Hydroxy phytoene

Phenol, 4-4-vinyl Fr fixed oipE° Phenylacetic acid, para-hydroxy Fr Ju E074 Phenylethanol, 3-4-dihydroxy Fr°E05i Phenylethanol, 4-hydroxy, glucoside Fr E034 Phenyl-glycol, 3-4-dihydroxy Fr EOSl Phytoene Fr fixed oiP ... 

Fig. 4 Reconstruction of the carotenoids biosynthetic pathway in S. cerevisiae. Heterologous activities t-HMGl 3 hydroxy-3-methylglutaryl-coenzymeA, ctrE geranylgeranyldiphosphate synthase (from Xanthophyllomyces dendrorhous), Ctrl phytoene desaturase, ctrYB bifunctional enzyme phytoene synthase and lycopene cyclase. Endogenous yeast activities ISIS I geranylgeranyldiphosphate synthase. Metabolites IPP isopentenyl diphosphate, GPP geranyl diphosphate, FPP famesyl-diphosphate, GGPP geranylgeranyl diphosphate...

In the photosynthetic bacteria Rhodomicrobium vannielii, which normally contains acyclic carotenoids with tertiary hydroxy- and methoxy-groups at C-1 and C-T, phytoene only accumulated when diphenylamine was present, but the occurrence of hydroxy-derivatives of phytofluene, 7,8,11,12-tetrahydrolycopene, neurosporene, and lycopene in the presence of the inhibitor indicated that hydroxylation could take place at any level of desaturation although only the more desaturated half of the molecule was so substituted. 

A large number of carotenoid compounds have been isolated from saffron. Crocins and crocetin have been already mentioned above and are listed in Table 2. a-Carotene (V), p-carotene (VI), lycopene (VII), zeaxanthin (VIII), phytoene (IX), phytofluene (X) are the minor ones [22]. Straubinger et al [23] have reported the identification of four novel glycoconjugated carotenoid breakdown products of saffron that are the P D-glucosides of (4R)-4-hydroxy-3,5,5-trimethylcyclohex-2-enone, (4S)-4-hydroxy-3,5,5-trimethylcyclohex-2-enone and (4S)-4-(hydroxymethyl)-3,5,5-trimethylcyclohex-2-enone as well as the P-D-gentiobiosyl ester of 2-methyl-6-oxohepta-2,4-dienoic acid. 

An additional technique for the characterization of polar carotenoids makes use of the europium-induced shifts in the n.m.r. spectrum. A range of hydroxy-, methoxy-, and keto-derivatives each gave significantly different relative shifts which can be used to identify the position of the polar group even with a 60 MHz instrument. A detailed second analysis of the vinyl n.m.r. signals of phytoene (1) and related model compounds (2)—(5) at 220 MHz confirmed that the natural... 

The degree of unsaturation in the molecule, i.e. the length of the conjugated polyene chromophore, has a substantial effect on retention times. Thus the acyclic hydrocarbons of the biosynthetic desaturation series, namely phytoene, phytofluene, tetrahydrolycopene, neurosporene and lycopene are well resolved, as are compounds having the same substituent group but different levels of desaturation, e.g. the 1-hydroxy-derivatives of these hydrocarbons. The 1,2-dihydrocarotenes, found in Rps. viridis are eluted later than their parent hydrocarbons e.g. 1,2-dihydroneurosporene after neurosporene. 

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