Cycloartane triterpenes and ingol diterpenes isolated from Euphorbia neriifolia in a screening program for death-receptor expression-enhancing activity.

In our screening program for natural products that increase death-receptor 5 expression, seven new cycloartane triterpenes, euphonerins A-G (1-7), and 3-O-acetyl-8-O-tigloylingol (8), a new ingol diterpene, were isolated from the MeOH extract of Euphorbia neriifolia leaves, together with 3,12-di-O-acetyl-8-O-tigloylingol (9), (24R)-cycloartane-3ß,24,25-triol (10), and three known flavonols (11-13). The structures of 1-8 were elucidated by spectroscopic analysis. Among these compounds, 1-11 showed death-receptor 5 expression enhancing activity.