Retrochalcone

FIGURE 3.5 Biosynthetic route to isoflavonoids (and some derivatives) from the 5-deoxyflavanone liquiritigenin. A possible route to the retrochalcone echinatin is also shown. Unlabelled arrows indicate biosynthetic steps for which the enzyme(s) have not been characterized. Enzyme abbreviations are defined in the text and in Table 3.1, except for P2CP, pterocarpan 2-C-prenyltransferase P4CP, pterocarpan 4-C-prenyltransferase. 

Myrtaceae used in Australian traditional medicine), exists in a keto-enol tautomer ratio of 3 2. This compound was known previously as a synthetic product but only limited physical (melting point) and no spectroscopic data were available. The (3-hydroxychalcone constituent obtained from Millettia leucantha (26) is a further example of a retrochalcone. ... 

Saitoh, T. et al., Biosynthesis of echinatin. A new biosynthetical scheme of retrochalcone. Tetrahedron Lett., 16, 4463, 1975. 

Ayabe, S. and Furuya, T., Studies on plant tissue cultures. Part 36. Biosynthesis of a retrochalcone, echinatin, and other flavonoids in the culture cells of Glycyrrhiza echinata. A new route to a chalcone with transposed A- and B-rings, J. Chem. Soc. Perkin Trans. 1, 2725, 1982. 

Kajiyama, K. et al., Two prenylated retrochalcones from Glycyrrhiza inflata, Phytochemistry, 31, 3229, 1992. 

Recently Dr. Shibata has informed us that he wishes to change the name retrochalcone to reversely constructed chalcone based precisely on the biosynthetical scheme. 

Saitoh, T, S. Shibata, U. Sankawa, T. Furuya, and S. Ayabe Biosynthesis of Echinatin. A New Biosynthetical Scheme of Retrochalcone. Tetrahedron Letters, 1975, 4463. 

Kajiyama, K., S. Demizu, Y Hiraga, K. Kinoshita, K. Koyama, K. Takahashi, Y. Tamura, K. Okada, and T. Kinoshita Two Prenylated Retrochalcones from Glycyrrhiza inflata. Phytochem., 31, 3229 (1992). 

Ayabe, S., T. Yoshikawa, M. Kobayashi, and T. Furuya Studies on Plant Tissue Culture. 34. Biosynthesis of a Retrochalcone, Echinatin Involvement of O-Methyl-transferase to Licodione. Phytochem., 19, 2331 (1980). 

Ayabe, S., T. Yoshikawa, and T. Furuya Biosynthesis of Retrochalcone and Related Flavonoids the Tissue Culture of Glycyrrhiza echinata. In Plant Tissue Culture 1982. Proc. 5th Inti. Cong. Plant Tissue and Cell Culture. (Fujiwara, A, ed.), pp. 379-380. Tokyo Maruzen, 1982 Chem. Abstr., 99, I55308z (1983). 

Haraguchi H, Ishikawa H, Mizutani K, Tamura Y, Kinoshita T (1998) Antioxidative and superoxide scavenging activities of retrochalcones in Glycyrrhiza inflata. Bioorg Med Chem 6 339... 

Retinal pigment epithelium (RPE), 3925, 3927-3929, 3937, 3939 3941, 3943-3947 Retinoids, 2675, 2695 Retinol, 3369 Retinopathy, 1450 Retroaldol-aldol mechanism, 2700 Retrochalcones, 1869, 1874, 1875 Retrograde amnesia, 292 Retronecine, 1058, 1064 Retro-Prince reaction, 3075, 3076 Retrorsine, 1061, 1063, 1385 Reversed phase... 

Fig. 1.3 Anthocyanin equilibria in aqueous solution and the corresponding structural transformations. AH2 represents the flavylium cation that predominates at acidic pH values AH represents the two tautomeric quinonoid bases A depicts the anionic quinonoid bases that appears in alkaline solutions BH2 is the colorless hemiketal adduct and and are isomeric retrochalcones.

Fig. 1.6 H NMR spectra of malvin chloride at 25 °C (a) pure malvin chloride, (b) malvin with ferric chloride after 1 h, and (c) at equilibrium after a full day. Symbols indicate the different forms (see Fig. 1.3) ( ) flavylium cation, ( /°) hemiketal, (A) 5-retrochalcone, ( ) Z-retrochalcone, and ( ) Z-chalcone-iron complex.

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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