Phytofluene from phytoene

Phytofluene. Porter and Lincoln s work with various tomato selections indicated the presence of phytofluene, along with other precursors (7). In an enzyme system obtained by ammonium sulfate precipitation of proteins from spinach (Spinacia oleracea) leaves, phytoene, phytofluene, and lycopene were produced from labeled isopentenyl pyrophosphate (11). Curiously, no f-carotene or neurosporene was reported. 

Fig. 2.16. HPLC profile of carotenoids in an extract of vegetable soup. An expansion of the profile from 30 to 39 is shown in the inset (A). Monitored wavelengths were 436, 440, 464, and 409 nm for peaks 9,10,11,12, and 14, respectively, in the inset (A). Peak identification 1 + 1" = all-trans-lutein and cw-lutein 2 = 5,6-dihydroxy-5,6-dihydrolycopene (lycopene-5,6-diol) 3 = j3-apo-8 -carotenal (internal standard) 4 = lycopene 1,2-epoxide 5 = lycopene 5,6-epoxide 6 = 1,2-dimethoxyproly-copene (tentative identification) 7 = 5,6-dimethoxy-5,6-dihydrolycopene 8 = lycopene 9 = pheo-phytin b 10 = neurosporene 11 = (-carotene 12 = pheophytin a 13 = (-carotene 14 = pheophytin a isomer and (-carotene 15 = a-carotene 16 and 16" = all-trans-/fcarotene, cis-/J-carotene 17 and 17" = all-trans- or cA-phytofluene 18 and 18" = all-trans- or cw-phytoene. Reprinted with permisson from L. H. Tonucci et al. [40].

In the APPI method of ionization, the solvent is vaporized in a heated nebulizer and the gaseous analytes are then ionized with photons from a lamp (Rivera et ah, 2011). It has been observed that certain solvents, called dopants, enhance the ionization of analytes via this technique. To date only one study has been published with carotenoids and APPI (Rivera et ah, 2011). APPI was compared to ESI and APCI as ionization techniques, and the authors observed that APPI positive produced approximately a 2- to 4-fold greater total ion signal for lycopene and (3-carotene as compared to APCI positive and ESI positive. In contrast, APCI positive outperformed APPI positive for a number of xantho-phylls and phytoene and phytofluene. 

No carotenoids were detected in tissues of animals sacrificed after 6 weeks. However, as shown in Table 10.4, after 24 weeks, nearly all carotenoids (lutein, zeaxanthin, lycopene, y-carotene, -carotene, a-carotene, P-carotene, phytofluene, phytoene) were bioavailable in colon and liver of the animals that received MCM. A typical HPLC profile of carotenoids in a pooled extract from mouse liver is shown in Figure 10.2. The major carotenoids in brain were lycopene, lutein, and P-carotene. Carotene predominated in the breast tissues, while lutein, lycopene, y-carotene, and a-carotene were detected in low concentrations. Carotenoids were not detected in tissues of the mice on WD without MCM. 

Even people who have been taking blood pressure-lowering drugs will benefit from this natural choice. And individuals who are determined to get their blood pressure down without drugs will benefit enormously. Tomato extract, which is rich in the antioxidant polyphenols lycopene, phytoene, and phytofluene, has been shown to reduce blood pressure for treated but not completely controlled hypertensive individuals, as well as for never-treated men and women in the category of prehypertension. Two studies have been done at the University of the Negev in Beer Sheva, Israel, by Dr. Esther Paran and her colleagues. 

It can be established from these investigations that unlike triazines and diuron, norflurazon damages the photosynthetic system of the plants. The main action is the blocking of carotenoid synthesis, as a result of which carotenoid precursors (phytoene and phytofluene) are accumulated because of the inhibition of dehydrogenation reactions. 

Pathways. Studies of carotenoid transformations that take place when a mutant strain, PGl, of the green alga Scenedesmus obliquus is transferred from dark to light conditions have indicated that the transformations 15-cw-phytoene (180) 15-c/5-phytofluene (181) - 15-cis- -carotene (182) -> trans-C-caro-tene (183) (Scheme 7) take place in the biosynthesis of the normal cyclic carotenoids. The results were also in agreement with the formation of the xanthophylls lutein (16) and zeaxanthin (174) from the corresponding carotenes. 

Phytoene (150), phytofluene (151), -carotene (152) and neurosporene (153), the biosynthetic precursors of lycopene (1), also contain the y-end group. They differ from lycopene (1) in the degree of saturation of the 7,8, 7, 8, 11,12 and/or IT,12 double bond(s). Different building blocks as starting material have therefore been used for the synthesis of these compounds. 

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. 

If this hypothesis is true, one would also expect to find poly-cis-C-carotene, -phytofluene, and -phytoene present in the fruit. Poly-cis induction appears to differ from the lycopene inducer in another respect. In addition to gene derepression, the lycopene inducers inhibit the cyclase(s), causing lycopene to accumulate at the expense of the cyclic carotenes. The accumulation of significant amounts of poly-cis-y-carotenes I and II indicates that the cyclase(s) is not inhibited by the poly-cis inducers and that their only apparent function is to derepress the recessive gene. 

In tomatoes and other higher plants, formation of lycopene (5) from Z-phytoene (11) occurs via -carotene (16). Z-phytoene (11) is converted to Z-phytofluene (14), E-phytofluene (15), -carotene (16), neurosporene (17), and, finally, lycopene (5) by extracts of tomato fruit plastids (Fig. 26.5) (Porter et al., 1984 Spurgeon and Porter, 1983). 

Studies with cell-free systems have now confirmed the proposed desaturation of phytoene to the more unsaturated carotenes. Cell-free systems obtained from tomato plastids and spinach chloroplasts will convert [ C]phy-toene (the 15-cis isomer) into lycopene and cyclic carotenes (Kushwaha et al., 1970 Subbarayan et al., 1970), as will an extract from P. blakesleeanus (Davies, 1973). Extracts ofH. cutirubrum (Kushwaha et al., 1976) incorporate radioactivity from tran.s-phytoene into the more unsaturated carotenes. With Flavobacterium extracts [ CJphytoene (the 15-cis isomer) was also converted to the more unsaturated carotenes (Brown et al., 1975). Later studies with tomato plastid extracts have demonstrated the conversion of c/i-[ C]phytofluene, rra/ij-[ C]phytofluene, and /ra/i5- -[ C]carotene to neurosporene and lycopene (Qureshiet al., 1974a,b). Cell-free extracts from H. cutirubrum (Kushwaha et al., 1976) also convert tran -phytofluene to fra/is- -carotene, -carotene to neurosporene, and neurosporene to lycopene. The conversion of neurosporene to lycopene has also been demonstrated using extracts from the Cl 15 mutant of P. blakesleeanus (Davies, 1973). 

Phytoene an aliphatic, colorless hydrocarbon carotenoid, M, 544. P. is a polyisoprenoid containing six branch methyl groups, two terminal isopropyli-dene groups and nine double bonds, three of them conjugated. Only the A double bond has cis configuration. Biosynthetically, P. is derived from two molecules of geranylgeranyl pyrophosphate, and it serves as a C40-starter molecule in the biosynthesis of other carotenoids phytofluene, carotene, neurosporene and lycopene are formed by the stepwise dehydro-... 

The simplest prototype of carotenes, called I/-carotenes, is the polyunsaturated acyclic hydrocarbon (15Z)-7,8,11,12,7, 8, llM2 -octahydro- r, Ir-carotene, known as phytoene, which is synthesised from two molecules of geranylgeranyl diphosphate. Isomerisation of phytoene yields the trans-isomer phytofluene (7,8,1 l,12,7, 8 -hexahydro- Ir, Ir-carotene). Oxidation of phytofluene gradually gives -carotene (7,8,7, 8 -tetrahydro-vIf,vIf-carotene), neurosporene (7,8-dihydro- f, Ir-carotene) and lycopene(vIf,vIr-carotene), which is the final product of the biosynthesis (9-180) and the main pigment of tomatoes (30-200 mg/kg), watermelons (33 121 mg/kg) and rose hips (101-834 mg/kg... 

Dehydrogenations (Fig. 88). The key substance phytoen is subjected to a series of dehydrogenations which lead to phytofluen, -carotene, neurosporene and, finally, lycopene. As already mentioned -carotene is the first colored carotene in this sequence. Apart from both ends of the molecule lycopene consists of a sequence of completely conjugated double bonds. Its name comes from its occurring in certain breeds of tomatoes (Lycopersicon esculeiuum). 

The desaturation of phytoene occurs in a stepwise sequence to form phytofluene (7,8,1 l,12,7, 8 -hexahydro-i/r,i/r-carotene), f-carotene (7,8,7, 8 -tetrahydro-(/, (/ -carotene), neurosporene (7,8-dihydro-i/r,i/r-carotene), and lycopene (Figure 4.3). At each stage, two hydrogen atoms are lost by trans elimination from adjacent positions to extend the polyene chromophore by two double bonds." Desaturation can be carried further to 3,4,3 4 -tetrahy-drolycopene, as demonstrated in spinach chloroplasts." ... 

Figure 4.6. Separation by HPLC of plant carotenoids extracted from untreated (A) and diflufenican-treated (B, C) carrot cells. Traces A and B were monitored at 450 nm trace C was monitored at 285 nm. 1, All- neoxanthin 2, violaxanthin 3, antheraxanthin 4, lutein 5, a-carotene 6, )3-carotene 7, phytofluenes 8, 15-Z phytoene. Data kindly provided by Dr. K. Pallett.

Carotenoids are believed to play a significant role in protecting skin from oxidative damage. In vivo measurements in humans of lycopene, fi-, C, 7-, and a-carotenes, lutein and zeaxanthin, phytoene, and phytofluene have shown that carotenoid concentrations are correlated with the presence or absence of skin cancer and precancerous lesions. Carotenoids are also believed to protect against several other types of cancer, cardiovascular diseases, and cataract formation and aid in immune function and gap-junction communication between cells, which is believed to be a protective mechanism related to their cancer-preventative activities. 

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