Norcassane- and cassane-type furanoditerpenoids from the seeds of Caesalpinia sappan

Abstract Three novel furanoditerpenoids, norcaesalpinin J ( 1 ) featuring an unusual 20-norcassane hydroperoxide and phangininoxys B ( 2 ) and C ( 3 ) possessing cassane hemiketal skeletons, were isolated from the seeds of Caesalpinia sappan . Their structures were elucidated by extensive spectroscopic methods. All isolates were evaluated for the cytotoxic activities on three human cancer cell lines.