Efficient Conversion of All-E-Lutein Esters to Z-Lutein Esters and Physiological Activities and Physicochemical Properties of Free and Esterified Lutein Isomers.

A rapid method for producing cis-(Z)-lutein esters from all-E-lutein esters was developed using I2, AlCl3, and sulfides as catalysts. Z-Isomer-rich lutein (38.6%) and Z-isomer-rich lutein esters (34.8%) by I2 were obtained. The antioxidant activities of Z-isomer-rich lutein and Z-isomer-rich lutein esters were higher than those of their all-E-isomers by Ferric Reducing Antioxidant Power, ORAC-L, and ABTS assays. The UV-A and UV-B blocking activities of Z-isomer-rich lutein esters were higher than those of all-E-lutein esters. After short-term ingestion by rats, the in vivo absorption concentration of Z-isomer-rich lutein (222.3 pmol/mL) in a high dose was higher than those of other forms of lutein (<125.6 pmol/mL). Enrichment of Z-lutein (Z-ratio: 59.5%) and Z-lutein esters (Z-ratio: 44.4%) was achieved in hexane and ethanol, respectively. We conclude, for the first time, that Z-isomer-rich lutein esters play a more important role than all-E-lutein esters in preventing oxidation and UV-blocking activity and are estimated to exhibit higher bioavailability than all-E-lutein esters and all-E-lutein.