Vitamin A in Human Skin: II Concentrations of Carotene, Retinol and Dehydroretinol in Various Components of Normal Skin

Abstract

Pro-vitamin A(beta-carotene) and the predominant forms of vitamin A in human skin (retinol and dehydroretinol) were analyzed in hydrolyzed specimens from 4 cadavers and 22 healthy subjects. Beta-carotene was identified in extracts of epidermis by its specific absorption spectrum. Vitamin A was determined by high-pressure liquid chromatography. The concentrations were related to the wet weight or protein content of the sample. The analysis of different skin compartments showed that the concentrations of the 3 constituents were usually related as follows: carotene greater than retinol greater than dehydroretinol. The concentrations were always higher in the epidermis than in the upper dermis. Skin surface lipids contained carotene and retinol but not in amounts sufficient to contribute to the higher epidermal values. Analysis of epidermal autopsies from 5 different skin areas (back, breast, arm, leg and foot) and of epidermal biopsies from the back of the healthy subjects showed that the interindividual differences were larger for carotene and dehydroretinol than for retinol, whereas the intraindividual variations were larger for retinol. The mean (+/- SD) concentrations of carotene, retinol and dehydroretinol in back skin epidermis of healthy subjects were 13 +/- 5, 1.7 +/- 0.4 and 0.4 +/- 0.2 microgram/g protein, respectively. No significant variations with age and sex were found.

Retinol and retinal metabolism. Relationship to the state of differentiation of cultured human keratinocytes

“…150 times lower than that of retinol, and since retinoic acid is rapidly eliminated [8], it is suspected that retinoic acid is formed from retinol near to the site of its action, probably within the target cells. The presence of retinol esters stored in human epidermal cells [9] supports -this hypothesis.…”

“…the question of whether retinal is generated in the system studied. This appeared to be the case, since when the pH was raised to 9 in the incubation mixture, the formation of retinal became measurable (1.73 pmol/h per mg of protein). At this pH, a concomitant decrease in retinoic acid production was observed (Fig.…”

Vitamin A and β-Carotene Concentrations at Different Depths of the Epidermis: A Preliminary Study in the Cow Snout

“…In a typical experiment, &carotene eluted at 27 min. The &carotene and retinol concentrations were related to the protein content of the sample as determined by the biuret assay (12).…”

“…mixtures of cells at different stages of keratinization (12). In the present study, we have focused on the distribution of retinol and &carotene in cow snout epidermis which can be easily cut into 5 or 6 horizontal layers of sufficient s size to permit chemical characterization (7).…”

Role of Fat-Soluble Vitamins A and D in the Pathogenesis of Influenza: A New Perspective

“…Dermal retinol is derived partly from the adjacent subcutis, which contains 10-20 times more vitamin A than both skin and blood [83]. 3-Dehydroretinol occurs mainly in the epidermis and may be a metabolite of retinol [84]. Small amounts of retinoic acid are also found in human skin and represent a mixture of 13-cis/trans isomers of retinoic acid.…”