Screening of Some Medicinal Plants for Their Antimicrobial Activities

Objective: Our objective of this research work was to investigate antimicrobial activity of five species of traditionally used medicinal plants namely Adhatoda vasica, Artemisia annua, Cordia oblique, Croton bonplandianum and Euphorbia milli against different strains of bacteria and fungi which are known to cause various types of infectious diseases. Methods: Organic extracts of these plants leaves (dry) were prepared, and antimicrobial sensitivity of these organic extracts (Hexane, chloroform, acetone, and methanol) against selected bacterial and fungal strains were performed by disc diffusion assay method and Resazurin-based Microtitre Dilution Assay method. Results: Among these plants, Cordia oblique (chloroform extract) and Croton bonplandianum (Hexane extract), which showed superior antimicrobial activity in the primary screening test. Croton bonplandianum showed the maximum yield (7.3%) and Adhatoda vasica showed minimum yield (0.57) of plant extract. Chloroform extracts of Cordia oblique and hexane extract of Croton bonplandianum showed very good antimicrobial activity (MIC 0.37 mg/ml) against Staphylococcus aureus and Klebsiella pneumoniae. With this Artemisia annua (chloroform extract) showed very remarkable antifungal activity (MIC 0.37 mg/ml) against Aspergillus niger. Among the different fractions (Hexane, chloroform, acetone and methanol) tested for antimicrobial activity, the non-polar fractions were more active than the polar fractions. Conclusion: In this study all the tested plants Adhatoda vasica, Artemisia annua, Cordia oblique, Croton bonplandianum and Euphorbia milli showed antimicrobial activity against at least one strain of bacterium and fungus. This might justify their claimed uses in the treatment of various infectious diseases.