Zeaxanthin, a retinal carotenoid, protects retinal cells against oxidative stress.
OBJECTIVE
To investigate whether zeaxanthin, the predominant carotenoid pigment of the macular pigments in human retina, provides neuroprotection against retinal cell damage.


METHODS
We used in vitro cultured retinal ganglion cells (RGCs), specifically RGC-5, an E1A virus-transformed rat cell line. Cell damage was induced either by a 24-hr exposure to hydrogen peroxide (H2O2) or by serum deprivation. Cell viability was measured using the tetrazolium salt, WST-8. The scavenging capacity of zeaxanthin for H2O2, superoxide anion radical (O2.-), and hydroxyl radical (HO.) was measured using a radical scavenging capacity assay with CM-H2DCFDA, a reactive oxygen species (ROS)-sensitive probe.


RESULTS
When added to RGC-5 cell cultures, 0.1, 10, and 1 microM zeaxanthin scavenged the free radicals induced by H2O2, O2.-, and HO., respectively. In addition, pretreatment with 1 microM zeaxanthin permitted scavenging of staurosporine-induced intracellular radicals. Zeaxanthin also inhibited the neurotoxicity induced by H2O2 or serum deprivation and scavenged the intracellular radicals induced by H2O2 or serum deprivation.


CONCLUSIONS
Our results suggest that zeaxanthin provides effective protection against oxidative stress-induced retinal cell damage.
Department of Biofunctional Evaluation, Molecular Pharmacology, Gifu Pharmaceutical University, Gifu, Japan.
Yoshimi
Y
Nakajima
Masamitsu
M
Shimazawa
Kazumasa
K
Otsubo
Takashi
T
Ishibashi
Hideaki
H
Hara
D000818:Animals; D002461:Cell Line, Transformed; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D018384:Oxidative Stress; D051381:Rats; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D024341:Xanthophylls / Q000008:administration & dosage / Q000494:pharmacology*; D065146:Zeaxanthins
D016895:Culture Media, Serum-Free; D016166:Free Radical Scavengers; D005609:Free Radicals; D018696:Neuroprotective Agents; D024341:Xanthophylls; D065146:Zeaxanthins; D006861:Hydrogen Peroxide; D019311:Staurosporine