Natural anthocyanins

Hagiwara, A. et al., Pronounced inhibition by a natural anthocyanin, purple com color, of 2-amino-l-methyl-6-phenylimidazo[4,5-b]pyridine (PhlP)-associated colorectal carcinogenesis in male F344 rats pretreated with 1,2-dimethylhydrazine. Cancer Lett., 171, 17, 2001. 

Bicard, V., Fougerousse, A., and Brouillard, R., Analysis of natural anthocyanins by capillary zone electrophoresis in acidic media, J. Liq. Chromatogr. Rel. Technol, 22, 541, 1999. 

Goto, T., Structure, stability and color variation of natural anthocyanins, Fortsch. Chem. Org. Natur., 52, 113, 1987. 

Fiorini, M., Preparative high-performance liquid chromatography for the purification of natural anthocyanins, J. Chromatogr. A, 692, 213, 1995. 

Nymphaea caerulea, for seven natural anthocyanins stabilizing a DNA triplex, etc. Sequential analysis of the oligosaccharide structures of the flavonol tamarixetin-7-O-rutino-side has been performed by ID multistep-relayed COSY-ROESY experiments. Selective excitation was performed by Gaussian-shaped soft pulses. 

Brouillard, R. and Lang, J., The hemiacetal-cis-chalcone equilibrium of malvin, a natural anthocyanin. Can. J. Chem. 68, 755, 1990. 

Each anthocyanidin is involved in a series of equilibria giving rise to different forms, which exhibit their own properties including color. One- and two-dimensional NMR have been used to characterize the various forms of malvidin 3,5-diglucoside present in aqueous solution in the pH range 0.3 to 4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. In a reexamination, the intricate pH-dependent set of chemical reactions involving synthetic flavylium compounds (e.g., 4 -hydroxyflavylium) was confirmed to be basically identical to those of natural anthocyanins (e.g., malvidin 3,5-diglucoside) in... 

The occurrence of the diester structures of the malonic acid moiety in natural anthocyanin pigments has so far been reported in pigments from flowers of Eichhornia crassipes and chive. Allium schoenoprasum, where the anthocyanin-flavone and anthocyanin-flavonol disubstituted malonate structures were exhibited, respectively (Figure 10.8 and Figure 10.9). In some anthocyanins from flowers of Anemone coronaria, malonic acid is esterified with galactose in one end and tartaryl in the other end. ... 

It is well known that anthocyanins with hydroxyl groups in orr/zo-position to each other form complexes with aluminum ion leading to bathochromic and hyperchromic shifts in their absorption spectra. Complexation of AF" " with synthetic and natural anthocyanins has been investigated in aqueous solutions within the pH range 2 to 5. As shown by UV-vis... 

All natural anthocyanins suffer from inherent instability, so they may be degraded to form colorless or brown-colored, often insoluble products. It is evident, that depending on the reaction type, different degradation products are formed however, only little analytical data is available. For example, after reaction of anthocyanins with hydrogen peroxide, substances of the benzofu-ran type were detected (139). Studies with grape must like model solutions indicated that anthocyanins are degraded by coupled oxidation and that they form adducts with caffeoyltartaric acid... 

The potential of a natural anthocyanin with purple corn color (PCC) has been tested against colorectal carcinogenesis, using male F344/DuCrj rats that were initially treated with 1,2-dimethylhydrazine (DMH). 2-Amino-l-melhyl-6-phenylimidazo [4,5-fc] pyridine (PhIP) exerted promoting effects on... 

Pawlowicz, P, Wilczynski, J., Stachowiak, G., and Hincz, P, Administration of natural anthocyanins derived from chokeberry retardation of idiopathic and preeclamptic origin. Influence on metabobsm of plasma oxidized lipoproteins the role of autoantibodies to oxidized low density bpoproteins, Ginekol. Polska, 71, 848-853, 2000. 

In aqueous media, most of the natural anthocyanins behave like pH indicators, being red at low pH, bluish at intermediate pH, and colorless at high pH. According to Brouillard (1982), in acidic and neutral media four anthocyanin structures exist in equilibrium the red flavylium cation (AH+), blue or red quinonoidal base (A), colorless carbinol pseudobase (B), and colorless chalcone (C) (Reaction 9.3). 

GOTO T (1987), Structure, stability and colour variation of natural anthocyanins . In Herz W, Griesebach H, Kirby, G and Tamm C,... 

The pH of cell sap of most flowers is such that many antho-cyanin-containing flowers should be colorless, yet the presence in nature of colorless anthocyanins is rare. Anthocy-anidins undergo a series of complex color changes in water at varying pH (Brouillard, 1988). The flavylium cation of natural anthocyanins behaves as a weak diacid, whereas a neutral quinonoid base is at the same time a weak acid and a weak base. The pH of crude extracts of flowers varies from 2,8 to 6.2. 

Contents U. Weiss, L. Merlini, and G. Nasini Naturally Occurring Perylene-quinones. — H. Achenbach The Pigments of the Flexirubin-Type. A Novel Class of Natural Products. — T. Goto Structure, Stability and Color Variation of Natural Anthocyanins. — P. Bhattacharyya and D. P. Chakraborty Carba-zole Alkaloids. 

Brouillard R, Lang J (1990) The hcaniacetal-cis-chalcone equilibrium of malvidin, a natural anthocyanin. Can J Chem - Revue Canadienne De Chimie 68 755-761... 

In vitro anticancer tests have been performed using aglycones and natural anthocyanins (Meiers et al, 2001 Chen et al, 2006). The most striking result is reported by Feng et al (2007). Cyanidin 3-0-rutinoside can kill selectively leukemia cells by a mechanism suggested to be an anthocyanin prooxidant effect active on the malignant cells. 

The recent discovery that Z-retrochalcones (natural anthocyanin retrochalcones) encapsulate iron (III) points out that they can play a nutritional role. Owing to this property, anthocyanins may take part in the uptake and regulation of this vital metal in the human body. If it is the case, it would be wise to consume red fruits (edible berries) with good amounts of structurally simple glycosylated anthocyanins whose Z-chalcones are perfectly sized for complexing iron (III). 

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