Study on extraction, purification and antimicrobial activity of pomegranate peel tannins

Pomegranate peel is rich in tannins which have a good antibacterial activity. Pomegranate peel tannins were extracted by acetone in ultrasonic-assisted extraction method. After that they were purified by Amberlite XAD-16 macroporous resin. Then high performance liquid chromatography (HPLC) analysis was taken to determine the components and agar dilution method was adopted to test the minimal inhibitory concentration (MIC) . The results indicated that the concentration of punicalagin, the main component of pomegranate peel extract, increased from 12.3% to 64.2% after purification. The MICs of pomegranate peel crude extract on Staphylococcus aureus, Listeria monocytogenes, Salmonella and E.coli were 0.312, 10, 0.625mg/mL and larger than 10mg/mL, while the MICs of purified extract for these four kinds of bacteria were 0.156, 5, 0.625 and 10mg/mL respectively.