Identification of a decarboxylation product of retinoic acid.

The oxidative decarboxylation of retinoic acid was investigated utilizing a model system consisting of all-trans-retinoic acid, H2O2 and horseradish peroxidase. The decarboxylation products were purified by high-performance liquid chromatography on bonded, octadecylsilane columns. Based on mass spectral, nuclear magnetic resonance, ultraviolet and Fourier transform infrared analyses, the major decarboxylation product was identified as a 4-oxo-C19 aldehyde with a hydroxyl group on the side chain at C9, specifically 8-(2,6,6-trimethyl-3-oxocyclohex-1-enyl)2,6-dimethyl-6-hydroxyoctatrienal.