Hexadecenoic acid (cis-6) is an unusual unsaturated fatty acid that is the major constituent of human sebaceous lipids, from which it derives its common name sapienic acid, where it is involved in self-sterilization and atopic dermatitis amelioration.1 Among all hair-bearing animals, humans are the only ones to produce this fatty acid and it is not found in any organ other than the skin.2 It is formed from palmitic acid by the action of the enzyme delta-desaturase (or fatty acid desaturase-2).3 hexadecenoic acid (cis-6) can then be converted to sebaleic acid (C18:2 delta-5,8), another fatty acid unique to sebum, by the extension of two carbons and the addition of a double bond.4 It has been found that hexadecenoic acid (cis-6) has powerful antibacterial properties although the mechanisms have not been fully explored. Besides being found in human skin hexadecenoic acid (cis-6) has been found in some marine organisms and in some seed oils.
