Inhibition of low-density lipoprotein oxidation by carnosine histidine.
Carnosine is a beta-alanylhistidine dipeptide found in skeletal muscle and nervous tissue that has been reported to possess antioxidant activity. Carnosine is a potential dietary antioxidant because it is absorbed into plasma intact. This research investigated the ability of carnosine to inhibit the oxidation of low-density lipoprotein (LDL) in comparison to its constituent amino acid, histidine. Carnosine (3 microM) inhibited Cu2+-promoted LDL (20 of protein/mL) oxidation at carnosine/copper ratios as low as 1:1, as determined by loss of tryptophan fluorescence and formation of conjugated dienes. Carnosine (6 microM) lost its ability to inhibit conjugated diene formation and tryptophan oxidation after 2 and 4 h of incubation, respectively, of LDL with 3 microM Cu2+. Compared to controls, histidine (3 microM) inhibited tryptophan oxidation and conjugated diene formation 36 and 58%, respectively, compared to 21 and 0% for carnosine (3 microM) after 3 h of oxidation. Histidine was more effective at inhibiting copper-promoted formation of carbonyls on bovine serum albumin than carnosine, but carnosine was more effective at inhibiting copper-induced ascorbic acid oxidation than histidine. Neither carnosine nor histidine was a strong inhibitor of 2,2'-azobis(2-amidinopropane) dihydrochloride-promoted oxidation of LDL, indicating that their main antioxidant mechanism is through copper chelation.
Decker
E A
EA
Department of Food Science, Chenoweth Laboratory, University of Massachusetts, Amherst 01003, USA. edecker@foodsci.umass.edu
Ivanov
V
V
Zhu
B Z
BZ
Frei
B
B
D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000737:chemistry; D002336:Carnosine / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology; D005453:Fluorescence; D006639:Histidine / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000737:chemistry*; D010084:Oxidation-Reduction; D012710:Serum Albumin, Bovine / Q000737:chemistry; D014364:Tryptophan / Q000737:chemistry
D000975:Antioxidants; D008077:Lipoproteins, LDL; D012710:Serum Albumin, Bovine; D006639:Histidine; D003300:Copper; D014364:Tryptophan; D002336:Carnosine; D001205:Ascorbic Acid