Phytochemicals From Salvia substolonifera With Anti-Angiogenic Properties and Substolide H Decreased Oxygen-Induced Retinal Neovascularization.

Retinal neovascularization is a pathological feature of ischemic retinopathy. Current therapeutic approaches are limited, and additional treatment options are needed. This study aims to discover lead compounds from Salvia substolonifera that inhibit angiogenesis. As a result, an undescribed norditerpene lactone, substolide H (3), and eight known compounds (1, 2, and 4-9) have been isolated. The structure was elucidated using synthetic spectroscopy and electron circular dichroism. Compounds 2, 3, 5, 7, and 9 inhibited human umbilical vein endothelial cells (HUVEC) proliferation with IC50 values of 26.47, 6.10, 43.27, 36.81, and 35.11 µM, respectively. Compounds 2, 3, and 7 inhibited HUVEC migration with IC50 values of 12.48, 8.37, and 7.63 µM, respectively. Further studies have shown that the substolide H (3) suppresses tube formation in human umbilical vein endothelial cells and that intravitreous administration suppresses retinal neovascularization in oxygen-induced retinopathy mice. Turning to its mechanism of action, we have shown that the anti-angiogenic effect of the substolide H may be through the downregulation of vascular endothelial growth factor expression and the phosphorylation of VEGFR2, ERK1/2, and protein kinase B. Our study represents the first report of these anti-angiogenic compounds from this plant, and substolide H may be a potential candidate for the treatment of retinal neovascularization.