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Evidence-Based Complementary and Alternative Medicine
Volume 2012, Article ID 697183, 6 pages
http://dx.doi.org/10.1155/2012/697183
Research Article

Antibacterial Activity of Rhodomyrtus tomentosa (Aiton) Hassk. Leaf Extract against Clinical Isolates of Streptococcus pyogenes

1Faculty of Traditional Thai Medicine and Natural Products Research Center, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
2Department of Bio- and Chemical Engineering, Technical University of Dortmund, Technical Biochemistry, Emil-Figge-Strasse 66-68, 44227 Dortmund, Germany
3Department of Microbiology and Natural Products Research Center, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand

Received 3 May 2012; Revised 26 July 2012; Accepted 31 July 2012

Academic Editor: Jenny M. Wilkinson

Copyright © 2012 Surasak Limsuwan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ethanol extract of Rhodomyrtus tomentosa (Aiton) Hassk. leaf was evaluated for antibacterial activity against 47 clinical isolates of Streptococcus pyogenes. The extract exhibited good anti-S. pyogenes activity against all the tested isolates with similar minimum inhibitory concentration (MIC, 3.91–62.5 μg mL−1) and minimum bactericidal concentration (MBC, 3.91–62.5 μg mL−1) ranges. No surviving cells were detected at 16 h after treatment with 8 × MIC of the extract. The extract-treated cells demonstrated no lysis and cytoplasmic leakage through the bacterial membrane. Electron micrographs further revealed that the extract did not cause any dramatic changes on the treated cells. Rhodomyrtone, an isolated compound, exhibited good anti-S. pyogenes activity (14 isolates), expressed very low MIC (0.39–1.56 μg mL−1) and MBC (0.39-1.56 μg mL−1) values. Rhodomyrtus tomentosa leaf extract and rhodomyrtone displayed promising antibacterial activity against clinical isolates of S. pyogenes.