The first investigation on chemical constituents and biological activity of Rubia philippinensis

Despite the genus Rubia being researched to identify valuable commercial and medicinal virtues, Rubia philippinensis has rarely been investigated. In the present study, seventeen arborinane-type triterpenoids, including nine new compounds (1-9), were isolated from the underutilized plant species. Structures of new compounds were determined as 3-O-Acetylrubiarbonol L (1), 3-O-Acetylrubianol C (2), 28-Deoxyrubiarbonone E (3), 19-Dedihydrorubiarbonol B (4), 2-Deoxyrubianol F (5), 3-O-Acetylrubiarbonol B (6), 3-O-Acetylrubiarbonol A (7), 19-O-Acetylrubiarbonol B (8), and 19-O-Acetyl-28-deoxyrubiarbonone (9). The new chemical entities were assessed for their inhibitory potential on platelet derived growth factor-induced proliferation and the migration of vascular smooth muscle cells. Treatment with 5 µM of compounds 5 (62.6 ± 10.7%) and 9 (41.1 ± 4.7%) impeded proliferation without exerting cytotoxicity. Compound 7, meanwhile, exhibited antimigration activity in a dose-dependent manner (38.5 ± 3.0% at 10 µM and 57.6 ± 3.2% at 30 µM, respectively). These results suggest that the arborinane-type triterpenoids may be a pertinent starting point for the development of cardiovascular drugs capable of preventing neointimal hyperplasia of vascular smooth muscle cells.