Antibacterial potential and ethnomedical relevance of Kumaun Himalayan Gymnosperms
Ethnomedicinal information is one of the powerful criteria for new drugs discoveries therefore; present investigation was carried out to evaluate the ethnomedicinal and antibacterial potential of traditional Kumaun Himalayan gymnosperms. Besides, an antibacterial value index and relative antibacterial activity of studied plants have been established. Forty four plant leaves extracts in different organic solvents (methanol, ethanol, chloroform and hexane) of 11 gymnosperms (Araucaria cunninghamii, Biota orientalis, Cedrus deodara, Cephalotaxus griffithi, Cryptomeria japonica Cupressus torulosa, Ginkgo biloba, Juniperus communis, Picea smithiana, Pinus wallichiana and Taxus baccata) occurring in Kumaun Himalaya were screened for their antimicrobial activity against five pathogenic bacteria using disc diffusion method. The antibacterial activity of studied gymnospermic plant extracts against a panel of bacteria was found effective at 1000 µg/ml. The MIC and MBC values of each extract (where ZOI ≥ 15 mm) were also determined. The methanol extract of screened gymnosperms were found the most effective against all the bacteria (54% to 81%), followed by ethanol extract (45-72%), hexane extract (18-27%), while in chloroform extract it ranged 9-27% only. The extracts of G. biloba exhibited superior Relative Antibacterial Activity (RAA, 20%), followed by A. cunninghamii and P. wallichiana (12% RAA, each). The lowest RAA value was observed for C. torulosa (1%). All data were also analyzed for determination of an Antibacterial Value Index (ABVI) for each studied species of gymnosperm. G. biloba had maximum ABVI i.e. 90 % followed by A. cunninghamii and P. wallichiana (ABVI, 55% each). C. torulosa showed the least ABVI and RAA i.e. 5% and 11%, respectively. The present work fully highlighted the utility of traditionally known 11 gymnosperms of Kumaun Himalaya for their antibacterial activities against pathogenic bacteria.