ISOLATION, STRUCTURAL ELUCIDATION, AND PARTIAL SYNTHESIS OF LUTEIN DEHYDRATION PRODUCTS IN EXTRACTS FROM HUMAN PLASMA

6'R)-3-hydroxy-3',4'-didehydro-beta,gamma-carotene (anhydrolutein I) a nd R)-3-hydroxy-2',3'-didehydro-beta,epsilon-carotene (2',3'-anhydrolu tein II) have been isolated and characterized from extracts of human p lasma using semipreparative high-performance liquid chromatography (HP LC) on a C-18 reversed-phase column. The identification of anhydrolute ins was accomplished by comparison of the UV-Vis absorption and mass s pectral data as well as HPLC-W-Vis-mass spectrometry (MS) spiking expe riments using fully characterized synthetic compounds, Partial synthes is of anhydroluteins from the reaction of lutein with 2% H2SO4 in acet one, in addition to anhydrolutein I (54%) and 2',3'-anhydrolutein II ( 19%), also gave (3'R)-3'-hydroxy-3,4-dehydro-beta-carotene (3',4'-anhy drolutein III, 19%), While anhydrolutein I has been shown to be usuall y accompanied by minute quantities of 2',3'-anhydrolutein II (ca. 7-10 %) in human plasma, 3:4'-anhydrolutein III has not been detected. The presence of anhydrolutein I and II in human plasma is postulated to be due to acid catalyzed dehydration of the dietary lutein as it passes through the stomach. These anhydroluteins have also been prepared by c onversion of lutein diacetate to the corresponding anhydrolutein aceta tes followed by alkaline hydrolysis. However, under identical acidic c onditions, loss of acetic acid from lutein diacetate proceeded at a mu ch slower rate than dehydration of lutein. The structures of the synth etic anhydroluteins, including their absolute configuration at C(3) an d C(6') have been unambiguously established by H-1 NMR and in part by C-13 NMR, and circular dichroism.