Evaluation of antimycobacterial, leishmanicidal and antibacterial activity of three medicinal orchids of Arunachal Pradesh, India.

BACKGROUND: The ethnic population of Arunachal Pradesh uses a number of orchids as such, or in decoction for various ailments. Three untapped orchids namely, Rhynchostylis retusa, Tropidia curculioides and Satyrium nepalense, traditionally used in tuberculosis, asthma and cold stage of malaria in folk medicine, were selected for the present study. METHODS: Dried material of each plant was divided into three parts. Solvent extraction and fractionation afforded altogether 30 extracts and fractions, which were evaluated against Mycobacterium tuberculosis (H37Rv and MDR strain) for antimycobacterial activity; promastigotes and amastigotes of Leishmania donovani for leishmanicidal activity and two gram positive and three gram negative clinical isolates for antibacterial activity. RESULTS: The most significant antimycobacterial activity was observed with n-hexane fraction of the flower of Satyrium nepalense with MIC of 15.7 µg/mL. The most promising leishmanicidal activity was observed with diethyl ether fraction of the roots of Rhynchostylis retusa with IC50 values of 56.04 and 18.4 µg/mL against promastigotes and intracellular amastigotes respectively. Evaluation of antibacterial activity identified S. nepalense flower n-hexane and R. retusa roots diethyl ether as potential fractions with MIC values of ≤100 µg/mL against selected clinical isolates. CONCLUSIONS: This is the first report of the plants possessing antimycobacterial and leishmanicidal activity. The investigation resulted in identification of S. nepalense as the most promising plant, which possessed all three activities in significant proportion. This laboratory outcome could be translated to marketable pharmaceutical products and also to produce maximum benefits to the local of nearby area. Antimycobacterial and leishmanicidal activity of medicinal orchids.

Bioassay guided screening, optimization and characterization of antioxidant compounds from high altitude wild edible plants of Ladakh.

Seven edible plants including three unexplored species of high altitude (Ladakh) region were screened for antioxidant activity by bioassay guided fractionation method. The objective of the study was to dereplicate the complex phytochemical matrix of a plant in reference to antioxidant activity in vitro. The screening result showed that ethylacetate fraction of Nepeta longibracteata possesses maximum antioxidant activity, comparable to that of green tea. It also exhibited significant protecting effect against oxidative stress induced by t-BHP in human RBCs. Phytochemical profiling of the most active fraction by nontargeted RP-HPLC-MS and MS/MS technique showed that rosmarinic acid and methylrosmarinate constituted nearly 51 % of the total metabolites apart from twelve other major chemotypes.

Assessment of microtubule depolymerization property of flavonoids isolated from Tanacetum gracile in breast cancer cells by biochemical and molecular docking approach.

The chemical investigation of the bioactive nonpolar fractions of Tanacetum gracile afforded two flavonoid analogues namely, 5-hydroxy-3,6,7,3',4'-pentamethoxyflavone (1) and 5,4'-dihydroxy-3,6,7,3',4'-tetramethoxyflavone (2) which were identical to the previously reported artemetin and chrysosplenetin respectively. The structure of the compounds was elucidated on the basis of spectroscopic evidences and they showed significant cytotoxic activity against human breast cancer cells (MCF-7 and T47D). Mechanism based study showed that the compounds modulated microtubule depolymerization by activating mitotic spindle checkpoint. Molecular docking at the colchicine binding pocket revealed that the compounds bind at α-ß interfacial site of tubulin, correlating binding interactions with probable inhibition mechanism. The study reveals important observations to generate improved flavonoids that leads to cell apoptosis. The compounds were also evaluated for absorption, metabolism and toxicity by online webserver admetSAR. The significant microtubule disassembling property and less toxicity paves way for consideration of the compounds as chemopreventive agents.