Isoflavone synthesis

AOPP has been used in many studies to examine the role of PAL in the synthesis of secondary aromatic compounds. The results summarized in Table I indicate that levels of AOPP that have little or no effect on growth can strongly affect production of secondary aromatic products. Other studies have shown rapid cessation of isoflavone synthesis in Cicer ariethinum by 0.3 mM AOPP (61). 

The same one-carbon unit has been employed in a convenient isoflavone synthesis from deoxybenzoins (76S326). Other methods of ring closure of phenyl benzyl ketones to this heterocycle have been reviewed (B-62MI22400) and include triethyl orthoformate (56PIA(A)(44)36), zinc cyanide (58CB2858), ethyl formate (80BCJ831) and ethoxalyl chloride (70JCS(C)1219). 

Evidence has been presented that 2-hydroxychalcones are also transformed into flavones on reaction with thallium(III) nitrate (equation 16) (78TL3359). Such a method would be complementary to the isoflavone synthesis if it proves to be of general applicability. 

The behaviour of the tyrosyl radicals involved in different processes and environments is not yet well understood Relatively little is known about the structure and selectivity of aryloxylium cations (Ar—0+) that are produced in the phenolic oxidation reactions and implicated in biological processes such as isoflavone synthesis . The thermochemistry which is relevant to the antioxidant properties of phenols as well as the solvent effects on their reactivity ° remain also a largely under-explored topic. Finally, the structure of phenol dimers and oligomers or even of some specific phenols also deserve more attention. We expect that these problems will be subjects for theoretical research in the coming years. 

Isoflavone content in response to genetic modification also was reported. Although little is known about the genetic regulation of isoflavone synthesis, several pathways were studied and the relationship between protein and fatty acid composition and isoflavone content was observed (Tsukamoto et al., 1995). For example, isoflavone content was negatively correlated with linolenic acid content, and also with protein content. 

Figure 8.2 A partial diagram of the phenylpropanoid pathway. Intermediates and en7ymcs involved in isoflavone synthesis, as well as some branch pathways, are shown. Dashed airow.s represent multiple steps the dotted arrow represents a speculative step.

Tsukayama, M., T. Horie, K. Fujimoto, and M. Nakayama A Convenient Synthesis of Prenylated Isoflavones Synthesis of Licoricone and Related Compounds. Chem. Pharm. Bull. (Japan), 34, 2369 (1986). 

Gattermann-Koch synthesis s. 13,183 One step isoflavone synthesis... 

The isoflavone 406 is prepared by the indirect a-phenylation of a ketone by reaction of phenylmercury(II) chloride with the enol acetate 405, prepared from 4-chromanone[371]. A simple synthesis of pterocarpin (409) has been achieved based on the oxypalladation of the oriho-mercurated phenol derivative 408 with the cyclic alkene 407[372,373]. 

Synthesis and reactions of isoflavone analogs, 3-hetarylchromones 99KGS3. 

Isoflavones have been implicated in goiter induction. Soybean extracts inhibit reactions catalyzed by thyroid peroxidase (TPO), essential to the synthesis of thyroid hormones (Divi et al., 1997). Genistein and daidzein (at about 1-10 p,M of IC50) may act as alternative substrates for tyrosine iodination (Divi et al., 1997). Furthermore, genistein and daidzein have also been shown to cause the irreversible inactivation of TPO in the presence of hydrogen peroxide. Genistein also inhibits thyroxine synthesis in the presence of iodinated... 

Leonard, E. and Koffas, M.A. (2007) Engineering of artificial plant cytochrome P450 enzymes for synthesis of isoflavones by Escherichia coli. Applied and Environmental Microbiology, 73, 7246—7251. 

An efficient synthesis of flavones, which occurs without formation of the corresponding aurone, involves the carbonylative cyclisation of oacetoxyiodophenols and arylalkynes (Scheme 48) . A large scale, one-pot synthesis of isoflavones has been described <00SC469>. 

Koch-Haaf reaction, 17, 3 Kornblum oxidation, 39, 3 Kostaneki synthesis of chromanes, flavones, and isoflavones, 8, 3... 

However, studies in hypercholesterolemic subjects, using soy protein depleted of isoflavones have shown that soy protein independently of isoflavones can favorably affect LDL size, LDL particle distribution was shifted to a less atherogenic pattern,and can decrease triglyceride concentrations, triglyceride fatty acid fractional synthesis rate, and cholesterol... 

Enone formation-aromatization has been used for the synthesis of 7-hydro-xyalkavinone (716)[456], The isoflavone 717 was prepared by the elimina-tion[457]. The unsaturated j-keto allyl esters 718 and 719. obtained in two steps from myreene. were subjected to enone formation. The reaction can be carried out even at room temperature using dinitriles such as adiponitrile (720) or 1,6-dicyanohexanc as a solvent and a weak ligand to give the pseudo-ionone isomers 721 and 722 without giving an allylated product(458]. 

Protection of the 2 -hydroxy group is not necessary when thallium(III) nitrate is used <74JCS(Pl)305). The reaction is also much faster and this technique appears to be the one of choice, especially for the synthesis of naturally occurring isoflavones (75CB3883). 

Chang, Y.C., Nair, M.G., Santell, R.C. and Helferich, Microwave-mediated synthesis of anticarcinogenic isoflavones from soybeans, /. Agric. Food Chem., 1994, 42, 1869. 

Liu M, Yanagihara N, Toyohira Y, Tsutsui M, Ueno S, Shinohara Y. 2007c. Dual effects of daidzein, a soy isoflavone, on catecholamine synthesis and secretion in cultured bovine adrenal medullary cells. Endocrinology 148 5348-5354. 

Nitric Oxide Synthesis as a Vascular Target for Dietary Isoflavones 252... 

NITRIC OXIDE SYNTHESIS AS A VASCULAR TARGET FOR DIETARY ISOFLAVONES... 

Similar intermediates might be involved in the rearrangement of chalcones 83 by [bis(trifluoroacetoxy)iodo]benzene 4 in refluxing methanol. Compounds of type 84 can be obtained, Scheme 36, which have been employed in the synthesis of isoflavones. The yield of this reaction is dependent on the electron density of the aromatic moieties [144]. 

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