Electronic Description of Few Selected Flavonoids by Theoretical Study

The electronic properties responsible for free radical scavenging and metal chelation of a set of 7 flavonoids compounds were studied. Electronic parameters were calculated using semi empirical PM3 method. The structure activity relationship of OH substitution, C2-C3 double bond, chelation site of flavonoid and related property of antioxidant efficiency, BDE, mulliken atomic charge, electron current movement among A, B and C-rings were investigated. The relative change in energy (Hf) associated with the formation of phenoxyl radicals and spin density distribution of phenoxyl radicals were determined. The complexation mechanism of seven flavonoids quercetin, morin, apigenin, naringenin, chrysin, taxifolin and fisetin with metal ions, by molecular mechanics (UFF) method was investigated. Flavonoids metal chelation site order on toxic metals Pb, Bi and Cd was investigated. The most likely chelation site for metal ion was 5-OH & 4=O group, followed by 4=O & 3-OH group and the 3’& 4’ hydroxyl for all the flavonoid molecules studied. In the absence of C2-C3 double bond (taxifolin) the order of metal chelation site with metal was 3-OH & 4=O, followed by 5-OH & 4=O group and 3’ & 4’ hydroxyl.