Synthesis carotenoids

Zinc acetylides, prepared in situ by the treatment of lithium acetylides with ZnCF, are widely used. The zinc acetylide 311, prepared in situ, reacts with (Z)-3-iodo-2-buten-l-ol (312) with nearly complete retention of stereochemistry to afford an important intermediate 313 for carotenoid synthesis[227]. 

FRASER P D, KIANO I W, TRUESDALE M R, SCHUCH W and BRAMLEY P M (1999) PhytOene synthase-2 enzymes activity in tomato does not contribute to carotenoid synthesis in ripening fruit . Plant Mol Biol, 40, 687-98. 

Cunningham, F.X., Regulation of carotenoid synthesis and accumulation in plants. Pure Appl. Chem. 74, 1409, 2002. 

Tao, L. et al., A carotenoid synthesis gene cluster from Algoriphagus sp. KK10202C with a novel fusion-type lycopene beta-cyclase gene. Mol. Genet. Genomics 379, 101, 2006. 

Bramley, P. et al.. Biochemical characterization of transgenic tomato plants in which carotenoid synthesis has been inhibited through the expression of antisense RNA to pTOM5, Plant J. 2 (3), 343, 1992. 

Hot water treatment was reported to delay carotenoid synthesis and thus yellowing of broccoli florets (at 40°C for 60 min) and kale (at 45°C for 30 min), but did not affect Brussels sprouts (Wang 2000). Hot air treatment (38°C and 95% RH for 24 hr) slightly decreased lycopene and (3-carotene content in tomato fruit (Yahia and others 2007) however, fruit heated at 34°C for 24 hr and stored 20°C developed higher lycopene and (3-carotene than nonheated fruit (Soto-Zamora and others 2005). Moist (100% RH) hot air (48.5 or 50°C) for 4 hr caused injury to papaya and losses in lycopene and (3-carotene, but similar treatment with dry air (50% RH), alone or in combination with thiabendazole, had no effect on lycopene and (3-carotene (Perez-Carrillo and Yahia 2004). High-temperature treatment also suppressed 1-aminocyclopropane-l-carboxylic acid oxidase activity and thus indirectly prevented carotenoid synthesis (Suzuki and others 2005). 

Phosphonium salts, e.g. (124), derived from polynuclear hydrocarbons and used as intermediates in helicine synthesis, have been prepared by the reaction of the appropriate benzylic alcohol with triphenylphosphine hydrobromide.120 Similarly, the salt (125), of value as an intermediate in carotenoid synthesis, has been prepared by the reaction of a precursor allylic alcohol with triphenylphosphine hydrobromide.121 Bromomethyl a-diketones react with triphenylphosphine to form... 

Ethylene coordinates the expression of genes responsible for enhanced respiratory metabolism, chlorophyll degradation, carotenoid synthesis, conversion of starch to sugars, increased activity of cell wall-degrading enzymes, aroma volatile production, and so on. All these events stimulate a series of biochemical, physiological, and structural changes making fruits mature and attractive to the consumer. 

DC063 Mok, M. C., W. H. Gabelman, and F. Skoog. Carotenoid synthesis in tissue cultures of Daucus carota. J Amer Soc Hort Sci 1976 101 442. 

Light is a major regulatory influence on carotenoid synthesis in many plant and microbial systems. A review of this photoregulation has been published. Other papers report the photoinduction of the biosynthesis of phytoene and other carotenoids in strains of Neurospora crassa. " ... 

Chemi cals, parti cularly 2-(4-chlorophenylthi o)-triethyl amine (CPTA) and some related compounds have been applied postharvest to citrus fruit to enhance carotenoid synthesis (22 26, 151,... 

Electroreduction of conjugated enone systems is a possible route for carotenoid synthesis. The electroreduction of astaeene 88 gives 90 after passage of 2 F/mol of electricity in a CHjClj—Bu4NBF4—(Hg) system in the presence of acetic anhydride. Similar electrolysis of 88 in a C Clj/MeCN—LiC104 system (4 F/mol of electricity) provides 89 in 25% yield (Scheme 3-33)80). 

Inhibitors of carotenoid synthesis also lead to chlorophyll destruction by destabilizing the photosynthetic apparatus. Total carotenoid content decreased with increased (-)-usnic concentration (Fig. 1.4). Carotenoid biosynthesis can be interrupted by inhibiting the enzyme phytoene desaturase that converts phytoene to carotenes or by inhibiting the enzyme HPPD responsible for plastoquinone (required for phytoene desaturase activity) synthesis.14 Usnic acid possesses some of the structural features of the triketone HPPD inhibitors, such as sulcotrione (Fig. 1.1C).8 (-)-Usnic acid had a strong inhibitory activity on HPPD, with an apparent IC50 of 70 nM, surpassing the activity obtained with the commercial herbicide sulcotrione (Fig. 1.5). 

Carotenoid synthesis—> Destruction of pigments Cell or nuclear division -----------------v... 

Liaaen-Jensen, S., Cohen-Bazire, G., Nakayama, T.O.M. and Stanier, R.Y. 1958. The path of carotenoid synthesis in a photosynthetic bacterium. Biochim. Biophys. Acta, 29,477-498. 

Neoxanthin, a precursor of the plant hormone abscisic acid, is an allenic xantho-phyll recognized as the last product of carotenoid synthesis in green plants. A cDNA for neoxanthin synthase (NSY) was isolated from tomato cv. Philippino using a molecular approach based on the mechanistic and structural similarities of NSY to two other closely related carotenogenic enzymes, lycopene cyclase (LCY) and capsanthin-capsorubin synthase (CCS) (Bouvier et al., 2000). 

Although chloramphenicol inhibits carotenoid synthesis, it also inactivates photo-chemically responsive membranes in which carotenoids are located, and hence previous conclusions that the enzymes involved in carotenoid biosynthesis are themselves synthesized in the cytoplasm are not strictly valid. However, the demonstration367 that dark-grown Euglena gracilis, which has carotenoids localized in the proplastids, can synthesize carotenoids in the presence of chloramphenicol indicates that such synthesis is not dependent on protein synthesis in the proplastid. 

In plastids of etiolated radish seedlings, far-red light stimulated the synthesis of all prenyl chains, but it did not alter the relative concentrations of the various chains synthesized under dark conditions. White light further stimulated chain synthesis, particularly the formation of phytyl chains,370 and a similar situation occurred with barley.371 In contrast, both far-red and white light changed the pattern of carotenoid synthesis in etioplasts of Raphanus seedlings372 and it seems that phytochrome in its excited state controls light-induced synthesis of carotenoid. This synthesis was also... 

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