3'-Hydroxyflavone

Preference for O-demethylation reactions in the oxidation of 2'-, 3'-, and 4'-methoxyflavones by human cytochrome P450 enzymes.[Pubmed:32312164]

Xenobiotica. 2020 Oct;50(10):1158-1169.

2'-, 3'-, and 4'-Methoxyflavones (MeFs) were incubated with nine forms of recombinant human cytochrome P450 (P450 or CYP) enzymes in the presence of an NADPH-generating system and the products formed were analyzed with LC-MS/MS methods.CYP1B1.1 and 1B1.3 were highly active in demethylating 4'MeF to form 4'-hydroxyflavone (rate of 5.0 nmol/min/nmol P450) and further to 3',4'-dihydroxyflavone (rates of 2.1 and 0.66 nmol/min/nmol P450, respectively). 3'MeF was found to be oxidized by P450s to m/z 239 (M-14) products (presumably 3'-hydroxyflavone) and then to 3',4'-dihydroxyflavone. P450s also catalyzed oxidation of 2'MeF to m/z 239 (M-14) and m/z 255 (M-14, M-14 + 16) products, presumably mono- and di-hydroxylated products, respectively.At least two types of ring oxidation products having m/z 269 fragments were formed, although at slower rates than the formation of mono- and di-hydroxylated products, on incubation of these MeFs with P450s; one type was products oxidized at the C-ring, having m/z 121 fragments, and the other one was the products oxidized at the A-ring (having m/z 137 fragments).Molecular docking analysis indicated the preference of interaction of O-methoxy moiety of methoxyflavones in the active site of CYP1A2.These results suggest that 2'-, 3'-, and 4'-methoxyflavones are principally demethylated by human P450s to form mono- and di-hydroxyflavones and that direct oxidation occurs in these MeFs to form mono-hydroxylated products, oxidized at the A- or B-ring of MeF.

Biotransformations of Flavones and an Isoflavone (Daidzein) in Cultures of Entomopathogenic Filamentous Fungi.[Pubmed:29874813]

Molecules. 2018 Jun 5;23(6). pii: molecules23061356.

Entomopathogenic filamentous fungi of the genus Isaria are effective biocatalysts in the biotransformation of flavonoids as well as steroids. In the present study, the species Isariafumosorosea and Isariafarinosa isolated from the environment were used. Their catalytic capacity to carry out biotransformations of flavones-unsubstituted, with hydroxy- and amino-substituents as well as a hydroxylated isoflavone-was investigated. Biotransformations of flavone, 5-hydroxyflavone, 6-hydroxyflavone, 7-hydroxyflavone, and daidzein resulted in the formation of O-methylglucosides, in the case of flavone and 5-hydroxyflavone with additional hydroxylations. 7-Aminoflavone was transformed into two acetamido derivatives. The following products were obtained: From flavone(-)flavone 2'-O-beta-d-(4''-O-methyl)-glucopyranoside, flavone 4'-O-beta-d-(4''-O-methyl)-glucopyranoside and 3'-hydroxyflavone 4'-O-beta-d-(4''-O-methyl)-glucopyranoside; from 5-hydroxyflavone(-)5-hydroxyflavone 4'-O-beta-d-(4''-O-methyl)-glucopyranoside; from 6-hydroxyflavone(-)flavone 6-O-beta-d-(4''-O-methyl)-glucopyranoside; from 7-hydroxyflavone(-)flavone 7-O-beta-d-(4''-O-methyl)-glucopyranoside; from daidzein(-)daidzein 7-O-beta-d-(4''-O-methyl)-glucopyranoside; and from 7-aminoflavone(-)7-acetamidoflavone and 7-acetamido-4'-hydroxyflavone. Seven of the products obtained by us have not been previously reported in the literature.

Two new 5-deoxyflavonoids from Calliandra inermis.[Pubmed:15304993]

Chem Pharm Bull (Tokyo). 2004 Aug;52(8):974-5.

Two new 5-deoxyflavonoids, 7,2',3',4'-tetramethoxyflavone (1) and 7,2',3',4'-tetramethoxyflavanone (2) together with a known flavone 7,4'-dimethoxy-3'-hydroxyflavone (3) were isolated from the whole plant of Calliandra inermis. The structures of these new compounds were elucidated by high resolution electron impact mass spectrometry (HR-EI-MS) and 1D and 2D-NMR spectral studies including 1H-1H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser enhancement spectroscopy (NOESY).

Two new 5-deoxyflavones from Albizia odoratissima.[Pubmed:12237551]

Chem Pharm Bull (Tokyo). 2002 Sep;50(9):1271-2.

Two new 5-deoxyflavones, 7,8-dimethoxy-3',4'-methylenedioxyflavone (1) and 7,2',4'-trimethoxyflavone (2) together with a known flavone, 7,4'-dimethoxy-3'-hydroxyflavone (3) were isolated from the rootbark of Albizia odoratissima. The structures of these new compounds were elucidated by electrospray ionization mass spectrometry (ESI-MS) and 1D and 2D-NMR spectral studies including (1)H-(1)H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser enhancement spectroscopy (NOESY).

Anti-inflammatory activity of flavone and some of its derivates from Virola michelli Heckel.[Pubmed:10197753]

J Ethnopharmacol. 1999 Feb;64(2):173-7.

The phytochemical study using Virola michelli Heckel (Myristicaceae) leaves allowed the isolation of a flavone named titonine (7,4'-dimethoxy-3'-hydroxyflavone). Titonine was further submitted to methylation and acetylation reactions yielding a 7,3',4'-trimethoxyflavone and a 7,3'-dimethoxy-4'-acetylflavone, respectively. These compounds were evaluated for both anti-inflammatory and analgesic activity. The anti-inflammatory activity was evaluated in rats using the paw edema test with carrageenin, while the analgesic activity was determined in mouse using the writhing test method. The different animal groups were treated with three compounds (10 mg/kg -i.p.) thirty min prior to stimuli application. The inhibition levels obtained for each compound were 22, 41 and 68%, respectively. Using the writhing test, oral doses of 5, 10 and 15 mg/kg of natural flavone reduced the acetic acid-induced contortions in a dose-dependent manner.