Distribution of Glycolipid and Unsaturated Fatty Acids in Human Hair

The study investigated the distribution and structure of minor lipids in human hair, including the surface, the interface between cuticle and cortex, and the interior (cortex, medulla, and melanin granules). Using infrared spectroscopy and mass spectrometry techniques (FTIR, ToF-SIMS, GCMS, and ESI-MS), researchers found that unsaturated fatty acids were more prevalent in the cortex than on the hair surface. Steryl glycoside-like lipids containing N-acetylglucosamine were suggested to contribute to the adhesion between the cuticle and cortex. Oxidative metabolites from fatty acids such as linoleic and alpha-linolenic acids were discovered in the hair bulb and melanin granules, with those from alpha-linolenic acid being tightly bound to melanin granules and potentially involved in melanosome biosynthesis.