SMTP-44D Improves High Glucose-Induced Vascular Endothelial Dysfunction

Chronic diabetic complications are mostly caused by vascular disorders, with only a few effective treatments or preventive measures currently available. In this study, we investigated the effects of Stachybotrys microspora triprenyl phenol-44D (SMTP-44D), a fungus-derived compound that inhibits both the epoxide hydrolase and phosphatase activities of soluble epoxide hydrolase (sEH), using human umbilical vein endothelial cells (HUVECs) in a high glucose treatment model. When HUVECs were treated with high glucose (30 mM) for 24 h, cell viability decreased to 69% compared with that under normal glucose (5.6 mM) conditions. When SMTP-44D was added, cell viability increased to 111%. In addition, nitric oxide levels in HUVECs decreased to 52% after 24 h of high-glucose treatment but increased to 82% after SMTP-44D treatment. Under the same conditions, high-glucose treatment increased intracellular reactive oxygen species levels and reduced Akt activation. SMTP-44D significantly improved both these changes, compared with the high glucose group. Under high glucose conditions, it is likely that oxidative stress and the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway are involved in endothelial dysfunction, and that SMTP-44D restores vascular function by acting on these pathways. In this study, we demonstrated, for the first time, SMTP-44D improves diabetic vascular endothelial dysfunction, suggesting that it may be a novel therapeutic and preventive candidate for the treatment of chronic complications of diabetes.