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 I 2, AlCl 3, and sulfides as catalysts. Z -Isomer-rich lutein (38.6%) and Z -isomer-rich lutein esters (34.8%) by I 2 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.