Modulatory Effects of Resveratrol, Citroflavan-3-ol, and Plant-Derived Extracts on Oxidative Stress in U937 Cells

다국어 초록 (Multilingual Abstract)

Phytochemicals and plant extracts, present in fruit, vegetables, plants, herbs, and beverages, have been shownto have antioxidant potential that may modulate the etiology of certain chronic diseases. The objective of the present studywas to determine the concentration of compound that inhibited cell growth by 50% (IC50) of a range of phytochemicals andplant extracts and to investigate their antioxidant and genoprotective effects under conditions of oxidative stress in U937 cells.Two phytochemicalsresveratrol and citroflavan-3-oland four plant extractsgrapeseed polyphenols, olive leaf extract,bearberry, and Echinacea purpureawere examined. Viability was assessed by the fluorescein diacetate/ethidium bromideassay. The IC50 was calculated. To examine their antioxidant and genoprotective effects, U937 cells were pretreated with thetest compounds at levels below the IC50 and then exposed to oxidants: 0.5 .M etoposide or 100 .M hydrogen peroxide (H2O2)or 400 .M tert-butylhydroperoxide (tBOOH). Cellular reduced glutathione levels were measured as an indicator of oxidativestress. DNA damage was assessed by the alkaline single-cell gel electrophoresis assay or comet assay. Resveratrol demon-strated the highest IC50 value of 13.7 .g/mL, with Echinaceathe lowest at 9,400 .g/mL. Etoposide-induced oxidative stresswas strongly reduced by olive leaf extract and bearberry. Grapeseed polyphenols and bearberry strongly protected againstH2O2- and tBOOH-induced DNA damage. In conclusion, these results provide evidence that non-nutrient dietary constituentsmay act as significant bioactive compounds and that plant extracts, such as bearberry, grapeseed polyphenols, and olive leafextract, strongly protect against oxidative stress.

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