NATURALLY OCURING DI-CIS-VIOLAXANTHINS FROM VIOLA TRICOLOR: ISOLATION AND IDENTIFICATION BY 1H NMR SPECTROSCOPY OF FOUR DI-CIS-ISOMERS

Article abstract of DOI:10.1016/S0031-9422(00)94528-X

From blossoms of Viola tricolor, four new naturally occuring geometrical isomers of violaxanthin (5,6,5',6'-diepoxy-5,6,5',6'-tetrahydro-β,β-carotene-3,3'-diol) have been isolated in the crystalline state.By two-dimensional 1H NMR methods, the new pigments are shown to be the 9,9'-, 9,13'-,9,15-and 9,13-di-cis isomers.Thermal and iodine-catalysed photochemical stereomutations of the new natural pigments have also been studied.Key Word Index-Viola tricolor; Violaceae; 9,9'-, 9,13'-, 9,15- and 9,13-di-cis-violaxanthins.