Eight new limonoids from Turraea pubescens

Eight new ring B-seco limonoids, turrapubesic acids A–C (1–3) and turrapubesins C–G (4–8), along with turraflorin E and isoazadironolide were isolated from the twigs and leaves of Turraea pubescens. Turrapubesic acids A–C (1–3) are a group of ring B-seco limonoid 17-carboxylic acids with a new C23 skeleton, and turrapubesin C (4) incorporates an unprecedented 1,30-oxygen bridge. The structures including absolute stereochemistry of 1–8 were established on the basis of extensive NMR spectroscopic analysis and CD study. The cytotoxicity of the isolates against the P-388 and A-549 cells was evaluated.