RADICAL-CAPTURING REACTION AND ITS REACTION MECHANISM OF QUERCETIN REPRESENTING FLAVONOIDS

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13660160
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 林産学
• Research Institution: GIFU UNIVERSITY
• Principal Investigator: OHASHI Hideo GIFU UNIVERSITY, AGRICULTURE, PROFESSOR, 農学部, 教授 (80021723)
• Project Period (FY): 2001 – 2002
• Keywords: radical-capturing reaction / antioxidative constituent / flavonoid / quercetin / eriodictyol / reaction mechanism / 2,2'-azobis-butylritrile (AIBN) / 1,1-diphenyl-2-picrylhydrazile (DPPH)

Research Abstract

Following the study on the radical-capturing reaction mechanism of 3,5,7-trimethyiquercetin and 3,7-dimethylfisetin against a synthetic radical of 2,2'-azobis-isabutylnitrile ( AIBN) in the last year, the reactions of quercetin and/or eriodictyol against 1,1-diphenyl-2-picrylhydrazil (DPPH) and/or galvinoxyl under various conditions such as pH, reaction solvent and temperature were undertaken in order to understand the actual condition on radical-capturing reactions.
From the experiments using plural buffer solutions depending upon different pH, the results were obtained as below. It was revealed that DPPH-capturing abilities of quercetin and eriodictyol were more active in the acidic condition compared to the alkaline condition. Contrary to those of DPPH, galvinoxyl-capturing abilities of both flavonoids were more active in alkaline condition. From the experiments using plural reaction soluvents such as methanol, ethanol and acetone, it was presumed that DPPH- and galvinoxyl-capturing abilities of quercetin and eriodictyol were mainly influenced by reaction time, not reaction solvents. The experiments while changing reaction temperature were indicated that DPPH- and galvinoxyl-capturing abilities of quercetin depended the reaction temperature, though the increasing tendency of abilities was little beyond my expection. Still, in this work, the data on eriodictyol were not obtained, because I was restricted by time.
From the above, the following view was led, though the experiments in this year were not enough. For the purpose of efficacious utilization of antioxidative constituents, there were the most important things to understand the chemical and biochemical properties of antioxidant and target radicals and to consider the conditions of the reaction field. And then, it can be found out the inherent condition for the use of each antioxidant.