Skin surface lipids of the mole Scalopus aquaticus.

Skin surface lipids of the mole Scalopus aquaticus were found to consist principally of squalene (70%), wax esters (15%), and sterol esters (5%), together with small amounts of triglycerides, free fatty acids, free fatty alcohols, and free sterols. Analysis of the fatty acids occurring free and as wax esters and sterol esters showed these to consist of approximately equal amounts of saturated and monounsaturated compounds. The saturated fatty acids consisted predominantly of odd-carbon anteiso and even-carbon straight-chain compounds, with minor amounts of even-carbon iso-branched chains. The unsaturated fatty acids had double bond positions that would have been produced by delta 9-desaturation of C14, C16 and C18 straight chain saturated precursors. Both the free and the esterified fatty alcohols had chain structures corresponding with those of the fatty acids but of somewhat greater average chain length. Discovery of a major proportion of squalene in the sebum of this animal extends the number of non-human species that have this characteristic to four, all of which inhabit a damp environment, suggesting that squalene conveys some biological advantage under these conditions.