ANTIBACTERIAL AND ANTIMYCOBACTERIAL ACTIVITY OF MEDICINAL ORCHID OF ARUNACHAL PRADESH

Orchidaceae, one of the largest families of plant kingdom, possesses high aesthetic, medicinal and economic value. However, medicinal properties of orchids has not been investigated to its fullest potential. Hence, an orchid of Arunachal Pradesh, Pleione maculata, which has not been studied from pharmacological and phytochemical view point so far, is selected for the study. The present study was conducted for antibacterial and antimycobacterial activity by bioassay guided fractionation. The whole plant material was divided into diethyl ether (Et₂O), n-butanol (n-BuOH) and aqueous (Aq) fractions. The antibacterial activity was evaluated by agar well diffusion method against three Gram negative and two Gram positive multi drug resistant clinical isolates. The antimycobacterial activity was performed by Colorimetric redox indicator assay against H37Rv strain of Mycobacterium tuberculosis. The screening result identified Et₂O fraction as the most active fraction showing significant zone of inhibition against E.coli and Staphylococcus aureus sp. and moderate antimycobacterial activity (MIC value 104.16 μg/mL) against H37Rv strain of Mycobacterium tuberculosis. Phytochemical screening of the fractions revealed the presence of triterpenes, phlobatannins, alkaloids and cardiac glycosides in the most active Et₂O fraction. Isolation from the active fraction could lead to interesting compounds. Thus bioassay guided fractionation, successfully divided the phytochemicals and biological activity in a particular fraction, making it suitable for commercial use in herbal formulations.