Bicyclic lactones and racemic mixtures of dimeric styrylpyrones from the leaves of Miliusa velutina

Abstract

A unique class of eight bicyclic lactones with a C₁₈ carbon architecture, named velutinones A–H (1–8), three new dimeric styrylpyrones, velutinindimers A–C (9–11), five known compounds, the kawapyrone, yangonin (12), three flavonoids (13–15), and an acetogenin, cananginone H (16) were isolated from the leaves of Miliusa velutina. The absolute configurations of 2 and 5 were assigned by Mosher's method, whereas ECD, optical rotations, and X-ray crystallographic analysis indicated the racemic nature of compounds 10 and 11. Compounds 2–4 and 7–11 showed antimalarial activity with IC₅₀ values in the range of 5.4–10.0 μM. Moreover, 1–4 and 6–8 displayed cytotoxicity against the KB, MCF7, and NCI-H187 cancer cell lines and Vero cell lines with IC₅₀ values in the range of 4.0–24.1 μM.