In vitro antibacterial activity of certain folk medicinal plants from Darjeeling Himalayas used to treat microbial infections

Abstract

Antibacterial activity of ethanolic extracts of 33 folk medicinal plants used for the treatment of parasitic diseases were examined with four bacteria (two Gram positive-Bacillus subtilis and Staphylococcus aureus and two Gram negative - Escherichia coli and Salmonella typhi) following disc diffusion method. Among 33 plants examined 21 (63 %) plants showed antibacterial property with B. subtilis, 16 (48 %) plants with S. aureus, 18 (54 %) plants with E. coli and 8 (24 %) with S. typhi. Five of the medicinal plants (Asparagus racemosus, Prunus cerasoides, Rhododendron arboreum, Terminalia bellerica and Woodfordia fruticosa) were found inhibitory against all the bacteria. Inability of six plants (Acer thomsonii, Alnus nepalensis, Castonopsis hystrix, Evodia fraxinifolia, Symplocus theifolia and Zanthoxylum nitidum) to inhibit the growth of any of the bacteria tested indicates that these are less utilized plants to treat skin diseases where fungi are common pathogens. Plants utilized to combat enteric and urinary tract infections viz., A. racemosus, Cyperus rotundus, Docynia indica, Ficus cunea, Rheum australe, Rhododendron arboreum, Rhus semialata, Terminalia bellerica and Woodfordia fruticosa showed antibacterial activity preferably to Gram-negative organisms. Careful phytochemical, pharmacological and toxicological standardisation for these medicinal plants must be instituted for their development as safe, efficacious, cheap antibacterials of plant origin vis-a-vis conservation of traditional knowledge.