Zeaxanthin, a Retinal Carotenoid, Protects Retinal Cells against Oxidative Stress

Abstract

Purpose: 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 μM zeaxanthin scavenged the free radicals induced by H₂O₂, O₂·⁻, and HO ·, respectively. In addition, pretreatment with 1 μ M 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.

Keywords:

• neuroprotection
• oxidative stress
• retinal ganglion cell
• zeaxanthin