Carotene, synthesis

Fig. 12. Light threshold of photophorogenesis in dependence of residual (3-carotene synthesis. Mycelia, 50h after inoculation, were irradiated at various fluence rates for 1 min. The threshold was determined by extrapolation. From Gal-land and Russo (1979,inpress)...

Use in synthesis. The reagent has been used extensively, particularly by Isler in the synthesis of carotenoids, for lengthening the chain of an o,j8-unsaturated aldehyde by two carbon atoms. In the technical )3-carotene synthesis by Hoffmann-La Roche, Basel, the reaction is used for the conversion of the Cu-aldehyde (1) into the Cie-aldehyde (4). The procedure is as follows. A mixture of 325 g. of (1),... 

Perez, A., Sanz, C., Richardson, D., and Olias, J. Methyl jasmonate promotes 3-carotene synthesis and chlorophyll degradation in golden delicious apple peel. J. Plant Growth Regul. 12, 163-167, 1993. 

In view of the synthetic importance of dicarbonvl compounds surprisingly little has been done, apart from carotene synthesis, on dialkenylation with Wittig reagents. However, from the few examples reported one may conclude, that no special problems are involved. Benzocyclobutanedione was converted by two equivalents of methoxycarbonylmethylidenetri-phenylphosphorane to the corresponding diene in 85% yield (M. P. Cava, 1960). 

Fig. 13. Oxygen threshold of pho-rogenesis in dependence of residual (J-carotene synthesis as compared to...

DC030 Rhodes, B. B., and C. V. Hall. Effects of CPTA 2-(4-chlorophenyltio)-tri-ethylamine hydrochloride, temperature, and genotype on carotene synthesis in carrot leaves. Hortscience 1975 10 22. 

By this route, the C10 dialdehyde, 2,7 dimethyl-2,4,6-octatriene-l,8-dial (22), is readily obtainable 26a) from 2-butene-l,4-bis(dimethylphosphonate) (19, n = 1) and methylglyoxaldimethylacetal (21). It is employed as the C10 building block in an industrially used P-carotene synthesis (see page 16). 

Further demonstration of these two distinct and separate properties is evident in the carotene response pattern observed in further studies of the bioregulation of carotene synthesis in the carotenogenic mold Phvcomvces blakesleeanus. Mycelia of P. blakesleeanus cultured on media containing 10 ppm DCPTA show the acyclic lycopene as the main pigment constituent as shown in Table III. 

As pointed out previously for chlorophyll destruction and ethane evolution with algae in the presence of norflurazon (Tables I,III), peroxidative reactions may show up as a consequence of a primary inhibition of carotene synthesis, which itself does not induce peroxidation-initiating radicals. 

Generally, the response increases with increasing concentration of the bioregulator to a maximum value. Further increases in the concentration cause no further increases in carotene content, or the bioregulator can even become somewhat inhibitory to overall carotene synthesis. Doubling of the concentration of diethylamiro-ethylphenylether from 0.26 to 0.52 M reduced the observed response... 

Inhibition and Regulation. Evidence has been obtained for the existence of two /S-carotene pools and two biosynthetic sites in the chloroplast. Light-induced carotene synthesis has been studied in mutants of Phycomyces blakesleeanus with abnormal phototropism. The use of substances which affect carotenoid biosynthesis continues. Nicotine has been used in studies of C50 carotenoid formation in Halobacteria and of arylcarotene synthesis in Chlorobium. ... 

RABBANI, S., BEYER, P., LINTIG, J., HUGUENEY, P., and KLEINIG, H., Induced beta-carotene synthesis driven by triacylglycerol deposition in the unice hi sLr a ga Dunaliella bardawii. Plant Physiol 1998, 116, 1239-48. 

The time courses of xanthophyll synthesis (especially lutein) and bulk carotene synthesis in the same developing system appear to be different [8]. Thus when either dark-grown or light-grown seedlings are incubated, in the light, with [ H]-MVA and C02 simultaneously, lutein and 6-carotene show different ratios, reflecting... 

Among the above-mentioned changes, application of exogenous methyl jasmonate has been shown to stimulate ethylene formation [15-17], carotene synthesis [18] and chlorophyll degradation [15,18] in tomato and/or apple fruits. In ripening tomato fruits, methyl jasmonate also increased the level of the precursor free 18 3 as well as aromatic compounds [19]. Methyl jasmonate is reported to have... 

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