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In our previous study, a peroxisome proliferator-activated receptor γ γ γ γ (PPARγ γ γ γ) agonist, pioglitazone, suppressed both hyperlipidemia and intestinal polyp formation in Apc 1309 mice at doses of 100 and 200 ppm in the diet. In contrast, it has been reported that doses of 1500 or 2000 ppm of another PPARγ γ γ γ agonist, troglitazone, enhanced colon polyp development in Min mice. In the present study, we therefore investigated the effects of a wide range of pioglitazone doses on both hyperlipidemia and intestinal polyp formation in Min mice. Serum triglycerides and very low density lipoprotein (VLDL) cholesterol in the basal diet group were elevated to levels 13-15 times higher than those in the wild-type counterparts at 20 weeks of age. They were reduced dose-dependently by treatment with 100, 200, 400 and 1600 ppm pioglitazone from 6-20 weeks of age with suppression to almost the wild-type level at the highest dose. Moreover, up-regulation of the liver mRNA levels for lipoprotein lipase (LPL) was evident in the pioglitazone-treated animals. Dose-dependent reduction of intestinal polyps was observed in Min mice given 100-1600 ppm for 14 weeks, total numbers being decreased to 63-9% of the control value. A suppressive effect of pioglitazone on colon polyp formation was also found. The PPARγ γ γ γ agonist, pioglitazone, may thus be a promising candidate chemopreventive agent for colon cancer. onsumption of a high fat diet is epidemiologically related to the risk of colon cancer.

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Polyethylene glycol (PEG)-linked manganese halogenated porphyrins (Chart ) catalyzed oxidation of azo dyes (Chart ) by H2O2 under mild conditions such as pH 8.0 at 25 °C especially when imidazole was present, causing the decoloration of azo dyes. The decoloration of azo dyes by synthetic manganese porphyrins under mild conditions was first reported. The decoloration rate depended on the structures of the porphyrins, in which the largest rate was observed in the presence of PEG−MnDCPP. The decoloration may be contributed by radical species rather than electrophilic species, consistent with the side-chain oxidation of toluene. Kinetics on polyethylene glycol-linked manganese porphyrin-catalyzed decoloration of C.I. Acid Orange 7 by hydrogen peroxide revealed that the decoloration was contributed at the oxidation process by manganese porphyrins with hydrogen peroxide in the polymer domain rather than the complex-formation process between manganese porphyrins and azo dyes.

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