4-Hydroxyretinoic acid

4-Hydroxyretinoic acid (4-HRA) is a naturally occurring retinoid derivative with diverse biological effects. 4-Hydroxyretinoic acid is formed from retinol catalyzed by cytochrome P-450 isozyme(s), and is mainly metabolized by the liver in the body. 4-Hydroxyretinoic acid also serves as the substrate for human liver microsomal UDP-glucuronosyltransferase(s) and recombinant UGT2B7. 4-Hydroxyretinoic acid regulates gene expression and cell differentiation via binding to nuclear receptor RAR (Retinoic Acid Receptor), and activates RARs and RXR-alpha, to induce cancer cell apoptosis. In addition, 4-Hydroxyretinoic acid is also involved in various physiological processes such as immune regulation, neuroprotection, and anti-oxidation.