Selection of solvent and extraction method for determination of antimicrobial potential of Taxus wallichiana Zucc.
Antimicrobial potential of different plant parts (needle, stem and bark) of Himalayan yew (Taxus wallichiana Zucc.) has been investigated with particular reference to selection of solvents and extraction methods. Two extraction methods (maceration and soxhlet), seven solvents (methanol, ethanol, acetone, chloroform, ethyl acetate, di chloro methane and Petroleum ether), and 3 groups of microorganisms (bacteria, actinobacteria and fungi) were considered for detection of antimicrobial activity. While qualitative estimations were done using agar well diffusion method, quantitative analysis was based on dilution method. All the plant part showed significant activity against all 3 groups of microorganisms in qualitative bioassays; maximum being in case of needles. Among solvents, ethanolic extract of needles (maceration) showed highest antibacterial activity (15.33 ± 0.25 mm). Growth of actinobacteria was inhibited maximum (22.0±0.26 mm) by the methanolic extracts of needles (maceration). Ethyl acetate extract of needles (soxhlet) showed higher antifungal activity (7.84±0.21 mm). Antibacterial and antifungal activities were higher in maceration and soxhlet methods, respectively. The most affected group among the test microorganisms was bacteria which may be due to their prokaryotic organization. This was also supported by the low minimum inhibitory concentration (MIC) values. Di chloro methane and petroleum ether did not show any antifungal activity. The antimicrobial activity of various plant parts of T. wallichiana varied with respect to the solvent as well as the extraction method. The study will have implications in selection of the use of solvent and the extraction procedure in obtaining the antimicrobial metabolites from various plant parts of T. wallichiana.