Absolute Stereostructures of Olibanumols A, B, C, H, I, and J from Olibanum, Gum-Resin of Boswellia carterii, and Inhibitors of Nitric Oxide Production in Lipopolysaccharide-Activated Mouse Peritoneal Macrophages

Three new monoterpenes, olibanumols A (1), B (2), and C (3), and three new triterpenes, olibanumols H (4), I (5), and J (6), were isolated from olibanum, the exuded gum-resin from Boswellia carterii BIRDW. Their structures including the absolute configuration were determined by chemical and physicochemical evidence. Among the constituents, olibanumols A (1), H (4), and I (5), and isofouquierol (12) exhibited nitric oxide production inhibitory activity in lipopolysaccharide-activated mouse peritoneal macrophages.