Chromatographic performance on a C-30-bonded stationary phase of monohydroxycarotenoids with variable chain length or degree of desaturation and of lycopene isomers synthesized by various carotene desaturases

Selectivity towards geometric isomers is a superior feature of a C-30 polym eric stationary phase. Therefore, lycopene isomers synthesized in Escherich ia coli transformants by catalysis of divers carotene desaturases were sepa rated on this stationary phase. Due to their spectral characteristics and b y co-chromatography with nuclear magnetic resonance-characterized carotene standards, some of them could be identified. Most of the lycopene isomers w ere cyclized by lycopene cyclase yielding mainly 9Z, 13Z and all-E beta -ca rotene. In contrast, 7,9,7',9'Z prolycopene is accumulating since it cannot be converted by this enzyme. Finally several acyclic hydroxycarotenoids wi th a chain of 30, 40 and 45 carbon atoms differing in the length of the pol yene chain from 9 to 13 were separated on the C-30 stationary phase. Longer retention times were observed when the length of the molecule increased an d also when the conjugated double bond system was extended. Corresponding m onocyclic carotenoids were less retained on the C-30 stationary phase and d erivatives with an epsilon -ionone end group eluted earlier than with a bet a -end group. (C) 2001 Elsevier Science B.V. All rights reserved.