Antimicrobial Efficacy of Ethanolic Extracts Obtained from Leaves of Camellia japonica L. Cultivars against Escherichia coli Strain

Abstract

The present study was aimed to determine the antibacterial activity of six plants, i.e. Camellia japonica L. (cultivars Kramer’s Supreme, C.M. Wilson, La Pace, Mrs. Lyman Clarke, Benikarako, Fanny Bolis) against Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™) strain. Ethanolic extracts were prepared by freshly crushed leaves and evaluated for their antimicrobial activity against Escherichia coli ATCC® 25922™ strain using disc diffusion assay. The increase of the mean of the diameters of the inhibition zone was 58.4 % for cv. Kramer’s Supreme, 29.2 % for cv. La Pace and cv. Mrs. Lyman Clarke, 22.5 % for cv. Fanny Bolis, 19.1% for cv. Benikarako, and 18 % for cv. C.M. Wilson compared to the control samples (96 % ethanol). Among the six plant extracts, C. japonica ’Kramer’s Supreme‘ exhibited the highest inhibitory zones against the tested strain (the mean of the zone of inhibitions was 14.1 ±1.1 mm). The intermediate activity was presented by other cultivars studied. The findings reported herein give scientific credence to the traditional uses of these plants and suggest that extracts derived from the leaves of Camellia japonica and its cultivars merit further chemical study as natural antibiotics to identify the secondary metabolites. These results could provide a theoretical basis for making full use of Camellia japonica and its cultivars. Moreover, their antibacterial activities can play an important role in medicine, veterinary, food preservation, and other aspects. Mechanisms of antibacterial activities remain to be studied.