Sulforaphane Protects Against Cell‐mediated LDL Oxidation and Potentiates the Effects of Alpha Tocopherol

Increased consumption of cruciferous vegetables is associated with health, especially, lower incidence of certain cancers. Broccoli accumulates significant amounts of glucoraphanin, the only dietary source of sulforaphane (SF). There are several studies reporting on SF dependent antioxidant enzyme induction in cell‐based, animal human clinical studies that indicate a protective effect of SF against oxidative stress. However, a direct effect of SF on cell‐mediated LDL oxidation has not been reported. Oxidized LDL (OxLDL) levels are increased in atherosclerosis and higher levels predict cardiovascular events. In this study, we tested the effects of SF (0.1–10uM) alone and in combination with alpha‐tocopherol (AT) on human monocyte derived macrophage (HMDM) mediated LDL oxidation. LDL oxidation was assessed using OxLDL ELISA. Ratio of reduced to oxidized glutathione (GSH:GSSG) was measured. SF (5 uM) caused 40% inhibition of LDL oxidation and potentiated the effects of AT (25uM, 65% inhibition, p<0.001). Furthermore, SF (>1uM) significantly increased GSH:GSSG ratio in HMDM. These studies provide evidence for SF as an antioxidant per se and also a potentiator of the antioxidant activity of AT by increasing cellular GSH:GSSG ratio. Future studies will provide mechanistic insights for these beneficial effects of SF and potential benefits relevant to heart health.