Ethnomedical uses, Phytochemistry, Pharmacological and therapeutic properties of Desmodium gangeticum (L.) DC. - A scoping review

A surge in laboratory research into the pharmacological properties of bioactive compounds, as well as their potential to cure a wide range of ailments, has resulted in an influx of new herbal medications and extracts onto the international market in recent years. Desmodium gangeticum (L.), one of the essential herbs of Indian traditional system of medicines is part of many essential formulations viz. " Dashamoola " and is used to treat various diseases. It is a perennial herb, locally known as " Shalparni " (Hindi) in India and also reported in many other tropical countries. This review presents the traditional uses, phytochemistry, pharmacology, and clinical effectiveness of D. gangeticum. Literature was systematically searched through various databases, journals and gray literature through electronic and manual search. Collected data was further critically reviewed and summarized in this paper. It contains many bio - active phytochemicals viz. gangeticoside, leonuriside A, tortoside A, dehydrosoyasaponin, gangetin, gangetinin, desmocarpin, desmodin etc. among them, some have drug likeliness properties. Critical literature analysis revealed that it possessed many pharmacological activities viz. anti - inflammatory, antinociceptive, anti - oxidant, cardioprotective, antidiabetic and hepatoprotective anti - bacterial, and anti - amnesic activities. Despite a large number of traditional therapeutic uses, D. gangeticum was evaluated for limited therapeutic efficacy through clinical trials and evidence suggested it may have therapeutic benefits on bronchitis, gout, hypertension. The biochemical and physiological mechanisms involved in the different biological effects exhibited by it need to be investigated. The herb should be investigated further, focusing on pharmacody-namic, pharmacokinetic and safety profiles. Well - designed Randomized Controlled trials (RCTs) should be conducted to support its therapeutic use.


Introduction
Since the earliest days of civilization, plants had been employed for health promotion and disease treatment in many regions and communities worldwide. For many people in the developing world, plant based traditional medicine is crucial for their healthcare. Plants are the source of around a quarter of all prescribed medications globally (1). Drug development and pharmacology rely heavily on ethnobotanicals, which can be employed in various ways, from raw materials for drug production to modeling biologically active chemicals (2). Ethnomedicinal knowledge and natural sources have developed the basis of biomedicine and contribute largely to the commercial drug preparations manufactured today.
Experiments on medicinal plants and their possible properties have drawn attention of many scientists. Contemporary research in drug development from herbal plants includes a multidimensional approach combining pharmacognostical, phytochemical, pharmacological biotechnology and molecular sciences (3). Many therapeutic agents employed presently for various targets have been discovered through their known ethnomedical use (4). Therefore, it is essential to screen medicinal to provide novel and significant leads against various pharmacological targets.
Desmodium gangeticum (L.) DC. (Fabaceae), commonly known as 'Salpan' or 'Shalaparni,' is distributed wildly in several regions in Asia, Africa and Australia (5,6). D. gangeticum is an erect undershrub, up to 1.2 m tall; the stem is angled, hairy when young, glabrescent on aging. It can be characterized among Desmodium species by lax flowers scattered on peduncles and joints of pods longer than broad ( Fig. 1) (7).
It is one of the essential herbs of ethnomedicine that have been used extensively either as a single drug or in combination with other drugs in the traditional system of medicines in India (8). In Ayurveda (Indian traditional system of medicine), it has been reported for various therapeutic uses such as in oedema, fever, cough, worm infestation, dyspnoea, diarrhoea, vomiting, pain and inflammation (9). It is one of the ingredients of 'Dashamoola' an essential herbal formulation of Ayurveda which is widely prescribed for many health ailments (10). Its roots have been used ethnomedicinally as an expectorant for lower respiratory tract infections and as an antitoxin in snakebite and scorpion sting (11,12).
In the last few decades, D. gangeticum was screened to explore its biochemistry, pharmacological activities and clinical uses through scientific experiments. Findings of such researches supported its traditional uses and established it as potential herbal therapeutics. Many secondary metabolites and bioactive compounds have been reported in plants having various pharmacological activities (13,14). Attempts have been made to review the researches carried out previously, but gathered data were not comprehensive (15). Thus, the purpose of this review is to provide comprehensive information on the ethnomedicinal uses, phytochemical profile, pharmacological activities and clinical trials on D. gangeticum, to investigate their therapeutic potential, identify gaps in our current knowledge and assess future research prospects.

Materials and Methods
Scientific published literature on D. gangeticum was strategically searched through various platforms to collect optimum available literature. Electronic databases such as PubMed, Google scholar, AYUSH Research portal, AYUSHDHARA, J-GATE, Research Gate portals, INFLIBNET, and preprint were searched from inception to June 2021 through a search strategy developed using key search terms. Keywords and terms used in search strategy included 'Shalaparni,' 'Desmodium gangeticum,' 'preclinical study,' 'Ethno medicine,' 'phytochemical,' 'pharma cological,' 'experimental' Boolean operator (AND, OR, NOT) was also used to limit or broaden the search wherever required. Ayurveda text books, unpublished dissertations and research were also searched manually.
Published or unpublished researches on ethnomedicine, phytochemistry, animal experiments, and clinical research carried out on D. gangeticum were included. Information was rigorously retrieved, critically analyzed and systematically summarized.

Results
Of 344 citations retrieved through systematic search from different databases, 46 (Fig. 2).

Ethnomedicinal/traditional uses
D. gangeticum is traditionally used as therapeutics in many different geographical regions. In India, root decoction of Shalaparni is used as a snake bite remedy (16). Root paste also traditionally taken orally as an antidote for snake and scorpion bites in the Dudhi block of District Sonebhadra, Uttar Pradesh, India (17). Its root decoction is utilized in rheumatism with a dose of one spoon in Eastern Ghats of Andhra Pradesh, India (18). Aqueous leaf extract is poisonous towards E. coli. In Odisha, India (19). The plant's stem and leaf are used as a diuretic, antitoxic, vomiting and diarrhea as a decoction in the Chandra Prabha Wildlife Sanctuary, Chandauli District, Uttar Pradesh (20). It is utilized in fever, vomiting, Vata-Dosha in Raipur District (21). In tribal areas of Adilabad District, Telangana Region, plant roots, bark and leaves are used to treat fever and kidney disorders (22). Inhabitant of eastern Ghats, Andhra Pradesh, India, its root decoction is traditionally utilized with half cup dose once daily for 2-3 months to alleviate respiratory disease (23). Paste of its stem bark is externally applied in goiter daily once for 3-4 days by tribes of Chhattisgarh state (24). Tonic "Salampak" prepared from D gangeticum is employed in gynecological diseases by tribals of Jhalod taluka of Dahod district, Gujarat, India (25). Root is used in premature ejaculation in Bulamogi district, Uganda (26). The root is also used for cough and cold in Deolapar forest range, Maharastra (27). D. gangeticum is being utilized in Stomach ache and menstrual ache ethnomedicinally by the Khasia community people in Moulibazar district of Bangladesh (28).

Pharmacological/ Experimental study
Plant was reported for many pharmacological activities ( Table 1). Details of pharmacological activities has been described below.

Anti-Inflammatory activity
The anti-inflammatory activity of several extracts of aerial parts of D. gangeticum (aqueous, ethanolic, petroleum, acetone, benzene and chloroform extracts) was evaluated through carrageenan-induced paw edema method on albino rats. It reported an aqueous extract of D. gangeticum, at concentration of 100 mg/kg, b.w., p.o. exerted 48.33% inhibition of paw edema, followed by ethanolic extract 39.27% inhibition, petroleum extract 38.49% inhibition, acetone 36.94% inhibition, benzene 33.12% inhibition and chloroform 33.04 % inhibition. Standard reference NSAID demonstrated significant paw edema inhibition of 54.88 % at a 100 mg/kg dose. The aqueous extract of D. gangeticum demonstrated significant anti-inflammatory efficacy in a dose-dependent manner among all extracts (46). In another carrageenan-induced rat paw oedema study carried out on male Wistar rats, different doses of ethanolic extract  (47). Furthermore, the plant's aqueous extract was tested for COX-1 (cyclooxygenase), COX-2 and LOX (lipoxygenase) inhibitory activities to determine a valid mechanism for anti-inflammatory effect. The results of the study indicated that plant extract reduces paw swelling significantly (p<0.0001) when compared to the standard medicine Ibuprofen (100 mg/kg b.w.). The % inhibitory activity of D. gangeticum AqE against COX-2 (IC50=39. 5 g/ ml) was significantly higher than that of COX-1 (IC50=49. 5 g/ml). The plant also showed moderate inhibition of LOX interest (IC50=57.0 g/ml) (48). Another study on antiinflammatory activity on albino rats revealed that standard control diclofenac sodium (10 mg/kg) reduced oedema volumes by 30.07 % and 44.95 % and oral administration of D. gangeticum water decoction reduced oedema volumes by 9.80 % and 26.74 % at the 3 rd and 6 th hrs respectively (49).

Cardiotonic effect
The aqueous root extract of D. gangeticum was effective for treating ischemic reperfusion injury at a dose of 50 mg/kg weight in rat hearts. The level of creatinine phosphokinase in the coronary perforate was lower. Significant improvement in Sarcoplasmic ATPase and mitochondrial enzymes were observed in D. gangeticum treated rat hearts. A structural improvement in the myocardium was also observed in D. gangeticum treated rats. The study revealed aqueous root extract improved cardiac function after ischemia reperfusion injury by mitochondrial and sarcoplasmic ATPase preservation in the myocardium. Gas chromatography-mass spectrometry and atomic absorption study of Shalaparni root extract the showed presence of bio-constituents that can activate the release of calcium in cardiac tissue (50).
The mechanism of action of methanol extract of D. gangeticum root was investigated for the anti-ischemic reperfusion property in an isolated frog heart and rat heart. The findings revealed that methanolic extract exerted dose-dependent negative inotropic and chronotropic effects on isolated frog hearts, mimicking acetylcholinelike action. Root extract exhibited a cardio-protective effect in the isolated rat heart model for ischemia reperfusion injury and action was similar to acetylcholine (G protein agonist). Thus, root extract showed cardioprotection through negative inotropic and chronotropic effects by activating the G-coupled receptors analogous to the action of acetylcholine (51).

Antinociceptive activity
The antinociceptive activity of the ethanolic extract of D. gangeticum leaves was evaluated in rats by thermal

Antioxidant activity
The antioxidant and experimentally induced ischaemic reperfusion effects of aqueous extract of D. gangeticum root were evaluated in an isolated rat heart. Oral administration of extract (50 and 100 mg/kg once daily for thirty days) increased enzymatic activity of superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) and reduced the lipidperoxidations. The results indicated that the liquid extract of the root has a significant radical scavenging effect (52).

Anti-Asthmatic activity
Chloroform, ethanolic and hydro-alcoholic root extracts were evaluated for the anti-asthmatic activity in ovalbumin-induced Wister rats.WBC count was significantly lower in extract-treated rats than sensitized control (ovalbumin treated) rats in the study. There was also a significant decrease in Malonyldialdehyde (MDA) levels in the experimental rats compared to ovalbumin-treated rats (53).

Antibacterial activity
The antibacterial activity of ethanol, methanol, aqueous and chloroform extract of D. gangeticum was evaluated against bacterial pathogens such as Klebsiella pneumoniae, E. coli, Streptococci, Pseudomonas aeruginosa, S. mutants and S. typhi. Amoxicillin, Ciprofloxacin, Kanamycin, Penicillin and Tetracyclin were used in the antibiotic sensi- tivity test. The methanolic extract showed the maximum zone of inhibition (24±2.3 mm) against S. mutants, whereas the aqueous extract showed the minimum zone of inhibition (7±0.08) against P. aeruginosa. Antibiotic sensitivity was also found against all microorganisms with tetracyclin, kanamycin, and ciprofloxacin. The methanolic extract of D. gangeticum had the maximum antibacterial potential among all extracts. The methanolic extract of D. gangeticum can serve as a potential antibacterial source for various infections (54).

Anti-amnesic activity
An antiamnesic effect of D. gangeticum aqueous extract was assessed at concentrations of 50, 100 and 200 mg/kg was administered orally to young and aged mice for one week. Elevated plus-maze and the fear-aggravated passive avoidance task were used to test learning and remembrance. Scopolamine (intraperitoneal) produced and ageing-linked amnesia were served as the interoceptive paradigm. Intraperitoneal piracetam (200 mg/kg) was administeredas standard memory enhancer medicine. Animals treated priorly with aqueous extracts enhanced cognitive function remarkably in both models, scopolamine induced and ageing-linked amnesia. In addition, test drug lowered acetylcholinesterase effect in brain. D. gangeticum appears to be a promising cognitive function enhancer agent (55).

Antidiabetic activity
An antidiabetic activity was evaluted wherein diabetic rats were given aerial parts of D. gangeticum extract for three weeks. Blood glucose levels were significantly decreased after 30 min in D. gangeticum-treated rats compared to the control. It was suggested that D. gangeticum might act by direct stimulation of b-cells to secrete insulin (56).
In another antidiabetic study, D. gangeticum aqueous extract exhibited good alpha glucosidase and DPP-IV (Dipeptidyl peptidase IV) inhibitory activity, with IC50 values of 950 g/ml and 255.5 g/ml respectively (57).

Antiulcer study
An antiulcer activity has been evaluated through four gastric ulcer models such as cold restraint stress induced, aspirin induced and ethanol inducedand pyloric ligation induced in Sprague Dawley rats; and histamine produced duodenal ulcer paradigmin guinea pigs. Oral administration of plant extract at 200 mg/kg dose remarkably decreased the occurrence of ulceration among all paradigms. Plant extract provided 68.37 % protection against cold restraint stress, 38.2 % protection against aspirin, 40.63 % against pyloric ligation and 63.15 % protection against histamine induced ulcer models, whereas active comparator omeprazole provided protection of 83.86%, 56.35%, 70.31% and 84.21% in respective models. Plant extract reduced gastric juice secretion by 41.61 %, whereas omeprazole reduced it by 43.13%. Plant extract administration increased 56.17 % in mucin secretion, whereas 12.45 % rise was observed in omeprazole treated group (58).
In another study where in root extract oraly administered remarkably protected the gastric ulcer by reducing size and lesion number in a concentration-depending way at the doses of 50 mg/kg, 100 mg/kg and 150 mg/kg against an ethanol-induced gastric ulcer model in mice. Prior treatment of plant extract also decreased ulcer index in chronic state in Pylorus ligated mice model. At higher concentration (150 mg/kg), the plant extract increased protein and glutathione levels significantly. Moreover, concentration-dependent significant reduction was observed in gastric secretion, free acidity and total acid output in extract-trated animals suggesting potential of gastroprotection of plant extract through regeneration of gastric mucosal injury (59).

Renal protective study
Renal protective activity of D. gangeticum was observed along with antidiabetic activity in Streptozotocin-induced diabetic rats. The administration of D. gangeticum ethanolic extract (100, 200 and 400 mg/kg body weight) for 30 days lowered levels of renal markers (Blood Urea Nitrogen (BUN), Serum Creatinine and Urea) in dose depending manner, indicating its renal protective potential (60).

Anti-histaminic activity
The in vitro anti-histaminic activity was investigated against histamine-induced contraction of isolated guinea pig ileum. At the dose of histamine (100 ng/ml bath fluid), D. gangeticum produced 41.33% inhibition of histamine-induced contraction of guinea pig ileum (62). In another study on the same model, D. gangeticum produced 41.86% inhibition of histamine-induced contraction of guinea pig ileum (43).

Antidiarrheal activity
Antidiarrheal activity against castor oil-induced diarrhea was conducted in Wistar albino rats. A concoction of D. gangeticum showed significant antidiarrheal activity against castor oil-induced diarrhea in ratscompared to the castor-oil control group (43).

In vitro Mast cell stabilization study
In vitro Mast cell stabilization study, the aqueous and methanolic extract of D. gangeticum exerted the mast cell stabilization effect in a dose-dependent manner against control (compound 40/80) in the isolated mesentery of albino rats (43,62).

Bronchitis
A randomized, open-labeled, single-centric clinical trial was conducted for evaluating efficacy of D. gangeticum on bronchitis. Arm of patients was treated with 50 ml decoction of D. gangeticum and another with 50 ml decoction of Pseudarthria viscida for 2 weeks. Participants were randomly divided into D. gangeticum and P. viscida groups. D. gangeticum exhibited better effectiveness compared to P. viscida on bronchitis symptoms. However, the difference was not statistically significant. The small sample size, open-labeled study and Ayurvedic drug control were limitations. Thus, D. gangeticum needs to be further evaluated in a sufficient sample size with a standard control from a conventional system of medicine to assess the effect on bronchitis (62).

Gout
The effectiveness of D. gangeticum on Vatarakta (gout) was investigated through a randomized, double-blind, single-centric clinical trial. In the trial, total 76 participants were randomized equally in two arms, receiving either 50 ml decoction of D. gangeticum or Flemingia strobilifera for one month. At the end of the trial, symptomatic improvement was observed in both groups (63). In another randomized, double-blind, single-centric clinical trial, comparing the effect of D. gangeticum and Desmodium laxiflorum on gout (Vatarakta), was conducted (64). Total 66 patients were randomized, wherein 33 were treated with D. gangeticum decoction and 33 with D. laxiflorum decoction for one month. The outcome was clinical improvement in the symptoms. At the end of the trial, clinical improvement was observed in both groups. The small sample size and Ayurvedic drug control were limitations of both trials. Thus, further study on D. gangeticum is needed with a sufficient sample size and having appropriate control to assess its effect on gout.

Hypertension
The effect of the drug on hypertension was also assessed by randomized control trial. Patients were randomly divided into two groups (30 each group). One group of patients were treated with active control Telmisartan-20 mg or 40 mg per day, and another group of patients with Shalaparni Ksheerapaka (D. gangeticum processed with milk), 150 ml twice a day for 45 days. The active control Telmisartan reduced blood pressure better compared to it. However, D. gangeticum improved the hypertension symptoms and the cholesterol level. The sample size was small which compelled further clinical evaluation (65).

Discussion
D. gangeticum is believed to be native to India and also found in tropical Africa and Australia. Other than that, it has also been famously used as medicinal herbs, mainly as an ingredient of Dashamoola formulation in Ayurveda, the Indian traditional system of medicines since ancient times. Its documented therapeutic uses recorded in Ayurvedic texts are oedema, fever, cough, worm infestation, dysp-noea, diarrhoea, vomiting, pain and inflammation. Other than that, it is also used therapeutically in various ways by many ethnic groups for snake bites, diuretic, antitoxic, goiter, gynecological diseases, premature ejaculation, cold, abdominal pain and menstrual ache. Many of these claims have been evaluated experimentally via in vitro and in vivo techniques of biological evaluation and confirmed its bio-activities.
Due to high medicinal values, its root, stem and leaves have been evaluated extensively through phytochemical investigations and revealed many bio-active phytochemical contents, viz. Gangeticoside, Leonuriside A, Methyl benzoate 2-O-β-D-glucopyranoside, Tortoside A, Dehydrosoyasaponin, gangetin, gangetinin, desmocarpin, desmodin etc. Further, phytochemical and in-silico study assessing ADME properties of selected pterocarpan of D. gangeticum viz. gangetin, gangetinin, desmocarpin and desmodin revealed drug-likeliness of molecules (66). It may lead to further exploration of these molecules for effective drug development. There is still a lot of confusion about the pharmacological effects of plants that are influenced by their known or unknown compounds. Thus, structure-guided isolation and identification of the bioactive components are needed to understand these active compounds' structure-activity relationship.
Experiment on animal models suggested D. gangeticum can be confirmed to possess anti-inflammatory, antinociceptive, antiamnesic, antidiabetic, antiulcer, antibacterial, antidiarrheal and antioxidant, antitussive, antihistaminic, hepatoprotective, renal protective and cardioprotective activities. However, the biochemical mechanisms of D. gangeticum on the human body remain largely unexplored. Various bio-activities of D. gangeticum may be attributed to multiple compounds rather than a single molecule. D. gangeticum containing multi-components may produce multi-target activities that are difficult to detect by the present pharmacological one-target, onedrug approach. A new approach is required to understand multi-component effects of traditional medicine's effects. Network pharmacology, a novel approach in systems biology, may satisfy the need for herbal medicines and effectively explore the mechanism of the biochemical pathway for multi-components herbs (67,68).
Presently, natural source is its only source. As D. gangeticum is a high-demand herb of Ayurveda, its root is being collected from natural source. It may lead to its scarcity and adulteration in the market for commercial purposes. Ayurvedic Pharmacopoeia of India also recommended the whole plant alternate to the root (69). An effort has also been made to find alternate sources for the root. Aerial parts and other closely related Desmodium species were evaluated for alternate sources through insufficient preliminary investigations (70,71). However, further experiments were highly warranted to confirm the alternate source. Adulteration is a considerable concern for traditional medicines due to the lack of an effective quality control system that provides genuine and highquality herbs for therapeutic use. The scientific and reliable quality assurance system complying with the characteristics of traditional medicine is yet to be entirely con-structed.
Considering traditional Ayurvedic uses and preliminary animal experiments, few clinical trials were conducted to evaluate the therapeutic effect of D. gangeticum on various diseases, viz. hypertension, bronchitis and gout, and showed a trend towards benefits. However, its findings are uncertain as all trials had a small sample size and concern of bias. Well-designed randomized clinical trials are warranted to prove the therapeutic benefits of the species.

Conclusion
Desmodium gangeticum has been used in Ayurvedic medicine for centuries. The thorough literature review revealed that it is an essential source of medicinally important compounds such as gangetin, gangetinin, desmocarpin and desmodin.The plant has also been widely studied for its various pharmacological activities like anti-inflammatory, antinociceptive, antioxidant, cardioprotective, antidiabetic, hepatoprotective, antibacterial and antiamnesic activities. It was also evaluated clinically in bronchitis, gout, hypertension for possible therapeutic benefits through clinical trials. Despite the positive results of the review, there are some limitations observed in the present literature on the use of the plant as a multi-purpose therapeutic agent. The biochemical and physiological mechanisms involved in the different biological effects exhibited by D. gangeticum need to be investigated. Further research is required focusing pharmacodynamic, pharmacokinetic and safety profiles to validate its efficacy reported through preliminary animal experimentations. Moreover, welldesigned RCTs should be conducted to support its therapeutic use.

Authors contributions
DV participated in data search, wrote the original draft and serve as a corresponding author. HV contributed to conception and designing of article and reviewed the original draft. KP and BP interpreted the data, reviewed and edited the original draft critically. PS, AV and SP contributed in data search and writing the original draft. All authors read and approved the final manuscript.