Cassane-type diterpenes from the seeds of Caesalpinia minax with their antineoplastic activity.

Five new cassane-type diterpenes, neocaesalpin AA (1), neocaesalpin AB (2), neocaesalpin AC (3), neocaesalpin AD (4) and neocaesalpin AE (5), were isolated from Caesalpinia minax together with three known compounds, 12α-methoxyl,5α,14β-dihydroxy-1α,6α,7β-triacetoxycass-13(15)-en-16,12-olide (6), spirocaesalmin (7) and magnicaesalpin (8). Their structures were elucidated based on 1D and 2D NMR, MS and CD analyses. Compounds 1-6 were tested against Hela, HCT-8, HepG-2, MCF-7 and A549 cancer cells and showed moderate cytotoxicity with IC₅₀ values from 18.4 to 83.9 µM.