Isoflavonoids

Dewick, Paul M.

doi:10.1007/978-1-4899-2911-2_5

Cited by 41 publications

(36 citation statements)

References 228 publications

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“…The isoflavonoids enjoy a restricted distribution in the plant kingdom, being mostly limited to the subfamily Papilionoideae of the Leguminosae (44). The first evidence that plants contained estrogenic compounds came from investigations on the negative effects of clovers on fertility in cattle and sheep, reviewed in (163).…”

Section: Occurrence and Dietary Sourcesmentioning

confidence: 99%

Phytoestrogens

Dixon

2004

Annu. Rev. Plant Biol.

449

319

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▪ Abstract Collectively, plants contain several different families of natural products among which are compounds with weak estrogenic or antiestrogenic activity toward mammals. These compounds, termed phytoestrogens, include certain isoflavonoids, flavonoids, stilbenes, and lignans. The best-studied dietary phytoestrogens are the soy isoflavones and the flaxseed lignans. Their perceived health beneficial properties extend beyond hormone-dependent breast and prostate cancers and osteoporosis to include cognitive function, cardiovascular disease, immunity and inflammation, and reproduction and fertility. In the future, metabolic engineering of plants could generate novel and exquisitely controlled dietary sources with which to better assess the potential health beneficial effects of phytoestrogens.

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Section: Occurrence and Dietary Sourcesmentioning

confidence: 99%

Phytoestrogens

Dixon

2004

Annu. Rev. Plant Biol.

449

319

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“…Their biosynthesis diverges from the ubiquitous plant flavonoid pathway after the formation of committed flavanone intermediates, namely liquiritigenin or naringenin (Figure 1). The oxidative aryl ring migration and coupled introduction of a 2-OH moiety catalyzed by the cytochrome P450 isoflavone synthase (IFS) (Hashim et al, 1990) together with the subsequent 49-Omethylation of the IFS product, 2-hydroxyisoflavanone, comprise critical catalytic steps at the entry point into the formation of a structurally and functionally diverse group of isoflavonoid phytoalexins, including isoflavans, coumestans, and pterocarpans (Wong, 1975;Dewick, 1993;Dixon, 1999;Aoki et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Structural Basis for Dual Functionality of Isoflavonoid O-Methyltransferases in the Evolution of Plant Defense Responses

et al. 2006

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In leguminous plants such as pea (Pisum sativum), alfalfa (Medicago sativa), barrel medic (Medicago truncatula), and chickpea (Cicer arietinum), 49-O-methylation of isoflavonoid natural products occurs early in the biosynthesis of defense chemicals known as phytoalexins. However, among these four species, only pea catalyzes 3-O-methylation that converts the pterocarpanoid isoflavonoid 6a-hydroxymaackiain to pisatin. In pea, pisatin is important for chemical resistance to the pathogenic fungus Nectria hematococca. While barrel medic does not biosynthesize 6a-hydroxymaackiain, when cell suspension cultures are fed 6a-hydroxymaackiain, they accumulate pisatin. In vitro, hydroxyisoflavanone 49-O-methyltransferase (HI49OMT) from barrel medic exhibits nearly identical steady state kinetic parameters for the 49-O-methylation of the isoflavonoid intermediate 2,7,49-trihydroxyisoflavanone and for the 3-O-methylation of the 6a-hydroxymaackiain isoflavonoid-derived pterocarpanoid intermediate found in pea. Protein x-ray crystal structures of HI49OMT substrate complexes revealed identically bound conformations for the 2S,3R-stereoisomer of 2,7,49-trihydroxyisoflavanone and the 6aR,11aR-stereoisomer of 6a-hydroxymaackiain. These results suggest how similar conformations intrinsic to seemingly distinct chemical substrates allowed leguminous plants to use homologous enzymes for two different biosynthetic reactions. The three-dimensional similarity of natural small molecules represents one explanation for how plants may rapidly recruit enzymes for new biosynthetic reactions in response to changing physiological and ecological pressures.

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“…They are ubiquitous in fruits, vegetables, and beverages, with more than 4,000 chemically different flavonoids identified to date. They are assigned to different groups according on their structure: anthocyanins, flavonols, flavones, catechins, isoflavones, and flavonones (1,8,38,43). Owing to their ubiquity in plants, humans are constantly exposed to a wide variety of flavonoids.…”

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confidence: 99%

The splanchnic metabolism of flavonoids highly differed according to the nature of the compound

Crespy

Morand

Besson

et al. 2003

American Journal of Physiology-Gastrointestinal and Liver Physi

118

101

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Crespy, Vanessa, Christine Morand, Catherine Besson, Nicole Cotelle, Hervé Vé zin, Christian Demigné , and Christian Ré mé sy. The splanchnic metabolism of flavonoids highly differed according to the nature of the compound. Am J Physiol Gastrointest Liver Physiol 284: G980-G988, 2003; 10.1152/ajpgi.00223.2002.-The absorption and splanchnic metabolism of different flavonoids (namely quercetin, kaempferol, luteolin, eriodictyol, genistein, and catechin) were investigated in rats after an in situ perfusion of jejunum plus ileum (14 nmol/min). Net transfer across the brush border ranged widely according to the perfused compound (from 78% for kaempferol to 35% for catechin). This variation seems linked to the lipophilicity of a given flavonoid rather than to its three-dimensional structure. Except for catechin, conjugated forms of perfused flavonoids were also detected in the intestinal lumen, but the extent of this secretion depended on the nature of the perfused compounds (52% for quercetin to 11% for genistein). For some of the perfused aglycones, biliary secretion was an important excretion route: 30% of the perfused dose for genistein but only 1% for catechin. Thus the splanchnic metabolism of flavonoid is controlled by several factors: 1) the efficiency of their transfer through the brush border, 2) the intensity of the intestinal secretion of conjugates toward the mucosal and serosal sides, respectively, and 3) the biliary secretion of conjugates. These data suggested that the splanchnic metabolism of perfused flavonoids depends on the nature of the compound considered, which in turn influences their availability for peripheral tissues. absorption; biliary excretion; rats FLAVONOIDS are phenolic secondary plant metabolites responsible for much of the color and flavor of plant foods. They are ubiquitous in fruits, vegetables, and beverages, with more than 4,000 chemically different flavonoids identified to date. They are assigned to different groups according on their structure: anthocyanins, flavonols, flavones, catechins, isoflavones, and flavonones (1,8,38,43). Owing to their ubiquity in plants, humans are constantly exposed to a wide variety of flavonoids. A wealth of beneficial properties has been reported: antibacterial, antioxidant, anti-inflammatory, and anticarcinogenic effects (2, 21, 29) and estrogenic effects for isoflavones (33). Understanding the absorption and metabolism of dietary flavonoids is fundamental to determining their potential biological activity.The small intestine is a crucial site for the absorption of dietary flavonoids. In this tissue, aglycones are metabolized by intestinal conjugation enzymes, and the resulting metabolites are then secreted toward the mucosal and/or serosal sides (5, 6, 10, 13, 37). Circulating forms of absorbed flavonoids have been identified as methylated and/or glucuronidated and/or sulfated metabolites (9,12,19,23,39), resulting from the conjugative activities of both liver and intestine (7). Flavonoid metabolites are then eliminated in urine and by the bili...

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Isoflavonoids

Cited by 41 publications

References 228 publications

Phytoestrogens

Phytoestrogens

Structural Basis for Dual Functionality of Isoflavonoid O-Methyltransferases in the Evolution of Plant Defense Responses

The splanchnic metabolism of flavonoids highly differed according to the nature of the compound

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