Taxonomic and phytomedicinal properties of Oroxylum indicum ( L . ) Vent : A wonderful gift of nature

This paper is a review on pharmacological studies, phytochemical analysis and problems associated with natural seed germination of Oroxylum indicum (L.) Vent. The different parts of this plant like leaves, fruits, stem bark, seeds and roots are used in indigenous medicine preparation against various diseases. Chemical investigation of various parts of this plant resulted in characterization of various bioactive principles. It shows antioxidative, antitumour, antiinflammatory, analgesic, antimicrobial and hepatoprotective activity. Due to significant medicinal properties and continuous increasing demand, this plant has been put in endangered category (IUCN).


INTRODUCTION
Over the last thirty years, medicinal plants are 'important' natural resources used by indigenous medicinal system for treatment of diseases.A list of 243 commonly used medicinal plants is drawn having great demand for manufacture of mixtures, compound formation and potent medicine by the Central Council of Research on Ayurveda and Sidha (Thatoi, 2008).The Indian Himalayan Region (IHR) recognized amongst 34 biodiversity hotspots in the world.It contains about 1,748 different species of medicinal plants (Samant et al., 1998).
Among different medicinal plants of IHR, Oroxylum (Family: Bignoniaceae) possess high economical, ecological and medicinal importance and has about 112 genera and more than 725 species of trees, shrubs and vines spreading all over the world.
Oroxylum indicum is a small to medium sized deciduous tree widely distributed in tropical and subtropical regions.This plant is native to the Indian subcontinent, in the Himalayan foothills with a part extending to Bhutan, South China and Malaysia ecozone (Lawania et al., 2010).In India, it is distributed in Eastern and Western Ghats and North East India (Jayaram and Prasad, 2008).North East India comprising the states of Arunanchal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura lying between 21°34´N to 29°50´N latitude and 87°32´E to 97°52´E longitude (Mao et al., 2009).
The English name of this plant is "Indian trumpet flower" and commonly known as "Shyonaka".It grows upto 10 to 12 m with light grayish brown, soft and spongy bark, in its natural habitat.Leaves are compound, 60 to 120 cm in length, pinnate and stipules are absent.The flowers are bisexual and zygomorphic.Androecium consists most commonly of didynamous stamens that are attached to the corolla tube.The gynoecium consists of a single compound pistil of two carples, a single style and a superior ovary with typically two locules, each bearing numerous axile ovules.An annular or cupular nectary disk is usually found around the base of ovary.The fruit is capsular with winged seeds or sometimes indehiscent with wingless seeds (Angiosperm phylogeny website, Wikipedia).O. indicum is chiropterophilous in nature, and while studying its pollination ecology it has been reported that dawn bat Eonycteris spelaea is the pollinator of O. indicum in Western Malaysia and Leschenault's Rousette (Rousettus leschenaultii) as a pollinator in India (Fujita, 1991).
O. indicum lives in relationship with an actinomycete Pseudonocardia oroxyli, a high-G+C-content, Grampositive bacterium, strain D10T present in the soil surrounding the roots.Based on 16S rRNA gene sequence analysis, strain D10T was a member of the genus Pseudonocardia and was most closely related, albeit loosely, to Pseudonocardia halophobica.(Gu et al., 2006).Numerous studies have indicated that these prolific actinobacteria appear to have a capacity to produce an impressive array of secondary metabolites exhibiting a wide variety of biological activity, such as antibiotics, antitumor and anti-infection agents, plant growth promoters and enzymes, and may contribute to their host plants by promoting growth and enhancing their ability of withstanding the environmental stresses (Qin et al., 2011).In nature, different developmental stages of O. indicum are shown in Figure 1.
Therefore, this study was done to evaluate the different medicinal properties of O. indicum and to explore the need of conserving this plant.

CHEMICAL CONSTITUENTS OF O. INDICUM
The plant O. indicum contains flavonoids like chrysin, oroxylene, and baicalein as active principal component (Choudhury et al., 2011).From the seeds of O. indicum, amounts of bioactive flavonoids such as baicalein-7-odiglucoside, baicalein-7-o-glucoside, baicalein, chrysin, and apiagenin have been identified (Chen et al., 2003).Flavonoids such as chrysin, oroxylin-a, scutellarin, baicalein, biochanin-a and ellagic acid shows antiarthritic, diuretic, antifungal, anti-inflammatory and antibacterial activities (Zaveri et al., 2008).Chemical investigations of acetone and hexane extracts of stembark resulted in isolation and characterization of two new flavonoids which are found to possess gastroprotective activity (Babu et al., 2010).The root extracts of O. indicum inhibited the activity of both enzymes-5lipooxygenase and cyclocoygenase (Ali et al., 1998).Seeds of this plant are also reported to contain ellagic acid, which is an important polyphenolic compound (Sastry et al., 2011).Flavones, sterols and prunetin have been reported in different parts of O. indicum (Chen et al., 2003).Different phytochemical and their quantitative Joshi et al. 1149 values are as shown in Table 1.

TRADITIONAL/FOLK USES
"Shyonaka" is a wonderful plant because almost every part such as leaves, stem bark, root bark, and fruits possess medicinal properties.It has been used in several traditional Ayurvedic and Folk medicines.The root bark of this plant is reported to be administered as astringent, bitter tonic, stomachic and anodyne.The root bark is an important ingredient in famous tonic formulations such as Chyawanprash, Dashmularisht, Narayan taila, Bhrama Rasayna, Dhanwatara, etc., (Sastry et al., 2011).
The decoction of the bark is taken for curing gastric ulcer and a paste made of the bark powder is applied for mouth cancer, scabies and other skin diseases.The seed is ground with fire-soot and the paste applied to the neck for quick relief of tonsil pain.Also, a paste made of the bark is applied to the wounds of animals to kill maggots.Decoction of the bark is given to animals for de-worming.The sword-like fruit or a branch of the plant is used by the farmers to kill crabs in wet paddy fields (National Innovation foundation-India).Mature fruits are acrid, sweet, anthelmintic, and stomachic.They are useful in pharyngodynia, cardiac disorders, gastropathy, bronchitis, haemarrhoids, cough, piles, jaundice, dyspepsia, smallpox, leucoderma and cholera (Warrier et al., 1995).Seeds are used as purgative.Dried seed powder is used by women to induce conception.Seeds yield non-drying oil used in perfume industry.The seeds are ground with fire soot and the paste is applied to the neck for quick relief of tonsil pain.The medicated oil of O. indicum in sesame oil base instilled into ears mitigates the pain in otitis (Chauhan, 1999).Roots are sweet, astringent, acrid, refrigerant (Yoganarasimhan, 1996), aphrodisiac, expectorant, carminative, digestive, anthelmintic, constipating, diaphoretic, diuretic, antiarthritic, antidiabetic and febrifuges.Tonic is useful in dropsy, cough, sprains neuralgia, hiccough, asthma, bronchitis, anorexia, dyspepsia, flatulence, colic, diarrhea, strangury, gout, vomiting, leucoderma, wounds, rheumatoid arthritis and fever.Root bark is used in stomatitis, nasopharyngeal cancer and tuberculosis (Khare, 2004;Bhattacharje, 2005).
It is believed to have been prescribed by Malayasians to treat toothache, wound, splenomegaly, gastralia, dysentry, cholera, loss of appetite and fever.Any part of the plant may be used for making a decoction for external uses in childbirth.In Philippine Islands, the bark of the root is claimed as a diaphoretic.An alocoholic maceration of fresh bark is applied externally as a lacquer to relieve allergic dermatitis (Herbal Medicine Research Institute, 2002).In Vietnamese folk medicine, a decoction of the seeds is used for cough, bronchitis and gastritis.
In China, the seeds of O. indicum are used to cure liver and stomach problems and to heal ulcers and boils.In Table 1.Quantitative phytochemical values (D' Mello et al., 2012).
Total tannins Total glycosides Total phenolics dry weight Total phenolic acids mg/g dry weight 10.63% w/v 12.95% w/v 1.436 1.275 ± 0.062 Burma, Vietnam and Philippines, the bark is used to treat dysentery and rheumatism (Choudhury et al., 2011).

PHARMACOLOGICAL USES
O. indicum seeds, leaves, stem bark and root bark are used in treatment of remittent fever, otorrhoea, bronchitis, leucoderma, diarrhea, inflammation and acute rheumatism (Bisht et al., 2011;Sastry et al., 2011).Various medicinal properties are shown Table 2.The different chemical extracts from stem bark, fruits and roots have different pharmacological activities.

Antitumor activity
Root bark of O. indicum shows antiproliferative activity on HL-60 cell line and anticancerous on CEM, B-16 and HCT-8 cell lines (Thatoi et al., 2008).Baicalein, the most abundant flavonoid present in the leaves of O. indicum has been isolated and tested on the viability and induction of apoptosis in the HL-60 cell line.Pretreatment with baicalein for 24 h caused a 50% inhibition of HL-60 cells at concentrations of 25 to 30 μM exposure of HL-60 cells to 10 to 20 μM baicalein for 36 to 48 h caused the cells to accumulate at S or G2M phases.The result of the study indicated that the baicalein has anti-tumor effect on human cancer cells (Roy et al., 2007).Non-polar extracts of O. indicum (especially PHO, petroleum ether hot extract) can effectively target Estrogen Receptor (ER)negative breast cancer cells to induce apoptosis, without harming normal cells by cancer-specific cytotoxicity.Hence, it could be considered as an extract with candidate precursors to possibly harness or alleviate ERnegative breast cancer progression even in advanced stages of malignancy (Kumar et al., 2012).
The antitumor property of O. indicum has been evaluated in the experimental animals induced by different types of carcinogens, and in human cell lines by a number of experiments.Ethanolic extract of O. indicum was found to have antiproliferative effect on Hep 2 cell lines.Ethanolic extract exhibited cytotoxic activity against the Hep 2 cell lines at a concentration of 0.05% (Narisa et al., 2006).(Zaveri et al., 2008;Choudhry et al., 2011).

Antioxidant activity
The production of different oxidative species and free radicals due to stress leads to adverse effects on various vital organs and tissues of body.Antioxidants are now standing on the mainstay of the treatment and prevention of several diseases (Uttara et al., 2009).Current research is directed towards finding naturally occurring antioxidants particularly of plant origin.In vitro antioxidant activity of n-butanol extract of stem and root bark of O. indicum was determined by 2, 2′-Azino-bis(3ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical cation decolorization assay and reveals the presence of very high significant antioxidant activity (Zaveri and Dhru, 2011).In vitro antioxidant activity (IC 50 22.7 μg/ml) was the highest in methanolic extract of stem bark of O. indicum (Moirangthem et al., 2013).The ethanol extract of stem bark exhibited maximum antioxidant potential due to its free radical scavenging activities in b-carotene bleaching assays, whereas chloroform extract showed maximum reducing power in total antioxidant activity may be due to its reducing potential (Kalaivani and Mathew, 2009).The ethyl acetate extract (EAE) of stem bark showed the lowest IC 50 value (0.76 mg/ml) with the highest inhibition of 2, 2-diphenyl-1picrylhydrazyl (DPPH).In the ferric reducing antioxidant power (FRAP) assay, the hexane extract (HE) showed the highest ferric reducing ability whereas the EAE showed better antioxidant ability with the lowest IC 50 value (0.80 mg/ml) (Kumar et al., 2011) (Ahad et al., 2012).

Antiinflammatory activity
O. indicum is found to possess an efficient antiinflammatory activity.Dichloromethane extract of the stem bark and root of O. indicum were found to have antiinflammatory properties (Ali et al., 1998).Different extracts of O. indicum against experimental acute and chronic inflammatory model has proven the occurrence of anti-inflammatory activity in the plant extracts.O. indicum showed most promising NF-kappa B inhibitory effect with the lowest IC (50) value and is identified as Thai antiinflammatory remedy (Siriwatanametanon et al., 2010).Arya and Arya (2011) reported that O. indicum have flavones and glycosides such as baicalein and scutelarcin which imparts anti-inflammatory effect to its bark.
The antiinflammatory activity was evaluated by carageenan induced rat paw edema model in rats using diclofenac sodium as standard drug.Two doses 150 and 300 mg/kg of aqueous extract of O. indicum were used.Result showed that paw volume was significantly reduced in dose dependent manner as compared to control.Extract at a dose of 300 mg/kg showed maximum antiinflammatory activity.However, the activity produced by both the doses was less than the reference standard.Extract at both doses showed significant (P<0.05)antiinflammatory activity at 5 h suggesting that the extract predominantly inhibit the release of prostaglandin like substances (Upaganlawar et al., 2009).

Antimicrobial activity
The anti-microbial activity of various extracts of O. indicum has been screened against various pathogens and reveals the use of plant extract and phytochemicals for therapeutic treatment (Das and Chaudhry, 2010).The antimicrobial activity of crude extract of O. indicum (petroleum ether, ethyl acetate and methanol), compound 1 (2,5-dihydroxy-6,7-dimethoxy flavone) and compound 2 (3, 7, 3 ' ,5 ' -tetramethoxy-2hydroxy flavone) was tested against fourteen pathogenic bacteria (5 Gram-positive and 9 Gram-negative) and seven pathogenic fungi.Nutrient agar and nutrient broth were used as bacteriological media and potato dextrose agar (PDA) was used for fungal growth.In antibacterial screening, each sample was dissolved in methanol at a concentration of 200 μg/10 μl.The activity of these samples was compared with standard kanamycin disc (K-30 μg/disc) using the standard disc diffusion method.Similarly, antifungal screening was done at a concentration of 300 μg/disc for each sample and the activity was compared with the standard clotrimazole disc (K-30 μg/disc).From the antibacterial and antifungal experimental results, it was evident that the crude extracts (petroleum ether, ethyl acetate) and compounds 1 and 2 showed significant antibacterial and antifungal activity, but were less potent than that of standard kanamycin and clotrimazole, whereas methanol extract showed little activity.The findings support the use of O. indicum in traditional medicine for the treatment of bacterial and fungal infection (Chopade et al., 2008).The antimicrobial activity of 40 medicinal plants has been examined from Similipal Biosphere Reserve, Orissa, India.O. indicum was one of those plants with prominent antimicrobial activity in root bark against various pathogenic bacteria e.g., Staphylococcus aureus, Bacillus licheniformis, Bacillus subtilis, Pseudomonas aeruginosa, Vibrio cholerae, etc., (Thatoi et al., 2008).Dichloromethane extracts of stem bark and root of O. indicum were found to have antimicrobial activities against Grampositive (B.subtilis and S. aureus), Gram-negative (Escherichia coli and P. aeruginosa) and a Yeast (Candida albicans) (Ali et al., 1998).Uddin et al. (2003) isolated two flavonoid from O. indicum-2,5-dihydroxy-6, 7-dimethoxy flavones (1) and 3,7,3´,5´-tetramethoxy-4´hydroxy flavones (2).The MIC of compounds 1 and 2 were measured against B. subtilis, S. aureus, E. coli and Shigella dysenteriae and values were found between 64 and 128 µg/ml.

Immunomodulatory activity
The root bark of O. indicum was found to have immunostimulant/immunomodulatory activity (Zaveri et al., 2006).Research showed that treatment with nbutanol fraction of the root bark of O. indicum resulted in significant rise in circulating hemagglutinating antibody titers during secondary antibody responses, represents the potentiation of certain aspects of the humoral response.The treatment also resulted in a significant rise in paw edema formation, indicating increased host delayed type hypersensitivity (DTH) response.Additionally, the antioxidant potential of the drug was exhibited by significant reductions in whole blood malondialdehyde (MDA) content along with a rise in the activities/levels of superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH).In addition, histopathologic analysis of lymphoid tissues showed an increase in cellularity, e.g., T-lymphocytes and sinusoids, in the treatment group.The reported immunomodulatory activity of an active fraction of O. indicum might be attributed to its ability to enhance specific immune responses (both humoral and cell-mediated) as well as antioxidant potential.
The immunomodulatory properties of O. indicum have also been evaluated through estimation of humoral and cell mediated immune response in broiler chicks.Day old broiler chicks were grown up to 7 days and divided into different groups.All the groups were vaccinated against Ranikhet disease (RD) virus on days 7 and 28 except one group which served as unvaccinated control.All the groups of chicks were vaccinated against infectious bursal disease (IBD) on day 14.Two groups of chicks were fed O. indicum stem bark and root bark powder, respectively each at 250 mg/kg body weight.One group was fed levamisole at 10 mg/kg body weight, which acts as standard drug.Humoral immune response was measured by hemagglutination (HA) test and hemagglutination inhibition (HI) test against ND virus.Cell mediated immune response was studied on the basis of delayed hypersensitivity reaction or measured by contact sensitivity test with 2, 4-dinitrofluorobenzene (DFNB).The highest MHI antibody titter was found in levamisole treated group, followed by groups treated with root powder and stem powder of O. indicum, respectively.Similarly, six hours post DNFB challenge, a significant rise in mean skin thickness (MST) was observed in all the treated groups.The highest was observed in levamisole treated group, followed by groups treated with root powder and stem powder of O. indicum, respectively.These findings suggested that the root bark of O. indicum possessed the significant immunomodulatory activity, that ism stem bark counterpart.Thus, O. indicum root bark powder may be recommended as safe and commercially beneficial immumomodulator (Kumari et al., 2011).

Hepatoprotective activity
Hepatoprotective activities of petroleum ether, chloroform, methanolic and aqueous extracts of O. indicum were examined against carbon tetrachloride induced liver damage in mice using silymarin as control.These studies indicate that alcoholic stem bark extracts of O .indicum had activity over carbon tetrachloride treatment as compared to control.Results of the present investigation confirmed the traditional use of this plant as a potential hepatoprotective agent (Tripathy et al., 2011).O. indicum has been found to offer liver protection against various experimentally induced damages.Different extracts of leaves of O. indicum showed significant hepatoprotective activity against CCl 4 induced hepatotoxicity in Wistar albino rats.Carbon tetrachloride injection leads to the significant increase in the level of serum enzymes.Ethanolic extract was found to be more effective than all other extracts (Siddiqui et al., 2012).The aqueous root extract of O. indicum has potent hepatoprotective activity against paracetamol induced liver damage in rats, it also showed that, it has great influence on liver blood parameters.Thus, it is proved that O. indicum aqueous extract has potent hepatoprotective activity and was found to be dose dependant and this could be attributed to the new flavonoid Oroxylin-B (Sastry et al., 2011).The hepatoprotective activity of O. indicum was studied against carbon tetrachloride (CCl 4 )-induced hepatotoxicity in mice and rats.Biochemical study indicated that alcoholic (300 mg/kg), petroleum ether (300 mg/kg) and n-butanol (100 and 300 mg/kg) extracts significantly (P<0.05) lowered the elevated serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvate transaminase (SGPT), alkaline phosphatase (ALP) and total bilirubin (TB) levels as compared to the control group.The increased lipid peroxide (LPO) formation, reduced glutathione (GSH) and decreased antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT) in the tissues of CCl 4 -treated animlas were significantly normalized by O. indicum treatment.Histopathological study also revealed that pretreatment with O. indicum restored CCl 4 -induced alteration in antioxidant status of the tissues.It is suggested that root bark showed significant antioxidant activity, which might be in turn responsible for its hepatoprotective activity (Zaveri and Jain, 2009).The hepatoprotective activity of stem bark of O. indicum against CCl 4 induced liver damage in mice has also been confirmed.Pet ether, chloroform, methanolic and aqueous extracts of stem bark of O. indicum were examined against carbon tetrachloride induced liver damage in mice using silymarin as control.Enzyme activities of SGPT, ALP and SGOT were analyzed.All the extracts were shown to have significant hepatoprotective activity, with the methanolic extract being more efficient (Bichitra et al., 2011).

Antimutagenic activity
Methanolic extract of O. indicum strongly inhibited the mutagenicity of Trp-P-1 in Ames test.The major antimutagenic constituent was identified as baicalein with an IC 50 value of 2.78±0.15µM.The potent antimutagenicity of the extract was correlated with the high content (3.95±0.43%,dry weight) of baicalein.Baicalein acted as a desmutagen since it inhibited the Nhydroxylation of Trp-P-2 (Nakahara et al., 2001).Methanolic extract of the fruits of O. indicum, inhibited in vitro proliferation of HL-60 cells and flavonoid baicalein was found as an active component in the extract (Roy et al., 2007).In vitro anti-mutagenic activity of selected plants including O. indicum, was done by Ames Salmonella mutagenicity test using histidine mutants of Salmonella typhimurium tester strains, MTCC 98, MTCC 1251 and MTCC 1252.The hydroalcoholic extract of O. indicum significantly inhibited (P < 0.001) the in vitro by direct mutagens-sodium azide (NaN 3 ), 4-nitro-ophenylenediamine (NPD), and indirect mutagens benzo[a]pyrene (B[a]P) 2-aminoflourene(2-AF) induced his revertants in a dose dependent manner (Zaveri et al., 2011).Ethanol soluble fraction prepared from twigs and leaves of this plant have reported for their antimutagenic activity (Wall et al., 1988).Methanolic extracts have antimutagenic activity against hetrocyclic amines (ayurvedainstitute.org/shop/MNOMedicines.htm).

Gastroprotective activity
The n-butanol fraction of the root bark of O. indicum showed significant gastroprotective activity against both ethanol and Water Immersion Plus Restraint Stress (WIRS)-induced gastric ulcers in rats, that could be attributed to its antioxidant activity, vasodilatation, and gastric cytoprotection (Zaveri and Jain, 2007).Chemical investigation of the stem bark of O. indicum resulted in the isolation and characterization of two new flavonoid glycosides.Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis, and all the compounds were tested for their ulcer protective effects against various gastric ulceritis inducing models in rats (Babu et al., 2010).Various polyphenolic compounds have been reported for their anti-ulcerogenic activity with a good level of gastric protection.Besides their action as gastroprotective, these phenolic compounds can be an alternative for the treatment of gastric ulcers.Therefore, considering the important role of polyphenolic compounds in the prevention or reduction of gastric lesions induced by different ulcerogenic agents, in this review, we have summarized the literature on some potent antiulcer plants, such as, O. indicum, Zingiber officinale, Olea europaea L., Foeniculum vulgare, Alchornea glandulosa, Tephrosia purpurea, etc., containing phenolic compounds, namely, baicalein, cinnamic acid, oleuropein, rutin, quercetin, and tephrosin, respectively, as active constituents (Sumbul et al., 2011).
The 50% alcohol extract of the root bark of O. indicum and its petroleum ether, chloroform, ethyl acetate and n-butanol fractions were studied against ethanolinduced gastric mucosal damage.The alcohol extract (300 mg/kg, p.o.) and its different fractions (100 and 300 mg/kg, p.o.) showed reduction in gastric ulceration.The petroleum ether and n-butanol fractions showed maximum inhibition of gastric lesions against ethanolinduced gastric mucosal damage.The results were comparable with omeprazole (reference standard).In the ethanol-induced gastric ulcer model, treatment with both the active fractions and omeprazole showed significant antioxidant activity as evident from the reduction in the extent of lipid peroxidation.The effect of active fraction of root bark on the ulcer index, total acidity, total acid output, pepsin activity, pepsin output and total carbohydrate to protein ratio in pyloric-ligated rat was studied.The active fraction of root bark at a dose level of 100 mg/kg p.o. showed significant reduction (P<0.05) in the ulcer index, total acidity, total acid output, pepsin activity and pepsin output along with a significant rise in total carbohydrate to protein ratio.The mechanism of antiulcer activity could be attributed to a decrease in gastric acid secretory and antioxidant activities leading to gastric cytoprotection.This activity could be linked to the presence of baicalein in the root bark of the plant (Khandhar et al., 2006).

Commercial value
O. indicum has a number of medicinal properties and various parts of this plant have been used in Ayurvedic preparations.The large pods of this plant sold at a market downtown, Bangkok, Thailand.The tree is often grown as an ornamental for its strange appearance.Materials used include the wood, tannins and dyestuffs (Wikipaedia, 2013).Extracts of this plant are also used in herbal tea formulations like vata and kapha (BF1.biz, 2009).O. indicum is also used in mentat (mindcare) and mentat syrup preparation (La Medica, 2007).

PROBLEMS ASSOCIATED WITH THE PLANT
According to the Red list of threatened species, 44 plant species are critically endangered, 113 are endangered, and 87 vulnerable (IUCN, 2000).Many medicinal plants are also in trouble due to over harvesting and destruction of habitat.O. indicum has become 'vulnerable' in some states of India due to reduction of its population (Sharma et al., 2010).It has also been listed to 'endangered' category in some other states (Gokhale and Bansal, 2005;Tewari et al., 2007).This plant naturally germinate by seeds, in the beginning of rainy season; however, the seed set is poor and seed viability is low, are the problems for its natural propagation along with its indiscriminate exploitation for medicinal purpose have pushed it to this state.

CONCLUSION
Enormous uses of O. indicum in medicine and Ayurvedic preparations revealed its properties as antimicrobial, antimutagenic, antiinflammatory, gastroprotective, etc.Therefore, the plant has effective pharmacological action and has proven its potential for future researchers but still the antitumor property of this plant needed to be investigated and further studies may be carried out to prove its promising uses.Due to high medicinal value of this plant, there has been increasing pressure on the collection of this species.So, altitudinal characterization of genetic diversity for this plant shall be helpful for conservation strategies.In vitro propagation method offers highly efficient tool for mass multiplication of many threatened plants.Hence, there is an urgent need to develop efficient and rapid conservation strategy for this plant.

Figure 1 .
Figure 1.Different developmental stages of O. indicum: (a) Tree growing in its natural habitat (photograph taken from village Fatehpur, Haldwani (Uttarakhand) in the month of March, (b) Flowering during the month of August, (c) Flower and fruits, photograph taken in month of August, (d) Winged and naked seeds, and (e) Capsular fruits.

Table 2 .
Major constituents of O. indicum and their activity