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Cruciferous and apiaceous vegetables may be chemopreventive due to their ability to modulate carcinogen-metabolizing enzymes but whether the effects on such enzymes are sustained over time is unknown. To examine the short- and long-term effects of the vegetables, rats were fed one of four diets for 7, 30, or 60 d: AIN-93G, CRU (21% cruciferous vegetables-fresh broccoli, green cabbage, watercress), API (9% apiaceous vegetables - fresh parsnips, celery), or API + CRU (10.5% CRU + 4.5% API). Although CRU increased activity and protein expression of cytochrome P450 (CYP) 1A1 and CYP1A2 after 7 d, only activity was sustained after 30 and 60 d. There was a trend towards an interaction between the length of feeding period and CRU for CYP1A1 activity; activity increased with greater time of feeding. API increased CYP1A2 activity but decreased sulfotransferase 1A1 activity after 7 d, although not at later times. Altogether, increased CYP1A activity by CRU was maintained with long term feeding while protein amount decreased, suggesting influence by mechanisms other than, or in addition to, transcriptional regulation. Thus, response patterns and interactions with length of feeding may differ, depending upon the types of vegetables and enzymes, requiring caution when interpreting the results of short-term feeding studies. [ABSTRACT FROM AUTHOR]

Over the past years, there has been a growing interest in the natural constituents of foods as a potential means of cancer control. To date, epidemiology studies seem to indicate an inverse association between regular consumption of fruit and vegetables and cancer risk. Here, the potential chemopreventive activity of the polyphenolic extract (PPE) of peach ( Prunus persica L. Batsch) and of the freeze-dried fruit in toto (LFT), focusing on the modulation of xenobiotic metabolizing enzymes (XMEs) in vivo , was investigated. Rats were daily supplemented with LFT at 250 and 500 mg/kg b.w. or with the corresponding amount of PPE (2.5 and 5 mL/kg b.w., respectively) for either 7 or 14 days. While PPE treatment resulted in a widespread phase-I inactivation, a complex modulation pattern with drastic decreases (7α-testosterone hydroxylase, pentoxyresorufin O -dealkylase (PROD)), coupled with marked up-regulations of ethoxyresorufin O -deethylase (EROD) and methoxyresorufin O -demethylase (MROD) after LFT administration, was seen. A notable down-regulation (over 50%) following LFT or PPE treatment for the phase-II enzymes was also recorded. The observed remarkable changes in XMEs, if reproduced in humans, might have public health implications. These data suggest caution in promoting peach fruit (mono-diet) consumption or its polyphenolic extract in the field of chemoprevention. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to evaluate the effect of phloretamide (PA), an apple constituent, on the activation of the Nrf2 transcription factor and the expression of its target genes: glutathione S-transferases (GSTs), NAD(P)H:quinone oxidoreductase-1 (NQO1) and heme oxygenase-1 (HO-1) in normal human THLE-2 hepatocytes and the hepatoma HepG2 cell line. PA did not show significant cytotoxicity towards THLE-2 cells but such an effect was observed in HepG2 cells (IC50 ∼200μM). The treatment of cells with PA resulted in the translocation of Nrf2 from cytosol to nucleus in both cell lines, but increased the level of its transcript and protein only in THLE-2 cells. In this cell line an increased level of GSTA, GSTP, GSTT, NQO1 mRNA was also observed. Increased expression of GSTs was confirmed by enhancement of their protein levels. The increase in p53 protein content observed in THLE-2 may be associated with its stabilization induced by the enhancement of NQO1 level. PA did not affect Nrf2, GSTs, NQO1 or HO-1 expression in HepG2 cells. These results suggest that PA has rather chemopreventive than chemiotherapeutic potential and acts similarly as apple dihydrochalcones through the induction of detoxification/antioxidative enzymes. [Copyright &y& Elsevier]

Abstract: The mutagenic activation activity of hepatic microsomes from three meat-producing animals (cattle, deer and horses) was compared with those of rats as a reference species. In the Ames Salmonella typhimurium TA98 assay, the liver microsomes of all examined animals mutagenically activated benzo[a]pyrene, an ideal promutagens, in terms of production of histidine-independent revertant colonies. The microsomes of horses had the highest ability to produce revertant colonies of the examined animals under both low and high substrate concentrations. Inhibition of this mutagenic activity using α-naphthoflavone, anti-rat CYP1A1, CYP3A2 and CYP2E1 antibodies suggests that this activity was mainly because of CYP1A1 in these animals as well as in rats. The addition of co-factors for two phase II enzymes, microsomal UDP glucoronosyl transferase and cytosolic glutathione-S-transferase, reduced the production of the revertant colonies in a concentration-dependent manner. Interestingly, horses had the highest reduction rate among the examined animals, suggesting that phase II enzymes play a great role in producing a state of balance between the bioactivation and detoxification of xenobiotics in these meat-producing animals. This report is the first to investigate the mutagenic activation activity of the hepatic microsomes and the role of phase II enzymes against this activity in meat-producing animals. [ABSTRACT FROM AUTHOR]

Abstract: The expression level of phase I (CYP1A1 and CYP1A2) and phase II (GST, and UGT) enzyme-coded genes were measured in liver microsomes of 30 Sprague–Dawley rats fed sea weed (Monostroma nitidum). Quantitative and qualitative analysis of the detoxifying enzymes were investigated using reverse transcription polymerase reaction (RT-PCR) and real time polymerase reaction (Real-time PCR) techniques. The antioxidative properties of seaweed were screened and investigated for its hepatoprotective activity in rat. There was no significant induction of GSTYa1, GSTYa2, and CYP1A2. However, an M. nitidum diet was found to significantly increase UGT1A1 and UGT1A6 mRNA levels and to decrease CYP1A1 mRNA levels in rat liver. Structural studies confirmed the presence of sulfated polysaccharides in the seaweed samples. The results demonstrate the potential of seaweed as a natural source of sulfated polysaccharide substances with potential use in chemoprevention medicine. [Copyright &y& Elsevier]