Effects Of Lipoic Acid On Antioxidation And Protecting Cultured Bovine Aortic Endothelial Cells And Smooth Muscle Cells From Oxidative Damage

Lipoic acid (LA) exists widely in all kinds of cells .It can be converted into dihydrolipoic acid (DHLA) in mammal cells. Since it was discovered its pharmacological effect has been investigated through a lot of experiment in vivo and in vitro including cells culture technique . It has been shown that LA can be used in the prevention and therapy of diabetes, cataract, ischemia, hypoxia/reoxygenation, irradiation injury, etc. However, the studies about LA activity involved in protecting cardiovascular cells from oxidative damage are limited.In order to further elucidate the free radial biological mechanism ,by which LA and DHLA performs its ant-oxidation activities, the present study analyzed the ability of LA and DHLA to scavenge directly different free radicals and reactive oxygen species (ROS) and prevent DNA oxidative damage caused by ? OH using chemiluminescence and colorimetric systems, established cell oxidative damage model cause by H₂O₂, observed the cardiovascular protection effect of LA using in vitro cultured bovine aortic endothelial cells (EC) and smooth muscle cells (SMC) and established cell oxidative damage model.The free radicals and ROS scavenging experiments indicated that LA and DHLA could effectively scavenge H₂O₂, ? OH, 1,1-diphenyl-2-picryl-hydrazyl ( DPPH ? ) and ONOO^- , inhibit lipid peroxidation and protect DNA from oxidative damage caused by ? OH. DHLA could effectively scavenge O₂^- but LA could not. It seems that the antioxidation ability of DHLA is stronger than that of LA.The results of MTT showed that LA could promote the proliferation of EC and inhibit the proliferation of SMC. The results dealing with the effects of LA on protecting cultured bovine aortic endothelial cells and smooth muscle cells from oxidative damage caused by H₂O₂, demonstrated that LA could dose-dependently increase the activities of SOD, CAT and the level of GSH , inhibit malondialdehyde (MDA) and ONOO^- in the EC and SMC , as well as in the culture medium of EC and SMC.The present study indicates both LA and DHLA can effectively scavenge many kinds of free radicals and ROS, inhibit lipid peroxidation and prevent DNA oxidative damage caused by ? OH, they are effective antioxidants. LA can promote the proliferation of EC and inhibit the proliferation of SMC, improve antioxidation level and biochemical index of the EC and SMC injured by H₂O₂, protect EC and SMC from oxidative damage. Our results shows LA can possibly prevent and cure athrosclerosis . It can provide new free radical biological data for the further study on the medical and health-care use of LA and DHLA.