Covalent attachment of omega-hydroxyacid derivatives to epidermal macromolecules: a preliminary characterization.

The present report establishes that fatty acids, omega-hydroxyacids and omega-hydroxyacylsphingosines are covalently attached to macromolecules in mammalian epidermis. Extensive extraction of pig epidermis yielded 11.2% lipid on a dry weight basis. Reextraction of the epidermal residue did not yield additional lipid; however, a mild saponification of the delipidized residue followed by acidification and extraction yielded an additional 0.5% by weight of lipid-soluble material. The major components of this residual lipid fraction are omega-hydroxyacylsphingosine (60% of the total), free fatty acids (24%) and free omega-hydroxyacids (7%).