Effects of a water-soluble extract of rosemary and its purified component rosmarinic acid on xenobiotic-metabolizing enzymes in rat liver.

The effects of a water-soluble extract (WSE) of rosemary and its purified antioxidant rosmarinic acid (RA) on xenobiotic metabolizing enzymes (XME) were studied in rat liver after dietary administration. The modulation of phase I enzymes such as cytochrome P450 (CYP) 1A, 2B, 2E1, 3A, and phase II enzymes such as glutathione S-transferase (GST), quinone reductase (QR) and UDP-glucuronosyltransferase (UGT) was evaluated by measuring enzyme activities with specific substrates. Protein levels of CYPs and rGST A1/A2, A3/A5, M1, M2 and P1 were measured using antibodies in Western blots. Caffeic acid was also studied because it results from RA biotransformation in rat after oral administration. Male SPF Wistar rats received the different compounds at 0.5% (w/w) incorporated into their diet for 2 weeks. WSE, containing RA, flavones and monoterpenes enhanced CYP 1A1, 2B1/2, 2E1 and GST (especially rGST A3/A5, M1 and M2), QR and UGT. On the contrary, no modification of XME was observed in response to RA or CA (except for a slight increase of UGT activity after CA treatment). The induction of XME by WSE could be attributed to flavones, monoterpenes or an additive effect of all components.

Cyclic fatty acid monomers from heated oil modify the activities of lipid synthesizing and oxidizing enzymes in rat liver.

Cyclic fatty acid monomers purified from a heated linseed oil were given for 2 wk to adult rats as triacylglycerol at two dose levels, i.e., 0.1 and 1 g/100 g diet, to determine their effect on some aspects of lipid metabolism. Indirect evidence of a peroxisome proliferator-like effect was observed, as determined by an elevation of some characteristic enzyme activities, such as peroxisomal acyl-CoA oxidase, and the microsomal omega- but also (omega-1)-laurate hydroxylase (CYP4A1 and CYP2E1, respectively). The dietary cyclic fatty acids induced a coordinated regulation between the activities of the lipogenic enzymes studied (Delta9-desaturase, phosphatidate phosphohydrolase) and peroxisomal oxidation, but not with mitochondrial beta-oxidation. The dose-dependent decrease of Delta9-desaturase activity (P < 0.05) with cyclic fatty acid monomer intake was accompanied by a similar decrease of the monounsaturated fatty acid level in liver. The increase in the gamma-linolenic acid level also suggested an increase in Delta6-desaturase activity with cyclic fatty acid intake (P < 0.05). In addition, our results strongly suggested that the altered liver levels of eicosapentaenoic and arachidonic acids were due to the peroxisomal retroconversion process in rats fed cyclic acids. Finally, an effect of these cyclic compounds on the carbohydrate metabolism cannot be disregarded because they decreased liver glycogen concentration. We conclude that cyclic fatty acid monomers affect different aspects of lipid metabolism, including a phenotypic peroxisome proliferator response. This provides the ground for further studies investigating the biochemical pathways that underlie the nutritional effect of such molecules.

Comparative effects of flavonoids and model inducers on drug-metabolizing enzymes in rat liver.

The inducing effects of some flavonoids (flavone, flavanone, tangeretin and quercetin) and model substances have been studied in rats, and the activity and the expression of drug-metabolizing enzymes have been compared in rats. The addition of flavonoids to the diet (0.3% w/w) for 2 weeks did not change the liver cytochrome P450 content nor the activities of the NADPH-cytochrome P450 and NADH-cytochrome b5 reductases, but it affected the activities of phase I and phase II enzymes. Flavone, and to a lesser extent tangeretin, increased the activities mediated by the P450 1A1,2 (EROD) and 2B1,2 (PROD) as well as the activities of p-nitrophenol UDP-glucuronyl transferase (UGT) and glutathione transferase (GST). Flavanone mainly enhanced PROD, UGT and GST, whereas quercetin did not modify any enzyme activities. None of the tested flavonoids modulated the activities catalyzed by P450 2E1, 3A and 4A. Immunoblotting studies showed that flavone and tangeretin increased the expression of cytochrome P450 1A and 2B forms, whereas flavanone only induced cytochrome P450 2B. Flavone and to a lesser extent flavanone, markedly increased the phenol-UGT protein level. Both flavone and flavanone also increased the androsterone- and testosterone-UGTs, whereas tangeretin and quercetin did not increase any UGT isoform. We concluded that the flavonoids tested specifically affected the expression of the drug-metabolizing isozymes in rat liver, their inducing properties were dependent on their chemical structures.

Effects of canthaxanthin, astaxanthin, lycopene and lutein on liver xenobiotic-metabolizing enzymes in the rat.

1. The catalytic activities of several phase I and II xenobiotic-metabolizing enzymes and the immunochemical detection of P4501A and 2B have been investigated in liver microsomes and cytosol of male rats fed for 15 days with diets containing canthaxanthin, astaxanthin, lycopene or lutein (as lutein esters) (300 mg/kg diet) and in rats fed increasing levels (10, 30, 100 and 300 ppm) of canthaxanthin or astaxanthin in the diet. 2. Canthaxanthin increased the liver content of P450, the activities of NADH- and NADPH-cytochrome c reductase, and produced a substantial increase of some P450-dependent activities, especially ethoxyresorufin O-deethylase (EROD) (x 139) and methoxyresorufin O-demethylase (MROD) (x 26). Canthaxanthin also increased pentoxy-(PROD) and benzoxyresorufin O-dealkylases (BROD), but did not affect. NADPH-cytochrome c reductase and erythromycin N-demethylase (ERDM) activities and decreased nitrosodimethylamine N-demethylase (NDMAD) activity. Phase II p-nitrophenol UDP-glucuronosyl transferase (4NP-UGT) and quinone reductase (QR) activities were also increased by canthaxanthin treatment. These enhancing effects on EROD, MROD and 4NP-UGT were clearly detectable at a dose as low as 10 ppm of canthaxanthin in the diet; the induction of QR was only observed in rats fed > or = 100 ppm. Astaxanthin induced the same pattern of enzymes activities as canthaxanthin, but to a lesser extent: its effects on phase I enzymes and 4NP-UGT were observed in rats fed > or = 100 ppm, and QR was not increased. Western blots of microsomal proteins clearly showed the induction of P4501A1 and 1A2 by canthaxanthin and astaxanthin. By contrast, lutein had no effect on the phase I and II xenobiotic-metabolizing enzymes activities measured. Lycopene only decreased NDMAD activity. 3. The two 4-oxocarotenoids canthaxanthin and astaxanthin are substantial inducers of liver P4501A1 and 1A2 in the rat, and coinduce 4NP-UGT and QR, just like polycyclic aromatic hydrocarbon, beta-naphtoflavone or dioxin (TCDD). However, these latter classical P4501A inducers also induce aldehyde dehydrogenase class 3 (ALDH3); this enzyme is not increased, or only marginally, by canthaxanthin and astaxanthin. These two oxocarotenoids form a new class of inducers of P4501A, are structurally very different from the classical inducers quoted above, which are ligands of the AH receptor.

Comparison of the effects of feeding quercetin or flavone on hepatic and intestinal drug-metabolizing enzymes of the rat.

The influence of dietary flavone and quercetin on the components of the drug metabolizing enzyme system was examined in the liver and small intestine of the rat. Quercetin given at a concentration of 1% in the diet for 14 days produced no significant changes on phase I or phase II enzyme activities. In contrast, 0.25% flavone caused significant increases in relative liver weight, microsomal and cytoplasmic proteins, and cytochrome P-450 content. The activities of hepatic ethoxyresorufin, pentoxyresorufin and ethoxycoumarin deethylases were significantly increased (by 20, 30 and 2.5-fold, respectively) over control levels. Hepatic UDP-glucuronyl transferase and glutathione transferase activities were increased 3-4-fold. In contrast, flavone induced no changes in these two intestinal enzyme activities. It is concluded that flavone produces an induction that shows both phenobarbital- and methylcholanthrene-type characteristics and that its effects on conjugating enzymes is tissue specific.

Induction of hepatic drug-metabolizing enzymes by cyclic fatty acid monomers in the rat.

The effects of cyclic monomers on the activities of several drug-metabolizing enzymes were evaluated. Female Wistar rats were fed, for 4 wk, a semi-synthetic diet containing different quantities of cyclic monomers isolated from linseed oil heated at 275 degrees C for 12 hr under nitrogen. Microsomal proteins and cytochrome c were significantly increased in rats fed a diet containing 0.1 or 1% cyclic monomers. Aminopyrine demethylation, a model reaction preferentially induced by phenobarbital, was increased by this treatment. NADPH-cytochrome P-450 reductase was also stimulated. Moreover, ethoxyresorufin deethylation, known to be greatly increased by methylcholanthrene-type inducer was only increased threefold by this treatment. The activity of p-nitrophenol UDP-glucuronosyl transferase decreased while the conjugation of bilirubin was stimulated. These results suggest that cyclic monomers isolated from heated linseed oil show some characteristics of phenobarbital-type inducers.

[The effect of cholesterol and the nature of dietary fatty acids on the activities of some microsomal monooxygenases in the rat liver]. / Influence du cholestérol et de la nature des acides gras alimentaires sur les activités de quelques monoxygénases microsomales du foie chez le rat.

For 9 weeks, 2-month old male rats were fed diets containing 0 or 2% cholesterol and 15% corn oil or coconut oil (2 x 2 factorial experiment). The activity of several cytochrome P450-dependent monooxygenases from liver microsomes was measured. Dietary cholesterol increased liver weight; this effect was more marked in rats fed unsaturated fat than in those fed saturated fat. The activity of NADPH-cytochrome c reductase and cytochrome b5 contents was also enhanced by dietary cholesterol. The type of dietary fat mainly affected the activities of NADPH-cytochrome c reductase and aminopyrine demethylase. The latter was 34% higher in rats fed corn oil than in rats fed coconut oil. In contrast, the activities of aniline hydroxylase and laurate hydroxylase were not modified by dietary fat. Briefly, the dietary factors studied affected the activity of microsomal monooxygenases differently.

The influence of food flavonoids on the activity of some hepatic microsomal monooxygenases in rats.

The effects of several food flavonoids on the activities of some drug-metabolizing enzymes in rat-liver microsomes were determined in vivo. When quercetin, chrysin, hesperetin and (+)-catechin were injected ip at doses of 150 mg/kg body weight/day for 3 days, quercetin and chrysin stimulated aminopyrine demethylase. When quercetin, rutin, hesperetin and (+)-catechin were fed as components (0 . 1%) of purified diets administered to rats for 4 wk, rutin and (+)-catechin increased microsomal cytochrome b5 levels and quercetin and (+)-catechin increased aminopyrine demethylase activity. On the other hand rutin, quercetin and hesperetin inhibited NADH-cytochrome c reductase. Aniline hydroxylase was not affected by any of the flavonoids administered by either route. The results show that each flavonoid affects different components of the monooxygenase system. The fact that some flavonoids give different effects according to the route and/or the duration of administration is discussed.

[Effect of nitrite on the nutritional state of germ-free weaning rats (author's transl)]. / Effet du nitrite sur l'état de nutrition vitaminique B du rat axénique sevré.

For 14 days 2 groups of 10 young male Wistar rats in the germ-free state were fed on a chow ration, and to drink they were given either de-ionized water or a solution of sodium nitrite, 0.3 g per litre. At the end of the experiment thiamine, riboflavin, vitamin B6, niacin, biotin and pantothenic acid were estimated in various tissues (liver, kidneys, encephalon, heart, spleen, testes and muscle); nitrogen and phosphorus were estimated in the liver only. There was no difference between the groups in changes in body weight or fluid intake. But in the animals given sodium nitrite the liver weight was higher and there was an increase in kidney riboflavin content (+41 p. 100), and a decrease in heart riboflavin and vitamin B6 contents (-17 p. 100 and -10 p. 100, respectively) and liver pantothenic concentration (-26 p. 100). These results are different from those obtained with older S.P.F. rats [5], but are partially the same as those obtained with young S.P.F. rats [4].

[Effects of sodium nitrite on various vitamin concentrations in rat tissues]. / Effets du nitrite de sodium sur les concentrations en diverses vitamines de tissus de rat.

For 6 months 2 groups of 10 male Wistar rats were fed on a chow ration, and to drink they were given either de-ionized water or a solution of sodium nitrite, 0.3 g per litre. At the end of the experiment thiamine, riboflavin, vitamin B6, niacin, biotin and pantothenic acid were estimated in various tissues (liver, heart, muscle, encephalon, kidneys, spleen, lungs and duodenum); nitrogen, phosphorus, retinol and ascorbic acid were estimated in the liver only. There was no difference between the groups in changes in bodyweight or fluid intake, nor in weight of different organs. But in the animals given sodium nitrite there was an increase in riboflavin, vitamin B6, niacin and pantothenic acid spleen concentrations, and a decrease in liver niacin and encephalon biotin contents.