title: Protective effects of ursolic acid and luteolin against oxidative DNA damage include enhancement of DNA repair in Caco-2 cells.
abstract: Consumption of fruits and vegetables is associated with a reduced risk of developing a wide range of cancers including colon cancer. In this study, we evaluated the effects of two compounds present in fruits and vegetables, ursolic acid, a triterpenoid, and luteolin, a flavonoid, on DNA protection and DNA repair in Caco-2 cells using the comet assay. Ursolic acid and luteolin showed a protective effect against H(2)O(2)-induced DNA damage. Repair rate (rejoining of strand breaks) after treatment with H(2)O(2) was increased by pre-treatment of Caco-2 cells for 24h with ursolic acid or luteolin. To evaluate effects on induction of base oxidation, we exposed cells to the photosensitizer Ro 19-8022 plus visible light to induce 8-oxoguanine. Luteolin protected against this damage in Caco-2 cells after a short period of incubation. We also measured the incision activity of a cell extract from Caco-2 cells treated for 24h with test compounds, on a DNA substrate containing specific damage (8-oxoGua), to evaluate effects on base excision repair activity. Preincubation for 24h with ursolic acid enhanced incision activity in Caco-2 cells. In conclusion, we demonstrated for the first time that ursolic acid and luteolin not only protect DNA from oxidative damage but also increase repair activity in Caco-2 cells. These effects of ursolic acid and luteolin may contribute to their anti-carcinogenic effects.
authors.affiliation: Department of Nutrition, University of Oslo, Norway. aliceramos@biouminho.pt
authors.forename: Alice A
authors.initials: AA
authors.lastname: Ramos
authors.forename: Cristina
authors.initials: C
authors.lastname: Pereira-Wilson
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Collins
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D018938:Caco-2 Cells; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047311:Luteolin / Q000494:pharmacology*; D014315:Triterpenes / Q000494:pharmacology*; D000097245:Ursolic Acid
chemical_list: D000975:Antioxidants; D006861:Hydrogen Peroxide; D047311:Luteolin; D014315:Triterpenes; D000097245:Ursolic Acid