Hemin inhibits lipid peroxidation induced by ascorbate/FeSO4 and 2,2'-azobis-2-amidino-propane hydrochloride (ABAP)

ABSTRACT

Hemin blocked lipid peroxidations induced by either ascorbate/FeSO4, a metal-catalyzed oxidation system, or 2,2'-azobis-2-amidino-propane hydrochloride (ABAP) which produces peroxy radicals at constant rates. Hemin at very low micromolar concentrations strongly inhibited the ascorbate/FeSO4-induced peroxidation of rat liver phopholipids, soybean phosphatidylcholine and arachidonic acid, and this inhibition was also evident with the use of ABAP, although much higher concentrations of hemin were required than those for the inhibition of ascorbate/FeSO4-induced lipid peroxidation. However, hemoproteins such as hemoglobin, myoglobin and cytochrome C did not show any significant effect on this lipid peroxidation. Hemopexin and albumin abolished the inhibitory action of hemin. During incubation with ascorbate/FeSO4 or ABAP, hemin underwent a change in its absorption spectrum, resulting in a progressive decrease in the peak height of the characteristic absorption band at 385 nm. The above results suggest that hemin may act as an important antioxidant in vivo, protecting lipids from the peroxidative damage.