The ethyl acetate (C2H5COOCH3) extract of the roots of Vanda roxburghii Br. is known to have a significant antimicrobial activity. The investigation was carried out on the C2H5COOCH3 extract for the isolation and characterization of the active principle (s). The extract afforded a glycoside, 17-β-hydroxy-14, 20-epoxy-1-oxo- [22R]-3β-[O-β-D-glucopyranosyl]-5,24-withadienolide (VR-2), the structure of which was elucidated on the basis of spectral evidences. Compound VR-2 was screened against a wide variety of pathogenic bacteria and fungus for its antimicrobial activity by disc diffusion method. The compound showed significant antibacterial activity against most of the tested strain of bacteria and produced zone of inhibition between 14 to 28mm. The compound also showed significant antifungal activity and the minimum inhibitory concentration (MIC) of VR-2 against Bacillus cereus, Bacillus subtilis, Escherichia coli, Shigella dysenteriae and pseudomonus aeruginosa was determined and the values were 8, 32, 16, 8 and 16μg ml-1, respectively.
Farque Ahmed, Abu Sayeed , Anwarul Islam , S. M. Abdus Salam , Golam Sadik and G. R. M. Astaq Mohal Khan , 2001. Characterization and in vitro Antimicrobial Activity of 17-β-hydroxy-14, 20-epoxy-1-oxo-[22R]-3β- [O-β-d-glucopyranosyl]-5, 24-withadienolidefrom Vanda Roxburghii Br. Journal of Medical Sciences, 1: 324-326.