Inhibition Of PhIP In Roast Beef Patties By Dietary Flavonoids: Formation Mechanism

As one of the most abundant HAs,2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine(PhIP) may induce a variety of cancer, which causes serious health consequences. Somestudies suggest that naringenin and EGCG could reduce the level of PhIP in model systems,the possible mechanism is that naringenin and EGCG can trap phenylacetaldhyde throughadduct formation. Although there dietary flavonoids has been some progress in the study ofthe mechanism of inhibition of PhIP. However, despite the progress in the inhibitorymechanism of PhIP formation, as the wide range of flavonoids, more research is needed toinvestigate that if other types of flavonoids can inhibit PhIP formation in the same way.Besides, the PhIP inhibitory mechanism is still need to prove in food system.In order to investigate the inhibitory effect and mechanism of dietory flavonoids on PhIPformation in beef patties,8flavonoids were selected (naringenin, kaempferol, quercetin,phlorizin, EGCG, genistein, luteolin and apigenin). This paper may provide a theoreticalunderpinning for PhIP inhibition and some new ideas about comprehensive exploitation andapplication of dietary flavonoids.First of all, a detection method of17HAs was optimized. Harman, Norharman,4,8-DiMeIQx, MeIQx, DMIP and1,5,6-TMIP were detected from roast beef patties. Theresults indicated that all tested flavonoids showed significant inhibitory effects on total HAsformation in beef patties. Besides, all tested flavonoids had signigicant inhibitory effects onPhIP formation in roast beef patties except for luteolin.Next, the influence factors of flavonoids on PhIP formation were investigated. Firstly,the scavenging effect of flavonoids on phenylacetaldehyde was examined. The resultindicated that apigenin, plorizin, EGCG, quercetin, naringenin and kaempferol showedsignificant scavenging effects on phenylacetaldehyde. In addition, correlation analysisindicated a good linear relationship between the scavenging capability of flavonoids onphenylacetaldehyde and the inbition of flavonoids on PhIP formation, with correlationcoefficient r=0.8702. Secondly, the inhibitory effect of flavonoids on phenylacetaldehydeformation on PhIP model system. It turned out that all tested flavonoids had remarkableinhibitory effects on phenylacetaldehye formation. Moreover, correlation analysis showed agood correlation relationship between the inhibition of flavonoids on phenylacetaldehydeformation on PhIP model system and the inhibition of flavonoids on PhIP formation. Thirdly,the ABTS radical-scavening activities of flavonoids were investigated. Correlation analysisindicated that the antioxidant capacity of flavonoids was negatively correlated with theinhibition of flavonoids on PhIP formation.At last, with the purified phenylacetaldehyde-flavonoid adducts as reference standards, the same adducts in roast beef patties were identified. The mechanism of PhIP inhibition byflavonoids via scavenging of phenylacetaldehyde was demonstrated.