Skin lipids. III. Fatty chains in skin lipids. The use ofvernix caseosa to differentiate between endogenous and exogenous components in human skin surface lipid

The literature on the types of fatty chains that occur in skin lipids is reviewed and new data are presented. To ascertain whether certain unusual fatty acids found in human skin surface lipids are truly products of the human skin or are due to some type of external contamination (possibly bacterial), the fatty acids of vernix caseosa , (the lipoidal material covering the human fetus) were analyzed and compared to those found in human skin surface lipid. The same unusual fatty acids were found in vernix caseosa . This indicates that these acids are products of human skin. These acids consist of five classes of saturated branched chain acids and of three classes of monoenes: straight chain, iso and anteiso . All the monoenes are ख 6 or derivable from this position by addition of an integral number of 2 carbon units to the carboxyl group. On the polar phase diethylene glycol succinate polyester, the saturated branched chain methyl esters have fractional carbon numbers (by gas chromatography) of 0.15, 0.23, 0.45, 0.63 and 0.75. The series at 0.63 and 0.75 are iso and anteiso , respectively. The series at 0.15 and 0.23 appear to be two newly identified classes of branched chain fatty acids.