Cis-trãns Isomeric Carotenoids Vitamins A and Arylpolyenes

Ƶechmeister, L.

doi:10.1007/978-3-7091-5548-6

Cited by 324 publications

(292 citation statements)

References 83 publications

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“…The stereomutation of carotenoids by iodine catalyzed photoisomerization has been exhaustively treated in a monograph by Zechmeister (1962). Spectroscopic properties of fucoxanthin cis isomers are discussed by Bernard et al, (1974).…”

Section: Iodine Catalyzed Isomerizationmentioning

confidence: 99%

Transformations of carotenoids in the oceanic water column

Repeta¹

1982

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In an effort to understand the more general mechanisms and rates of pre-depositional reactions that transform organic matter, the types and relevant time scales of reactions that transform carotenoid pigments in the oceanic water column were studied.In the present study, a model was constructed for organic matter cycling that consisted of three parts: 1) the synthesis of carotenoid pigments by phytoplankton in the euphotic zone, 2) consumption and metabolism of some fraction of these pigments by heterotrophic organisms, and 3) removal of metabolic by-products to the sediments by large particle (e.g. fecal pellet) transport. The model separates particlate matter into reservoirs according to the degradation processes that have occurred since synthesis. The goal is to sample these particulate reservoirs, determine the compositional differences between them, and construct a mechanistic pathway for the transformations that occur as material is transferred between reservoirs.Suspended particulate matter collected in the surface waters of Buzzards Bay, Massachusetts and the Peru upwelling region has a carotenoid distribution reflecting the phytoplanktonic source of the material. The carotenoid distribution of sediment trap samples collected in these areas was dominated by transformation products. Fucoxanthin, the primary carotenoid of marine diatoms, typically constituted 77-100% of the total fucopigments in suspended particulate matter. In sediment trap samples this pigment constituted only 4-85% of the total. The remaining 15-96% of the pigments consisted of the fucoxanthin transformation products: free alcohols (2-94%), dehydrates (0-6%), and opened epoxides (0-19%).Postulated transformation products were synthesized to determine the structure of isolated compounds. Simultaneously, iodine catalyzed photoisomerization of fucopigments was tested as a potential method for the unambiguous identification of caotenoids requiring only the nanogram amounts of material typically found in samples.Preliminary results suggest that carotenoid esters are hydrolyzed at a rate determined by the turnover of primary productivity. The dehydrated and epoxide opened degradation products of fucoxanthin represent products of transformation reactions that operate over much longer time scales (0.1-10 yr). Dehydration and epoxide opening are not significant water column transformations, but are important in surface sediments. A trans-3 formation pathway of ester hydrolysis + dehydration + epoxide opening + further dehydration is proposed for fucoxanthin. Preliminary evidence for a parallel transformation squence for structurally similar carotenoids is also presented.

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Section: Iodine Catalyzed Isomerizationmentioning

confidence: 99%

Transformations of carotenoids in the oceanic water column

Repeta¹

1982

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“…Trans-astaxanthin is readily isomerized with heat and light to 9-cis and 13-cis isomers [18] that are more susceptible to oxidation than the trans isomer [19]. ␤-Carotene and lutein are also oxygen-sensitive and are subject to isomerization under heat and light.…”

Section: Introductionmentioning

confidence: 99%

Pressurized fluid extraction of carotenoids from Haematococcus pluvialis and Dunaliella salina and kavalactones from Piper methysticum

Denery

Dragull

Tang

et al. 2004

Analytica Chimica Acta

147

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Pressurized fluid extraction (PFE) was examined as an alternative technology for the extraction of carotenoids in the green algae Haematococcus pluvialis and Dunaliella salina and kavalactones in Piper methysticum. The extraction process was optimized by varying the key extraction factors of solvent, sample-solvent ratio, temperature, and time. The selectivity and efficiency of extraction parameters were determined with high performance liquid chromatography (LC) and LC-mass spectrometry (LC-MS). Results showed that PFE utilization of conventional solvents under controlled temperature and pressure in an oxygen and light-free environment could result in the use of less solvent in a shorter period of time. PFE showed higher or equal extraction efficiencies as compared with traditional solvent extractions while maintaining the integrity of chemical components. PFE showed high potential for extraction of natural products and nutraceuticals, particularly labile and light sensitive chemicals.

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“…Cis-isomers of carotenoid pigments are less stable in light and may oxidize more rapidly than the trans compounds. 11) Next we examined the effects of intense fluorescent light (1,500 lux), and red, blue, and near-infrared LED light on growth. Figure 2 shows that change in the growth curve was observed in dark and light conditions.…”

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confidence: 99%