In vitro Antifungal Activity and Mechanism of Action of Tea Polyphenols and Tea Saponin against Rhizopus stolonifer

摘要

The in vitro antifungal activities and mechanism of action of tea polyphenols (TP), tea saponin (TS) and their combination were evaluated against Rhizopus stolonifer. The results showed that both TP and TS inhibited the mycelial growth in a dose-dependent manner, and their combination at the ratio of 7:3 exhibited synergistic antifungal interaction. We also observed that the treatment of TP or TS significantly induced the production of H2O2 and resulted in membrane lipid peroxidation, thus leading to an increase in cell membrane permeability and the leakage of K+, soluble protein and soluble sugar. Moreover, combining them for treatment increased the induction of H2O2 production and oxidative damage. Scanning electron microscopic observations also showed the damage to the hyphal cell structure. It was concluded that TP, TS and their combination inhibit the growth of R. stolonifer through the induction of H2O2 production, leading to cell membrane oxidative damage and intracellular constituent leakage. These findings suggest that TP and TS can potentially be used as an alternative to control postharvest fruit diseases caused by R. stolonifer. (C) 2015 S. Karger AG, Basel