Microbial Metabolism Part 9. Structure and Antioxidant Significance of the Metabolites of 5,7-Dihydroxyflavone (Chrysin), and 5- and 6-Hydroxyflavones

Herath, Wimal; Mikell, Julie Rakel; Hale, Amber L.; Ferreira, Daneel; Khan, Ikhlas A.

doi:10.1248/cpb.56.418

Cited by 22 publications

(19 citation statements)

References 27 publications

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“…They were in total agreement with those of the flavanoid glycosides obtained during microbial transformation studies carried out by us using the same organism, M. ramannianus. 19) HMBC correlations permitted the assignment of the sugar unit at C-4Ј. ) were in close agreement with those of metabolite 13.…”

Section: Resultssupporting

confidence: 73%

Microbial Metabolism. Part 12.

Mikell

Herath

Khan

2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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Flavonoids which constitute an important part of human diet are associated with many beneficial biological activities, 2) though some may exhibit mutagenic and/or prooxidant properties.3) They are known to interact with the cytochrome P450 drug-metabolizing enzymes found in liver and other tissues including skin. The capability of flavonoids to induce biosynthesis of Cytochromes P450 (CYPs) and to modulate their activity could lead to loss of biological activity of a drug or to increase its concentration in the plasma resulting in an overdose.3) They may also activate or inhibit CYPs involved in the process of chemical carcinogenesis. It has been observed that Flavonoids with hydroxyl groups tend to inhibit these enzymes, whereas those without seem to stimulate them.4) The CYPs in turn can bring about transformation of flavonoids to metabolites which could interact with them and modify their activities. This underlines the importance of determining the metabolic pathways of flavonoids which are being consumed in measurable amounts by man. There are two major sites of flavonoid metabolism.3) They are the liver and the colon microflora. Several in vivo and in vitro experiments were conducted to identify the mammalian metabolites of different classes of flavonoids. Based on these observations various suggestions were made with regards to their metabolic pathways. The results of one such experiment involving the metabolism of 16 naturally occurring flavonoids by rat liver microsomes suggested that the B-ring was the main structural moiety that was subjected to biotransformation.5) The number and the position of the hydroxyl and methoxy groups in the B-ring seemed to determine the extent of metabolism. The non polar flavonoids were metabolized more extensively than the polar ones. The absence of hydroxyl groups in the B-ring or the presence of one such group at C-4Ј position resulted in 3Ј and 4Ј dihydroxylated (catechol) products. It was suggested that the semiquinones or quinones that could result from the oxidation of catechol may be a source of mutagenic free radicals. However, it has been demonstrated that partial detoxification takes place by O-methylation of the catechol moiety. 5,6) Flavanones, as compared to other flavonoids are less abundant in nature. Propolis, honey, citrus fruits and juices are their main dietary sources. 7) Flavanones are associated with many biological properties. The major constituent of citrus fruits, Naringenin for example was shown by in vitro experiments to have antioxidant, antiproliferative and estrogenic activities.7) Since citrus fruits and juices are consumed by man in considerable amounts, investigations have been carried out to evaluate their metabolic parthways. In a transformation study with six flavanones by rat liver microsomes the major metabolic pathway observed was aromatic hydroxylation. However, several previously unreported metabolic pathways including the reduction of the keto group were also discovered. 7) As many as 43 urinary metabolites of flavanone in the ra...

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Section: Resultssupporting

confidence: 73%

Microbial Metabolism. Part 12.

Mikell

Herath

Khan

2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…They were in total agreement with those of the flavonoid glycosides obtained during microbial transformation studies carried out by us using the same organism, M. ramannianus. 28) HMBC correlations permitted the assignment of the sugar unit at C-7. The structure of the metabolite 18 was determined as 4′-hydroxyflavanone 7-O-α-D-6-deoxyallopyranoside.…”

Section: Resultsmentioning

confidence: 99%

Bioconversion of 7-Hydroxyflavanone: Isolation, Characterization and Bioactivity Evaluation of Twenty-One Phase I and Phase II Microbial Metabolites

Mikell

Khan

2012

CHEMICAL & PHARMACEUTICAL BULLETIN

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Microbial metabolism of 7-hydroxyflavanone (1) with fungal culture Cunninghamella blakesleeana (ATCC 8688a), yielded flavanone 7-sulfate (2), 7,4′-dihydroxyflavanone (3), 6,7-dihydroxyflavanone (4), 6-hydroxyflavanone 7-sulfate (5), and 7-hydroxyflavanone 6-sulfate (6). Mortierella zonata (ATCC 13309) also transformed 1 to metabolites 2 and 3 as well as 4′-hydroxyflavanone 7-sulfate (7), flavan-4-cis-ol 7-sulfate (

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“…The acetylated thiazolidine derivative of the hydrolysis product of 5 and of authentic L-rhamnose displayed the same GC–MS retention time (15.64 min) (Shukla et al, 2009). The chemical shift of the anomeric carbon [ δ C 98.4 (C-1‴)] suggested an α- O -glycosidic linkage (Herath et al, 2008; Ibrahim et al, 2008), establishing 5 as 6″,7″-dihydroxycannflavin A 4′- O -α-L-rhamnopyranoside.…”

Section: Resultsmentioning

confidence: 99%

“…NMR spectroscopic data ( 13 C, DEPT-135 and HMQC) confirmed the presence of the methylated glycoside moiety via an anomeric ( δ C 100.1), two hydroxymethine ( δ C 73.6, 76.4), one methoxymethine ( δ C 79.0), one oxygenated methine ( δ C 76.4), one hydroxymethylene ( δ C 60.2) and one O -methyl ( δ C 59.5) carbon resonance, in addition to the resonances for the cannflavin B structure. The anomeric proton coupling constant ( J = 7.6 Hz) indicated β- O -glycosidic linkage, while HMBC correlation (H-1‴/C-7) revealed the location at C-7 (Herath et al, 2008, 2006; Ibrahim et al, 2008). Consequently, 6 was identified as cannflavin B 7- O -β-D-4‴- O -methylglucopyranoside.…”

Section: Resultsmentioning

confidence: 99%

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Microbial metabolism of cannflavin A and B isolated from Cannabis sativa

et al. 2010

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Microbial metabolism of cannflavin A (1) and B (2), two biologically active flavonoids isolated from Cannabis sativa L., produced five metabolites (3–7). Incubation of 1 and 2 with Mucor ramannianus (ATCC 9628) and Beauveria bassiana (ATCC 13144), respectively, yielded 6″S,7″-dihydroxycannflavin A (3), 6″S,7″-dihydroxycannflavin A 7-sulfate (4) and 6″S,7″-dihydroxycannflavin A 4′-O-α-L-rhamnopyranoside (5), and cannflavin B 7-O-β-D-4‴-O-methylglucopyranoside (6) and cannflavin B 7-sulfate (7), respectively. All compounds were evaluated for antimicrobial and antiprotozoal activity.

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Microbial Metabolism Part 9. Structure and Antioxidant Significance of the Metabolites of 5,7-Dihydroxyflavone (Chrysin), and 5- and 6-Hydroxyflavones

Cited by 22 publications

References 27 publications

Microbial Metabolism. Part 12.

Microbial Metabolism. Part 12.

Bioconversion of 7-Hydroxyflavanone: Isolation, Characterization and Bioactivity Evaluation of Twenty-One Phase I and Phase II Microbial Metabolites

Microbial metabolism of cannflavin A and B isolated from Cannabis sativa

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