High-Performance Liquid Chromatography of Isoprenoidquinones. III. Photo-isomerization of Phylloquinone and Menaquinone-4

Abstract

To study cis-trans photo-isomerization of phylloquinone (K) and menaquinone-4 (MK-4), a high-performance liquid chromatographic method for the determination of cis-trans isomers was developed. After removal of the surface active agent and photo-decomposition products, cis-trans isomers were separated on a Nucleosil 50 (particle size; 5 .mu.m) column using di-n-butyl ether-n-hexane (6:94) as a mobile phase. The internal standards used were MK-4 for K and K for MK-4. When either cis or trans compound of K and MK-4 were photo-irradiated in benzene cis .dblarw. trans photo-isomerization was observed and an equilibrium favoring the trans isomers was attained. Trans .fwdarw. cis photo-isomerization of MK-4 was also observed in injection and in infusion solution. Photo-isomerization and photolysis in their solution were inhibited considerably by using a light-intercepting shade.