Cassane butenolides from the fruits of Caesalpinia pulcherrima

Abstract

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.