Flavonols and flavan-3-ols as modulators of xanthine oxidase and manganese superoxide dismutase activity

Danila Di Majo, Maurizio La Guardia, Gaetano Leto, Marilena Crescimanno, Carla Flandina, Marco Giammanco
2014 International Journal of Food Sciences and Nutrition  
Experiments were performed to assess the dose-dependent effects of quercetin, kaempferol, (+) catechin, and (À) epicatechin on superoxide radical production through the modulation of manganese superoxide dismutase and xanthine oxidase activities. The experiments were carried out at flavanoid concentrations ranging from 1 mM to 100 mM. This investigation highlighted that flavonols induced opposite effects on superoxide radical production at different doses, i.e. pro-oxidant at the highest
more » ... the highest concentration (100 mM) and anti-oxidant at the lowest concentration (1 mM). Similar behaviors were observed for xanthine oxidase with flavan-3ols. The diastereoisomer (the catechin) acted as a stronger radical scavenger than the epicatechin. However, flavan-3ols were less pro-oxidant than flavonols: in fact, the addition of the superoxide dismutase enzyme was able to cancel the flavan-3ols' pro-oxidant effect. This study also shows that the absence of the 4-carbonyl group conjugated with the 2-3 double bonds in the heterocyclic ring cancelled the pro-oxidant effect of flavan-3ols. The opposite dose-dependent effects of flavonols suggest that they may be used as either a pro-oxidant or antioxidant. Flavonols and flavan-3-ols as modulators of XO and MnSOD 7 Int J Food Sci Nutr Downloaded from informahealthcare.com by Universita Studi Palermo on 07/03/14 For personal use only.
doi:10.3109/09637486.2014.931362 pmid:24975489 fatcat:aqe2amhly5cmdnhizy2ozh7vem