5-7-3--4--5--pentamethoxyflavone and tricin

The flavones tricin (4',5,7-trihydroxy-3',5'-dimethoxyflavone) and 3',4',5',5,7-pentamethoxyflavone (PMF) are under development as potential colorectal cancer chemopreventive agents as they reduced adenoma development in the Apc(Min) mouse model of intestinal carcinogenesis. Here, the pharmacokinetic properties and metabolism of these flavones after oral administration were compared in mice.. C57BL/6 J mice received an oral bolus of PMF or tricin (807 μmol/kg). Parent flavone and metabolites were analyzed by HPLC/UV in plasma, liver and gastrointestinal tissues. Flavones were incubated with mouse or human hepatic microsomes or 9000xg supernatant (S9), both fortified with a NADPH-generating system and either uridine 5'-diphosphoglucuronic acid (UDPGA, microsomes) or 3'-phosphoadenosine-5'-phosphosulfate (PAPS, S9). Disappearance of substrate was assessed by HPLC/UV, metabolites were characterized by HPLC/MS/MS.. Plasma concentrations and area under the plasma concentration versus time curve for PMF were higher than those for tricin. A mono-O-desmethyl PMF and several isomeric mono-O-desmethyl PMF glucuronides and sulfonates were major PMF metabolites in murine plasma, liver and intestinal tissue. In murine and human liver fractions, in vitro metabolic removal of tricin was faster than that of PMF. On kinetic analysis of metabolite generation in these incubations, apparent maximal velocity (V(max)) values for the generation of tricin O-glucuronide or O-sulfonate were consistently several fold higher than those characterizing the production of mono-O-desmethyl PMF glucuronides or sulfonates via the intermediacy of O-desmethyl PMF.. The results suggest that inclusion of methoxy moieties confers metabolic stability onto the flavone scaffold.

Topics: Adult; Animals; Area Under Curve; Arylsulfonates; Biocatalysis; Blood; Cytosol; Female; Flavones; Flavonoids; Glucuronates; Humans; Intestinal Mucosa; Kinetics; Liver; Male; Mice; Mice, Inbred C57BL; Microsomes, Liver; Middle Aged; Young Adult

In a preliminary experiment 3',4',5',5,7-pentamethoxyflavone (PMF) inhibited adenoma development in Apc(Min) mice, a model of the human heritable condition familial adenomatous polyposis. An HPLC method for tricin was modified and validated to permit measurement of PMF in mouse plasma and intestinal mucosa. HPLC analysis was carried out on a Hypersil-BDS C(18) column with detection at 324 nm and tricin as internal standard. The assay was linear in the range of 100-2000 ng/mL plasma and 1.0-40 microg/mL mucosa. PMF in plasma was efficiently extracted using solid-phase columns. In the case of mucosa organic solvent protein precipitation displayed satisfactory accuracy and precision. The assay recovery at low, medium and high concentrations was between 85 and 103% for both biomatrices, with a relative standard deviation of <15%. The lower limits of quantitation for plasma and mucosa were 100 ng/mL and 1.0 microg/mL, respectively. This method allowed measurement of PMF steady-state median concentrations in plasma (1.08 nmol/mL, n = 11; 10th and 90th percentiles: 0.633 and 2.385 nmol/mL) and mucosa (108.5 nmol/g, n = 9; 10th and 90th percentiles: 38.9 and 164.4 nmol/g) in mice which had received PMF (0.2%, w/w) with their diet.

Topics: Animals; Chromatography, High Pressure Liquid; Feeding Behavior; Flavonoids; Humans; Intestinal Mucosa; Mice; Mice, Inbred C57BL; Sensitivity and Specificity