Morphological, Ethno biological and Phytopharmacological Attributes of Tridax procumbensLinn. (Asteraceae): A Review

Tridax procumbens Linn. is an widespread herbaceous weed distributed throughout India. It is commonly known as coat buttons, is also dispensed as Bhringraj, and used as Ayurvedic medicine for liver disorders and hair growth. The plant is an annual or perennial herbaceous weed, found mainly in the croplands, disturbed areas, lawn, and roadsides. Literature survey suggested that the various parts of the plant were reported to possess phytochemical compounds like alkaloids, carotenoids, flavonoids, saponins, fumaric acid, β-sitosterol, and tannins. It was richly endowed with oleanolic acid, and high content of sodium and potassium are also present. Bioactive components like luteolin, glucoluteolin, quercetin, and isoquercetin also have been reported from its flowers. Primary plant pigments such as chlorophyll and carotenoids also analyzed from leaves. So, it is well known for several potential pharmacological activities like anti-microbial, anti-oxidant, wound healing, insecticidal, hepato-protective, anti-diabetic, immune modulating, anti-cancer, anti-dysentery, anti-inflammatory, and anti-hair fall. The present review study deals with natural habitat, taxonomical, phytochemical, pharmacological and toxicological activities of Tridax procumbens. This study may be helpful for identification and preparation of a clear profile of the plant which may open new avenues in the medical field in the treatment of various diseases. KeywordsTridax procumbens, Medicinal Weed, Ethnobotany, Morphological, Phytopharmacology.


INTRODUCTION
Tridax procumbens Linn., (Figure 1) commonly known as Coat Buttons or Tridax Daisy, belongs to the family of Asteraceae. In West Bengal, it is known as Tridhara or Bishalyakarani [1]. It is a small, semi prostate, annual or perennial and herbaceous creeper weed having short, hairy blade-like leaves. Corolla is yellow color. The stem is elongated to the height of 20-60 cm tall, branched, sparsely hairy, rooting at nodes. Leaves are simple, opposite, stipulate, lanceolate or ovate. 4-8 cm long, toothed margin, base wedge-shaped, shortly and petiole, hairy on both surfaces. Flowers are tubular, yellow with hairs, inflorescence capitulum. The plant has two types flower, ray florets and disc florets [2]. The plant is screened for the presence of phytochemical constituents, and anti-oxidant properties [3,4,5] and the results obtained from this investigation have aided in the rationalization of the medicinal use of this plant [6,7].From earlier researches, it was already showed the presence of dexamethasone, luteolin, glucotureolin, β-sitosterol, flavone, glycoside and quercetin in this plant [8,9,10]. The plant has been established for the treatment of wound healing [11], dysentery [12], epilepsy, malaria [13], stomachache, diarrhea, high blood pressure, diabetes [14], hemorrhage and metabolic syndrome [15]. It also possesses insecticidal, anti-septic, parasiticidal and hepato-protective properties and has marked depressant action on respiration [16,17,18]. It is a well-known ayurvedic medicine for liver disorders or hepato-protective nature besides gastritis and heartburn [19]. This plant is also used as bioabsorbent for removal of harmful Cr (VI) from the industrial wastewater [20].

Taxonomic Classification Kingdom
Plantae Subkingdom Tracheobionta Division Spermatophyta Subdivision Magnoliophyta  Leaves: Leaves are opposite, simple, carried by a petiole, 1 to 2 cm long. They are thick, soft and dark green. The lamina is oval to lanceolate, 2 to 6 cm long and 2 to 4 cm wide, base attenuate in the corner and with strongly and irregularly serrated margin ( Figure 4). Both sides are hispid, with tuberculate based bristles. Pubescence is most abundant on the underside.  Figure 5), held by a peduncle, 12 to 32 cm long, abundantly hispid. The bracts of the involucre are arranged in 2 rows. They are oval to lanceolate; 6 mm long, pubescent and green. Flower: Capitulum formed of 3 to 8 ligulate daisy like female flowers, creamy white on the periphery of capitulum, tridentate ( Figure 6). In the center of capitulum, flowers are yellow, tubulate bisexual. The tube, 6 mm long, with five short tines at the top. This plant has two types of the flower as ray florets and disc florets with basal placentation.   (Figure 7).The root is a strong taproot ( Figure 8) system [26]. Genetics: The chromosome numbers of Tridax procumbens has been registered as 2n=36 [27].

III. TRADITIONAL USES
Tridax procumbens is a widespread weed and a flowering plant that contains various medicinal values. Traditionally, it has been used in India as anti-coagulant, anti-microbial, insect repellent and as a wound healing agent. It is also used to cure boils, and blisters. This medicinal plant is widely used as a folk medicine like ulcer and hair tonic. Its leaf decoctions were known to treat infectious skin diseases in ethno medicines. It is a well-known ayurvedic medicine for liver disorders because the plant decoctions are acted as hepato-protective in nature. Besides the extracts are also used in gastritis and heartburn [28].It is widely used in wound healing to stop hemorrhage from cuts, bruise, and wounds. The plant is also used to reduce high blood pressure and blood glucose level as well as in dysentery and severe diarrhea [29,30,31].
It can be used to prevent falling of hair, and it promotes the growth of hair. The plant is also used in respiratory treatment. It has potent immuno-modulating and insect repellent activity [32].In West Africa and the tropical zone of the world, rural medical practitioners and the tribal peoples use the leaves of the plant as a remedy against conjunctivitis [33]. This medicinal herb was also used in the ethnic system against jaundice and in liver disorders [34]. Ethanol decoctions of Tridax procumbens were also used for curing kidney stone diseases [35].

IV. PHYTOCHEMICAL CONSTITUENTS
In various research studies, it was showed that the plant has different phytochemical compounds. From the phytochemical screening, it was observed that alkaloids, carotenoids, saponins, flavonoids, and tannins are present in this medicinal plant. The proximate characteristics showed that Tridax procumbens is rich in sodium, potassium, and calcium [36].In an earlier research study, it has been estimated that the leaf of the plant mainly contains crude proteins 26%, crude fiber 17%, soluble carbohydrates 39%, and calcium oxide 5%. On the other hand, luteolin, glucoluteolin, quercetin, and isoquercetin have been reported from its flowers.Fumaric acid, β-sitosterol also has been reported in the plant [37]. Oleanolic acid which was obtained in reasonable amounts from this plant found to be a potential anti-diabetic agent when tested against alpha-glucosidase [38].
A new bisbithiophene named tri-bisbithiophene along with four known terpenoids such as taraxasteryl acetate, β-amyrenone, lupeol, and oleanolic acids were isolated from the ethyl acetate soluble part of hexane decoctions of this plant [42]. With the help of graded ethanol precipitation followed by mild delignification and size-exclusion chromatography, two water-soluble polysaccharide fractions, WSTP-IA and WSTP-IB were purified from the leaves of Tridax procumbens [43].
In a research study, the plant pigments of Tridax procumbens along with some other ethno medicinal plants were estimated. The study showed that total chlorophyll content was 1.424 mg/g tissue and total carotenoids content was 0.724 mg/g tissue in this plant. Other two plant pigment research studies observed that these plant pigments content may fluctuate due to the various environmental or other biogeochemical factors like effects of air pollution and it may differ with seasonal changes also [44,45,46].

V. PHARMACOLOGICAL PROPERTY
Various solvent extracts of Tridax procumbens have been investigated, and it showed different biological activities in animal models and reported to possess anti-oxidant, anti-microbial, wound healing, anti-malarial, anti-cancer, blood coagulation, repellency, anti-inflammatory, hepato-protective, immune-modulatory, anti-diabetic, anti-lithiatic, anti-obesity, antihyperglycemic, analgesic, hemostatic and hypotensive properties. These bioactivities are described as follows.

Anti-oxidant Activity
The free radicals scavenging activity of the Tridax procumbens fractions and Ascorbic acid was measured in terms of hydrogen donating or radical scavenging ability using the stable free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) [47]. The antioxidant activity of the fractions was expressed as IC 50 which was defined as the concentration (mg/ml) of methanol extract fractions that indicates the formation of DPPH radicals by 50% [48].

Anti-bacterial Activity
In an earlier research study, it has reported that the whole plant parts of Tridax procumbens have anti-microbial activity on various species of bacteria. An entire plant is squeezed between the palms of hands to obtain juice which is applied twice a day for 4-5 days to cure cuts and wounds. The extract of the whole plant showed anti-microbial property only against Pseudomonas aeruginosa with the help of disk diffusion assay. Four strains of bacteria employed in a test among them two were grampositive Bacillus subtilis, Staphylococcus aureus and two were gram-negative Escherichia coli and Pseudomonas aeruginosa [49]. Only ethanol extract was prominently showed this activity only against Pseudomonas aeruginosa strains. Multidrugresistant nosocomial strains of Pseudomonas isolated from ventilator-associated pneumonia, urinary tract infection as well as bloodstream infection showed significant sensitivity to extracts. This study showed the efficacy of Tridax procumbens as an anti-pseudomonal agent as well as a source of formulations for the treatment of nosocomial infections caused by Pseudomonas aeruginosa [50].

Wound Healing Activity
Wound healing activity of the plant decoction involves a complex interaction between epidermal and dermal cells, the extracellular matrix, controlled angiogenesis, and plasma-derived proteins all coordinated by cytokines and growth factors [51]. Waterleaf decoctions were also effectively increasing lysyl oxidase but to a lesser degree than whole plant decoctions. It has been observed that the extract of leaves of this plant promotes wound healing in both healthy and immune-compromised rats. The plant can increase lysyl oxidase as well as protein and nucleic acid content in the granulation tissue, as a result of the increase in glycosaminoglycan content [52].

Anti-fungal Activity
In a research study, disc diffusion method was performed against two fungal strains namely, Aspergillus flavus and Aspergillus niger to determine the antifungal activity of the plant decoctions.Total activity was observed by minimum inhibitory concentrations and by minimum fungicidal concentrations.The flavonoidsdecoction showed the highest activity against Aspergillus niger, but alkaloids decoction showed no activity against both the test fungi [53].

Anti-malarial Activity
The water and ethanol decoctions have anti-plasmodial properties against chloroquine-resistant Plasmodium falciparum. The decoctions have low toxicities to human RBCs though further animal toxicity studies need to be carried out on the plant [54].

Anti-cancer Activity
The plant-derived compounds were used to observe the cytotoxicity against human lung cancer cell line by MTT assay. The compound showed 90% reduced cell viability. The result of NMR, MS and IR spectra revealed that the compound is Lupeol. The anti-cancer potential of the Lupeol against human lung cancer cell line has been evaluated by clonogenic survival determination, cell cycle control, Cell-based assay for inhibition of COX-2 activity and DNA fragmentation. The analysis showed that 320 μg/ml concentration of Lupeol compound exhibited significant anti-cancer activity [55].

Blood Coagulation and Haemostatic Activity
Water decoctions of leaves showed significant blood coagulation activity, and for that reasons, it may be used as a potent haemostatic agent [56]. The haemostatic property of the leaves of the plant of the various solvent extracts was determined in vitro by employing Lee-White's method as the ethanol extract reduces the clotting time in the blood samples of all the experiments [57].

Repellency Activity
In a research study, essential oils were extracted by steam distillation process from leaves and investigated for its local repellency activities against malaria parasite Anopheles stephensi in mosquito cages [58,59]. All essential oils were tested at three various concentrations. The essential oils of the plant exhibited noticeable repellency effect [60].

Anti-inflammatory Activity
Tridax procumbens have significant anti-inflammatory properties. The anti-inflammatory action of the plant decoction may be due to corticotrophic influence as evident from the increase in weight [61].The active fraction of the plant was ethyl acetate fraction and was found to contain moderate polar natural compounds: alkaloids and flavonoids. These bioactive compounds have applied in counteracting reactive oxidative species indicated the pathogenesis of inflammation and related ailments [62].

Hepato-protective Activity
The hepato-protective property of leaves showed significant protection in the alleviation of D-Galactosamine/Lipopolysaccharide-induced hepato-cellular injury. Both the compounds have been proposed to be hepato-toxic due to its ability to damage liver cells. The multifocal necrosis produced by D-Galactosamine and the lesion of viral hepatitis in humans is similar. This amino sugar bloc the transcription process and indirectly hepatic protein synthesis and as a consequence of toxicity; it causes hepatitis within 8 hr after administration [63].

Immuno-modulatory Activity
Ethanol decoctions of leaves of the plant have shown an immune-modulatory effect in an animal model [64]. Stimulation of immune response was also observed along with an elevation in haemo-agglutination antibody [65].

Anti-diabetic Activity
Water and alcoholic decoctions of leaves showed a significant decrease in the blood glucose level in the animal model. The oral administration of acute and sub-chronic doses of 50% methanol decoctions significantly reduces fasting blood glucose levels in diabetic rats [66].The plant extracts have been widely used in various herbal drugs and is also reported to possess the activities of lowering blood glucose levels. The oral administration of water, alcoholic and petroleum ether decoctions of the leaves on animals at a dose level of 200 mg/kg of body weight orally administered for seven days. Among these water and alcoholic decoctions significantly reduces the blood glucose level in the animal model and petroleum ether extract exhibits a feeble anti-diabetic effect [67].

Anti-lithiatic Activity
Ethanol extract of the plant was also used for treating kidney stone disorders. It showed activity against 0.75% v/v ethylene glycol and 2% w/v ammonium chloride induced calcium oxalate urolithiasis, and hyperoxaluria induced oxidative stress in animal models. Treatment with the decoctions of the plant was able to reduce calculogenesis induced urinary excretion and renal deposition of calcium oxalate and resultant lipid peroxidation, indicating anti-urolithiasis and anti-oxidant effects [68,69].

Anti-obesity Activity
In a research investigation, the animal receiving treatment with the plant decoctions showed a significant reduction in total cholesterol, triglycerides, total protein, free fatty acids and elevation of high-density lipoprotein cholesterol levels [70].

Analgesic Activity
Lyophilized decoctions of the plant were found to be potential analgesic [71].

Hypotensive Activity
The cardiovascular effect was obtained from the water decoctions of leaves were investigated on anesthetized animals. The water decoctions can cause significant dose-dependent decreases in the mean arterial blood pressure. The higher dose leads to a significant reduction in heart rate whereas lower dose did not cause any changes in the same [72].

Toxicity Studies
From various research studies, the decoctions of Tridax procumbens were reported to have different pharmacological effects. The acute toxicity study was done by using the method of Lorkes [73]. The result of acute toxicity was based on intraperitoneal administration where the compound in the decoctions was directly transported through the blood and circulated to the target organ to exhibit their toxicity. The administration to the test animal was oral, and the LD 50 may be much higher since the decoctions will undergo metabolism to produce a new product which could be less toxic. After acute administration, signs of toxicity observed including salivation, nose, and mouth on the floor of the cage and restlessness. The LD 50 of the decoctions was 2100 mg/kg body weight, and all the survived animals gained body weight and organ ratio as compared to the untreated control [74].
Results from short term toxicity studies of the crude ethyl acetate decoctions of the plant were concluded that the liver of test animals was significantly affected at all the dose levels. There was a significant increase in ALT and decrease in AST effects [75].The reduction in the serum AST activity following administration of the decoctions may be attributed to the reduced rate of synthesis in the liver. The rise in the ALT activity may imply that the administration of the decoction has resulted in hepatocellular destruction that leads to the leakage of these enzymes into circulation. The administration of the decoction did not produce a significant increase in ALP activity. In histopathology, there was old hemorrhage indicated by haemosiderin deposition throughout the entire liver and kidney tissues [76].

VI. CONCLUSION
Tridax procumbens Linn. has enormous potential for botanical, phytochemical, nutritional and pharmacological properties. From the above review study and explanation, it is observed that the plant has been extensively used in the ancient system of medicine for various biological disorders and it possess various prominent phytopharmacological activities, as it is briefly discussed in the review article. There is vast scope for research in the direction of more pharmacological activities of this plant and to elucidate the mechanism of action of the same in the future. This medicinal plant can be a vital source of herbal drugs for the pharmaceutical industry in the future as well [77,78].