Synergistic Antibacterial Activity of an Active Compound Derived from Sedum takesimense against Methicillin-Resistant Staphylococcus aureus and Its Clinical Isolates.

There are a growing number of reports of hospital-acquired infections caused by pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). Many plant products are now being used as a natural means of exploring antimicrobial agents against different types of human pathogenic bacteria. In this research, we sought to isolate and identify an active molecule from Sedum takesimense that has possible antibacterial activity against various clinical isolates of MRSA. NMR analysis revealed that the structure of the HPLC-purified compound was 1,2,4,6-tetra-O-galloyl-glucose. The minimum inhibitory concentration (MIC) of different extract fractions against numerous pathogenic bacteria was determined, and the actively purified compound has potent antibacterial activity against multidrug-resistant pathogenic bacteria, i.e., MRSA and its clinical isolates. In addition, the combination of the active compound and ß-lactam antibiotics (e.g., oxacillin) demonstrated synergistic action against MRSA, with a fractional inhibitory concentration (FIC) index of 0.281. The current research revealed an alternative approach to combating pathogenesis caused by multi-drug resistant bacteria using plant materials. Furthermore, using a combination approach in which the active plant-derived compound is combined with antibiotics has proved to be a successful way of destroying pathogens synergistically.

Preservative effect of Camellia sinensis (L.) Kuntze seed extract in soy sauce and its mutagenicity.

The purpose of this study was to investigate the applicability of green tea seed (GTS) extract as a natural preservative in food. Food preservative ability and mutagenicity studies of GTS extract and identification of antimicrobial compounds from GTS extract were carried out. The GTS extract showed only anti-yeast activity against Candida albicans with MIC value of 938µg/mL and Zygosaccharomyces rouxii with a MIC of 469µg/mL. The active compounds were identified as theasaponin E1 (1), assamsaponin A (2), and assamsaponin B (3). And GTS extracts didn't show mutagenicity because there were no dose-dependent changes in colonies of Salmonella typhimurium TA98, TA100, TA1535, TA1537, and Escherichia coli WP2uvrA regardless of the metabolic activation system. And GTS extract also showed a potent food preservation affect which eliminated all yeast below the MIC value in application test at soy sauce. Overall, these results indicate that GTS extract could be a safe and effective food preservative with anti-yeast activity.