Identification of ß, ß-Caroten-2-ol and ß, ß-Carotene-2,2'-diol in the Stick Insect, Carausius morosus Br.; a Reinvestigation Study

Two major carotenoids of the stick insect were reinvestigated and shown to be /?,/?-caroten-2-ol and /?,/?-carotene-2,2'-diol and not isocryptoxanthin (/?,/?-caroten-4-ol) and isozeaxanthin (/?,/?-carotene-4,4'-diol). Both pigments are esterified with fatty acids. The identification is based on cochromatography with authentic 2-, 3and 4-isomers of the monoand dihydroxy pigment, mass spectra, and chemical behaviour. In acid solution /?-/?-carotene-2,2'-diol is specifically dehydro­ genated and rearranged to ketones with retro structures in analogy to the reaction of /?,/?-caroten2-ol as recently reported. The final product of the diol is 4,5-dihydro-4,5'-reZro-/?,/?-carotene-2,2'dione. This is the first demonstration of /?,/?-carotene-2,!