Thermal Isomerization of All-trans-Lutein in a Benzene Solution

Article abstract of DOI:10.1271/bbb.62.2453

Four major cis-lutein isomers could be identified after thermal isomerization of all-trans-lutein in a benzene solution system; namely, 13'-, 13-, 9'- and 9-cic-luteins. Using both all-trans-lulein and a mixture of these purified cis-luteins as starting materials, the quantitative changes determined by HPLC response show that this thermal isomerization was a reversible reaction. The equilibrium constants (K_c) of 13'- and 13-cis-luteins were higher than those of 9'-, and 9-cis-luteins, suggesting that the amount formed of the former isomers was higher than that of the latter. - Keywords: carotenoid; isomerization; lutein.