L-sulforaphane confers protection against oxidative stress in an in vitro model of age-related macular degeneration

Background: In age-related macular degeneration, oxidative damage and abnormal neovascularization in the retina are caused by the upregulation of vascular endothelium growth factor and reduced expression of Glutathione-S-transferase genes. Current treatments are only palliative. Compounds from cruciferous vegetables (e.g. L-Sulforaphane) have been found to restore normal gene expression levels in diseases including cancer via the activity of histone deacetylases and DNA methyltransferases, thus retarding disease progression. Objective: To examine L-Sulforaphane as a potential treatment to ameliorate aberrant levels of gene expression and metabolites observed in age-related macular degeneration. Method: The in vitro oxidative stress model of AMD was based on the exposure of Adult Retinal Pigment Epithelium-19 cell line to 200μM hydrogen peroxide. The effects of L-Sulforaphane on cell proliferation were determined by MTS assay. The role of GSTM1, VEGFA, DNMT1 and HDAC6 genes in modulating these effects was investigated using quantitative real-time polymerase chain reaction. The metabolic profiling of L-Sulforaphane-treated cells via gas-chromatography massspectrometry was established. Significant differences between control and treatment groups were validated using one-way ANOVA, student t-test and post-hoc Bonferroni statistical tests (p<0.05). Results: L-Sulforaphane induced a dose-dependent increase in cell proliferation in the presence of hydrogen peroxide by upregulating Glutathione-S-Transferase μ1 gene expression. Metabolic profiling revealed that L-Sulforaphane increased levels of 2-monopalmitoglycerol, 9, 12, 15,-(Z-Z-Z)- Octadecatrienoic acid, 2-[Bis(trimethylsilyl)amino]ethyl bis(trimethylsilyl)-phosphate and nonanoic acid but decreased β-alanine levels in the absence or presence of hydrogen peroxide, respectively. Conclusion: This study supports the use of L-Sulforaphane to promote regeneration of retinal cells under oxidative stress conditions.