Jatrophane Diterpenoids from <i>Euphorbia esula</i> as Inhibitors of RANKL-Induced Osteoclastogenesis

Eighteen new jatrophane diterpenoids, euphoesulatins A–R (1–18), and three known diterpenoids (19–21) were isolated from Euphorbia esula. Compounds 1–7, 14, and 18 represent a rare type of jatrophane-type diterpenoid containing a nicotinoyloxy group. The absolute configuration of 1 was determined by X-ray crystallography. The compounds were assayed for their antiosteoporotic activity in a bone-marrow-derived macrophage cell line, and compounds 1, 8, and 10 significantly inhibited the formation of osteoclasts, with IC50 values of 1.2, 3.5, and 2.3 μM, respectively. These three compounds also dose-dependently reduced the activity of nuclear factor activated T-cell cytoplasmic 1. This study reveals the antiosteoporotic effects of jatrophane diterpenoids for the first time.