Study on antioxidant and antibacterial activity of apple leaf polyphenols of seven cultivars

In order to investigate the antioxidant and antibacterial activity of apple leaf polyphenols of seven cultivars, total phenolic content was determinated by Folin-ciocalteu method, antioxidant activity was evaluated by ferric-reducing antioxidant power (FRAP) assay, DPPH scavenging assay, superoxide anion scavenging assay and ABTS scavenging assay. The antibacterial activity of Qinguan were evaluated by comparing their minimum inhibitory concentrations (MIC) against five bacterial strains. It was showed that Qinguan exhibited the best antioxidant properties, whereas Qinyang and Gale Gala possessed better antioxidant properties among seven apple cultivars. The strongest antibacterial activity of Qinguan leaf polyphenols was recorded against Escherichia coli, Staphyloccocus aureus, Salmonella typhimurium with MIC value of 25μg/m L, and the lower activity was observed against Shigella and Enterobacter Sakazakii with MIC value of 50μg/m L. Antibacterial activity of Qinguan polyphenols was remarkably better than any monophenol contained in apples, and 3 ⁴ times better than tea polyphenols.