Flavanols and procyanidins as antioxidants: is calcium a key player?

C. G. FRAGA

Jaipur, India

Congreso; Society for Free Radical Research-India, VII Annual Meeting; 2008

Society for Free Radical Research-India

Polyphenols as antioxidants: is calcium a key player? Cesar G. Fraga, S. V. Verstraeten, G. G. Mackenzie, and P. I. Oteiza Department of Nutrition, University of California, Davis, California, USA; and Physical Chemistry-PRALIB, School of Pharmacy and Biochemistry, University of Buenos Aires, Argentina   Epidemiological evidence demonstrates that diets rich in fruit and vegetables promote health by attenuating or delaying the onset of various diseases associated to inflammation, e.g. cardiovascular and neurodegenerative diseases, diabetes, and cancer. The chemical components involved, and the physiological and molecular mechanisms by which fruit and vegetables reduce the risk of disease, are matters of intensive investigation. Flavanols are polyphenols that are gaining acceptance as responsible for the health benefits offered by fruit and vegetables. Because of their chemical structure, flavanols and related procyanidins (PC) can scavenge free radicals and inactivate other pro-oxidants, and can also interact with a number of biological molecules. The association of these chemical properties to a physiological antioxidant action is the engine for extensive and thriving research. We have investigated in Jurkat cells the effects of epicatechin (EC) and related procyanidins (PC) on calcium mobilization. Doubling intracellular calcium induced NADPH oxidase activation, oxidant production, and NFAT activation. These effects were prevented by EC and PC at concentrations as low as 10 nM. The obtained results indicate that EC and PC effects were unlikely due to a direct free radical scavenging action or to a direct inhibition of NADPH oxidase activity, but to the modulation of membrane-related calcium uptake, probably by inhibiting store operated channels. Maintaining optimal levels of intracellular calcium will minimize cell oxidant production and pro-inflammatory events. Calcium regulation by flavanols provides a putative mechanism that can explain the health promoting effects of the consumption of foods containing high levels of flavonoids and polyphenols. Supported by NIH AT2966, and UC Davis CHNR which was established with funding from the State of California Vitamin Price Fixing Consumer Settlement fund.