Two new cassane-type diterpenoids from the seeds of Caesalpinia sappan.

A new cassane diterpenoid, caesappine A (1), and a new natural cassane diterpenoid, caesappine B (2) were isolated from the seeds of Caesalpinia sappan. The new structures of compounds 1 and 2 were elucidated by analysing their 1D NMR, 2D NMR and HR-ESI-MS spectra. Compounds 1 and 2 were evaluated for the cytotoxic activities on Hela and HepG-2 human cancer cell lines.