Chalcones flavanones

Figure 3.6. Synthesis of chalcone, flavanone, and stilbene from p-coumaric and malonic acids.

Moustafa E, Wong E (1967) Purification and properties of chalcone-flavanone isomerase from soya bean seed. Phytochemistry 6 625-632... 

Flavonols, proanthocyanindins Chalcones, flavanones, Flavonols Pure compounds FAB (+) Glycerol 163... 

Van Tunen, A.J., Hartman, S.A., and Mur, L.A., Regulation of chalcone flavanone isomerase (CHI) gene expression in Petunia hybrida the use of alternative promoters in corolla, anthers and pollen, Plant Mol Biol, 12, 539, 1989. 

In contrast to the ubiquitous distribution of flavonoids hydroxylated at C-3 or C-4 of their heterocyclic rings, the unsubstituted flavans (2-phenylchromans) are more rarely found. The flavans co-occur with chalcones, flavanones, flavan-3,4-diols, flavonols, and 1,3-diphenyl-propanes. 

Genkwanol C Dimers (chalcone-flavanone) C30H22O11 Daphne genkwa Thymelaeaceae 146... 

Dorstenia chalcone dimer Chalcone-flavanone C40H38O8 Dorstenia zenkeri Moraceae 83... 

Flavonoids can be classified according to their biosynthetic origins. Some flavonoids are both intermediates in biosynthesis and end-products, e.g. chalcones, flavanones, flavanon-3-ols and flavan-3,4-diols. Other classes are only known as the end-products of biosynthesis, e.g. anthocyanins, flavones and flavonols. Two further classes of flavonoids are those in which the 2-phenyl side-chain of flavonoid isomerizes to the 3-position (giving rise to isoflavones and related isoflavonoids) and then to the 4-position (giving rise to the neoflavonoids). The major classes of flavonoids, with specific examples, are summarized helow. 

Fig. 1. Simplified diagram of the phenylpropanoid and flavonoid biosynthetic pathways. Enzymes that catalyze the reactions are placed on the left-hand side, and transcription factors on the right-hand side of the arrows. Both transcription factors for which their control over the enzymatic steps has been genetically proven, as well as transcription factors that have been shown to interact with promoters of the structural genes, are shown. PAL Phenylalanine ammonia lyase C4H cinnamate 4-hydroxylase 4CL 4-coumaroyl-coenzyme A ligase CHS chalcone synthase CHI chalcone-flavanone isomerase F3H flavanone 3(3-hydroxylase DFR dihydroflavonol 4-reductase AS anthocyanin synthase UFGT UDP glucose-flavonol glucosyl transferase RT anthocyanin rhamnosyl transferase...

Almost every class of natural phenolic compounds contains examples of substances with a 2,2-dialkylchromene ring, and the number of those that are discovered increases every year. It would be difficult to give an exhaustive list of these compounds. Their chemistry will be discussed here only when it is related to some particular behavior of the benzo-pyran ring. Examples include simple chromenes substituted in the aromatic ring, - " benzodipyrans, - dimers of chromenes, naphthopyrans, - quinones, flavones, flavonols, chalcones, flavanones, isoflavonoids, rotenoids, pterocarpans, couma-j,ing 17,51-53 3.aryl-4-liydroxycoumarins, ° 4-phenylcoumarins, chroma-... 

The apparent bioactivity of the chalcones in the mixture, coupled with reports that chalcones are known to have anti-plasmodial activity,and that they are available in large quantities, led us to submit them to assays for anti-plasmodial activity the chalcones, flavanones and the homoisoflavanone (Table 5) were found to have redueed but still significant anti-plasmodial activities with IC50 values in the range of 2-20 ig/ml. This is an illustration of the principle that plant extracts and component compounds that are bioactive should be surveyed for anti-malarial activity and for activities against other diseases for which they are not already known. 

Flavonoids can be classified according to the degree of oxidation of the three-carbon central segment. From lower to higher degree of oxidation, flavonoids are usually classified as catechins, chalcones, flavanones, isoflavones, flavan-3, 4-diols, flavones, aurones, flavonols and anthocyanins (Fig. (2)) [5],... 

This reaction has general application in the preparation of chalcones, flavanones, 1,3-diarypropanes, etc. 

It shlklmate dehydrogenase, 2t phenylalanine ammonia-lyase, 3> cinnamic acid 4-hydroxylase, 4 SAMI caffeate 3-0-methyltransferase, 5t hy-droxyclnnamatet CoA llgase, 6t "flavanone synthase", 7t chalcone-flavanone isomerase, 8t SAMt 3, 4 -dihydroxyflavonoid 3 0-methyltrans-[Pg.236]

Substituents Ri Rg R3 Cinnamoyl CoA derivatives Chalcones Flavanones Dihydro- Flavones flavonols ... 

Flax Petunia hybrid/ overexpression CaMV35S/CHS + CHI + DFR Chalcone synthase, chalcone isomerase, and dihydroflavonol 4-reductase Chalcones, flavanones, chlorogenic acid Higher in flavonoids (kaempferol), phenolic acids (coumaric, ferulic, synaptic acids) in seedcake extracts [65]... 

Fig. 53.7 Biosynthesis of natural and unnatural flavonoids and stillxaies in E. coli. Supplementation of unnatural synthesized carboxylic acids and natural carboxylic acids in E. coli recombinants produced unnatural and natural respective chalcones, flavanones, flavones, flavonols, and stilbenes. The red circle shown in the figure is one of the structure/groups shown in the inset...

Minor Flavonoids (Chalcones, Flavanones, Dihydrochalcones, and Aurones) ... 

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