Anti-osteoclastogenic effects of isoquinoline alkaloids from the rhizome extract of Sinomenium acutum.

A phytochemical investigation for the rhizome extract from Sinomenium acutum (Menispermaceae) resulted in the isolation of several active principles responsible for the anti-osteoclastogenic property of the extract, together with related isoquinoline alkaloids (1-13) including two new compounds, 1 and 2. Among isolated compounds, salutaridine (7), dauricumine (10), cheilanthifoline (12), and dauriporphine (13) were observed to give significant inhibitions on receptor activator of nuclear factor-κB ligand-induced differentiation of mouse bone marrow-derived macrophages into multinucleated osteoclasts, respectively. The chemical structures of two newly isolated compounds, 1 and 2 were established as 8-demethoxycephatonine (1) and 7(R)-7,8-dihydrosinomenine (2), by spectroscopic analyses including 2D NMR experiments.