Abstract
BackgroundThe 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.MethodsDried 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.ResultsThe 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.ConclusionsThis 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.Graphical abstractAntimycobacterial and leishmanicidal activity of medicinal orchids
Highlights
The ethnic population of Arunachal Pradesh uses a number of orchids as such, or in decoction for various ailments
India harbors a rich repository of untapped medicinal plants, with plenty of associated knowledge that needs to be appropriately utilized
It is interesting to note that nearly 300 species of the total orchids are rare whereas, only 37 species are of medicinal importance [2]
Summary
The ethnic population of Arunachal Pradesh uses a number of orchids as such, or in decoction for various ailments. 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. Arunachal Pradesh (AR) is a natural habitat of 5000 flowering species including 550 species of orchid plants. It is interesting to note that nearly 300 species of the total orchids are rare whereas, only 37 species are of medicinal importance [2]. Considering serenity of the habitat of AR and traditional use of orchids by the locals, we selected three relatively unexplored plants including Rhynchostylis retusa (Rr), Tropidia curculioides (Tc), and Satyrium nepalense (Sn) for the present investigation. R. retusa of the genus Rhynchostylis is widely distributed all over North-eastern Himalayas and specially linked with the people of Assam, commonly called
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