title: Cis astaxanthin and especially 9-cis astaxanthin exhibits a higher antioxidant activity in vitro compared to the all-trans isomer.
abstract: In recent years, a number of studies have implicated the potent antioxidant property of astaxanthin in various experimental systems; however, these studies employed only the all-trans isomer. On the other hand, it has been reported that all-trans natural astaxanthin is readily isomerized to cis-trans, especially 9-cis and 13-cis isomers, under certain conditions by chemical analysis; however, the biological activities of the cis isomers of astaxanthin are little known. In the present study, we investigated the antioxidant activity of 9-cis and 13-cis astaxanthin compared to the all-trans isomer in vitro. In a stable radical DPPH scavenging activity test and in rat microsome and rabbit erythrocyte ghost membrane lipid peroxidation systems induced by AAPH and t-BuOOH, respectively, the results apparently showed that cis-astaxanthin, especially 9-cis astaxanthin, exhibited a higher antioxidant effect than the all-trans isomer. In addition, during polyunsaturated fatty acid (PUFA) oxidation, both DHA and linoleic acid hydroperoxides formation were markedly inhibited by astaxanthin isomers addition in the order 9-cis >13-cis >all-trans. Furthermore, 9-cis also exhibited the most effective inhibition of the generation of ROS induced by 6-hydroxydopamine (6-OHDA) in human neuroblastoma SH-SY5Y cells among the astaxanthin isomers, as well as on the degradation of collagen type II induced by DHA and linoleic acid hydroperoxides. The above-mentioned results suggest, for the first time, that cis isomer astaxanthin, especially 9-cis astaxanthin, has a much higher antioxidant potency than that of the all-trans isomer.
authors.affiliation: Laboratory of Food and Biodynamics, Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Xuebo
authors.initials: X
authors.lastname: Liu
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Osawa
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000737:chemistry; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D007536:Isomerism; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013329:Structure-Activity Relationship; D024341:Xanthophylls / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D024341:Xanthophylls; C005948:astaxanthine