Flavone, 3’,4’,5,7-Tetrahydroxy

Figure 2 Structures of flavonoids present in root exudates of host plants and inducing nod gene expression in rhizobia (1) as 3,5,7,3 -tetrahydroxy-4 -methoxyflavanone, inducer in Rhizohium legiiminosarum bv. viciae (2) as 3, 4, 5, 7-tetrahydroxy-flavone, inducer in Rhizohium melilotr, (3) as 4, 7-dihydroxyisoflavone, inducer in Bradyrhizohium japonicum (4) as couinestrol, intermediate in phenylpropane metabolism, weak inducer. (From Ref. 64.)...

Xanthium chinense Mill. X. japonicum Widder X. mongolicum Kitag. X. sibiricum Patr. ex Widd. X. strumarium L. Cang Er (Cocklebur) (fruit) Xanthinin, xanthumin, xanthanol, isoxanthanol, strumaroside, tetrahydroxy flavone, caffeic acid, dicaffeoxylquinic acid.33-48 Antibacterial, antitussive, respiratory stimulating effect, lower blood pressure and blood sugar levels. 

Rhamnetin (3,3 -4, 5-tetrahydroxy-7-methoxy flavone, 7-methyl quercitin) [90-19-7] M 316.3, m >300"(dec), several phenolic pKs -7-10.5. Crystd from EtOH. 

The basic structures of flavanones, flavones, and isoflavones together with coumestrol, an intermediate in the phenylpropane metabolism, are given in Fig. 2. The 3,5,7,3 -tetrahydroxy-4 -methoxyflavanone is a nod gene inducer in Rhizo-bium leguminosarum bv. viciae the 3, 4, 5,7-tetrahydroxyflavone, in Rhizobium ineliloti and 4,7-dihydroxyisoflavone, in Bradyrhizobium japonicum. Coumestrol, an intermediate in phenylpropane metabolism, is only a weak inducer (7). 

Prenyl- and pyranoflavonol glycosides 8-Prenylkaempferol[noranhydroicaritin, 3,5,7,4 -tetrahydroxy-8-(3",3"-dimethylallyl)flavone] 3,7-Diglucoside Vancouveria hexandra Berberidaceae 466... 

There are three new isomers of pentose-hexose disaccharides in Table 13.4. These include a-L-arabinopyranosyl(l 3)galactose found in combination with 3,5,7,4 -tetrahydroxy-6,8,3 -flavone at the 3-hydroxyl in the heartwood of the legume, Pongamia pinnata Lathyrose, xylosyl(l 6)galactose was found in a member of the Anacardiaceae, Semecarpus kurzii, at the 7-hydroxyl of scutellarein (6-hydroxyapigenin). The third new isomer in this... 

Seven new aglycones support the C-glycosidic bond in this class 5,7-dihydroxyflavone (chrysin) in Scutellaria5-hydroxy 7-methoxyflavone (tectochrysin) in Piper 5,7,2, 4, 5 -pentahydroxyflavone (isoetin) in Hordeum, 5,7,2, 3, 5, 6 -hexahydroxy-flavone in Polygala 3,5,7,4 -tetrahydroxy 3, 5 -dimethoxyflavone (myricitrin) in... 

Kaempferol glycoside (3,5,7,4 -tetrahydroxyflavone glycoside) Limocitrin 3-3-D-glucoslde (3,5,7,4 -tetrahydroxy-8,3 -dimethoxy-flavone 3-3-D glucoside)... 

Lens aldose reductase has been implicated in the pathogenesis of cataracts in diabetic and galac-tosemic animals. The enzyme catalyzes the reduction of glucose and galactose to their polyols, which accumulate in large quantities in the lens and ultimately lead to mature lens opacities. Several key bioflavones have activity against this enzyme. Oral administration of quercitrin decreased the accumulation of sobital in the lens. Therefore, the accumulation of lens opacities could be partially abrogated by certain flavonoids. In a study of 30 flavones, 4 isoflavones, and 13 coumarins, many potent inhibitors were found, but 5,7,3, 4 -tetrahydroxy-3,6-dimethoxyflavone and 6,3, 4 -trihy-droxy-5,7,8-trimethoxyflavone were especially active. 

The main flavonoid skeleton derives from the stepwise condensation of three molecules of malonyl CoA with one molecule of 4-coumaroyl CoA, a reaction catalyzed by chalcone synthase (CHS) to form naringenin (2, 4,4 ,6,-tetrahydroxy) chalcone, the common intermediate in the formation of all flavonoids with 5,7-dihydroxy (flavone numbering) A-ring substitution. In some plants, however, an NADP-dependent chalcone-ketide reductase coacts with CHS to form 6 -deoxychalcone, the precursor of 5-deoxyflavonoids. The resulting chalcones undergoe a stereospecific cyclization to the corresponding (2S) flavanones, the... 

Some bioactive flavones include aldose reductase inhibitors (apigenin 4 -methyl ether (acacetin), apigenin 7-0-apioside (apiin), 5,7-dihydroxyflavone (chrysin) and luteolin) antiinflammatory 5-LOX inhibitors (5,6,7-trihydroxyflavone (baicalein), 5,6,3, 4 -tetrahydroxy 7-methoxyflavone (pedalitin), 5,3, 4 -trihydroxy 6,7-dimethoxyflavone (cirsiliol, 6-0-methylpedalitin) and flavone) a COX inhibitor (flavone) iodothyronine deiodinase inhibitors (acacetin, chrysin and luteolin) a NADH and succinate dehydrogenase inhibitor (luteolin) millet-derived, goitrogenic inhibitors of thyroid peroxidase (flavone C-glycosides orientin and vitexin) and protein kinase inhibitors (acacetin, apigenin, baicalein, flavone, luteolin, 5,7,3, 4, 5 -pentahydroxyflavone (tricetin) and tricetin 3, 4, 5 -trimethyl ether). 

Swertifrancheside (= 1,5,8-Trihydroxy-3-methoxy-7-(5, 7, 3", 4"-tetrahydroxy-6 -C-(3-D-glucopyranosyl-4 -oxy-8 -flavyl )-xanthone) Flavone-xanthone C-glycoside)... 

Tetrahydroxy-8, 3 -dimethoxyflavone] (flavone) Semi-synthetic AR (bovine lens) (3), AR (rat lens) (1)... 

Since ancient times, the roots of Scutellaria baicalensis have been used to treat allergic and inflammatory diseases in China and Japan. We reported the isolation from these roots of three new compounds, i.e., 2 S), 2, 5,6, 7-tetetahydroxy flavanone[25], 2 R), 3(i )-2, 3,5,6, 7-pentahydroxyflavanone and 2, 5,5, 7-tetrahydroxy-6, 8-dimethoxy-flavone, as antibacterial or anti-lipid peroxidation substances [26, 27], as well as six flavonoids, i.e., baicalein, bailcalin, oroxylin A, wogonin, skullcapflavone II, etc. Furthermore, we found that baicalein and baicalin "Fig. (47)" suppressed the development of secondary lesions in adjuvant-induced arthritis in rats "Fig. (48)". 

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