4’-hydroxy-3-methoxyflavones

In the area of medicinal chemistry, Haemers and coworkers synthesized a series of 4 -hydroxy-3-methoxyflavones that exhibited antiviral activity against poliomyelitis and rhinoviruses. A representative number of compounds is shown below. First, O-hydroxyacetophenones 61 were converted to the corresponding flavones 64 using standard conditions in yields of 74-92%. Cleavage of the benzyloxy groups of 64 was then achieved under acidic conditions to deliver the requisite flavones 65. 

De Meyer, N., Haemers, A., Mishra, L., Pandey, I.A.C., Pieters, D.A.V., Berghe, A.J., Viletinck, A.J. 1991.4 -Hydroxy-3-methoxyflavones with potent antipicomavirus activity. Journal of Medicinal Chemistry 34 736-746. 

Seshradi and coworkers showed that potassium carbonate was an effective base in the K-R reaction for the conversion of resacetophenone (37) to 7-hydroxyflavone 39a and 7-hydroxy-4 -methoxyflavone 39b in 57% and 46% yield, respectively. In addition, the reaction proceeded at a significantly lower temperature than the traditional K-R reaction by conducting the reaction in refluxing acetone. 

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. ... 

Horie, T. et al., Studies of the selective O-alkylation and dealkylation of flavonoids. XIV. A convenient method for synthesizing 5,6,7,8-trihydroxy-3-methoxyflavones from 6-hydroxy-3,5, 7-trimethoxyflavones, Bull. Chem. Soc. Jpn, 66, 877, 1993. 

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... 

The most important group of compounds for our purposes, the flavonoids, are shown with coumarins in Table VII. The flavonoid agly-cones precipitated nearly quantitatively except for fisetin, myricetin, and tectochrysin. Tectochrysin, 5-hydroxy-7-methoxyflavone, still preceipi-tated to 51% without phloroglucinol even though two of the three... 

Luteolin 7-3-neohesperldoslde (5,7,3, 4 -tetrahydroxyflavone) Natsudaldain (3-hydroxy-5,6,7,8,3, 4 -hexamethoxyflavone) Neodlosmln (5,7,3 -trlhydroxy-4 -methoxyflavone 7-3-neohesperldoslde)... 

Fortunellin (= 5-Hydroxy-7-glucosyl-rhamnosyl-4 -methoxyflavone) (glycosylated flavone) See Acacetin HIV-1 protease (< 84 pM) [42]... 

Voirin (1983) reported a complete study of the UV spectra of 151 flavonoids in methanol alone and with added AICI3 and AICI3/HCI for the differentiation of 5-hydroxy- and 5-hydroxy-3-methoxyflavones with mono-(4 )-, di-(3, 4 )-, or tri-(3, 4, 5 )-substituted B rings, and he... 

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. 

EGTA, ethyleneglycol bis(2-aminoethyl ether)-A/,A/,W, W -tetraacetic acid DTNB, 5,5 -dithiobis-(2-nitrobenzoic acid) MTB, Methyl-thymol Blue PT, pyridoxal thiosemicarbazone DGT, dipyridylglyoxal dithiocarbazone HMF, 3-hydroxy-7-methoxyflavone TCSP, 5,10,15,20-tetrakis-(3-chloro-4-sulfophenyl)porphine BSD, relative standard deviation PAR 4- 2 -pyridylazo)resorcinol DCTA, 1,2-diaminocyclohexane-N,N,N, N tetraacetic acid. 

Hydroxy-5-methoxyflavone, in D-20116 3-Hydroxy-7-methoxyflavone, in D-20117 5-Hydroxy-3-methoxyflavone, in D-20116... 

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