Anti-Hepatotoxic Effects ofRosa rugosaRoot and Its Compound, Rosamultin, in Rats Intoxicated with Bromobenzene

The effects of a methanol extract of Rosa rugosa root and its triterpenoid glycoside, rosamultin, on hepatic lipid peroxidation and drug-metabolizing enzymes were investigated in rats treated with bromobenzene. The methanol extract of R. rugosa root reduced the activities of aminopyrine N-demethylase and aniline hydroxylase, which had been increased by bromobenzene, but rosamultin did not affect the activities of the two enzymes. Both the methanol extract and rosamultin restored the activity of epoxide hydrolase, which had also been decreased by bromobenzene. Hepatic glutathione concentrations were lowered and hepatic lipid peroxides were increased in rats intoxicated with bromobenzene. The hepatic lipid peroxidation induced by bromobenzene was prevented with the methanol extract and rosamultin. However, the decrease in glutathione was not altered by the methanol extract of R. rugosa. These results suggest that the extract of R. rugosa and its compound, rosamultin, may protect against bromobenzene-induced hepatotoxicity through, at least in part, enhanced activity of epoxide hydrolase. Antioxidant properties may contribute to the protection of R. rugosa against bromobenzene-induced hepatotoxicity.

Effects of long-term tea polyphenols consumption on hepatic microsomal drug-metabolizing enzymes and liver function in Wistar rats

AIM: To investigate the effects of long-term tea polyphenols (TPs) consumption on hepatic microsomal drug-metabolizing enzymes and liver function in rats.

METHODS: TPs were administered intragastrically to rats at the doses of 833 mg·kg^-1·d^–1 (n = 20) and 83.3 mg·kg^-1·d^-1 (n = 20) respectively for six months. Controlled group (n = 20) was given same volume of saline solution. Then the contents of cytochrome P450, b5, enzyme activities of aminopyrine N-demethylase (ADM), glutathione S-trasferase (GST) and the biochemical liver function of serum were determined.

RESULTS: The contents of cytochrome P450 and b₅ in the livers of male rats in high dose groups (respectively 2.66 ± 0.55, 10.43 ± 2.78 nmol·mg MS pro^-1) were significantly increased compared with the control group (1.08 ± 1.04, 5.51 ± 2.98 nmol·mg MS pro^{- 1}; P < 0.01, respectively). The enzymatic activities of ADM in the livers of female rats in high dose groups (0.91 ± 0.08 mmol·mg MS pro^-1min^-1) were increased compared with the control group (0.82 ± 0.08 mmol·mg MS pro^-1·min^-1; P < 0.05). The GST activity was unchanged in all treated groups, and the function of liver was not obviously changed.

CONCLUSION: The antidotal capability of rats’ livers can be significantly improved after long-term consumption of TPs. There are differences in changes of drug-metabolizing enzymes between the sexes induced by TPs and normal condition.

Interaction of fluoroquinolones and certain ionophores in broilers: effect on blood levels and hepatic cytochrome p450 monooxygenase activity

The concomitant administration to broilers of ionophore coccidiostats and certain chemotherapeutic agents may cause deleterious interactions, with toxicosis and death as possible sequelae. In this study, co-administration of the ionophore monensin was not shown to alter blood levels of enrofloxacin or norfloxacin. In addition, exposure to lasalocid was not shown to change blood levels of enrofloxacin. However, norfloxacin + lasalocid co-administration induced aminopyrine N-demethylase (AD) activity by day 5 after the last administration of norfloxacin, and induced a rise of norfloxacin levels in the blood. This rise of blood norfloxacin levels after co-administration of norfloxacin + lasalocid implies that lower levels of norfloxacin could be administered in birds also receiving lasalocid.

Changes in rat liver monooxygenase activities after administration of atenolol, nifedipine and diltiazem alone and in combination

The effects of the Ca2+ antagonists nifedipine (NF) and diltiazem (DL) and of the cardioselective beta 1-adrenergic blocking agent atenolol (AT) on the hexobarbital (HB) sleeping time and on the activity of some liver drug-metabolizing enzyme systems in male Wistar rats were studied. Two hours after single oral administration, atenolol (150 mg/kg) did not change hexobarbital sleeping time, while nifedipine (50 mg/kg) and diltiazem (30 mg/kg) prolonged it by 171.2 and 99.6%, respectively. Coadministration of atenolol with diltiazem or with nifedipine significantly prolonged hexobarbital sleep by 205 and 283%, respectively. Administered alone, atenolol decreased the ethylmorphine-N-demethylase (EMND) activity, but the amidopyrine-N-demethylase (APND) activity was not changed in any of the treated groups. Atenolol and nifedipine significantly increased aniline-4-hydroxylase (AH) activity and this effect was also observed with the combinations AT + NF and AT + DL. The NADPH cytochrome P-450 reductase activity was significantly decreased by nifedipine and diltiazem. Only nifedipine increased the total content of cytochrome P-450 (by 23.8%). Atenolol and diltiazem tended to increase the content of cytochrome b5 which was increased by nifedipine by 97.6%. The same effect was observed with the combinations AT + NF and AT + DL. The results suggest that NF, AT + NF and AT + DL produced the manifested changes in hepatic oxidative metabolism. The decreased EMND activity by atenolol, however, and the prolongation of hexobarbital sleeping time by nifedipine, diltiazem and their coadministration with atenolol did not correlate with enhanced microsomal P-450 and b5 content.

Protection by Osbeckia aspera against carbon tetrachloride-mediated alterations in microsomal drug metabolizing enzyme activity

Previous investigations have confirmed the protective effect of Osbeckia aspera leaf extract on carbon tetrachloride-mediated liver injury in rat models. It is well known that the earliest alterations in liver cell structure and function following carbon tetrachloride poisoning involve the endoplasmic reticulum and its drug metabolizing enzymes. Therefore, we investigated whether an aqueous leaf extract of O. aspera could offer protection against carbon tetrachloride-induced changes in the microsomal drug metabolizing enzymes aniline hydroxylase and p-aminopyrine N-demethylase. This enzyme activity was compared with phenobarbital-induced righting reflex and lipid peroxidation. Treatment of rats with the aqueous leaf extract of O. aspera (before or after the administration of carbon tetrachloride) resulted in a marked decrease in carbon tetrachloride-mediated alterations in aniline hydroxylase and p-aminopyrine N-demethylase activity, phenobarbital-induced loss of righting reflex and malondialdehyde formation due to lipid peroxidation. The Km value of these enzymes in control and Osbeckia-treated rats were the same. These results show that the plant extract can markedly decrease the carbon tetrachloride-mediated reduction in aniline hydroxylase and p-aminopyrine N-demethylase activity and inhibit peroxidative damage to the cell membrane. Phenobarbital-induced sleeping time in rats and kinetic enzyme studies suggested that the effects of the plant extract was neither due to an induction of the drug-metabolizing enzymes under investigation, nor due to an alteration in the Km values of these enzymes.

Hepatic drug metabolizing enzyme induction and serum triacylglycerol elevation in rats treated with chlordiazepoxide, griseofulvin, rifampicin and phenytoin

Five days intraperitoneal administration of rats with chlordiazepoxide (0.4 mg/kg), griseofulvin (7 mg/kg), rifampicin (8. 6 mg/kg), phenytoin (4.3 mg/kg) and phenobarbitone (1.4 mg/kg; an established inducer of microsomal enzymes) caused a significant increase in serum triacylglycerol (P<0.001) and the activities of aniline hydroxylase, aminopyrine N-demethylase and p-nitroanisole O-demethylase (P<0.001). Aniline hydroxylase, aminopyrine N-demethylase and p-nitroanisole O-demethylase activities were increased 1.48-, 1.15- and 1.47-fold, respectively, in chlordiazepoxide-treated rats, 1.65-, 1.20- and 1.38-fold in griseofulvin-treated rats, 1.74-, 1.36- and 1.44-fold in rifampicin-treated rats, 1.56-, 1.29- and 1.62-fold in phenytoin-treated rats and 2.26-, 1.72- and 1.93-fold in phenobarbitone-treated rats. Chlordiazepoxide, griseofulvin, rifampicin, phenytoin and phenobarbitone increased the activity of cytosolic phosphatidate phosphohydrolase by 52, 58, 67, 73 and 82%, respectively, while the drugs elicited 50, 60, 60, 73 and 87% increases in the activity of the microsomal phosphatidate phosphohydrolase. Similarly, chlordiazepoxide, griseofulvin, rifampicin, phenytoin and phenobarbitone elicited 2.4-, 2.39-, 2.34-, 1.69- and 3.75-fold increases in serum triacylglycerol concentrations. The correlations between serum triacylglycerol concentrations and the activities of aniline hydroxylase, aminopyrine N-demethylase and p-nitroanisole O-demethylase were significant in all treatment groups (r=0.83, r=0.92 and r=0.87, respectively, n=30, P<0.001). Our results suggest that induction of hepatic enzymes by the administered drugs may lead to hypertriglyceridaemia as an adverse effect, possibly by inducing the activity of regulatory enzymes in the biosynthesis of triglyceride.

Combined effect of propranolol with nifedipine or with diltiazem on rat liver monooxygenase activities

The effects of two Ca2+ antagonists nifedipine (NF) and diltiazem (DL) and of the nonselective beta-adrenergic blocking agent propranolol (PR) on the hexobarbital (HB) sleeping time and on the activity of some liver drug-metabolizing enzyme systems in male Wistar rats were studied. Two h after single oral administration PR (50 mg/kg) did not change HB sleeping time, while NF (50 mg/kg) and DL (30 mg/kg) prolonged it by 171.2 and 99.6%, respectively. Coadmistration of PR with DL or with NF significantly prolonged HB sleep by 240.7 and 129%, respectively. Only NF increased aniline 4-hidroxylase (AH) activity (by 92%) and the total P-450 content (by 24%). PR and NF increased cytochrome b5 content and this effect was also observed with the combinations PR + NF (by 109%) and PR + DL (by 102%). The NADPH cytochrome P-450 reductase activity was significantly decreased by NF and DL and after their combination with PR. The ethymorphine-N-demethylase (EMND) and amidopyrine-N-demethylase (APND) activities were not changed. The effects of PR, NF and DL administrated alone or in combination on liver oxidative metabolism are considered as possible mechanisms of drug interactions.

The inhibitory effects of the fluoroquinolone antimicrobials norfloxacin and enrofloxacin on hepatic microsomal cytochrome P-450 monooxygenases in broiler chickens

The fluoroquinolone antimicrobials norfloxacin and enrofloxacin were found to inhibit hepatic microsomal cytochrome P-450 monooxygenases in the livers of broiler chickens using dosages as given in commercial flocks. Norfloxacin inhibited the process of N-demethylation of aminopyrine to a greater degree, while enrofloxacin more markedly inhibited hydroxylation of aniline.

[Effect of the cholesterol and protein diet on cytochrome P-450 dependent monooxygenase activity]

The effect of cholesterol and protein diet on mixed-function oxidase activity and desaturation of fatty acids were studid as well as phenobarbital inducibility of those parameters. Investigations were carried out on Wistar adult male rats. The animals were on the cholesterol (0.25%) and protein (32%) diet for 45 days. Cytochrome P-450 and cytochrome b5 contents, NADPH-cytochrome P-450 reductase, NADH-cytochrome b5 reductase, aniline hydroxylase and 4-aminopyrine N-demethylase activities were measured in a hepatic microsomal fraction. The cholesterol diet exerted a negative effect on all parameters except NADH-cytohrom b5 reductase. The protein diet did not change the activity or levels of enzymes under study. The only exception applied to induction of NADH-cytochrome b5 reductase and 4-aminopyrine N-demethylase activities. Simultaneous treatment with phenobarbital had a heterogenous effect depending on the type of diet and parameters examined.

Effect of gossypol on hepatic and serum gamma-glutamyltransferase activity in rats

A single intraperitoneal dose (25 mg/kg) of gossypol given to male Sprague-Dawley rats caused marked changes in the activity of the hepatic and serum gamma-glutamyltransferase (GGT) and microsomal monooxygenases. The GGT activity in liver homogenate, S-9 supernatant fraction and microsomes was significantly depressed; however, the level of serum GGT was elevated. While the hepatic glutathione concentration was not greatly changed, the aminopyrine N-demethylase activity and microsomal cytochrome P450 content of the liver were significantly decreased in the treated rats. At necropsy, the livers of the treated rats appeared generally pale with distinct pinpoint foci. Histopathological examination of the liver showed degenerative changes and coagulative necrosis. The results indicate that gossypol is a strong hepatotoxic agent which can produce severe hepatic damage.

[Effect of paracetamol on the microsomal oxidation, oxidative phosphorylation and liver mitochondria swelling in rats of various ages]

The effect of hepatotoxic dose of paracetamol (800 mg per kg, intraperitoneally, once a day during two days) on the system of microsomal oxidation, respiration, oxidative phosphorylation and high amplitude swelling of liver mitochondria was studied on 1-, 4- and 30-months old Wistar male rats. It has been shown, that paracetamol injection leads to the decrease of content of cytochrome P-450, to disorders of the function of monooxygenase system (the aminopyrine-N-demethylase and aniline hydroxylase activities were diminished), mitochondria macrostructure (the mitochondria high amplitude swelling time was decreased) and function (the respiratory control was decreased). These alterations have been observed to manifest to more extent in the liver of young rats as compared with old ones.

Molecular non-genetic biomarkers related to Fenarimol cocarcinogenesis: organ- and sex-specific CYP induction in rat

Selective biochemical markers of effect have been used to evaluate some non-genotoxic cocarcinogenic properties of Fenarimol. Several CYP-dependent reactions have been monitored in liver, kidney and lung microsomes of male and female Sprague-Dawely rats treated (i.p.) with 200 or 400 mg/kg body wt dose of this pesticide. Highly specific substrates were used as probes of various isoforms, such as CYP1A1, 1A2, 2B1, 2E1 and 3A. A complex pattern of CYP induction, including organ- and sex-related differences in the inductive response by Fenarimol, has been recorded in this investigation, the kidney (mainly male) being more responsive when compared to other tissues. A 6.6-fold increase in the 2B1-like activity, probed by dealkylation of pentoxyresorufin was observed in the liver at a higher dose. On the contrary, a marked induction of CYP1A1 mediated ethoxyresorufin O-deethylase activity, ranging from 20- to 35-fold in female and male, respectively, was observed in the kidney at a lower dose tested. In the lung, at a higher dose, the p-nitrophenol hydroxylase activity (2E1) was enhanced up to 3.5-fold in male animals, whereas the 3A-like activity, probed by the N-demethylation of aminopyrine, was induced up to 2.6-fold in females. A weak, although significant reduction of CYP2B1 isoforms in lung was also recorded. Taken together, these data corroborated by means of Western immunoblotting analysis (using rabbit polyclonal antibodies anti-CYP 2B1/2, 1A1, 2E1, and 3A1/2) indicate a possible cotoxic, comutagenic cocancerogenic and promoting potential of this fungicide.

Induction of hepatic cytochrome P450 by phenobarbitone in rhesus monkey (Macaca mulatta)

An intraperitoneal administration of PB at a daily dose of 50 mg Kg-1 body wt for 4 days increased the specific content of hepatic microsomal heme, cytochrome P450 and the activity of aminopyrine N-demethylase by 1.8, 2.8 and 3.5 fold respectively. These results were substantiated by the intensification of the 52.5 KDa polypeptide in the electrophoretogram of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the hepatic microsomes obtained from PB-pretreated versus control macaques. PB did not affect the hepatic content of cytochrome b5 and the activity of NADPH cytochrome c reductase, whereas it decreased the activity of NADH cytochrome c reductase in the rhesus monkeys. To the best of our knowledge this is a first report on the induction of hepatic cytochrome P450 and related enzymes by PB in rhesus monkeys.

Effect of sulfamethazine on mixed function oxidase in chickens

Sulfamethazine (SMZ) ip administration for 3 d to chickens showed significant induction of cytochrome P-450 levels and in the activities of aminopyrine N-demethylase, aniline hydroxylase and glutathione s-transferase at the dosage of 150 mg SMZ/kg body weight. Cytochrome P-450 and the activity of aniline hydroxylase were significantly decreased at 300 mg SMZ/kg body weight when compared to 150 mg SMZ/kg body weight. Other doses produced no significant changes in the parameters studied. One hundred fifty mg SMZ/kg for 1 or 3 d caused significant induction of cytochrome b5, cytochrome P-450, the drug metabolizing enzymes and glutathione s-transferase; however, 5 d of SMZ produced no significant changes. The in vitro 10 mM SMZ inhibition of aminopyrine N-demethylase and aniline hydroxylase and the induction of enzymes at 150 mg SMZ/kg body weight indicates that SMZ is a substrate of the mixed function oxidase system and may be an inducer of specific forms of cytochrome P-450.

The impact of vitamins A,C,E, and selenium compound on prevention of liver cancer in rats

A study was initiated to determine the impact of vitamins A, C, E, and selenium compound (Se) on the prevention of liver cancer. Sixty animals were fed a diet with or without these vitamins followed by aflatoxin B treatment for a period of 24 months. Most of the animals fed a diet devoid of vitamins developed liver cancer, while none or only a few of the animals given vitamins suffered during this period. We suggest that vitamins can inhibit liver cancer by inducing hepatic microsomal enzymes that metabolise aflatoxins to noncarcinogenic products.

[Effects of sino-Japanese herbs in the family Compositae on the hepatic drug metabolizing enzymes and lipid peroxidation in rats]

The effects of hot water extracts (HWEs) from 15 kinds of Compositae herbs and distanninized fractions (DTFs) from 9 of these herbs on rat hepatic lipid peroxidation (LPO) and the activities of aminopyrine N-demethylase (APD) and aniline hydroxylase (ANH) were examined in vitro. The APD activity was inhibited by HWEs from 12 herbs, of which the effect of HWE from Inchinko was remarkable. Inhibitory effects of DTFs from Inchinko, Gaiyo, Kantoka, Sojustu and Byakujutsu on the APD activity were smaller, if any, than those of the corresponding HWEs, whereas DTF from Koka enhanced the activity of APD. The ANH activity was inhibited by HWEs from 11 herbs. HWEs from Inchinko, Gaiyo and Senpukuka increased the ANH activity, whereas the DTFs from them caused inhibition. The inhibitory effect of DTF from Shion on the ANH activity was smaller than that of the corresponding HWE, but the effects of DTFs from Koka, Byakujutsu, Sojutsu and Mokko were larger than those of the respective HWEs. LPO was inhibited by HWEs from 14 herbs, of which the HWEs from Inchinko, Gaiyo, Kantoka, Koka and Mokko caused marked inhibitions. Except in the case of Shion, the inhibitory effects of DTFs on LPO were smaller than those of the corresponding HWEs, whereas DTF from Koka still showed a marked inhibition. In the present experiments, it is suggested that Inchinko, Gaiyo, Koka, Kikuka, Senpukuka, Byakujutsu, Sojutsu and Mokko, which showed remarkable effects on LPO and the activities of APD and ANH, might also exert their effects in vivo.

The effect of subacute prazosin treatment on hepatic metabolic enzyme system of young and elderly rats

We have studied cytochrome P-450 content, aminopyrine-N-demethylating activity, serum bilirubin level, in young 10 weeks old and elderly, 14 months old CFY rats grouped according to sex. The effect of the selective alpha 1-adrenoceptor antagonist antihypertensive prazosin was examined in the previously described groups of animals. We could state that neither oxidative nor conjugative reactions of the liver declined with aging. In a subacute 12 days treatment period prazosin has not impaired liver functions.

Lack of in vitro and in vitro effects of fenbendazole on phase I and phase II biotransformation enzymes in rats, mice and chickens

Intraperitoneal administration of 10 mg fenbendazole/kg bw daily for 5 d caused no significant alterations in the activities of hepatic microsomal drug-metabolizing enzymes viz aminopyrine N-demethylase, aniline hydroxylase and cytosolic glutathione S-transferase in rats, mice and chickens. Similarly no significant difference in the amount of microsomal cytochrome P-450 and NADPH-cytochrome c reductase was found between control and treated animals. In vitro incubation of fenbendazole with rat, mouse and chicken microsomes suggests that the drug neither binds to microsomal protein cytochrome P-450 nor inhibits the activities of aminopyrine N-demethylase and aniline hydroxylase. Similarly in vitro addition of fenbendazole to cytosolic glutathione S-transferase from the above species did not alter the activity of this enzyme. The results indicate that fenbendazole does not alter the activity of hepatic microsomal monooxygenase system significantly in rats, mice and chickens at a dosage level of 10 mg/kg body weight. In vitro studies also indicate that fenbendazole does not interact with the hepatic microsomal monooxygenase system, indicating it is not a substrate for cytochrome P-450-dependent monooxygenase system.

Possible role of glutathione depletion in the induction of rate-limiting enzymes involved in heme degradation and polyamine biosynthesis in the liver of rats

Ten compounds with a wide variety of structures, which decreased hepatic glutachione (GSH) content at an early time period after their administration, simultaneously increased hepatic heme oxygenase, ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) activities in rats. The compounds examined were four alpha, beta-unsaturated carbonyl compounds, two prototype substrates for GSH transferase(s), one epoxide, two isothiocyanates, and an indicator of hepatic function test. Time course studies with 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB), which are prototype substrates for GSH transferases, showed that there was an inverse relationship between the early depletion of hepatic GSH content and induction of heme oxygenase, ODC and SAMDC together with a decrease in cytochrome P-450 content and an increase in putrescine content. Buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, also increased heme oxygenase and SAMDC activities, but not ODC, and it tended to enhance the induction of the enzymes evoked by diethyl maleate (DEM), phorone and CDNB with the sustained depletion of GSH content. In contrast, GSH treatment inhibited DEM-, phorone-, and CDNB-mediated induction of these enzymes and the early depletion of GSH content. N-Acetylcysteine failed to inhibit DEM- and phorone-mediated induction of these enzymes and the early depletion of GSH content, while it inhibited somewhat these changes produced by CDNB. The findings suggest that the early depletion of hepatic GSH content is prerequisite for and plays a role in the induction of heme oxygenase, ODC and SAMDC.