Evaluation of prevention of DNA damage and induction of DNA repair in Saccharomyces cerevisiae by Ginkgo biloba leaf extracts

Abstract

Extracts of Ginkgo biloba leaves (GBE) have been used for centuries in traditional oriental medicine to treat a very wide range of ailments. These extracts contain flavone glycosides, terpene trilactones (ginkgolides and bilobalide), ginkgolic acids, proanthocyanides and other uncharacterized compounds. The flavone glycosides and terpene trilactones fractions are believed to be responsible for the pharmacological properties of GBE, which are very popular, making it as one of the best-selling herbal medications worldwide. In this work we investigated the DNA protective effect of GBE in the model organism Saccharomyces cerevisiae. Typical experiments involved incubation of yeast cells with GBE before and during oxidative shock by hydrogen peroxide. Our results obtained with the comet assay show that DNA damage is significantly decreased upon GBE treatment (before and during H2O2 incubation) in a dose-dependent manner. In addition, DNA repair is significantly improved in cells pre-treated with GBE. As expected, GBE treatment improved survival of yeast cells when challenged with oxidative shock with H2O2. Intracellular oxidation of yeast cells was considerably decreased upon pre-treatment with GBE as revealed by flow cytometry with the redox sensitive probe dichlorofluorescein diacetate. Even in the absence of H2O2, yeast cells showed a decreased intracellular oxidation state, suggesting that GBE can protect cells from endogenous reactive oxygen species.