Diterpenoids of the Cassane Type from Caesalpinia decapetala

Eighteen compounds, including eight new cassane-type furanoditerpenoids, 3β-hydroxyphanginin H (1), 3β-acetoxyphanginin H (2), 7β-acetoxyphanginin H (3), 7β-hydroxyphanginin H (4), 4-epi-3β-hydroxycaesalpinilinn (5), 4-epi-3β-acetoxycaesalpinilinn (6), 20-acetoxytaepeenin D (7), and tomocin E (8), along with 10 known compounds (9–18) were isolated from the roots of Caesalpinia decapetala. Compounds 1–13 were isolated from C. decapetala for the first time. The new compounds with their absolute configurations were determined by extensive spectroscopic analysis, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Compounds 1, 4, 5, 7, and 11 exhibited inhibitory activities against the SW1990 human pancreatic cancer cell line with IC₅₀ values ranging from 2.9 to 8.9 μM.