Reduction of catechin, rutin, and quercetin levels by interaction with food-related microorganisms in a resting state



Flavonoids are plant secondary metabolites abundant in foods and beverages of plant origin. These compounds are free radical scavengers and their consumption is linked to reduced incidence of coronary heart disease. In this study, two wine-related microorganisms and one probiotic bifidobacteria strain were examined for their ability to absorb and/or transform the common flavonoids: quercetin, rutin, and catechin. Flavonoid absorption and/or transformation was determined using a resting cell assay (RCA) combined with high-performance liquid chromatographic detection of the flavonoid losses. RCAs with Pediococcus pentosaceus ATCC 25745, Saccharomyces cerevisiae ATCC 36026, and Bifidobacterium longum DJO10A resulted in losses of rutin and quercetin. Further analysis of cell pellets indicated that, unlike rutin and catechin, most of the quercetin present in the assay was transported/adsorbed only into metabolically active cells. In 24 h the net quercetin loss from the resting cells of P. pentosaceus, S. cerevisiae, and B. longum was 21.3%, 27.1%, and 63.4%, respectively. These results suggest that these microorganisms, which are frequently present or added to food products, can decrease the overall concentration of quercetin, either through absorption or transport into the cell. The implications for the overall bioavailability of quercetin in humans remain to be determined. Copyright © 2006 Society of Chemical Industry