Carotenoid glycoside esters from the thermophilic bacterium Meiothermus ruber

The thermophilic bacterium Meiothermus ruber produces a series of carotenoi d glycoside esters. The major carotenoid has been identified as 1'-beta-glu copyranosyl-3,4,3',4'-tetradehydro-1',2'-dihydro-beta,psi-caroten-2- one (1 ). It is acylated at the 6 "-position of the glucose unit by a series of C- 10-C-17 fatty acids. The structure of 1 was established by spectral means, including complete assignment of the H-1 and C-13 NMR resonances by inverse 2D NMR spectroscopy. These carotenoids are thought to play roles in stabil izing membranes of this thermophilic organism.