Inhibition of oral cancer cell proliferation by dietary flavonoids: Importance of bioactivation by saliva Thomas Walle, Cheryl I. Widejko, U. K. Walle. Medical University of South Carolina, Charleston, SC. Oral squamous epithelial cell cancer, which has a particularly high incidence among black men, responds poorly to treatment. It may therefore benefit from chemopreventive strategies, e.g. inhibition of neoplastic growth. Although dietary interventions have not received much attention in oral cancer, epidemiological studies suggest that this could be an important protective factor. In this study we focus on dietary flavonoids. In the first part of this study we show that quercetin-4’-O-glucoside (QG) and genistein-7-O-glucoside (genistin, GIN), two of the most abundant flavonoids in the human diet, are effectively hydrolyzed by human saliva, collected from three normal volunteers, to their more bioactive forms quercetin (Q) and genistein (GEN). This hydrolysis appears to be related to beta-glucosidase(s) expressed by the oral bacterial flora and thus varied substantially with the level of oral hygiene. In the second part of this study, we used the oral squamous epithelial cancer cell SCC-9 to determine the antiproliferative effects of Q, GEN, QG and GIN, using 96-well plates and the MTT assay, which determines the number of viable cells. Both aglycones, i.e. Q and GEN, inhibited SCC-9 cell proliferation in a concentration-dependent manner with about 50% inhibition at flavonoid concentrations of 20 microM (P < 0.05). In sharp contrast, neither of the dietary forms, i.e. QG and GIN, had any effect. Thus, dietary QG and GIN are hydrolyzed to the bioactive Q and GIN by saliva, liberating them in the oral cavity to potentially inhibit oral cancer cell proliferation. The mechanisms of the antiproliferative effects of Q and GEN, presently under investigation, are quite distinct, affecting different molecular signaling targets. AACR, Abstract Number: 3904 2003 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.