Influences of retinoic acid and retinoid on skin metabolism. Investigations of oxygen consumption and enzymatic activities of human skin.

All-trans retinoic acid and its derivative retinoid, two new compounds with expanding therapeutic spectrum in dermatology, were investigated in biochemical assays. Both substances provoke an increase in oxygen consumption of rat skin whereas in human skin only retinoid was found active in this respect. In resting yeast cells, both substances failed to exert any significant influence on oxygen consumption.--Pure G-6-PDH was inhibited by retinoic acid and retinoid in concentrations as low as 5 mug/ml. In human skin homogenates, LDH-, GAPDH-, and G-6-PDH-activities were inhibited by retinoic acid whereas GOT-, LAP-, and ALD-activites remained practically unchanged following an incubation with retinoic acid in concentrations between 1 and 100 mug/ml for 60 min.--The data collected in this study were briefly discussed with regard to the use of retinoic acid and its derivatives in psoriasis.