Tangeretin Inhibition of High-Glucose-Induced IL-1, IL-6, TGF-1, and VEGF Expression in Human RPE Cells.

Tangeretin, a natural compound extracted from citrus plants, has been reported to have antiproliferative, antidiabetic, anti-invasive, and antioxidant properties. However, the role of tangeretin in diabetic retinopathy (DR) is unknown. In the present study, we investigated whether tangeretin had any effect on the expression of interleukin 1 beta (IL-1), interleukin 6 (IL-6), transforming growth factor beta 1 (TGF-1), and vascular endothelial growth factor (VEGF) in human retinal pigment epithelial (RPE) cells under high-glucose (HG) conditions. Our results illustrated that HG levels induced IL-1, IL-6, TGF-1, and VEGF expression and that tangeretin significantly reduced HG-induced IL-1, IL-6, TGF-1, and VEGF expression in human RPE cells. Moreover, tangeretin efficiently inhibited the activation of the protein kinase B (Akt) signalling pathway in HG-stimulated RPE cells. Therefore, tangeretin may serve a role in the treatment of DR.