Lipoxygenase (LOX) are enzymes that catalyze the addition of oxygen to polyunsaturated fatty acidscontaining a cis, cis-1,4- pentadiene structure. The most common analogs are 5-LOX, 8-LOX, 12-LOX, and 15-LOX, with the number indicating at which carbon the oxygen is inserted. LOXs are commonly found in animals, plants, fungi and bacteria, where they create signaling molecules or induce structural or metabolic changes in cells, and are thus targets for control by inhibition. Arachidonate 5-lipoxygenase (5-LO) transforms essential fatty acids (EFAs) into leukotrienes, and selective inhibitors are currently being investigated as therapeutics for coronary artery disease (CAD), cancer, and asthma. Many lipoxygenase (LO)-catalysed metabolites affect the development and progression of human cancers, so LOX inhibitors are promising therapeutic targets and many are available at Sigma.