Carotene derivatives

Sliwka HR. 1999. Conformation and circular dichroism of P,P-carotene derivatives with nitrogen-, sulfur-, and selenium-containing substituents. Helvetica ChimicaActa 82(2) 161-169. 

The cyclization was also successful with natural unsaturated aldehydes such as /J-carotene, c/s-retinal (95%), and trans-retinal (50%).183,1842 Compounds like 142 are potential intermediates in the syntheses of /J-carotene derivatives and polymeric alkenes.184,185,186... 

Carotene derivatives absorb different wavelengths of light, depending on the length of the conjugated system and the presence of other functional groups. 

IP-PP and DMA-PP can yield volatile C3 hemiterpenes. At the other extreme, extensive polymerization of the C3-pyrophosphates (with release of pyrophosphate, PP ) yields the formation of the plant latex polymers such as eis-polyisoprenes (rubber) and trans-polyisoprenes (gutta-percha). In between these extremes, a variety of monoterpenes, sesquiterpenes, triterpenes and C3() carotenes derive from these C3-pyrophosphate precursors. 

Lutein is the predominant xanthophyll in all LHCs and ranges between a low of <40% of total carotenoids in LHClla to >65% in LHCllb. Other carotenoids, particularly the )3-carotene derived xanthophylls, violaxanthin and neoxanthin, vary much more widely in concentration. Neoxanthin is present at similar proportions in LHClla, b and c but is virtually absent from LHClld (Bassi et al, 1993). Interestingly, LHCllb is nearly devoid of/3-carotene but the minor complexes contain 5-10% of their total carotenoids as /3-carotene (Bassi et al, 1993 Ruban et al., 1994). Violaxanthin is also proportionally enriched in the minor LHCs accounting for 30-40% of the total minor LHC carotenoids and in aggregate up to 80%... 

All lutl alleles are recessive mutations (Fig. 3 A) that accumulate an additional carotenoid with an HPLC retention time and UV/visible absorption spectrum characteristic of a monohydroxy / , e-carotenoid (an a-carotene derived xanthophyll). The identification of the accumulating compound as zeinoxanthin ()3,e-caroten-3-ol) was confirmed by mass spectrometry (Pogson et al., 1996). The only difference between lutein and zeinoxanthin is the presence of an hydroxyl group on carbon 3 of the -ring in lutein. The decrease in lutein and its partial replacement by its immediate precursor, zeinoxanthin, defines lutl as a mutation... 

The number of recorded carotene derivatives is increasing as both chromatographic systems and detection methods improve and at present more than 300 naturally occurring carotenoids have been discovered. A recent comparison of the methods available for the assay of the carotenoids concluded that HPLC was superior to other techniques for reasons of speed and ease of quantitation (Krinsky and Wecankiwar, 1984). 

Carotene derives its name from the carrot, from which it was first isolated 100 years ago. It is the yellow-colored, fat-soluble substance that gives the characteristic color to carrots and butter. 

Made only from vegetable fats, and fortified only with carotene (derived from vegetable sources). 

Polydiacetylene LB films showed a conductivity of 10 S/cm after iodine doping [323,324] or ion irradiation [325], and polyacene-type ladder polymer can be formed by the irradiation of an electron beam or excimer laser [182,326]. The polyacetylene-type LB films were prepared using a diblock copolymer (Figure 14.44). The precursor block of the LB films could be converted to tra 5-polyacetylene by heat treatment, and the film showed a conductivity value of 2 x 10 S/cm after iodine doping [305]. LB films of carotene derivatives have also been reported [129,327,328]. 

Tsushima, M., Maoka, T, and Matsuno, T. (1989) Comparative biochemical studies of carotenoids in marine invertebrates the first positive identification of e,e carotene derivatives and isolation of two new carotenoids from chitons. Comp. Biodiem. Physiol., 93B, 665-671. 

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