Cis astaxanthin and especially 9-cis astaxanthin exhibits a higher antioxidant activity in vitro compared to the all-trans isomer

Biochem Biophys Res Commun. 2007 May 25;357(1):187-93. doi: 10.1016/j.bbrc.2007.03.120. Epub 2007 Mar 28.


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.

MeSH terms

  • Animals
  • Antioxidants / administration & dosage
  • Antioxidants / chemistry
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Erythrocyte Membrane / drug effects
  • Erythrocyte Membrane / metabolism*
  • Isomerism
  • Microsomes / drug effects
  • Microsomes / metabolism*
  • Oxidation-Reduction / drug effects
  • Rabbits
  • Rats
  • Rats, Wistar
  • Reactive Oxygen Species / metabolism*
  • Structure-Activity Relationship
  • Xanthophylls / administration & dosage
  • Xanthophylls / chemistry


  • Antioxidants
  • Reactive Oxygen Species
  • Xanthophylls
  • astaxanthine