Nyctanthes arbor‑tristis Linn. (Night Jasmine): extraction techniques, phytochemical constituents, and biological impacts of extracts and essential oil

Background Nyctanthes arbor-tristis Linn. is a small, sacred ornamental tree used in prayer. It is renowned throughout India for its aromatic white blossoms. The entire plant was widely used for several health applications particularly root and bark were used to treat fever and cough, respectively. Also, the leaf was used for managing fever and diabetes, and its cholagogue, diaphoretic, and anthelmintic properties. Main text The current review aimed to comprehensively analyze the botanical characteristics, phytochemistry, and pharmacology of N. arbor-tristis essential oil (NAEO) and extracts. Additionally, it wants to emphasize the latest advancements in phytochemistry and pharmacology related to this aromatic plant. Depending on the variety, origin, and plant parts used, the NAEO yield ranged from 0.002 to 0.10% on a dry basis. The NAEO has been investigated in only a few research studies and resulted, in the predominant levels of phytol and methyl palmitate chemical compounds. Furthermore, the NAEO was found to have significant volatile chemical constituents, including geranylgeran-iol, phytoene, nonadecane, linalool, and various other miscellaneous chemical components. The plant extracts and NAEO have numerous biological properties, including antioxidant, antimicrobial, anticancer, anti-inflammatory, analgesic, larvicidal, and other miscellaneous activities. Conclusion This paper analyzes and summarizes the diverse research potential associated with N. arbor-tristis . The results of the present study suggested that most of the biological and pharmacological investigations were carried out without including dosage, positive controls, and negative controls. Furthermore, several pharmacological investigations were exclusively carried out using cell lines and animal models. Hence, the following research endeavors aimed at assessing the medicinal properties of NAEO and extracts in human subjects would broaden the scope of its utilization.


Graphical abstract
Background N. arbor-tristis is a little, sacred ornamental tree in Indian mythology used for prayer.The plant is widely recognized across the country for its aromatic white flowers.As per Hindu mythology, the Parijata tree is recognized as one of the five wish-granting trees associated with Devaloka [1].N. arbor-tristis is commonly referred to as "Night Jasmine or Harsinghar." The genus name "Nyctanthes" is derived from the Greek phrases "Nykhta, " meaning night, and "anther, " meaning flower.Within the botanical family of Oleaceae, Night Jasmine genus encompasses more than 600 species of little trees and vines [2].These glabrous twining shrubs are commonly found in tropical Asia and warm temperate regions of Europe and Africa.Additionally, they are extensively cultivated in gardens within these areas [3].
The plant is distributed over several regions, namely southern India, northern Pakistan, Thailand, Malaysia, and Indonesia.Its original habitat is the subtropical Himalayas of Nepal and India [3].The species is distributed over several regions in India, including the outer Himalayas, the Jammu and Kashmir region, East Assam, Bengal, Tripura, and the central region extending to the Godavari River in the southern part.The plant flourishes in soil that is reddish-black in color and has a pH level between 5.6 and 7.5.It is well-suited for dry and semi-arid conditions [4].
Numerous research studies reported that extracts from the flowers and leaves of N. arbor-tristis possess stomachic, carminative, colon astringent, expectorant, anti-bilious, hair tonic, and therapeutic properties [2,3,[7][8][9][10].These features make them effective in treating piles and several skin problems.Recent pharmacological research has shown floral extract to possess several properties, such as antioxidant, anthelmintic, antidiabetic, and central nervous system (CNS) depressive effects [11].Furthermore, the leaf has medicinal properties that effectively treat fever and diabetes.It can also serve as a cholagogue, diaphoretic, and anthelmintic, as documented by Agarwal and Pal [10] and Sah and Verma [12].In several previous studies reported the pharmacological potential of crude extracts from N. arbor-tristis and other organic chemicals.However, the phytochemical composition and biological activities of NAEO and active components have not yet been compiled.The objective of this study is to comprehensively analyze the NAEO yield, chemical composition, and biological properties based on published literature up to May 2024.The study also aims to identify areas that require further investigation.
N. arbor-tristis is a notable linear botanical specimen distinguished by its polygonal branches, which attain a vertical stature of 7-10 m.The bark displays a rough and granular gray hue [14].The leaves are coarse and adorned with trichomes.The flowers tend to cluster together at the uppermost parts of the branches or within the axils of the leaves.The flowers are immobile, emit a nice scent, and have a hollow, bell-shaped coil.Chakraborty and De [13] have reported that fruits display a heart-shaped morphology and contain a brown coloration.The morphological identification of the complete N. arbor-tristis plant, with its leaves, fruit, and seed, is shown in Fig. 1.

Traditional medicine
N. arbor-tristis is well recognized as a highly efficacious medicinal plant within Ayurveda, Homoeopathy, Unani, and Siddha.In ethnomedicine, N. arbor-tristis therapy is beneficial in treating several disorders, such as persistent fever, rheumatism, malaria, wound healing, skin problems, stomachic issues, astringent effects, menstruation problems, and wound healing [15].The native inhabitants of the Chittoor region in Andhra Pradesh, India, make considerable use of the entire plant for therapeutic purposes.The root possesses therapeutic properties for managing fever, sciatica, and anorexia, while the bark is applied for its expectorant properties [10].An extract derived from the leaves has been administered to children to expel roundworms and threadworms.Fresh leaves have been utilized in the preparation of homeopathic remedies [1].The juice extracted from 3 to 7 leaves is employed by tribal communities in Orissa as a blood purifier, serving as a preventive measure against skin infections [1].The floral components of Nyctanthes arbor-tristis are utilized in India, Indonesia (Java), and Malaysia as emmenagogues, stimulating menstrual flow.A heated concoction of these flowers is employed by a subset of elderly Buddhist monks in Sri Lanka for its sedative properties [16].The oral intake of a decoction derived from these flowers has been found to alleviate flatulence, stimulate gastric secretions, and enhance pulmonary expectoration.This decoction has also been used in the management of gout.Furthermore, the juice extracted from these flowers is applied as a hair tonic, preventing hair graying and baldness [17].

Essential oil extraction methods
Essential oils find applications in a wide range of consumer products, including detergents, soaps, cosmetics, pharmaceuticals, perfumes, candies, soft drinks, alcoholic beverages, and insecticides.The global production and consumption of essential oils and perfumes have witnessed significant growth.Advanced production technologies play a pivotal role in enhancing both the quantity and quality of essential oils.Despite rapid advancements in production processes, many regions still rely on traditional methods for essential oil extraction.Common techniques include solvent extraction, steam distillation, supercritical CO 2 extraction, and hydrodistillation.Figure 2 illustrates the predominant techniques for extracting essential oils from medicinal and aromatic plants.

Solvent extraction
Solvent extraction is a modern technique that uses liquid solvents to remove solute components from solid materials.According to Babazadeh and Arumugam [18], solvent extraction is a process that can be used to extract valuable molecules or detoxify solvents by eliminating undesirable components.Additionally, n-hexane solvent extraction is a method for extracting floral and seed essential oils [19].The frequently employed solvents include hexane, petroleum ether, ethanol, isopropanol, acetone, chloroform, methanol, and 1-butanol [20].Solvent extraction has the potential to produce a larger volume of oil and isolate a wider range of compounds.However, the presence of residual solvent in the extract could pose a problem.Additionally, this method could result in the degradation of some thermolabile compounds [19].To the best of our understanding, more comprehensive research needs to be undertaken to estimate N. arbor-tristis flower essential oil using solvent extraction.

Steam distillation
Steam distillation is a very secure method for extracting essential oils from heat-sensitive plants and flowers, effectively safeguarding the integrity of volatile and aromatic chemicals.In contrast to alternative techniques, steam distillation effectively retains volatile compounds throughout heating, evaporation, separation, and reflux [21].This approach demonstrates enhanced efficacy with reduced duration of distillation and yields superior oil production.Steam distillation involves the introduction of steam into the botanical material to harvest the essential oil.Steam undergoes evaporation of essential oil by interacting with botanical material [22].To release essential oils without causing harm to their volatile components, it is necessary to heat the steam to a temperature range of 200-300 °C.Oil molecules are released from glandular trichomes located on the outer surfaces of the flowers and leaves of several fragrant plants through the process of steam.Concentrated steam destroys plant sacs, resulting in the release of oil molecules [23].The essential oil yield was influenced by various factors, including the quantity of inherent essential oil present in the oil sacs of the botanical material, the duration of the distillation process, the temperature of the steam, and the applied pressure [24].Higher temperatures during steam distillation can lead to the degradation of volatiles and the formation of undesirable chemical byproducts [2].So far, no study has been undertaken using steam distillation to estimate essential oil derived from the flowers of N. arbor-tristis.

Supercritical CO 2 extraction
Supercritical CO 2 extraction is a modern technique to extract essential oils from various parts of the plant [25].Carbon dioxide (CO 2 ) is employed as a solvent in the supercritical fluid extraction of essential oils [26].Plant material that has been pulverized is introduced into an extraction vessel, where carbon dioxide (CO 2 ) is subjected to supercritical conditions at elevated pressures and temperatures [27].Carbon dioxide was supercritical at a pressure of 78.3 bar and a temperature of 31.1 °C, allowing it to form bonds with plant volatiles [24].The carbon dioxide emitted by a pump facilitates the interaction between plant material and the extraction vessel.Carbon dioxide (CO 2 ) degrades glandular trichomes that carry oil molecules, isolating them.A low-pressure and temperature separator extracts all essential oils from CO 2 [28,29].The extraction of botanical oil is influenced by fluid density and dissolving power, particularly in the case of supercritical CO 2 [30].The recyclability of supercritical CO 2 extraction makes it an environmentally beneficial technology.CO 2 extraction is FDA-approved for industrial applications, unlike solvents like hexane, which leave residues and emit pollutants.This feature enhances the safety and sustainability of many processes.Furthermore, this innovative methodology for extracting essential oils from the flowers of N. arbor-tristis has not been implemented thus far.Hence, future studies must evaluate the quantification of essential oils using supercritical CO 2 extraction since it holds potential advantages for the fragrance sector.

Hydrodistillation
Hydrodistillation is a conventional method that utilizes water vapor to extract plant essential oils.The aromatic raw material was filled with water and subjected to boiling until it reached its boiling point.Plant cells undergo thermal decomposition, resulting in the emission of aromatic chemicals into the atmosphere.The condenser facilitates the cooling and condensation of steam containing aromatic chemicals [31].Hot water and steam facilitate the release and transport of bioactive chemicals from the plant matrix.The vapor mixture undergoes condensation via indirect cooling, separating essential oils and oil-based bioactive chemicals from water.The process of desiccation using anhydrous sodium sulfate is followed by the chromatographic analysis of essential oils and oil-based bioactive substances [32][33][34].This method routinely extracts essential oils from spices, medicinal plants, and aromatic crops [35][36][37][38][39]. Nevertheless, there is a need for more research that has explicitly concentrated on examining the process of extracting essential oil from the blooms of N. arbor-tristis.The study's findings revealed a decrease in oil production, with percentages ranging from 0.002 to 0.10% [7][8][9].It is vital to undertake additional study investigations using this approach.

Chemical composition Nyctanthes arbor-tristis essential oil (NAEO) and its composition
The NAEO yield ranged from 0.002 to 0.10% on a dry basis, depending on the variety, origin, and plant parts employed (Table 1).The flowers of N. arbor-tristis yielded 0.06% essential oil, whereas the barks yielded 0.005% [7,8].Different soil types, locations, origins, extraction techniques, and environmental factors could all have an Flowers Pannipitiya, Sri Lanka Hydrodistillation 0.06% [8] impact on the variations in N. arbor-tristis essential oil yields.

Biological and pharmacological potentials
The NAEO and extracts have various pharmacological and biological properties, such as antioxidant, antimicrobial, antidiabetic, anticancer, larvicidal, and other miscellaneous activities listed in Table 3.The potential biological and pharmacological effects of N. arbor-tristis are diagrammatically shown in Fig. 3.

Antioxidant activity
In response to oxidative stress, plants employ intricate defensive systems that depend on a synergistic interplay of metabolites and enzymes to address environmental complications effectively.An earlier study reported that methanolic leaf extract with a IC 50 of 63.6% showed significant antioxidant activity [41].According to Gulshan et al. [42], the ingestion of chloroform extracts derived from leaves and flowers, along with a 50% ethanolic extract of leaves, showed decrease in the level of SGPT, SGOT, cholesterol, and triglycerides in the blood.Additionally, it leads to an increase in the levels of catalase (CAT) and superoxide dismutase (SOD).A recent study examined the antioxidant properties of N. arbor-tristis using several methodologies, such as the assessment of total antioxidant capacity, the DPPH test, free radical scavenging activity, and reducing power assay.N. arbor-tristis exhibits antioxidant activity due to its ability to counteract different physiologically crucial reactive oxygen species, reducing lipid peroxidation and DNA damage [43].In another study, results remarked that the ethanolic extract of the N. arbor-tristis leaves with IC 50 values of 30.75 µg/ml and 30.83 µg/ml showed significant antioxidant activity using DPPH and ABTS assays, respectively [44].The N. arbor-tristis flower extracts demonstrate noteworthy antioxidant activity, indicating their potential suitability for utilization in the food industry.It has the potential to be both powerful antioxidant and viable food dye [12].These occurrences, various benefits, highlight its potential significance in improving both human welfare and industrial utilization.Nevertheless, most of the antioxidant properties were evaluated using DPHH assays, which no longer have pharmacological significance.It is necessary to investigate their potential under both in vitro and in vivo conditions [45].

Antimicrobial activity
The essential oil of N. arbor-tristis (NAEO) and its extracts exhibit notable antifungal properties, spanning from mild to potent levels.According to Al-Reza et al. [46], N. arbor-tristis extract demonstrates significant efficacy against a range of fungi and bacteria, such as Botrytis cinerea, Colletotrichum capsici, Fusarium oxysporum, Fusarium solani, Phytophthora capsici, Rhizoctonia solani, and Sclerotinia sclerotiorum.In addition, a recent study demonstrated that the leaf extract exhibits significant inhibitory effects on the radial growth of rice fungal diseases, such as Cochliobolus miyabeanus, Pyricularia oryzae, and R. solani.Furthermore, the methanolic extract derived from the leaves of N. arbor-tristis exhibits significant antibacterial properties against Salmonella typhi, Salmonella aureus, Staphylococcus epidermis, and Salmonella paratyphi.The minimum inhibitory concentrations (MIC) of methanolic extract ranged from 1 to 8 mg/ml [4].The leaves, roots, and shoots of N. arbor-tristis exhibit antibacterial solid properties against various pathogenic bacteria, such as Klebsiella pneumoniae, S. epidermidis, Bacillus subtilis, S. aureus, E. coli, Listeria monocytogenes, and P. aeruginosa, when extracted with methanol and water.In another study, Ankita et al. [47] revealed that the leaf extract demonstrates the highest level of inhibition against K. pneumoniae, E. coli, and L. monocytogenes.Conversely, the root extract exhibits the highest level of inhibition against S. epidermidis, and the shoot extract demonstrates the highest level of inhibition against Bacillus subtilis.The inhibition of Semliki Forest Virus (SFV) and the Encephalomyocarditis Virus (EMCV) is effectively demonstrated by arbortristoside-A and arbortristoside C, which have been extracted from N. arbor-tristis.Furthermore, the inhibitory efficacy against Fig. 3 Diagrammatic representation of the pharmacological potential of N. arbor-tristis these viruses is also shown in the ethanolic extract and n-butanol fractions obtained from N. arbor-tristis [48].In most of the research studies, the antimicrobial properties of N. arbor-tristis extracts and NAEO have primarily utilized the disk diffusion method [44,49].However, due to its inherent limitations, it is necessary to complement this method with the more appropriate MIC assay [50].

Anticancer and cytotoxic activity
Khatune et al. [51] found that floral extracts of N. arbortristis obtained from petroleum ether, chloroform, and ethyl acetate showed notable cytotoxic action.A further study was carried out to examine the possible anticancer activities of methanol extracts derived from the fruit, leaves, and stem of N. arbor-tristis in an in vitro setting.The methanol extract obtained from N. arbor-tristis fruit showed a substantial 71% reduction in dry nitrogen.The dosage of 30 mg/ml demonstrated a reasonable level of effectiveness.However, at a concentration of 10 mg/ml, the methanol extract from the leaves of N. arbor-tristis demonstrated the least inhibitory efficacy [42].The study also indicated that the dried fruit methanol extract of N. arbor-tristis may have anticancer properties due to the presence of glycosides, tannins, phenols, and steroids.Only a limited number of studies have examined the anticancer properties of N. arbor-tristis extracts and NAEO, and these investigations were carried out using animal models rather than human subjects.Therefore, future research should prioritize exploring the pharmacological capabilities of NAEO in diverse human clinical trials.

Analgesic activity
The analgesic effectiveness of the ethanolic, chloroform, and aqueous leaf extracts of N. arbor-tristis was evaluated using Eddy's hot plate analgesiometer in 250, 500, and 1000 mg/kg body weight mice.Results showed that ethanolic extract with a dosage of 1000 mg/kg body weight had a maximum reaction time of 76.17 min, which was comparatively higher than the standard drug Tramadol hydrochloride [52].Sharma et al. [53] have discovered that the petroleum ether extract and β-Sitosterol obtained from N. arbor-tristis leaves have the potential to be used as sources of analgesic activity.However, researchers have not conducted any studies to test the analgesic activity of NAEO.Also, limited studies only showed that N. arbor-tristis extracts tested for analgesic activity in animals.Therefore, future studies need to investigate the analgesic activity of NAEO and its bioactive compounds in animals and humans.

Anti-inflammatory activity
The in vivo tests showed that administering 1000 mg/kg and 2000 mg/kg of N. arbor-tristis water extract reduced the augmented vascular permeability and leukocyte migration induced by D-glucose.The study proposed a potential correlation between the anti-inflammatory properties of N. arbor-tristis and the abundant presence of flavonoids and saponins in its leaves [54].Gulshan et al. [42] conducted a study using ethanol to extract arbortristoside-A from N. arbor-tristis seeds.The study findings indicated that the arbortristoside-A demonstrated a substantial and dosage-dependent reduction in inflammation.Sana et al. [55] remarked that the ethanol extract of fresh and uncrushed aerial portions of N. arbor-tristis contains a fraction insoluble in petroleum ether.Researchers have discovered that this fraction possesses anti-inflammatory properties by suppressing reactive oxygen species (ROS).Only a limited number of studies have investigated the anti-inflammatory properties, and all of them were conducted using animal models instead of human subjects.Subsequent investigations should focus on examining the bioactivity of N. arbortristis in diverse clinical trials involving human subjects.

Hypoglycemic activity
The hypoglycemic effect of the ethanolic extract of N. arbor-tristis leaves was evaluated in albino rats with alloxan-induced diabetes.Administering an ethanolic extract at a dosage of 200 mg/kg body weight resulted in a considerable reduction in blood sugar levels in diabetic albino rats [56].The administration of a 500 mg/kg body weight aqueous extract derived from the flowers of N. arbor-tristis has hypoglycemic and hypolipidemic effects.Thus, the aqueous extract has the potential to serve as a substitute drug for the treatment of diabetes mellitus [57].

Larvicidal activity
Mathew et al. [58] discovered that extracts from the flowers of N. arbor-tristis, specifically methanol and chloroform extracts, exhibited larvicidal efficacy against Anopheles stephensi larvae.The LC 50 values for methanol and chloroform extracts were 244.4 ppm and 747.7 ppm, respectively.This work has significant implications for managing the Anopheles stephensi population and the potential decrease in the spread of filarial diseases.Naturally derived larvicidal chemicals provide the possibility of environmentally sustainable alternatives to manufactured pesticides for vector management.Nevertheless, this study requires rigorous experimentation techniques, such as positive and negative control measures and specific dosages.Hence, it is imperative for forthcoming research to conduct experiments more methodically to validate the larvicidal activity of N. arbor-tristis.In addition, Table 3 also provides a summary of the additional pharmacological potential of N. arbor-tristis and its active chemical components.

Conclusion
This paper provides a concise overview of the botanical characteristics, techniques for extracting essential oil, the amount of oil obtained, the chemical composition, and the pharmacological and biological effects of N. arbor-tristis extracts and essential oil.The plant's essential oil production and chemical compositions primarily concentrate on leaves and flowers, whereas the analysis of barks needs to be addressed or given more consideration.Hydrodistillation is the primary process of extracting essential oils among the several available extraction methods.Chromatographic techniques are employed to identify chemical components present in essential oils.The main chemical components of NAEO and extracts were phytol, methyl palmitate, cis-9-tricosene, geranylgeraniol, nonadecane, n-pentacosane, phytone, methyl myristate, eucarvone, and linalool.The chemical components found in N. arbor-tristis have the potential to be a new and natural source for the food, fragrance, and pharmaceutical industries.Our literature review revealed that N. arbor-tristis possesses biological solid activity that can effectively safeguard individuals against various ailments.Research studies have verified that N. arbor-tristis possesses antioxidant, antimicrobial, anti-inflammatory, analgesic, anticancer, antidiabetic, hepatoprotective, antiarthritic, and larvicidal properties.
Our comprehensive review indicates that the primary bioactive compounds in N. arbor-tristis can exhibit significant variability based on species, geographical location, growth conditions, and harvest time.This inconsistency poses challenges in standardizing herbal medicines and ensuring their consistent therapeutic effects.N. arbor-tristis has been utilized in traditional medicines for centuries, yet there is often a lack of rigorous clinical trials.Solid clinical evidence makes it easier to ascertain these herbal medicines' safety, efficacy, and optimal dosage.Many previous biological and pharmacological studies still need to provide specific details regarding positive and negative controls, as shown in Table 3.Consequently, future research should undertake meticulous investigations using cellular and animal models.The current state of pharmacological research on N. arbor-tristis needs to be improved.Some studies that explored biological activity employed extremely high dosage concentrations.Furthermore, several of these studies did not include comparisons with standard positive and negative controls, and some lacked determination of minimum inhibitory concentration (MIC) values, potentially leading to false positive results.Also, previous research has predominantly concentrated on crude extracts, and organic fractions, with the aqueous extracts receiving minimal focus.It is imperative to pay attention to its conventional usage.Furthermore, to assess the efficacy and safety, there is a need for extensive placebo-controlled and double-blind clinical trials.
Nevertheless, the clinical research was conducted exclusively on cell lines and animals, with no human clinical trials.Therefore, future studies should investigate the pharmacological activity of N. arbor-tristis and its active components in humans.Subsequent investigations should focus on examining the bioavailability, and pharmacokinetics of N. arbor-tristis to identify the specific chemical constituents responsible for its effects and broaden the current medical uses of N. arbor-tristis.The information discussed here will enhance public knowledge of N. arbor-tristis extracts and essential oils and prove valuable for future study.

Fig. 2
Fig. 2 Commonly used essential oil extraction methods in plants

Table 1
Yield of essential oil from various parts of N. arbor-tristis

Table 2
Major constituents of Nyctanthes arbor-tristis essential oils from various geographical origin

Table 3
Biological and pharmacological potential of N. arbor-tristis