Chemical modification of quercetin by the first transition metal and its antioxidant activity

Based on the chemical modification of quercetin,the complex of quercetin of first transition series chemical element was synthesized.The quercitin complexes solubility,total antioxidant capacity,clearing O2.-free radicals and DPPH.free radical ability were studied.The results showed that the solubility of quercetin complexes in water is better than that of quercetin.The order of total antioxidant ability of quercetin complexes: quercetin quercetin-Fe(III)quercetin-Cr(III)quercetin-Ni(Ⅱ)quercetin-Co(Ⅱ)quercetin-Mn(Ⅱ)quercetin-Cu(Ⅱ)quercetin-Zn(Ⅱ);the order of scavenging O2-radical ability: quercetinquercetin-Fe(III)quercetin-Cr(III)quercetin-Ni(Ⅱ)quercetin-Mn(Ⅱ)quercetin-Cu(Ⅱ)quercetin-Co(Ⅱ)quercetin-Zn(Ⅱ);the order of scavenging DPPH.radical ability: quercetinquercetin-Fe(III) quercetin-Ni(Ⅱ) quercetin-Cr(III) quercetin-Cu(Ⅱ)quercetin-Co(Ⅱ)quercetin-Mn(Ⅱ)quercetin-Zn(Ⅱ).The results showed that the product of quercetin chemical modification has better biological activity than that of quercetin.