Plant Material (Air dried and crushed) Evaluation of Anti-tubercular and Antibacterial activity of Rhynchostylis retusa, a medicinal orchid from Arunachal Pradesh Manisha Bhatnagar1 and Sabari Ghosal1* 1Amity Institute of Biotechnology, Amity University, Uttar Pradesh, Noida E-mail addresses: manisha.b2287@gmail.com, *sghosal@amity.edu Introduction Analysis Results Orchids are known for decorative and aromatic values. Very little attention has been paid towards medicinal properties of orchids. Rhynchostylis retusa (Rr) is a monopodial, epiphytic orchid found in North Eastern Himalayas. Most of the medicinal properties of the plant has not been investigated yet. The purpose of this study is to evaluate antibacterial and antimycobacterial potential of the plant. Et2O extract of roots showed promising results with both the assays performed. In case of antibacterial activity, overall diethyl ether fractions showed significant zone of inhibition against Acinetobacter sp. followed by Enterococcus sp. as compared to other bacterial clinical isolates The anti-mycobacterial activity was measured in terms of minimal inhibitory concentration (MIC) for each fractions. The most promising fractions were Et2O fraction of root and stem with MIC values within 250 and 500 µg/mL respectively. Antibacterial activity: Each fraction was evaluated for anti-bacterial activity using clinical isolates of bacterial MDR strains. Et2O fraction of root and n-butanol of leaves showed maximum zone of inhibition (Figure A).The maximum zone of inhibition was observed against Acinetobacter sp. in all fractions. Anti-tubercular activity: CRI assay performed showed the MIC value of Rr Roots Et2O fraction to be ≤ 250µg/mL and of Rr Stem Et2O fraction >500µg/mL. MIC of other fractions observed was found to be >1mg/mL Therefore Rr Roots Et2O fraction will be considered for further isolation and purification of bioactive compounds followed by their structure elucidation. Extraction Methodology Future Perspective Components/ compounds with anti-tubercular activity would be isolated from the active fractions. Compounds with novel structure could be identified from the novel plant species. Those compounds showing good activities in in-vitro model could be synthesized for in-vivo testing. Plant Material (Air dried and crushed) Roots Stem Leaves Graphs Extraction MeOH: H2O (9:1) Methanolic Extract (Organic Phase) Aqueous Extract (Aqueous phase) Fractionated with solvent in increasing order of polarity References Figure A : Antibacterial activity by Agar well diffusion method Mishra P, et al. Two new amides with cytotoxic activity from the fruits of Piper longum. Journal of Asian Natural Products Research. 2011; 13(2):143-148. Avasthi AS, Jain S, Bhatnagar M, Ghosal S “ In-vitro Antibacterial, Antifungal, Antioxidant and Antihemolytic activities of Alpinia Galanga.” International Journal of Phytomedicine, Vol 7, No 1 (2015). Singh S, Kumar P, Sharma S, Mumbowa F, Martin A, Durier N. Rapid Identification and Drug Susceptibility Testing of Mycobacterium tuberculosis: Standard Operating Procedure for Non-Commercial Assays: Part 3: Colorimetric Redox Indicator Assay v1.3.12. J Lab Physicians 2012;4:120-6. n-Butanol Fraction Residual Aqueous Fraction Diethyl Ether Fraction (Et2O) Antibacterial activity by agar-well diffusion method using four different MDR bacterial clinical isolates including Escherichia coli, Enterococcus sp., Acinetobacter sp. and Serratia sp. The anti-tubercular activity by Colorimetric redox indicator assay (CRI Assay) using pan sensitive strain of Mycobacterium tuberculosis H37Rv. Figure B: Colorimetric Redox Indicator assay for anti-mycobacterial activity