Elucidating the Improvement in Vascular Endothelial Function from Sakurajima Daikon and Its Mechanism of Action: A Comparative Study with Raphanus sativus.

Vascular diseases, such as myocardial and cerebral infarctions, are the leading causes of death. Some vascular diseases occur as the result of decreases in vascular endothelial function. The innermost layer of the vasculature is formed by vascular endothelial cells (VECs), which are critical for nitric oxide (NO) synthesis. In our search for active constituents in farm products with the potential for improving the vascular system, we examined the effect of Raphanus sativus cv. Sakurajima Daikon on NO production in VECs. In this study, we found that the underlying mechanism for stimulating NO production by Sakurajima Daikon extract involves endothelial-NO-synthase (eNOS) activation by the phosphorylation of Ser1177 and the dephosphorylation of Thr495, which are triggered by elevated concentrations of cytoplasmic Ca2+ resulting from the activation of Ca2+ channels in VECs. We observed that trigonelline, an active constituent of Sakurajima Daikon, improves NO production in VEC cultures.