beta-Carotene inhibits the oxidative modification of low-density lipoprotein.
Several lines of evidence indicate that oxidized LDL (Ox-LDL) may promote atherogenesis. Hence, the role of antioxidants in the prevention of LDL oxidation needs to be determined. beta-Carotene, in addition to being an efficient quencher of singlet oxygen, can also function as a radical-trapping antioxidant. Since previous studies have failed to show that beta-carotene inhibits LDL oxidation, we re-examined its effect on the oxidative modification of LDL. For these studies, LDL was oxidized in both a cell-free (2.5 microM Cu2+ in PBS) and a cellular system (human monocyte macrophages in Ham's F-10 medium). beta-Carotene inhibited the oxidative modification of LDL in both systems as evidenced by a decrease in the lipid peroxide content (thiobarbituric-acid-reacting substances activity), the negative charge of LDL (electrophoretic mobility) and the formation of conjugated dienes. By inhibiting LDL oxidation, beta-carotene substantially decreased its degradation by macrophages. beta-Carotene (2 microM) was more potent than alpha-tocopherol (40 microM) in inhibiting LDL oxidation. Thus, beta-carotene, like ascorbate and alpha-tocopherol, inhibits LDL oxidation and might have an important role in the prevention of atherosclerosis.
Jialal
I
I
Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas 75235.
Norkus
E P
EP
Cristol
L
L
Grundy
S M
SM
D000975:Antioxidants / Q000494:pharmacology*; D002338:Carotenoids / Q000494:pharmacology*; D002474:Cell-Free System; D006801:Humans; D066298:In Vitro Techniques; D008077:Lipoproteins, LDL / Q000187:drug effects* / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D019207:beta Carotene
D000975:Antioxidants; D008077:Lipoproteins, LDL; D019207:beta Carotene; D002338:Carotenoids