Antibacterial Activity of Some Folklore Medicinal Plants of Nepal

Abstract

Plants have been a good source of food and medicine since human civilization. The plants, which are used by human to cure various diseases and to relieve diseases, are called medicinal plants. In the present study, thirteen medicinal plants namely Piper longum, Achyranthes aspera, Oroxylum indicum, Acmella clava, Swertia chirayita, Bauhinia variegata, Phyllanthus emblica, Justicia adhatoda, Mentha Spicata, Azadirachta indica, Curculigo orchioides, Withania somnifera and Thalictrum foliolosum were screened for potential antibacterial activity against pathogenic bacterial strains viz Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhi, Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis and Staphylococcus aureus. All the parts of medicinal plants used were kept in methanol solvent by soaking method. The Azadirachta indica gave the highest yield (23.50%) whereas Achyranthes aspera gave lowest yield (5.60%) of crude extract. The methanol extracts of these plants were evaluated for antibacterial activity by agar disc diffusion method Among thirteen medicinal plants tested, all plants showed activity against at least two bacteria. Phyllanthus emblica, Swertia chirayita, Withania somnifera and Thalictrum foliolosum inhibited all the tested bacteria. Similarly three plants viz. Acmella clava, Bauhinia variegata and Mentha spicata inhibited 86% of tested bacteria, three plants Achyranthes aspera, Oroxylum indicum and Azdirachta indica were effective against 71% of screened bacteria, Piper longum was effective against 57% of tested bacteria, Curculigo orchioides was effective against only 43% of tested bacteria and Justicia adhatoda inhibited only 29% of tested bacteria. Among the tested bacteria, most resistant bacteria was Escherichia coli whose growth were inhibited by only 8 out of 13 plants extract where as Bacillus sublilis was most susceptible bacteria whose growth was inhibited by all plants extracts. Gram-ve bacteria were more resistant than Gram +ve bacteria. The screening of crude extracts made from tested plants used by traditional healers showed that these screened plants were potentially competent to control the bacterial growth.