In vitro antioxidant and antimicrobial properties of jambolan (Syzygium cumini) fruit polyphenols

The present study was undertaken to examine antioxidant and antimicrobial activities of jambolan fruit polyphenols against reference pathogenic strains (Staphylococcus aureus, methicillin-resistant S. aureus [MRSA], Escherichia coil, Klebsiella pneumoniae and Candida albicans) and were compared to that of polyphenol standards (gallic acid, quercetin, caffeic acid, sinapic acid and delphinidin chloride). DPPH, ABTS and FRAP assays showed that antioxidant activity for different polyphenols varied significantly (P < 0.05). Gallic acid and quercetin showed higher antioxidant activities (DPPH and ABTS) than the other standards. Jambolan fruit polyphenol extract exhibited a broad spectrum antimicrobial activity against reference pathogenic strains with a zone of inhibition and minimum inhibitory concentration in the range from 14.3 to 23.0 mm and 0.5-2.5 mg/ml, respectively. Moreover, most of the polyphenol standards inhibited the growth of pathogens used in this study. (C) 2015 Elsevier Ltd. All rights reserved.