Cassane butenolides from the fruits of Caesalpinia pulcherrima.

Seven undescribed cassane diterpenes, caeslpulrins A-G (1, 3, 4, and 6-9), the C-12 ethoxy derivatives of caeslpulrins A and C (2 and 5), along with five artificial or known cassane diterpenes (10-14) and eight known sesquiterpenoids (15-22) were isolated from the fruits of Caesalpinia pulcherrima. Their structures were elucidated by extensive spectroscopic analyses, including HR-ESI-MS, 1D and 2D NMR, and electronic circular dichroism (ECD) calculations. Caeslpulrins A-F were identified as a group of rare cassane butenolides possessing a C-3 benzoyloxy unit. This is the first report of a series of such cassane diterpenes from a Caesalpinia plants. Compounds 1-7 were evaluated their inhibitory effects on NO production in the LPS-induced RAW 264.7 macrophages, and their cytotoxicities against several human tumor cell lines using MTS method.