Research Of Inhibitory Effects Of Flavonoids On The Formation Of MeIQx And 7,8-DiMeIQx

This paper chose a optimal solution model system of MeIQx and 7,8-DiMeIQx:0.2 mmol creatinine,0.2 mmol glycine and 0.1 mmol glucose was dissolved in 3 mL diethylene glycol water solution(water content was 14%)and heated for 2 hours at 130 ?.A decolorizing process has been established for the MeIQx and 7,8-DiMeIQx solution model system by liquid-liquid extraction of water and C2H2Cl2.The LC-ESI-MS/MS condition for MeIQx and 7,8-DiMeIQx were optimized and established respectively.Nine flavonoids abundant in plant species were chosen to study the inhibitory effect of flavonoids on the MeIQx and 7,8-DiMeIQx formation.It was found that all nine flavonoids had obvious inhibitory effect on the fomation of MeIQx and 7,8-DiMeIQx.For every chosen flavonoid,seven additive concentration of different molar amounts were designed to investigate its inhibitory effect on MeIQx and 7,8-DiMeIQx formation.After the inhibition curve of MeIQx,7,8-DiMeIQx and this two HAAs of every flavonoids had been established,the middle inhibition ratio of the concentration(IC50)of MeIQx,7,8-DiMeIQx and this two HAAs was obtained according to the regression equation of fitting.The compared MelQx IC50 value order of nine flavonoids was proanthocyanidins<baicalein<(+)-catechinhydrate<liquiritin<isorhamnetin<isoliquiritin<hesperidin<puerarin<quercetin.The compared 7,8-DiMeIQx IC50 value order of nine flavonoids was proanthocyanidins<baicalein<liquiritin<isorhamnetin<(+)-catechinhydrate<isoliquiritin<hesperidin<puerarin<quercetin.The compared two HAAs IC50 value order of nine flavonoids was proanthocyanidins<baicalein<(+)-catechinhydrate<liquiritin<isorhamnetin<isoliquiritin<hesperidin<puerarin<quercetin.By analyzing the experiment result of the TEMPO test,it was validated that the MelQx and 7,8-DiMeIQx formation in solution model system was in afree radical way.And the free radicals were related to oxygen was proved by comparing the results of solution model systemin less oxygen conditionand oxygen enrichment condition.The oxygen related free radicals was proved to be the alkoxy radicals by ESR spectrum analysis.The alkoxy radicals scavenging capacity of the flavonoids was judged by the ESR spectrum,and the order was as followed:baicalein<proanthocyanidins<(?)-catechinhydrate<quercetin<isorhamnetin<hesperidin<puerarin<isoliquiritin<liquiritin.This was not entirely consistent with the inhibitory effect of flavonoids on the MeIQx and 7,8-DiMeIQx formation in solution model system.Thus,the inhibitory effect of the nine flavonoids on MeIQx and 7,8-DiMeIQx formation was not completely through the scavenging alkoxy radicals.