(21E/Z,36Z)-2-Docosyl-3-hydroxy-21,36-pentapentacontadienoic Acid is one of many mycolic acids found in the outer membrane of Mycobacterium tuberculosis. These are 2-alkyl, 3-hydroxy long chain fatty acids that are involved in the permeability of the mycobacterial cell envelope, and are essential to the bacterial survival.