- Microbial metabolism part 9.1 Structure and antioxidant significance of the metabolites of 5,7-dihydroxyflavone (chrysin), and 5- and 6-hydroxyflavones
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5,7-Dihydroxyflavone (chrysin) (1) when fermented with fungal cultures, Aspergillus alliaceous (ATCC 10060), Beauveria bassiana (ATCC 13144) and Absidia glauco (ATCC 22752) gave mainly 4′-hydroxychrysin (4), chrysin 7-O-β-D-4-O-methylglucopyranoside (5) and chrysin 7-sulfate (6), respectively. Mucore ramannianus (ATCC 9628), however, transformed chrysin into six metabolites: 4′-hydroxy-3′-methoxychrysin (chrysoeriol) (7), 4′-hydroxychrysin (apigenin) (4) 3′,4′-dihydroxychrysin (luteolin) (8), 3′-methoxychrysin 4′-O-α-D-6- deoxyallopyranoside (9), chrysin 4′-O-α-D-6-deoxyallopyranoside (10), and luteolin 3′-sulfate (11). Cultures of A. alliaceous (ATCC 10060) and B. bassiana (ATCC 13144) metabolized 5-hydroxyflavone (2) into 5,4′-dihydroxyflavone (12) and 4′-hydroxyflavone 5-O-β-D-4-O-methylglucopyranoside (13), respectively. 6-Hydroxyflavone (3) was transformed into 6-hydroxyflavanone (14), flavone 3-O-β-D-4-O- methylglucopyranoside (15) and (±)-flavanone 6-O-β-D-4-O- methylglucopyranoside (16) by cultures of Beauveria bassiana (ATCC 13144). The structures of the metabolic products were elucidated by means of spectroscopic data. The significance of the metabolites as antioxidants in relation to their structure is briefly discussed.
- Herath, Wimal,Mikell, Julie Rakel,Hale, Amber Lynn,Ferreira, Daneel,Khan, Ikhlas Ahmad
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experimental part
p. 418 - 422
(2009/04/11)
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- Isolation, antihypertensive activity and structure activity relationship of flavonoids from three medicinal plants
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Eight flavonoids, namely naringenin 1, 3-β-hydroxynaringenin designated as isoaromadendrin 2, taxifolin 3, isoaromadendrin-7-O-β-D- glucopyranoside designated as isosinensin 4 have been isolated from Euphorbia cuneata Vahl; 5-hydroxy-3, 4′, 7-trimethoxyflavone 5, 5-hydroxy-3, 3′, 4′, 7-tetramethoxyflavone (retusin) 6, 4′, 5-dihydroxyflavone-5-O-β-D-glucopyranoside named as verbenacoside 7 are obtained from Salvia verbenaca L; and epicatchin 8 is isolated from Osyris abyssinica. Their structures have been established by spectral and chemical methods, whereupon the compounds 2, 4 and 7 are found to be new flavonoids. Compounds 1-5, 7, 8 and alcoholic extract of Salvia verbenaca have also been screened biologically for antihypertensive activity in normotensive albino rats, which showed a varied degree in the decrease of blood pressure and heart rate. The flavonoids 2, 3 and 5 are found most potent exhibiting the decrease in blood pressure 36.5, 20.0 and 30.0 (mmHg) respectively in comparison to normal values. Other compounds also exhibit a good activity. The structure activity relationship (SAR) has also been discussed.
- Ahmed, Bahar,Al-Howiriny, Tawfeq A.,Mossa, Jaber S.,Tahir
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p. 400 - 404
(2007/10/03)
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- A one-step synthesis of 5-hydroxyflavones
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5-hydroxy flavones were prepared in one step starting from 2,6- dihydroxyacetophenone. The latter was treated with an aroyl chloride in the presence of an excess of potassium carbonate to afford 5-hydroxyflavones.
- Bois, Frédéric,Beney, Chantal,Mariotte, Anne-Marie,Boumendjel, Ahcène
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p. 1480 - 1482
(2007/10/03)
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- Synthesis of Flavones via Application of the Nitrile Oxide and the Stille Reactions
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Hydroxylated and methoxylated benzaldehyde oximes have been chlorinated, dehydrohalogenated and cycloadded to tributylstannylacetylene to give 3-aryl-5-tributylstannylisoxazoles in good to excellent yields.The palladium-catalyzed coupling reaction, the so-called Stille reaction, of hindered and electron-rich 2-iodophenols and a 2-iodo-1,4-benzoquinone with 3-aryl-5-tributylstannyl-isoxazoles gave 3-aryl-5-(2-hydroxyaryl)isoxazoles in moderate to excellent yields.The coupling reaction was studied under various conditions and with various Pd(II) and Pd(0) complexes.Reduction of the 3,5-diarylisoxazoles with H2/Raney-Ni, hydrolysis and acid-catalyzed cyclisation gave flavones.The synthesis of 2-iodo-3,5-dimethoxy-1,4-benzoquinone is described.
- Gothelf, Kurt V.,Torssell, Kurt B. G.
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- A Short and Facile Synthetic Route to Hydroxylated Flavones. New Syntheses of Apigenin, Tricin, and Luteolin
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Reaction of lithium polyanions generated from o-hydroxyacetophenones 3a-f with O-silyloxylated benzoates 2a-d gave 1-aryl-3-(2-hydroxyphenyl)-1,3-propanediones 4a-n, which on treatment with acetic acid containing 0.5percent H2SO4 at 95 - 100 deg C afforded hydroxylated flavones 5-18 in high yields (76 - 92percent).
- Nagarathnam, Dhanapalan,Cushman, Mark
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p. 4884 - 4887
(2007/10/02)
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- Synthesis of (+/-)-Fistacacidin
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Synthesis of fistacacidin and (+/-)-2,3-trans-5,4'-dimethoxyflavan-3-ol (XVII) are reported.Synthesis of XII, starting from monobenzyl ether of 2,6-dihydroxyacetophenone (I) involves the reacti
- Patil, A. D.,Deshpande, V. H.
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p. 109 - 113
(2007/10/02)
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