Theoretical Elucidation
on Activity Differences of Ten Flavonoid Antioxidants
ZHANG Hong-Yu1*, CHEN De-Zhan2
( 1Department of Biological and Chemical Engineering, Zibo
University, Zibo 255091, China； 2Department of Chemistry, Shandong
Teachers’University, Jinan 250014, China )
Abstract Theoretical
methods including structure-activity relationships (SAR) and quantum chemical
calculations were used to elucidate the free radical scavenging activity
differences of 10 flavonoid antioxidants. SAR could give a qualitative
explanation on the antioxidant activity differences. And a further elucidation
was performed by a theoretical parameter, the difference of heat of formation
between antioxidant and its free radical (ΔHOF), calculated by Austin Model 1
(AM1) method. Besides, ΔHOF showed a linear correlationship with the logarithm
of the relative antioxidant efficiency (lgRAE, r =－0.7523), indicating that the
theoretical methods were effective to elucidate the differences of antioxidant
activity. On the other hand, the ineffectiveness of another theoretical
parameter, the highest occupied molecular orbit (HOMO) energy level, was
verified further.
Key words AM1 method； antioxidant； flavonoids； free radical； structure-activity
relationships
*Corresponding author： Tel, 86-531-2962645； Fax, 86-531-2960682； e-mail, [email protected]