruginosa [2,46] (Table 4).The hepatoprotective activity of salvianolic acid C was tested in acetaminophen overdose in mice [104].It was reported that salvianolic acid C can prevent the elevation of the serum biochemical parameters and the lipid profile including aspartate aminotransferase, alanine aminotransferase, and total bilirubin.The study provided significant evidence that salvianolic acid C can protect the hepatocytes from acetaminophen-induced damage by mitigating mitochondrial oxidative stress and the inflammatory response and can be mediated by the caspase anti-apoptotic effect through the inhibition of the Kelch-like ECH-associated protein 1/erythroid 2-related factor 2/heme oxygenase-1 signalling axis [104].
Recently, the compound gained attention as a potential molecule that could be involved in the therapy of the early phase of ischemic stroke [105].Wenbo Guo and colleagues reported that treatment with salvianolic acid C can significantly reduce the infarct volume, improve the neurological deficits, and reverse the pathological changes in the transient middle cerebral artery occlusion in mouse models [105].Salvianolic acid C was isolated also from other Salvia species, such as Salvia miltiorrhiza.
The therapeutic potential of salvianolic acid C could be quite diverse.Moreover, a synergism exists between the beneficial effects of salvianolic acid C and the other compounds found in the composition of S. verticillata extracts.In the next decades, it is highly likely for this compound to be included in the composition of novel drug candidates with target oncology, neurology, cardiology, and gastroenterology.
S. verticillata EOs and its extracts are associated with significant antioxidant activity comparable to that of Salvia officinalis [81,91].The antioxidant activity varies according to the solvents used in the extraction process.According to Katanić Stanković, methanolic extracts of S. verticillata showed mild antimicrobial properties [1].It was reported that S. verticillata has significant antibacterial activity, especially against Escherichia coli and Staphylococcus aureus [39,41], and has no effect on Pseudomonas aeruginosa [2,46].α-Pinene found in the EO of S. verticillata demonstrates higher activity against strains of Escherichia coli compared to that of β-pinene and 1,8-cineole.These compounds do not show activity against the bacterial strains of Pseudomonas aeruginosa [2].Pseudomonas aeruginosa also shows resistance to S. verticillata EO from Iran, the main constituents of which are βcaryophyllene and germacrene D [46].Antifungal activity was also established against C. albicans [2,106], C. glabrata, and Saccharomyces cerevisiae [106].According to Kunduho glu, the EO has inhibitory activity against butylcholinesterase and acetylcholinesterase [106].Although the research is scarce, S. verticillata may be used as a neuroprotectant.One of the in vitro studies tested S. verticillata essential oil from Georgia for anti-inflammatory activity, demonstrating such activity [108].
Several in vivo studies investigated the biological activity of S. verticillata (Table 5).The main focus of these studies was the evaluation of the antioxidant potential, evaluation of the hepatoprotection, and evaluation of the anti-inflammatory activity [4, [109][110][111][112]. S. verticillata ethanol extracts increased the levels of insulin and decreased the levels of glucose, having also renal protective and hepatoprotective effects in a concentration-dependent manner. [110] S. fruticosa, S. verticillata, and S. trichoclada, methanol, aqueous, chloroform, acetone, and n-butanol extracts Investigation of the anti-inflammatory activity on rats of S. fruticosa, S. verticillata, and S. trichoclada from Turkey.

S. verticillata, alcoholic extract
Study of the antioxidant activity of S.
verticillata on 24 rats with cerebral hypoperfusion for 14 days.
A reduction in oxidative stress-related damage was observed. [111] S. verticillata L., S. patens L., aqueous/alcoholic extracts Examination of the anti-inflammatory activity and acute toxicity of S. verticillata and S. patens in rats for 14 days.
The extracts showed a moderate anti-inflammatory effect and no toxicity.[112] In vivo studies on S. verticillata are quite limited.The main focus of these studies is the antioxidant [109,111] and the anti-inflammatory activities [4,112].A study on the hypoglycaemic activity of Salvia showed that the extract significantly affected diabetic mice and had hepatoprotective activity [110].

Future Potential for Use of Salvia verticillata
There are few in vitro and in vivo studies, proving the neuroprotective effect of Salvia, specifically S. verticillata [94,98,100].The intake of S. verticillata extracts was associated with beneficial effects on the learning process, memory, and attention.This suggests that S. verticillata could be used as an adjunctive therapy in neurodegenerative diseases, including Alzheimer's disease [113].Future research may focus specifically on the chemical composition of the plant and more thoroughly explore its potential for slowing the progression of these diseases.Moreover, the EOs isolated from S. verticillata contain the cannabinoid type 2 receptor agonist β-caryophyllene, a compound with a prominent potential in the management of Alzheimer's disease [13].
Alzheimer's disease, which is an important challenge for contemporary medicine and science, is characterised by increased activity of the enzyme acetylcholinesterase, resulting in low synaptic cleft levels of acetylcholine.The disease has a negative effect on cognitive functions, with low levels of acetylcholine leading to impaired memory, concentration, motivation, and the ability to learn [100].Salvia constituents such as monoterpenes, phenolic diterpenes, quercetin, and rosmarinic acid show inhibitory activity against acetylcholinesterase [113].One of the in vitro and ex vivo studies used isolated guinea pig ileum, knowing that acetylcholine causes a concentration-dependent contraction.Salvia extracts demonstrated a slight dose-dependent effect on acetylcholinesterase inhibitory activity [100].
Another in vitro study compared the acetylcholinesterase and butylcholinesterase inhibitory activity of a petroleum ether extract of S. verticillata and Galantamine.The results showed relatively good concentration-dependent inhibitory activity [89].
The ability of S. verticillata to slow down the progression of the disease should be studied more profoundly.Currently, Alzheimer's disease remains an unsolved challenge, and the treatments focus mainly on the management of the symptoms and improving the quality of life.
Several studies investigated the hypoglycaemic activity of S. officinalis.One in vivo study investigated the effects of the methanolic extract and essential oil of S. officinalis leaves on rats with diabetes induced by streptozotocin injection.A significant increase in glucose levels was observed only after five days.The results showed that Salvia methanolic extract, unlike the essential oil, provided hypoglycaemic activity [114].This and many other studies could be a good basis for future research on the hypoglycaemic activity not only in S. officinalis but also in other species like S. verticillata.
Another important in vivo study demonstrated that the intake of ethanolic extract of S. verticillata for 14 days resulted in a decrease in the glucose levels, and a positive influence and protective effects on the liver and kidneys [110].
Some in vitro clinical studies have focused on the cytotoxic activity of S. verticillata, but their number is limited.One of them used essential oil from the leaves and flowers of S. verticillata and colorectal carcinoma and breast ductal carcinoma cell lines and embryo fibroblast from rats.The cytotoxic activity of the essential oil has been proven, with the greatest effect on colorectal adenocarcinoma [37].
The chemical profile of S. verticillata EOs highlights a potential for implementation in regenerative medicine.The main compounds isolated from the EOs were already reported to promote the wound healing processes.These effects in addition to the mild antibacterial and antifungal activity make the EO worth studying as a skin recovery therapy after surgical procedures, dermatological conditions, or other interventions [115][116][117][118]. Currently, there are no human or animal studies investigating the skin recovery effects of EOs isolated from S. verticillata.

Materials and Methods
The first step of the screening process involved identifying eligible studies as well as following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (Figure 4) [119].An extensive search of the PubMed, Scopus, Web of Science, and Google Scholar databases was performed.
The following keywords were used in the search process: "Salvia verticillata", "Salvia verticillata essential oil study", "Salvia verticillata antioxidant activity", "anticancer properties of Salvia verticillata", "Salvia verticillata composition", "Chemical composition of Salvia verticillata", "Salvia verticillata and Alzheimer's disease", and "Salvia verticillata antibacterial activity".In the final stage, relevant studies were selected based on the exclusion and inclusion criteria.The exclusion criteria were webinars or blogs, and articles containing a lack of data.The inclusion criteria were in vitro studies, animal studies, and studies investigating the impact of the chemical composition.A total of 57 studies on the biological activity of S.verticillata extracts and EOs were selected and included in the present review.

Conclusions
Salvia verticillata is a plant species which could play a crucial role in the future drug discovery strategies.Although the plant is associated with deep traditions in the folk medicine of different nations, studies that investigated its therapeutic potential are limited.The chemical profile of S. verticillata includes different compounds like phenolic acids, flavonoids, terpenes, and salvianolic acids.In the last decade, salvianolic acids were reported to provide different biological activities, including multiple mechanisms for cardiovascular protection, anticancer activity, etc.Although some small amounts of salvianolic acid B were found in S. verticillata extracts, the major compound among the salvianolic acids was salvianolic acid C, a compound associated with the potential for improving liver fibrosis, cardio-and hepatoprotection, the inhibition of SARS-CoV-2 infection by blocking the formation of the six-helix bundle of the core of the spike protein, and anti-inflammatory activity.
S. verticillata EOs seem to be rich sources of the cannabinoid type 2 receptor agonist β-caryophyllene, a compound with a prominent potential in a wide variety of medical fields.The in vivo and the in vitro studies regarding S. verticillata extracts and EOs highlighted significant antioxidant, anti-inflammatory, antibacterial, and antifungal activity.

Conclusions
Salvia verticillata is a plant species which could play a crucial role in the future drug discovery strategies.Although the plant is associated with deep traditions in the folk medicine of different nations, studies that investigated its therapeutic potential are limited.The chemical profile of S. verticillata includes different compounds like phenolic acids, flavonoids, terpenes, and salvianolic acids.In the last decade, salvianolic acids were reported to provide different biological activities, including multiple mechanisms for cardiovascular protection, anticancer activity, etc.Although some small amounts of salvianolic acid B were found in S. verticillata extracts, the major compound among the salvianolic acids was salvianolic acid C, a compound associated with the potential for improving liver fibrosis, cardio-and hepatoprotection, the inhibition of SARS-CoV-2 infection by blocking the formation of the six-helix bundle of the core of the spike protein, and anti-inflammatory activity.
S. verticillata EOs seem to be rich sources of the cannabinoid type 2 receptor agonist β-caryophyllene, a compound with a prominent potential in a wide variety of medical fields.The in vivo and the in vitro studies regarding S. verticillata extracts and EOs highlighted significant antioxidant, anti-inflammatory, antibacterial, and antifungal activity.Recently, S. verticillata has been reported as a potential agent for the treatment of neu-rodegenerative diseases such as Alzheimer's disease because of its inhibitory activity on acetylcholinesterase.However, the number of studies in this direction is limited.S. verticillata extracts could be also used in the food industry as novel food additives to slow the oxidation processes in meat or other food products.

Table 2 .
Composition of main volatile compounds in Salvia verticillata EOs.

Table 3 .
Biological activity of S. verticillata extracts-in vitro studies.

Table 5 .
Biological activity of S. verticillata-in vivo studies.