Biosynthesis and Metabolism of Prostaglandin E2in Human Skin

Abstract

The occurrence, biosynthesis, and metabolism of prostaglandins were studied in homogenates of excised human skin. Prostaglandin E₂ (PGE₂) was identified as the major prostaglandin by chromatographic procedures, enzymatic analysis, and mass spectrometry. Arachidonic acid was the major C₂₀ acid esterified to the phospholipid fraction. The content of PGE₂ in skin homogenates was 0–35 ng/g (mean value 15 ng/g, n=7). Upon incubation at 37°C the levels rose to 250–300 ng/g in 40 min. Incubation with ³H-labelled arachidonic acid gave a 2% conversion into ³H-PGE₂ in 20 min. ³H-PGE₂ was converted to 11α-hydroxy-9,15-diketoprost-5-enoic acid in a 70% yield by enzymes in a skin homogenate. The results show that the endogenous normal values of prostaglandins in human skin are low, but that efficient enzyme systems are available for both their formation and their metabolism.