Quercetin modifies reactive oxygen levels but exerts only partial protection against oxidative stress within HL-60 cells.
Quercetin may contribute to the protection afforded by fruit- and vegetable-rich diets against diseases for which excess production of reactive oxygen species (ROS) has been implicated as a causal or contributory factor. We examine the effect of short term (90 min) quercetin (1-100 microM) exposure on the progress of menadione induced oxidative stress within HL-60 cells. 2',7'-dichlorofluorescein and rhodamine-123 fluorescence, resulting from oxidation of the ROS-sensitive dyes dichlorodihydrofluorescein and dihydrorhodamine-123 respectively, were utilised as indicators of general ROS levels. Ethidium fluorescence, resulting from oxidation of dihydroethidium, was used as a potentially more specific indicator of O(2)(-). Exposure to quercetin alone induced a decrease in DCF and rhodamine fluorescence. Conversely, ethidium fluorescence was enhanced by treatment with >or=40 microM quercetin. Incubation with 1-100 microM quercetin reduced the extent of menadione-induced increase in DCF and rhodamine fluorescence but the menadione-induced increase in ethidium fluorescence was further elevated for cells treated with >or=25 microM quercetin. Exposure to >or=10 microM quercetin abrogated menadione-induced DNA single-strand breaks but, paradoxically, quercetin exacerbated membrane damage and failed to enhance the viability of menadione-challenged cells. In conclusion, quercetin exerts only site-specific protection against oxidative stress.
Bestwick
C S
CS
Antioxidant and DNA Damage Group, Cellular Integrity Programme, Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK. csb@rri.sari.ac.uk
Milne
L
L
D002463:Cell Membrane Permeability; D002470:Cell Survival; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005978:Glutathione / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D011794:Quercetin / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020112:Rhodamine 123; D014812:Vitamin K
D005452:Fluoresceins; D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species; D014812:Vitamin K; D020112:Rhodamine 123; C037631:2',7'-dichlorofluorescein; D011794:Quercetin; D005978:Glutathione