Four New Ursane-Type Triterpenes, Olibanumols K, L, M, and N, from Traditional Egyptian Medicine Olibanum, the Gum-Resin of Boswellia carterii

Four new ursane-type triterpenes, olibanumols K (1), L (2), M (3), and N (4), were isolated from traditional Egyptian medicine olibanum, the exuded gum-resin from Boswellia carterii BIRDW. Their structures were elucidated on the basis of chemical and physicochemical evidence.