PHOTOISOMERIZATION OF RETINOIC ACID AND ITS PHOTOPROTECTION IN PHYSIOLOGIC‐LIKE SOLUTIONS

Abstract The long wavelength UV‐induced photoisomerization of retinoic acid has been investigated in physiologic‐like solutions. By high‐performance liquid chromatographic analysis seven isomers of the parent molecule were observed at the photostationary state. The structures of these isomers have been determined using high‐field nuclear magnetic resonance spectroscopy. While addition of a non‐ionic detergent had no effect on the retinoic acid photoisomerization, a number of proteins, as well as a phospholipid, completely inhibited this process. Possible reasons for differences in observed isomer distribution relative to earlier studies, as well as for the effects of the photoprotectant compounds, are discussed.