Five terpenoids from the gum resin of Boswellia carterii and their cytotoxicity.

One undescribed tetracyclic triterpene (boswellicarin A), four undescribed pentacyclic triterpenes (boswellicarterins A-C) and one undescribed prenylaromadendrane-type diterpene (boscarterin A) were isolated from the gum resin of Boswellia carterii Birdw. (Burseraceae). Their structures were elucidated from NMR and HRESIMS spectroscopic data and ECD spectra. Boswellicarterins A-C and boscarterin A displayed weak and selective cytotoxicity against three human cancer cells (HepG2, A549 and MCF-7) by MTT assay.