title: Stimulation of DNA repair in Saccharomyces cerevisiae by Ginkgo biloba leaf extract.
abstract: Many extracts prepared from plants traditionally used for medicinal applications contain a variety of phytochemicals with antioxidant and antigenotoxic activity. In this work we measured the DNA protective effect of extracts of Ginkgo biloba leaves from oxidative stress using Saccharomyces cerevisiae as experimental model. The extract improved viability of yeast cells under oxidative stress imposed by hydrogen peroxide. In accordance with previous reports on antioxidant properties of G. biloba extracts, pre-incubation of yeast cells promoted a decrease in intracellular oxidation. We assessed DNA damage by our recently developed yeast comet assay protocol. Upon oxidative shock, DNA damage decreased in a dose-dependent manner in experiments of pre-incubation and simultaneous incubation with the extract, indicating a direct protective effect. In addition, the extract improved DNA repair rate following oxidative shock as measured by faster disappearance of comet tails. This suggests that the extract stimulates the DNA repair machinery in its DNA protective action in addition to directly protect DNA from oxidation. The observed DNA repair depends on the DNA repair machinery since no DNA repair was observed under restrictive conditions in a conditional mutant of the CDC9 gene (Accession No. Z74212), encoding the DNA ligase involved in the final step of both nucleotide and base excision repair.
authors.affiliation: Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Filipe
authors.initials: F
authors.lastname: Marques
authors.forename: Flávio
authors.initials: F
authors.lastname: Azevedo
authors.forename: Björn
authors.initials: B
authors.lastname: Johansson
authors.forename: Rui
authors.initials: R
authors.lastname: Oliveira
mesh_terms: D016587:Antimutagenic Agents / Q000494:pharmacology*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects*; D004271:DNA, Fungal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D020441:Ginkgo biloba / Q000737:chemistry*; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D016587:Antimutagenic Agents; C000607890:CDC9 protein, S cerevisiae; D004271:DNA, Fungal; D010936:Plant Extracts; D011088:DNA Ligases; D000072481:DNA Ligase ATP