N-(4-hydroxyphenyl)retinamide: a synthetic analog of vitamin A that is a potent inhibitor of prostaglandin biosynthesis.

In Madin-Darby canine kidney (MDCK) cells, 4-hydroxyphenyl retinamide, at levels ranging from 0.025 to 3.1 microM, inhibited serum- and TPA-stimulated biosynthesis of prostaglandin F2 alpha, prostaglanding I2 (measured as 6-keto-prostaglandin F1 alpha) and prostaglandin E2 but did not inhibit serum- or TPA-stimulated deacylation of cellular phospholipids. 4-Hydroxyphenyl retinamide was also a potent inhibitor of prostaglandin E2 and prostaglandin F2 alpha production by serum-stimulated methylcholanthrene-transformed mouse fibroblasts (MC5-5), normal human fibroblasts (D-550), "spindle-shaped" smooth muscle cells present in the intima layer of rabbit aorta (R-1), and thromboxane production by melittin-stimulated mouse lymphoma cells (WEHI-5). In the presence of 10% fetal bovine serum, 4-hydroxyphenyl retinamide inhibited prostaglandin production by MDCK cells 4 times less effectively than indomethacin and about 50 times more effectively than aspirin; while in the absence of serum, the inhibiting effectiveness of 4-hydroxyphenyl retinamide was equal to that of indomethacin.