Abstract
All-trans biscyclohexylammonium retinylphosphate was synthesized using bis(triethylammonium)phosphate as the phosphate donor. It was shown to be pure from physico-chemical evidence including ultraviolet, infrared, 1H- and 13C-nuclear magnetic resonance and mass spectrometry. In contrast to previous reports, the synthesized product is quite stable toward alkaline hydrolysis. Direct or iodine-catalyzed photo-isomerization of the all-trans compound can produce the corresponding 13-cis isomer. Simultaneous quantification of cis-trans stereoisomeric retinylphosphates was demonstrated by ion-pairing reversed-phase liquid chromatography with an isocratic mobile phase consisting of aqueous methanol and with ultraviolet detection at 300 nm. The mobile phase also contains tetrabutylammoniumphosphate as the counter-ion. The feasibility and extent of stereoisomerization of all-trans retinylphosphate have been compared with those of carotenoidal and retinoidal polyenes.
