dft study of substituent effects on antioxidant activity of kaempferol in the gas phase

in this work, the study of various substituted kaempferol derivatives is presented. the bond dissociation energies (bde) have been calculated using b3lyp level and different basis sets in gas-phase. calculated results show that the bde values of substituted kaempferol range from about 77 to100 kcal/mol, demonstrating that kaempferol is an effective chain-breaking antioxidant that prevents lipid peroxidation. also we can seen, cl, oh, cn, nh2 and ch3 groups in c3′ position, ch3, oh and nh2 groups in c5′ position and nh2 and cn groups in c6′ position destabilize the parent kaempferol molecule and stabilize the radical; hence, it decreases the o-h bde.