Anthocyanidin derivatives

Fig. 4.20 Compounds 384-388, anthocyanidin derivatives and anthochlors from Gesneriaceae...

Figure 6.14. Positive-ion mode fragmentation patterns of trimeric procyanidins. The ESI-MS conditions spray voltage 4.5 kV sheath gas nitrogen 0.9L/min capillary voltage 35 V capillary temperature 200 °C tube lens offset voltage 15 V. (Reprinted from Pati et al., 2006, Simultaneous separation and identification of oligomeric procyanidins and anthocyanidins-derived pigments in raw red wine by HPLC-UV-ESI-MSn, Journal of Mass Spectrometry, 41, p. 869, with permission from John Wiley Sons, Ltd.)...

Phloroglucinol (42) is a colorless and odorless solid which is only spariagly soluble ia cold water (82). It was discovered ia 1855 ia the hydrolysis products of the glucoside phloretia, which was obtained from the bark of fmit trees. Phlorogluciaol occurs ia many other natural products ia the form of derivatives such as flavones, catechins, coumaria derivatives, anthocyanidins, xanthins, and glucosides. 

Glycosides, particularly of phenoHc compounds, are widely distributed in plant tissues (2,10). Glycosides of anthocyanidins, flavones, flavanols, flavanones, flavanonols, stilbenes and saponins, gaUic acid derivatives, and condensed tannins are all common. 

The chemical formulae for a variety of plant phenols are given in Fig. 16.2, including examples of simpler phenols, such as cinnamic acid derivative, and of tocopherols, flavonoids, flavonoid glycosides and anthocyanidins. The flavonoids include the following subclasses flavanones (taxifolin), flavones (luteolin), flavonols (quercetin) and flavanols (catechin/epicatechin). The... 

Six anthocyanidins are commonly found in plants and plant-derived foods and beverages pelargonidin, cyanidin, delphinidin, peonidin, petunidin, and malvidin. Their structures differ in the number and position of hydroxyl and methoxyl groups on the flavan nucleus. The most commonly occurring anthocyanidin is cyanidin, and all these anthocyanidins are found in plants as glycosides with or without acylation, leading to around 400 different stractures. 

The anthocyanins are glucosides of polyhydric phenols and phenol ethers having OH and phenyl as substituents in the pyran ring. These glucosides can be regarded as derived from three types of sugar-free anthocyanidins. 

The fundamental nucleus in anthocyanidins (aglycones) is flavylium chloride. Most of the anthocyanidins are derivatives of 3,5,7-trihydroxyflavylium chloride. Thus, the hydroxylation patterns in the natural anthocyanidins fall into the three basic groups of pelargonidin, cyanidin and delphinidin. Anthocyanidins are rarely found in fresh plant material because of their instability [19]. 

Most of the pigments of flowers arise from a single polyketide precursor. Phenylalanine is converted to trans-cinnamic acid (Eq. 14-45) and then to cinnamoyl-CoA. The latter acts as the starter piece for chain elongation via malonyl-CoA (step a in the accompanying scheme). The resulting (3-polyketone derivative can cyclize in two ways. The aldol condensation (step b) leads to stilbenecar-boxylic acid and to such compounds as pinosylvin of pine trees. The Claisen condensation (step c) produces chalcones, flavonones, and flavones. These, in turn, can be converted to the yellow fla-vonol pigments and to the red, purple, and blue anthocyanidins.3 c... 

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