In vitro evaluation of crude extracts of Catharanthus roseus for potential antibacterial activity

Abstract

Context: Catharanthus roseus (periwinkle) is an important medicinal plant, mentioned in Ayurveda, an ancient Indian Sanskrit literature. Th e plant is selected to evaluate the possibility for novel pharmaceuticals since most of the bacterial pathogens are developing resistance against currently available antibiotics. Aims: To determine the antibacterial activity of crude extracts from diff erent parts of Catharanthus roseus against several bacterial species of clinical signifi cance. Materials and Methods: Extraction of each plant part in appropriate solvent followed by evaluation of antibacterial activity by agar well diff usion assay against a total of six bacterial stains. Further, minimum inhibitory concentration(s) was evaluated for active crude extracts. Results: Data indicated that the pattern of inhibition depends largely upon the extraction procedure, the plant part used for extraction, state of plant part (fresh or dry), solvent used for extraction and the microorganism tested. Dry powder extracts of all plant parts demonstrated more antibacterial activity than extracts prepared from fresh parts. Furthermore, extracts prepared from leaves were shown to have better effi cacy than stem, root, and fl ower extracts. Organic extracts provided more potent antibacterial activity as compared to aqueous extracts. Among all the extracts, the ethanolic extract was found to be most active against almost all the bacterial species tested. Hot water and cold water extracts were completely inactive. Gram-positive bacteria were found more sensitive than Gram-negative bacteria. Conclusions: Th e study promises an interesting future for designing potentially active antibacterial agents from Catharanthus roseus. Key words: Agar well diff usion assay, antibacterial activity, Ayurveda, Catharanthus roseus, minimum inhibitory concentration, periwinkle