3,4 ,7-Trihydroxyflavone

Trihydroxyflavone-7-0-glucoside Luteolin-7-O-glucoside Seed exudate Medicago saliva S. meliloli... 

Trihydroxyflavone Naringenin Root exudate Phaseohts vulgare R. legiiminosarum and R. elli... 

V. Synthesis of 5,7,4 -Trihydroxyflavone by v. Kostanecki and the Establishment of Its Identity with Natural Apigenin. 62... 

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. ... 

Eventually, flavonoids can be hydroxylated or demethylated by CYPs. For instance, hesperetin (4 -methoxy-3, 5,7-trihydroxyflavanone) is specifically demethylated by CYPs lAl and IBl, but not by CYPs 1A2 and 3A4. In addition, 3,5,7-trihydroxyflavone undergoes sequential CYP lAl-catalyzed hydroxylation at C4 and C3 to finally yield querce-tin. These reactions may be relevant to flavonoid metabolism and cytotoxicity since the corresponding products are more reducing and thus more prone to autoxidation with simultaneous ROS production. 

The occurrence of acylated flavones and flavonols still appears interesting enough to justify a short paragraph on this subject (for compilation see Table 12.5). Of the flavones, only three compounds are known to date, with one newly reported isobutyrate flavone from leaf exudates of Asarina procumbens (Scrophulariaceae). One further compound, the 5 -benzoate of 8,2, 5 -trihydroxyflavone, was isolated recently from the exudate of Primula palinuri (linuma and Wollenweber, unpublished). 

Horie, T. et al.. Studies of the selective 0-alkylation and dealkylation of flavonoids. 13. An improved method for synthesizing 5,6,7-trihydroxyflavones from 6-hydoxy-5,7-dimethoxyfla-vones. J. Org. Chem., 57, 3343, 1992. 

Trihydroxyflavone (galangin) 3-Glucoside-8-sulfate Phyllanthus virgatus whole plant Euphorbiaceae 165... 

Pelargidenon, Apigenol, 4, 5,7-Trihydroxyflavon, Versulin Systematic name... 

The parsley plant, Petroselinum crispum, for example, contains at least two of the D-apiose flavonoids, namely, apiin 4, 5-dihydroxy-flavon-7-yl 2-0- [3-C (hydroxymethyl)-/3-D-erythrofuranosyl] -/3-D-glucopyranoside (4) and petroselinin 3, 4, 5-trihydroxyflavon-7-yl 2-0- [3-C-(hydroxymethyl)-/3-D-erythrofuranosyl]-/3-D-glucopyrano-side. 1 The principal compound containing D-apiose in parsley... 

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