In vitro antimicrobial activity of Syzygium cumini fruit peel and identification of anthocyanins

The present investigation evaluated the antimicrobial potential of Syzygium cumini (SC) fruit peel against fourteen microorganisms and identified major anthocyanins. Methanol, ethyl acetate and dichloromethane extracts of shade dried SC fruit peel were screened for antimicrobial effects using disc diffusion and minimum inhibitory concentration (MIC) methods. Methanol extract showed maximum antimicrobial potency against all the test microorganisms with inhibition zone diameter (IZD) ranging from 9.35±0.49 to 19.25±0.35 mm and the lowest MIC of 0.18 mg/ml. Ethyl acetate and dichloromethane extracts moderately inhibited the growth of microorganisms. Separation of anthocyanins from crude methanol extract was carried out by thin layer chromatography (TLC) and the compounds were isolated with Liquid Chromatography-Electrospray-Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS). The compounds identified were malvidin, petunidin and cyanidin. Our results indicate the antimicrobial efficacy of SC fruit peel and subsequent identification of anthocyanins. However, further studies are required to explore anthocyanins in order to develop novel drug candidates.   Key words: Syzygium cumini, antimicrobial, anthocyanins, Liquid Chromatography-Electrospray-Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS), malvidin, petunidin, cyanidin.