Abstract

Rapid emergence of methicillin-resistant Staphylococcus aureus (MRSA) has made the search of a novel bioactive compound a necessity. In this study, two selected strains of actinomycetes (KB1 and KB3) were isolated from air samples from Aonang, Krabi province, southern Thailand and identified as Streptomyces spp., using 16S rDNA sequence analysis. The active molecules in crude extract of fermented broth from strain KB1 exhibited anti-MRSA activity. Partial characterization of the active molecules (heat labile) showed that it would be of protein nature. The identification of its cytotoxicity is an important first step in improving active metabolites safely use for human health. In this study, the cytotoxicity (IC<inf>50</inf>) of active molecules against Vero cells was found to be 12.5 μg protein/ml when compared with ellipticine (0.48 μg/ml). The results indicated that active molecules in bioactive compounds had the mild cytotoxic activity against Vero cells. Future works will investigate the mechanism of action, confirm the in vivo cytotoxicity, along with study the pharmacodynamics and pharmacokinetics of this compound, to develop bioactive compounds from the natural resources.