Catechol moieties are also found widely within the natural world. Arthropod cuticle consists of chitin linked by a catechol moiety to protein. The cuticle may be strengthened by cross-linking (tanning and sclerotization), in particular, in insects, and of course by biomineralization.[15] Catechols such as DHSA are produced through the metabolism of cholesterol by bacteria such as Mycobacterium tuberculosis.[16