title: DNA protecting and genotoxic effects of olive oil related components in cells exposed to hydrogen peroxide.
abstract: In search for compounds, able to protect nuclear DNA in cells exposed to oxidative stress, extracts from olive leaves, olive fruits, olive oil and olive mill waste water were tested by using the "single cell gel electrophoresis" methodology (comet assay). Jurkat cells in culture were exposed to continuously generated hydrogen peroxide (11.8+/-1.5 microM per min) by direct addition into the growth medium of the appropriate amount of the enzyme "glucose oxidase" in the presence or absence of the tested total extracts. The protective effects of the tested extracts or isolated compounds were evaluated from their ability to decrease hydrogen peroxide-induced formation of single strand breaks in the nuclear DNA, while the toxic effects were estimated from the increase of DNA damage when the extracts or isolated compounds were incubated directly with the cells. Significant protection was observed in extracts from olive oil and olive mill waste water. However, above a concentration of 100 microg/ml olive oil extracts exerted DNA damaging effects by themselves in the absence of any H2O2. Extracts from olive leaves and olive fruits although protective, were also able to induce DNA damage by themselves. Main compounds isolated from the above described total extracts, like oleuropein glucoside, tyrosol, hydroxytyrosol and caffeic acid, were tested in the same experimental system and found to exert cytotoxic (oleuropein glucoside), no effect (tyrosol) or protective effects (hydroxytyrosol and caffeic acid). In conclusion, cytoprotective as well as cytotoxic compounds with potential pharmaceutical properties were detected in extracts from olive oil related sources by using the comet assay methodology.
authors.affiliation: Laboratory of Biological Chemistry, University of Ioannina Medical School, 451 10, Ioannina, Greece.
authors.forename: Lambros
authors.initials: L
authors.lastname: Nousis
authors.forename: Paschalis-Thomas
authors.initials: PT
authors.lastname: Doulias
authors.forename: Nektarios
authors.initials: N
authors.lastname: Aligiannis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Bazios
authors.forename: Apostolos
authors.initials: A
authors.lastname: Agalias
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Galaris
authors.forename: Sofia
authors.initials: S
authors.lastname: Mitakou
mesh_terms: D002109:Caffeic Acids / Q000302:isolation & purification / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D020552:Comet Assay; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004249:DNA Damage; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D057888:Iridoid Glucosides; D039823:Iridoids; D019169:Jurkat Cells / Q000187:drug effects; D019906:Nuclear Magnetic Resonance, Biomolecular; D031658:Olea / Q000737:chemistry; D000069463:Olive Oil; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D010938:Plant Oils / Q000737:chemistry* / Q000494:pharmacology*; D011714:Pyrans / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D002109:Caffeic Acids; D057888:Iridoid Glucosides; D039823:Iridoids; D000069463:Olive Oil; D010936:Plant Extracts; D010938:Plant Oils; D011714:Pyrans; C005975:3,4-dihydroxyphenylethanol; C011867:4-hydroxyphenylethanol; C002769:oleuropein; D004247:DNA; D006861:Hydrogen Peroxide; D010626:Phenylethyl Alcohol; C040048:caffeic acid