Relationship between plasma levels of Zinc and lipid oxidizability in diluted plasma.

Zinc (Zn) is an essential trace element that has been regarded as having antioxidant properties. Some epidemiological studies have indicated the protective effect of Zn on lipid and lipoprotein peroxidation, but the underline mechanism is poorly understood. This study was conducted to evaluate the relationship between plasma Zn and copper-induced lipid peroxidation parameters in diluted plasma.Methods and Materials: In 100 healthy adult men (36.82 ± 10.33 years), fasting plasma levels of Zn, lipids, bilirubin, urate, malondialdehyde (MDA) and copper induced lipid peroxidation were evaluated. Lipid oxidation estimated by monitoring the change of conjugated dienes in 60-fold diluted plasma after addition of 60 μM Cu2+ and MDA was determined by thiobarbituric acid method. A significant correlation (r=0.24, p=0.024), between Lag-time (104 ± 33 min) and plasma Zn levels (128.76 ± 108.33 μg/dl) was found; however, no significant correlation was found between other parameters of lipid oxidation kinetics and MDA with plasma Zn levels. Based what the results indicated there is a delay in Cu-induced plasma lipid oxidation by higher levels of plasma Zn, but Zn level has no effect on finals oxidation products. It seems that Zn interferes with for Cu in the formation of an active oxidizing complex.