Ginkgo biloba and Dittrichia viscosa extracts protect Schizosaccharomyces pombe cells exposed to camptothecin

Abstract

Cells are continuously exposed to toxic agents that promote genotoxic stress, which affect genomic integrity and contribute to the development of human diseases. Therefore, there is an urgent need to find safe products that can protect cells from genotoxic damage. Medicinal plant extracts are associated to many health benefits, often linked to their antioxidant properties, and thus may contribute to the preservation of DNA integrity and consequently provide an anticancer effect.

In this work, we evaluated the protective effect of two medicinal leaf extracts, G. biloba extract (GBE) and D. viscosa extract (DVE), on the survival of Schizosaccharomyces pombe cells exposed to genotoxic stress induced by camptothecin (CPT). This compound inhibits DNA topoisomerase I activity which leads to the generation of DNA double strand breaks, compromising cell survival. The chemical analysis by electrospray ionization-mass spectrometry revealed that GBE and DVE are mainly composed of polyphenols. In vitro antioxidant assays indicate that GBE and DVE have the capacity to scavenge the radical DPPH and to chelate iron, but low capacity to scavenge NO. Schizosaccharomyces pombe cells incubated with GBE or DVE and CPT exhibited higher survival than cells only incubated with CPT, indicating the protective effect of the extracts against CPT. This effect seems to result from the ability to stimulate DNA repair through homologous recombination, since the mutant rad51, affected in this repair pathway, failed to be protected by both extracts. To our knowledge, this is the first report indicating the potential antigenotoxicity of these extracts against CPT.