Surface Lipids as Multifunctional Mediators of Skin Responses to Environmental Stimuli

Table 1

The skin surface lipid (SSL) composition (%) of Homosapiens adults and non-human primates (according to [65, 66]).

Lipid Fraction	Homo sapiens ($n=30$)	Gorilla gorilla ($n=3$)	Pongo pygmaeus ($n=3$)	Pan troglodytes ($n=4$)	Hylobates sp. ($n=1$)	Macaca sp. ($n=5$)
Squalene (SQ)	11.8 $\pm$ 0.6	n.d.	n.d.	n.d.	n.d.	n.d.
Cholesterol esters (CE)	1.4 $\pm$ 0.2	3.5	4.6	9.8	32.6	40.6
Cholesterol (CH)	1.4 $\pm$ 0.1	1.7	1.8	1.8	1.9	3.0
Triglycerides (TG)	34.1 $\pm$ 6.5	2.3	0.9	5.1	2.0	4.9
Diglycerides (DG)	1.3 $\pm$ 0.2	0.8	0.4	1.0	0.2	0.1
Monoglycerides (MG)	0.4 $\pm$ 0.1	0.1	tr	tr	0.2	0.2
Wax mono-esters (WE)	24.5 $\pm$ 2.1	37.4	25.0	31.3	2.0	15.2
Wax di-esters (WDE)	n.d.	tr	2.0	tr	1.5	2.3
Free fatty acids (FFA)	24.6 $\pm$ 6.1	3.4	2.5	7.4	5.0	8.3
Others (paraffins, etc.)	0.5	50.8	62.8	43.6	54.6	26.4

SSLs were sampled from the forehead and upper chest, with diethyl ether cup extraction method [30]. Results for human skin (30 subjects) are expressed as mean $\pm$ S.D.; for primates they are the results of the varying number of samples. Macaca sp. sample is a pooled extract of 5 samples, consisting in 1 single individual from each of the following species: Macaca sp., M. mulatta, M. nemestrina, M. assemensis, and M. fascicularis. tr: traces.