Fish skin surface lipids: phospholipids

Phospholipid components of skin surface secretions of four Indian freshwater fishes were analysed using different solvent systems in one‐dimensional and two‐dimensional thin‐layer chromatography, and quantified using a spectrophotometer. The phospholipid pattern of the skin secretions is similar to that of membrane lipids. Phosphatidyl choline and phosphatidyl ethanolamine are the major components constituting approximately two‐thirds of the total phospholipids. Sphingomyelin and phosphatidyl serine are present in relatively low quantities. Phosphatidic acid, phosphatidyl glycerol, lysophosphatidyl choline and lysophosphatidyl ethanolamine, which may be important metabolic intermediates, are present in very low quantities in the skin surface secretions of all four species. It is suggested that the lipids are derived from membranous profiles in the secretions of skin glands, extrusion of membrane‐bound vesicles from surface epithelial cells, and exfoliated cells. The results are discussed in relation to the biochemical and biological significance of these lipids in the skin secretions.