Dihydroxy-methoxyflavone

Huen MS, Leung JW, Ng W, et al. Dihydroxy-6-methoxyflavone, a benzodiazepine site ligand isolated from Scutellaria baicalensis Georgi, with selective antagonistic properties. Biochem Pharmacol 2003 66 125-127. 

Dihydroxyflavone geraldone (7,4 -dihydroxy-3 -methoxyflavone) 4 -hydroxy-7-methoxyflavone... 

Flavonoids, especially flavones and flavonols, also directly bind to several CYP isoforms (lAl, 1A2, IBl, 3A4) involved in xenobiotics metabolism and inhibit enzyme activity. Structure-activity relationships show rather high isoform selectivities depending on the flavonoid substitution pattern and contrasted inhibition mechanisms. For instance, inhibition by flavonoids of 7-methoxyresorufin O-demethylation in microsomes enriched in CYP lAl and 1A2 reveals that galangin (3,5,7-trihydroxyflavone) is a mixed inhibitor of CYP 1A2 (.ST = 8 nM) and a five times less potent inhibitor of CYP 1A1. By contrast, 7-hydroxy flavone is a competitive inhibitor of CYP lAl (Aii = 15 nM) and a six times less potent inhibitor of CYP 1A2. In addition, fairly selective inhibition of CYP IBl (specifically detected in cancer cells) by some flavonoids has been reported. For example, 5,7-dihydroxy-4 -methoxyflavone inhibits IBl, 1 Al, and 1A2 with IC50 values of 7, 80, and 80 nM, respectively. ... 

Guha, P.K. and Bhattacharyya, A., 5,8-Dihydroxy-7-methoxyflavone from the immature leaves of Didymocarpus pedicellata. Phytochemistry, 31, 1833, 1992. 

Sahu, N.P., Achari, B., and Banerjee, S., 7,3 -Dihydroxy-4 -methoxyflavone from seeds of Acacia farnesiana. Phytochemistry, 49, 1425, 1998. 

Dihydroxy-8-methoxyflavone 7-Rhamnoside Butea superba stems Leguminosae 166... 

C-Methylated flavonol glycosides 5,7-Dihydroxy-6,8-di-C-methyl-3-methoxyflavone 7-Galactosyl(l —> 2)rhamnoside Cotula anthemoides seeds 478... 

Some improvement in the often moderate yields associated with the Kostanecki-Robinson synthesis has been achieved by substitution of a catalytic amount of triethylamine for the stoichiometric quantity of sodium carboxylate (44CB202). It is also possible to work at somewhat lower temperatures using this technique, an obvious advantage when sensitive groups are present. The modification is particularly attractive in the synthesis of complex hydroxyflavones (77T1405, 1411). A further development, the use of a tertiary amine as a solvent, has been advocated (78JOC2344). For instance, in the synthesis of 5,7-dihydroxy-3-methoxyflavone (galangin 3-methyl ether) (447) from w-methoxyphloracetophenone, the... 

Dlosmin (5,7,3 -trihydroxy-4 -methoxyflavone 7-3-rutinoside) Fortunellin (5,7-dihydroxy-4 -methoxyflavone 7-3-neohesperido-slde)... 

Acacetin (= 5,7-Dihydroxy-4 -methoxyflavone) Anuni visnaga (Apiaceae), Ginkgo biloba (Ginkgoaceae), HIV-1 protease (> 176 pM) [42]... 

CHADENSON, M HAUTEVILLE, M CHOPIN, J., Synthesis of 2,5-dihydroxy-7-methoxyflavone, cyclic structure of the benzoyl (2,6-dihydroxy-4-methoxybenzoyl)-methane from Populus nigra buds. J. Chem. Soc., Chem. Common., 1972, 107-108. 

Hydroxylation at C-6 produces a larger bathochromic shift than hydroxylation at C-8. Moreover, the ratio of absorbance band I/absor-bance band II constitutes a criterion for distinguishing the substituted position on the Aring. Thus, 8-substitution particularly decreases this value whereas 6-substitution increasesit (Barberan et ah, 1985). Useful information to differentiate among 5,6- and 5,8-dihydroxyflavones, 3-methoxyflavones and flavonols trisubstituted on the Aring, as well as 5,6-dihydroxy-7,8-dimethoxy- and 5,8-dihydroxy-6,7-dimethoxy-flavones can be gained by comparison of their UV spectra in methanol (Barberan et ah, 1985). 

Three flavonoids, 5,7-dihydroxy-4 -methoxyflavone, 3,5,7-trihydroxy-4 -methoxyflavone and 3,5,7-trihydroxy-3 -methoxyflavone, were isolated in a bioguided study from the dichloromethane extract of Baccharis leptophylla [209]. Data on the activity of these compounds against Candida albicans. Trichophyton mentagrophytes. Trichophyton rubrum and Microsporum canum is reported. From another Baccharis species, Baccharis peduculata (Mill.) Cabrera., a flavone ether was isolated as an antifungal principle [223]. 

The antimicrobial polymethylated flavones, 5-hydroxy-3,6,7,8,4 -pentamethoxyflavone, 5-hydroxy-3,6,7,8-tetramethoxyflavone and 5,6-dihydroxy-3,7-dimethoxyflavone, have been isolated from Gnaphalium affine D Don. [229,230], These flavonoids showed antimicrobial activity against Spodoptera litura. Structure-activity studies suggested the importance of the 6-position substitution of the flavonoid however, hydrophilic substituents decreased the activity. The flavonoid 8-0-(2-methyl-2-butenoyl)-5,7-dihydroxy-3-methoxyflavone isolated from Gnaphalium robustum L. also inhibited the growth of Escherichia coli [231]. 

Pisutthanan et al. (27) isolated six flavonoids out of which three were reported in this plant for the first time. They include 3,5,4 -trihydroxy-7-methoxyflavanone 5,7,3 -trihydroxy-5 -methoxyflavanone and 3,5,7-trihydroxy-4 -methoxyflavanone. Ling et al. (28) also isolated a total of eleven flavonoids from the leaf extract and identified them as eriodictyol 7,4 -dimethyl ether, quercetin 7,4 -dimethyl ether, naringenin 4 -methyl ether, kaempferol 4 -methyl ether, kaempferol 3-0-mtinoside, taxifolin 4 -methyl ether, taxifolin 7-methyl ether and quercetin 4 -methyl ether. Suksamram et al. (23) isolated the flavanones, isosakuranetin (5,7-dihydroxy-4 -methoxyflavanone), persicogenin (5,3 -dihydroxy-7,4 -dimethoxyflavanone), 5,6,7,4 -tetramethoxyflavanone and 4 -hydroxy-5,6,7-trimethoxyflavanone, the chalcones, 2 -hydroxy-4,4, 5, 6 -tetramethoxychalcone and 4,2 -dihydroxy-4, 5, 6 -trimethoxychalcone, and the flavones, acacetin (5,7-dihydroxy-4 -methoxyflavone) and luteolin (5,7,3, 4 -tetrahydroxyflavone) from the flowers. 

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