Effects of α-lipoic acid and L-carnosine supplementation on antioxidant activities and lipid profiles in rats

Abstract

α-Lipoic acid and L-carnosine are powerful antioxidants and are often used as a health supplement and as an ergogenic aid. The objective of this study was to investigate the effects of α-lipoic acid and/or L-carnosine supplementation on antioxidant activity in serum, skin, and liver of rats and blood lipid profiles for 6 weeks. Four treatment groups received diets containing regular rat chow diet (control, CON), 0.5% α-lipoic acid (ALA), 0.25% α-lipoic acid + 0.25% L-carnosine (ALA + LC), or 0.5% L-carnosine (LC). Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and lipid peroxidation products, malondialdehyde (MDA) concentrations, were analyzed in serum, skin, and liver. Blood lipid profiles were measured, including triglycerides (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C). Skin and liver SOD activities of the ALA and LC groups were higher than those of the CON group (P < 0.05), but serum SOD activity was higher only in the LC group compared to that in the CON group (P < 0.05). Additionally, only liver GSH-Px activity in the LC group was higher than that of the CON and the other groups. Serum and skin MDA levels in the ALA and LC groups were lower than those in the CON group (P < 0.05). Serum TG and TC in the ALA and ALA + LC groups were lower than those in the CON and LC groups (P < 0.05). The HDL-C level in the LC group was higher than that in any other group (P < 0.05). LDL-C level was lower in the ALA + LC and LC groups than that in the CON group (P < 0.05). Thus, α-lipoic acid and L-carnosine supplementation increased antioxidant activity, decreased lipid peroxidation in the serum, liver, and skin of rats and positively modified blood lipid profiles.