Protective effect of rutin (vitamin p) against heme oxidation: A quantum mechanical approach

The methemoglobin (FeIIIHb) is product of the auto-oxidation of hemoglobin which cannot transport oxygen. Rutin (vitamin p) is one of the most important bioflavonoid with antioxidant activity in vivo and in vitro. Here, a systematic study of several interactions and arrangements between rutin, corresponding radical of rutin and methemoglobin (FeIIIHb) has been undertaken. Density Functional Theory (DFT) calculations by using B3LYP/6-31G* method were employed to calculate interaction energies, electronic states, and geometrical arrangements for the complex between the methemoglobin and rutin. Analysis of the theoretical bond dissociation enthalpy (BDE) values, for all OH sites of rutin, clearly shows the importance of the B-ring and the 3′-OH and 4′-OH groups in antioxidant reactivity. The results of calculations indicate that rutin and corresponding radical interact with methemoglobin with considerable stabilization energy and reduce the Fe(III) in the methemoglobin to Fe(II). Thus, rutin molecule plays a safeguard role against oxidative degradation of hemogolobin.