C. Prottey
May 1, 1976
Citations
2
Influential Citations
161
Citations
Quality indicators
Journal
British Journal of Dermatology
Abstract
The essential fatty acids arc a group of naturally occurring fatty acids of chain-lengtb 18, 20 or 22 carbon atoms and containing between 2 and 6 methylenc-interrupted unsaturatcd bonds, all in the CIS configurationThere are two fundamental essential fatty acids from which all others are derived by metabolic chain elongation and desaturation. These are linoleic acid, giving rise to the a)-6 series, and ::(-liDolenic acid, from which derives the (.'j-3 series (the (u-notation signifies the position of the first methylene-interrupted double bond numbered from the terminal methyl group ofthe acid). As their name implies, they are essential to the diet of man, indeed, of all higher animals, as they cannot be synthesized de novo from small molecular weight metabolites of carbohydrates and amino acids, as are all other lipids. Recent reviews comprehensively cover the chemistry and physiological function of the essential fatty acids in animals (Alfin-Slater & Aftergood, 1968; Holman, 1968, 1970) and man (Soderhjelm, Wicsc & Holman, 1970). Relatively little, however, has been reported for skin specifically. Fig. I illustrates interrelations of various essential fatty acids. All have been identified in the skin of man or laboratory animals ("except (u-3 Ci8:4 and o-^ 020:4) but some only in trace amounts (Vroman, Nemecek & Hsia, 1969; Jonsson & Anggard, 1972; Wilkinson, 1972; Prottey et al., 1975, 1976). By far the most abundant essential fatty acids in skin are linoleic acid, derived solely from the diet, and arachidonic acid, derived from linoleic acid, or from traces in the diet. The various acyl decarboxylation and elongation enzymes that convert dietary linoleic or linoknic acid to the polyunsaturated fatty acids have been characterized in certain organs, mainly the liver (Alfin-Slater & Aftergood, 1968), but there is no conclusive evidence that the skin can perform these reactions independently. Rather, it must be assumed that although certain essential fatty acids arc very important to the skin (e.g. arachidonic acid, as the precursor of prostaglandins) they originate from the liver via the plasma lipoproteins, and are not synthesized per se in the skin. Wilkinson (1972) has demonstrated labelling of various essential fatty acids in skin cultured in vitro with ['"^Cl-acetate but this is probably by acetate exchange, not synthesis de novo. Further research is necessary to establish whether the skin can perform any ofthe individual elongation and desaturation steps.