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At least 19 recordsLinked to original sources
PubMed1975

Bacterial carotenoids, XLVI. C50-Carotenoids, 14. C50-Carotenoids from Arthrobacter glacialis.

From the psychrophilic bacterium Arthrobacter glacialis have been isolated three C50-carotenoids with molecular formulae C50H72O2: the bicyclic decaprenoxanthin (1a, 7% of total carotenoids), the aliphatic bisanhydrobacterioruberin (2a, 10%) and the monocyclic A.g. 470 (3a, 83%). Decaprenoxanthin (1) and bisanhydrobacterioruberin (2) were in all respects, including chiroptical properties, identical with known carotenoids. The constitution of the previously undescribed A.g. 470 (3a) followed from its spectral properties (electronic, 1H NMR including Eu-shift experiments and mass spectra) and derivatization to 3b and 3c. 3a suffered remarkable elimination to the tridecaene 4a (C47H64O) upon DMSO/KOMe/MeOH treatment. Judged by CD data A.g. 470 (3a) also in stereochemical respect 3a appears to be half decaprenoxanthin (1a)+half bisanhydrobacterioruberin (2a). The intensity ratios of the M-92/M-106 ions on electron impact of 3a,b,c and 4a,b are consistent with the general theory.

Arthrobacter↗
PubMed2026

Nitric oxide enhances SlSPL10-mediated transcriptional repression of carotenoid synthesis genes to delay tomato fruit carotenoid accumulation.

Nitric oxide (NO) inhibits climacteric fruit ripening, but its mechanisms remain elusive. Here, S-nitrosoglutathione (GSNO, a NO donor) reduces carotenoid accumulation in tomato fruit, confirming NO's role as carotenoid biosynthesis suppressor. Transcriptome analysis identified SlSPL10 (SQUAMOSA promoter binding protein-like 10) as a key player during this process. Genetic evidence further revealed that SlSPL10 negatively regulates carotenoid synthesis. Moreover, GSNO fails to suppress carotenoid synthesis in slspl10 mutant fruit, in contrast to wild-type fruit, highlighting the involvement of SlSPL10 in NO-inhibited carotenoid synthesis. Transcriptomic profiling of slspl10 mutant fruit showed that both NO and SlSPL10 regulate key carotenoid synthesis genes (SlGPS, SlPDS, SlZDS, SlZISO, and SlCRTISO). SlSPL10 directly binds to the promoters of these genes to repress their transcription, and NO enhances the transcriptional inhibition of SlGPS, SlZISO, and SlCRTISO. These three genes are indispensable for SlSPL10's role in NO-mediated carotenoid suppression. Collectively, NO enhances SlSPL10-mediated repression of carotenoid biosynthesis gene expression, reducing carotenoid accumulation in tomato fruit.

Solanum lycopersicum↗
PubMed1978

Carotenoids of rhizobia. II. The effect of nicotine on the carotenoid pattern of Rhizobium lupini.

With increasing concentrations in the growth medium of the cyclization inhibitors nicotine or 2-(4-chlorophenylthio)-triethylamine hydrochloride (CPTA) the previously identified bicyclic carotenoids of Rhizobium lupini (2,3,2',3'-tetrahydroxy-beta,beta-caroten-4-one and 2,3,2',3'-tetrahydroxy-beta,beta-carotene) were successively replaced by hitherto unknown monocyclic carotenoids. By application of mass and nuclear magnetic resonance spectroscopy 3 carotenoids were identified as 2,3-trans-dihydroxy-beta,psi-caroten-4-one, 2,3-trans-dihydroxy-beta,psi-carotene, and 3-hydroxy-beta,psi-caroten-4-one. A further compound was tentatively established as (2- or 3-)monohydroxy-beta,psi-carotene. It was found that other inhibitors such as diphenylamine or 4-chloro-5-(dimethylamino)-2-alpha,alpha,alpha(trifluoro-m-tolyl)-3-(2H)-pyridazinone (San 6706) did not affect the pigment pattern. The results are discussed in relation to carotenoid biosynthesis in Rhizobium lupini.

Carotenoids↗
PubMed1975

On the utilization in vivo of lycopene and phytoene as precursors for the formation of carotenoid glucoside ester and on the regulation of carotenoid biosynthesis in Myxococcus fulvus.

During th logarithmic phase of growth of the myxobacterium Myxococcus fulvus the specific carotenoid content and the molar ratio of the two main carotenoids keto-torulene (3',4'-didehydro-beta,psi-caroten-4-one, 15%) and myxobacton ester (1'-glucosyloxy-3',4'-didehydro-1',2'-dihydro-beta,psi-caroten-4-one ester, 80%) are highly constant. When the formation of these carotenoids was prevented by an inhibitory block at the level of phytoene desaturation, the normal specific content is rapidly reached after release of this block by a two-three-fold enhanced rate of synthesis. The experimentally accumulated phytoene molecules however, are not used as a precursor pool for the formation of the coloured carotenoids. The absolute amount of phytoene does not decrease, although a considerable molecule exchange between this pool and the pathway occurs. Furthermore, experimentally accumulated lycopene is only converted into myxobacton ester when the carotenogenic pathway is blocked at an earlier step, at the level of phytoene desaturation. Without this blockage the lycopene pool remains unaffected. The results are discussed in terms of arrangement of the carotenogenic enzymes in a sort of assembly line in association with the cytoplasmic membrane. Four sites of control are suggested in this pathway.

Carotenoids↗
PubMed1978

Animal carotenoids 15. Carotenoid distribution and carotenoprotein of Asterias rubens.

A clear differentiation in localization according to functional groups in the carotenoids of the starfish, Asterias rubens, is reported. Only the free alpha-ketols, 7,8,7',8'-tetradehydroastaxanthin, 7,8-didehydroastaxanthin and astaxanthin, are present in the purified carotenoprotein. A post mortem liberated slime contained beta,beta-carotene, free and esterified alloxanthin and esterified alpha-ketols. Evidence suggesting the existence of an alloxanthin protein complex was obtained. The carotenoprotein, asteriarubin, accounts for approx. 10% of the protein extracted by low salt dialysis from the purple-blue part of the top skin of A. rubens and exhibits an absorbance maximum at 554 nm in buffer solution. Asteriarubin is a glycoprotein with an equivalent Stoke's radius corresponding to that of globular proteins of molecular weight 8--10 10(4) and contains 20 microgram carotenoid per mg asteriarubin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of purified asteriarubin disclosed two major components, one of which is a glycopeptide.

Animals↗
PubMedDate not supplied

[Hypophase carotenoids and the structure of epiphase carotenoids of Anabaena variabilis].

Four major and three minor carotenoids of the glucoside nature were isolated by column and thin-layer chromatography on cellulose from the hypophase fraction of the pigment extract of Anabaena variabilis growing for 8 days. One of these major pigment components was supposed to be myxoxanthophyll. The structure of some epiphase carotenoids of Anabaena variabilis was established. The following pigments were also found to be present in the cell: beta-carotene, echinenone, neoechinenone U, and 3'-hydroxyechinenone, cryptoxanthin, zeaxanthin.

Carotenoids↗
PubMed1977

Carotenoids in fish. XVIII--carotenoids in the brain of some fishes.

Using column and thin-layer chromatography the occurrence of various carotenoids was studied in the brain of some (11) fishes. In result of the analyses the presence of the following carotenoids has been established: beta-zeacarotene, canthaxanthin, cryptoxanthin, alpha-cryptoxanthin, isocryptoxanthin, lutein, lutein-5,6-epoxide, zeaxanthin, isozeaxanthin, tunaxanthin, flavoxanthin, astaxanthin ester, 4-hydroxy-alpha-carotene, 4-keto-alpha-carotene and unknown xanthophylls.

Animals↗
PubMed2026

Microbial decaprenoxanthin: From understanding an extremophile-derived C50 carotenoid to its bioprocessing for large-scale applications.

Decaprenoxanthin (DPXT) is an unusual bacterial C50 carotenoid that has historically received limited attention despite its well-defined structure. For decades, carotenoid research and industrial development have been dominated by C40 carotenoids, leaving longer-chain carotenoids largely overlooked. Recent discoveries, particularly from microorganisms inhabiting Antarctic and other extreme environments, have repositioned DPXT as an adaptive pigment shaped by intense environmental pressures. Its extended polyene chain and membrane-associated behavior suggest roles in membrane stabilization and protection against ultraviolet radiation and oxidative stress, features that may hold relevance for food and biotechnological applications. This review integrates historical and recent knowledge on DPXT, covering its structural characteristics, biosynthetic pathways, ecological function, and emerging technological relevance. Special attention is given to microbial sources, particularly Actinomycetota from extreme environments, and to recent advances in microbial genomics, metabolic engineering, and sustainable bioprocess development that enable the production and exploration of C50 carotenoids beyond their native extremophilic context. The analysis highlights DPXT as a representative example of stress-resilient carotenoids, with physicochemical and membrane-interacting properties that may offer advantages for future food and biotechnological systems. Although significant challenges remain in cultivation strategies, yield optimization, and downstream recovery, advances in microbial cell factories and green extraction technologies open new opportunities for valorizing C50 carotenoids. This review bridges extremophile microbiology, carotenoid biochemistry, and sustainable food innovation, positioning DPXT as an emerging molecule that may expand the functional and structural landscape of carotenoids relevant to food science.

Carotenoids↗
PubMed1977

Further evidence for dissipative energy migration via triplet states in photosynthesis. The protective mechanism of carotenoids in Rhodopseudomonas spheroides chromatophores.

The protection action of carotenoids against irreversible photodestruction was discovered in photosynthetic bacteria by Stanieda and coworkers. In green plant material it was found by Wolff and Witt (1969) Z. Naturforsch, 24b, 1031-1037 and (1972) Proc. 2nd. Int. Congr. Photosynthesis Res. Stresa (Forti, G., Avron, M. and Melandri, A., eds.), Vol. 2, pp. 931-936, Dr. W. Junk, N. V. Publ. The Hague) that the formation of special carotenoid triplet states (via very rapid energy transfer from excited chlorophylls) and their fast radiationless decay in tau1/2 approximately 3 microns is at least one mechanism for the protective action of carotenoids to irreversible photooxidation of the chlorophylls. Hence, it is anticipated that the same mechanism might be realized also in bacteria. The present study gives evidence for such a "triplet valve" to be established also in bacteria. This conclusion was derived from the following observations: 1. The light-induced difference spectrum shows a bleaching of a carotenoid at three characteristic wavelength between 400 and 500 nm. A positive peak around 533 nm indicates the formation of a carotenoid triplet state. 2. The absorption changes can be induced by red light which excites only bacteriochlorophyll. This indicates an energy transfer from bacteriochlorophyll to carotenoids. 3. The light-induced carotenoid triplets decay radiationless in 3 microns in air-saturated aqueous suspensions of the chromatophores. 4. The carotenoid triplet formation occurs only at actinic flash intensities where the photosynthesis becomes saturated. 5. Addition of dithionite, which blocks photosynthesis, markedly increases the extent of carotenoid triplet formation. The different types of exciton migration within the photosynthetic unit are discussed, especially the routes leading to the dissipation of excess excitation energy.

Bacterial Chromatophores↗