Carotenoid aldehydes

The intermediate 8,8 -diapo-20-acetoxycarotene-8,8 -dial (81) has been used to synthesize the cross-conjugated carotenoid aldehydes , y-caroten-20-al (82), (2/ ,2 J )-2,2 -bis-(3-methylbutyl)-3,4,3, 4 -tetrahydro-t/>, /f-caroten-20-al (83),... 

Carotene and Canthaxanthin Carotenoid aldehydes Ceramides Ceramide acetates... 

WiNTERSTEiN and coworkers [764] have isolated a series of carotenoid aldehydes from plant and animal tissues. This was rendered possible in some cases only by a markedly improved technique, especially by using TLC and radioactive derivatives [762]. 

WiNTERSTEiN et al. [148] have separated the carotenoid aldehydes on silica gel layers, impregnated with paraffin oil, using methanol. 

Carotenoid aldehydes form intensely coloured condensation products with the rhodanine reagent (No. 222) after drying, which serve for identification. As little as 0.02—0.03 g retinal can be seen as an orange-red spot [150]. Blue to deep violet complexes, depending on the compound, are yielded with the indandione reagent (No. 138). The sensitivity is similar and they also fluoresce orange in UV light [133] (Fig. b, Plate II). 

Carotenoid aldehydes Catechins Catechol amines Cations, inorganic... 

Since GAs as diterpenes share many intermediates in the biosynthetic steps leading to other terpenoids, eg, cytokinins, ABA, sterols, and carotenoids, inhibitors of the mevalonate (MVA) pathway of terpene synthesis also inhibit GA synthesis (57). Biosynthesis of GAs progresses in three stages, ie, formation of / Akaurene from MVA, oxidation of /-kaurene to GA 2" hyde, and further oxidation of the GA22-aldehyde to form the different GAs more than 70 different GAs have been identified. 

In nature, vitamin A aldehyde is produced by the oxidative cleavage of P-carotene by 15,15 - P-carotene dioxygenase. Alternatively, retinal is produced by oxidative cleavage of P-carotene to P-apo-S -carotenal followed by cleavage at the 15,15 -double bond to vitamin A aldehyde (47). Carotenoid biosynthesis and fermentation have been extensively studied both ia academic as well as ia iadustrial laboratories. On the commercial side, the focus of these iavestigations has been to iacrease fermentation titers by both classical and recombinant means. 

A number of keto-carotenoids have been prepared from the bis-phosphonium salt (130) and substituted Cjs-aldehydes, the keto-functions... 

There are basically two types of carotenoids those that contain one or more oxygen atoms are known as xanthophylls those that contain hydrocarbons are known as carotenes. Common oxygen substituents are the hydroxy (as in p-cryptoxanthin), keto (as in canthaxanthin), epoxy (as in violaxanthin), and aldehyde (as in p-citraurin) groups. Both types of carotenoids may be acyclic (no ring, e.g., lycopene), monocyclic (one ring, e.g., y-carotene), or dicyclic (two rings, e.g., a- and p-carotene). In nature, carotenoids exist primarily in the more stable all-trans (or all-E) forms, but small amounts of cis (or Z) isomers do occur. - ... 

Plant extracts rich in carotenoids, hydrolyzed with acetic and propionic aldehydes under controlled temperature and pressure... 

The origin of many of the components of black tea aroma has been studied. Aldehydes are produced by catechin quinone oxidation of amino acids. Enzymic oxidation of carotenoids during manufacture generates ionones and their secondary oxidation products such as theaspirone and dihydroactinidolide. Oxidation of linoleic acid is responsible for the formation of trans-2-hexenal.82... 

Moreover, carotenoids themselves are very susceptible to oxidative damage and their oxidation products include deleterious aldehydes (Failloux et al., 2003 Hurst et al., 2005 Rozanowski and Rozanowska, 2005 Siems et al., 2000, 2002 Sommerburg et al., 2003). Therefore it is of interest to find out how carotenoids can offer antioxidant protection in cellular systems, how stable the carotenoids are within cells, and what the fate of the carotenoid degradation products is. 

Nucleic acids are not the only biomolecules susceptible to damage by carotenoid degradation products. Degradation products of (3-carotene have been shown to induce damage to mitochondrial proteins and lipids (Siems et al., 2002), to inhibit mitochondrial respiration in isolated rat liver mitochondria, and to induce uncoupling of oxidative phosphorylation (Siems et al., 2005). Moreover, it has been demonstrated that the degradation products of (3-carotene, which include various aldehydes, are more potent inhibitors of Na-K ATPase than 4-hydroxynonenal, an aldehydic product of lipid peroxidaton (Siems et al., 2000). 

Kalariya, NM, Ramana, KV, Srivastava, SK, and van Kuijk, FJ, 2008. Carotenoid derived aldehydes-induced oxidative stress causes apoptotic cell death in human retinal pigment epithelial cells. Exp Eye Res 86, 70-80. 

A possible mechanism for this transformation, similar to the proposed enzymatic cleavage of carotenoids (Fig. 3), involves 0 = Ru = 0 porphyrin 21 catalyzed epoxidation of 17 to 22, followed by nucleophilic attack of TBHP and ring opening with assistance of 23. Subsequent fragmentation yields the aldehydes (Fig. 8). 

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