Dihydroxylycopene diglucoside diesters: a novel class of carotenoids from the phototrophic purple sulfur bacteria Halorhodospira abdelmalekii and Halorhodospira halochloris

The carotenoids in Halorhodospira abdelmalekii and Halorhodospira halochlor is were analyzed by spectroscopic methods. The carotenoid composition of th e two species was almost the same. Both species contained substantial amoun ts of unusual carotenoid glycoside fatty acid esters, which have been found for the first time in phototrophic purple bacteria. Methoxy-hydroxylycopen e glucoside was a major component, and dihydroxylycopene diglucoside and di hydroxylycopene diglucoside diester were also found. Lycopene, rhodopin, an d 3,4,3',4'-tetrahydrospirilloxanthin were present in very small amounts. M ethoxy, glucosyl, and glucosyl ester groups were observed as substituents a t the positions of the two original hydroxyl groups of dihydroxylycopene an d made up approximately 20, 50, and 20%, respectively, of the total end gro ups (100%). The fatty acid components of the three carotenoid glucoside est ers were the same (C12:0 and C14:1) and were rare in the cellular lipids of the two species.