Boswellic acids are pentacyclic triterpenes first isolated from the resin of Boswellia plants. They have anti-inflammatory and anti-arthritic actions in mice. β-acetyl-Boswellic acid is a non-reducing inhibitor of 5-lipoxygenase (5-LO) that shows selectivity for 5-LO over 12-LO or COX. When studied as a 1:1 mixture with α-acetyl-boswellic acid, it inhibits topoisomerase II activity and arrests cell cycling or induces apoptosis in cancer cells.