Bacterial carotenoids 55. C<SUB>50</SUB>-carotenoids 25: revised structures of carotenoids associated with membranes in psychrotrophic Micrococcus roseus

The carotenoid composition of a psychrotrophic bacterium Micrococcus roseus strain MTCC 678 has been re-examined qualitatively and quantitatively by chromatographic (TLC, HPLC) and spectroscopic (VIS, MS, <SUP>1</SUP>H NMR and CD) methods, partly in direct comparison with authentic carotenoids. The carotenoid content of 0.13% of the dry weight consisted of (2S,2'S)-bactedorubedn (68% of total), bacterioruberin monoglycoside (21%), monoanhydrobacterioruberin (6%), an unidentified polar tridecasne carotenoid (3%), haloxanthin (2%) and β,β-carotene (0.4%): a carotenoid complement associated with that of halophilic bacteria. Rapid analysis demonstrated that bacterioruberin occurred as the all-E isomer (75% of total), together with the 5Z-(5%), 9Z-(5%) and 13Z-(15%) geometrical isomers. The established interaction of the major carotenoid with membrane vesicles, compatible with cold adaptation, is rationalized

Algal carotenoids. Part 64. Structure and chemistry of 4-keto-19'-hexanoyloxyfucoxanthin with a novel carotenoid end group

8 pages, 2 figures, 5 schemes.The structural elucidation of a new carotenoid 4-keto-19-hexanoyloxyfucoxanthin 5 from Emiliania huxleyi is documented by chromatographic (HPLC, TLC), spectroscopic (VIS, EIMS, FABMS, FABMSMS, 2D 1H NMR) and chemical evidence. The novel carotenoid end group exhibits particular spectroscopic and chemical properties. In particular the reactions with base and acid are investigated.Due to a very weak molecular ion upon electron impact and facile cleavage to paracentrone 20 related fragments, the new carotenoid was previously misidentified as 19-hexanoyloxyparacentrone 3-acetate 8, also found in other prymnesiophytes (haptophytes).This novel carotenoid readily undergoes cleavage to a C31-skeletal paracentrone 20 related product upon storage, preferably in methanol solution.The new end group represents a plausible precursor for C31-skeletal methyl ketone apocarotenoid metabolites in animals, and differs from the previously suggested precursor.E. S. E. was supported by a research grant from Hoffmann- La Roche, Basel, to S. L.-J.Peer reviewe