Theoretical Investigation on Free Radical Scavenging Activity of 6,7-Dihydroxyflavone

✍ Scribed by Zhang, Hong-Yu

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 950 KB
• Volume: 19
• Category: Article
• ISSN: 1611-020X
• DOI: 10.1002/(sici)1521-3838(200002)19:1<50::aid-qsar50>3.0.co;2-#

✦ Synopsis

The difference of heat of formation between parent molecule and its free radical (DHOF), calculated by semiempirical quantum chemical method AM1, was employed as a theoretical index to characterize the OÀH bond dissociation energy (BDE) of antioxidant. Through a comparison between DHOF of model molecules, it was found that 6,7-dihydroxy¯avone (DHF) possessed two favorable structural factors, the presence of ortho hydroxyls and the existence of para oxygen, to weaken its OÀH bond at position 6, but the passive effect produced by electronwithdrawing property of the chromonoid ring C surpassed the active effect of the para oxygen. Therefore the free radical scavenging activity of DHF was lower than that of quercetin which possessed catecholic hydroxyl in ring B and was scarcely in¯uenced by ring C. As a result of the analysis, two more active ¯avonoid antioxidants were constructed theoretically.