Biotransformation In Rats Research Articles

Curcumin Alleviates High-fat Diet-induced Nonalcoholic Steatohepatitis via Improving Hepatic Endothelial Function with Microbial Biotransformation in Rats.

Hepatic endothelial function is central to the development of nonalcoholic steatohepatitis (NASH). Curcumin (Cur) is reportedly hepatoprotective, however, it remains unknown whether Cur improves hepatic endothelial function in NASH. Additionally, the poor bioavailability of Cur renders it difficult to elucidate its hepatoprotective effect, hence, its biotransformation should be considered. Herein, we investigated the effects and mechanisms of Cur and its bioconversion on hepatic endothelial function against high-fat diet-induced NASH in rats. The results revealed that Cur improved hepatic lipid accumulation, inflammation, and endothelial dysfunction by inhibiting NF-κB and PI3K/Akt/HIF-1α pathways, however, these effects were weakened via antibiotic addition, which was closely related to reduced tetrahydrocurcumin (THC) produce in the liver and intestinal content. Moreover, THC exerted a better effect than Cur on restoring liver sinusoidal endothelial cells function to attenuate steatosis and injury in L02 cells. Thus, these findings indicate that the effect of Cur on NASH is closely related to hepatic endothelial function improvement with intestinal microbial biotransformation.

Effects of excessive alcohol drinking on nicotine biotransformation in rats

Alcohol and nicotine (tobacco smoke) are often used together, and taking both addictive substances is associated with an increased risk of certain diseases. It is extremely important to understand the pharmacodynamic and pharmacokinetic mechanisms of the interaction between nicotine and ethanol, which are still not fully understood. The study aimed to evaluate the influence of chronic alcohol consumption on nicotine biotransformation in ethanol-preferring and non-preferring male and female rats. Rats were divided into four groups depending on their alcohol preferences and gender. Nicotine, nornicotine, nicotine N-oxide, cotinine, trans-3'-hydroxycotinine, and cotinine N-oxide in rats plasma were determined by LC–MS/MS after five days of exposure to tobacco smoke. A non-compartmental analysis of nicotine and its metabolites was used for pharmacokinetic parameters calculation. Our experimental results showed that the rate of nicotine elimination depends on gender, regardless of alcohol preferences (significantly slower in females than in males). Mean residence timeof nornicotine, cotinine, and trans-3'-hydroxycotinine were significantly higher in alcohol-preferring male rats than in alcohol preferring female rats. In non-alcohol preferring female rats compared to ethanol-preferring female rats, significantly more nicotine N-oxide (fivefold) and trans-3'-hydroxycotinine (twofold) reached the general circulation unchanged. Drinking ethanol influenced the elimination of nornicotine and cotinine in male rats. Ethanol consumption was identified as a modifier of nicotine pharmacokinetics and this was gender-dependent.

Экспериментальная фармакокинетика новых нейротропных пептидных лекарственных средств

Представлены результаты исследований сравнительной экспериментальной фармакокинетики и метаболизма 3 новых нейротропных пептидных лекарственных препаратов: аналогов природных нейропептидов — ноотропного препарата ноопепт, антипсихотического средства — дилепт и селективного анксиолитика — соединения ГБ-115 у 2 видов животных (крыс и кроликов). Установлено, что эфирные производные нейропептидов ноопепт и дилепт, в отличие от анксиолитика ГБ-115, являющегося амидом, подвергаются интенсивной биотрансформации у крыс с образованием активного метаболита ноопепта — циклопролил-L-глицина (ЦПГ) и активного метаболита дилепта — капроил-L-пролил-L-тирозина (М-1). Фармакокинетические параметры, характеризующие распределение анксиолитика ГБ-115 у крыс, свидетельствуют о его возможном накоплении во внутренних органах и тканях, что следует учитывать при его повторном введении. Установлено, что изучаемые соединения в организме кроликов в меньшей степени подвергаются энзиматическому воздействию и более продолжительное время определяются в плазме крови в неизмененном виде, что связано не только со структурными особенностями изучаемых дипептидов, но и с различиями активности энзиматических систем ЖКТ, принимающих участие в их пресистемном метаболизме, а также с различиями в скорости печеночного и почечного кровотока у крыс и кроликов.

Screening and Identification of the Main Metabolites of Schisantherin a In Vivo and In Vitro by Using UHPLC-Q-TOF-MS/MS.

Schisantherin A is an active ingredient originating from Schisandra chinensis (Turcz.) which has hepatoprotective and anti-oxidation activities. In this study, in vitro metabolisms investigated on rat liver microsomes (RLMs) and in vivo metabolisms explored on male Sprague Dawley rats of Schisantherin A were tested, respectively. The metabolites of Schisantherin A were identified using ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS). Based on the method, 60 metabolites were successfully identified and structurally characterized including 48 phase-I and 12 phase-II metabolites. Among the metabolites, 45 metabolites were reported for the first time. Moreover, 56 and eight metabolites were detected in urine and bile and 19 metabolites were identified in rats’ plasma. It demonstrated that hepatic and extra-hepatic metabolic pathways were both involved in Schisantherin A biotransformation in rats. Five in vitro metabolites were structurally characterized for the first time. The results indicated that the metabolic pathways mainly include oxidation, reduction, methylation, and conjugation with glucuronide, taurine, glucose, and glutathione groups. This study provides a practical strategy for rapidly screening and identifying metabolites, and the results provide basic data for future pharmacological and toxicology studies of Schisantherin A and other lignin ingredients.

In vivo genotoxicity evaluation of cylindrospermopsin in rats using a combined micronucleus and comet assay

Cylindrospermopsin (CYN) is a potent cyanotoxin recognized as an emerging human threat due to its cytotoxicity and potential carcinogenicity. Although the genotoxicity of CYN has been extensively studied in vitro, limited data are available on its in vivo genotoxicity. The aim of this study was to evaluate the in vivo genotoxicity of pure CYN (7.5–75 μg/kg body weight) after oral exposure of rats through a combined assay of the micronucleus test (MN) in bone marrow, and the standard and modified comet assay in stomach, liver and blood. Also, histopathological changes in stomach and liver were evaluated. Positive results in the MN test were observed in bone marrow in the exposed rats at all the tested concentrations. However, the comet assay revealed that CYN did not induce DNA strand breaks nor oxidative DNA damage in any of the tissues investigated. Finally, histopathological changes were observed in stomach and liver (7.5–75 μg/kg) in intoxicated rats. These results could indicate that CYN is able to induce irritation in stomach before its biotransformation in rats orally exposed, and genotoxicity in bone marrow.

Identification of metabolites of MDR-1339, an inhibitor of β-amyloid protein aggregation, and kinetic characterization of the major metabolites in rats

We previously reported that MDR-1339, an inhibitor of β-amyloid protein aggregation, was likely to be eliminated by biotransformation in rats. The objective of this study was to determine the chemical identity of metabolites derived from this aggregate inhibitor and to characterize the kinetics of formation of these metabolites in rats. Using high performance liquid chromatography coupled with mass spectrometry with a hybrid triple quadrupole-linear ion trap, 7 metabolites and 1 potential metabolic intermediate were identified in RLM incubations containing MDR-1339. In addition to these, 3 glucuronide metabolites were detected in urine samples from rats receiving a 10 mg/kg oral dose of MDR-1339. When the kinetics of the formation of two major metabolites, M1 and M2, were analyzed assuming simple Michaelis-Menten kinetics, the Vmax and Km values were found to be 0.459 ± 0.0196 nmol/min/mg protein and 28.3 ± 3.07 μM for M1, and 0.101 ± 0.00537 nmol/min/mg protein and 14.7 ± 2.37 μM for M2, respectively. When chemically synthesized M1 and M2 were individually administered to rats intravenously at the dose of 5 mg/kg respectively, the volume of distribution and elimination clearance were determined to be 4590 ± 709 mL/kg and 68.4 ± 5.60 mL/min/kg for M1 and 15300 ± 8110 mL/kg and 98.0 ± 19.5 mL/min/kg for M2, respectively. When MDR-1339 was intravenously administered to rats at a dose of 5 mg/kg, the parent drug and M1 were readily detected for periods of up to 6 h after the administration, but M2 was observed only from 2 to 4 h. A standard moment analysis indicates that the formation clearance of M1 is 6.01 mL/min/kg, suggesting that 19.7% of the MDR-1339 dose was eliminated in rats. These observations indicate that the hepatic biotransformation of MDR-1339 results in the formation of at least 10 metabolites and that M1 is the major metabolite derived from this aggregation inhibitor in rats.

Changes of intestinal microbiota and ivabradine biotransformation in rats after alcohol introduction

The role of intestinal microbiota in progress of many pathological processes is discussed in recent publications. It was shown that the continuous intestinal dysbiosis, including the increased bacterial growth syndrome, affects the digestion and the biotransformation of xenobiotics. Intestinal microbiota provokes metabolic failures leading to severe diseases acting via several mechanisms. Alcohol is found to be a common dysbiotic factor and toxic agent affecting the systems of biotransformation. This study was to estimate the associations between the intestinal microbiota and the biotransformation of ivabradine, CYP3A4 substrate, in rats during the chronic alcohol intake. The study used 30 male Wistar rats divided into two groups control and experimental, administrated 15% ethanol as a sole water supply during 40 days to model the chronic alcohol intake. The decrease of bifido- and lactobacterium spp. found in experimental group correlated with excretion and metabolic ratio of ivabradine metabolite and ivabradine in urine. These findings demonstrate the participation of intestinal microbiota in the metabolism of ivabradine after oral introduction.

Sex differences in hepatic and intestinal contributions to nevirapine biotransformation in rats

The understanding of the intestine contribution to drug biotransformation improved significantly in recent years. However, the sources of inter-individual variability in intestinal drug biotransformation, namely sex-differences, are still elusive. Nevirapine (NVP) is an orally taken anti-HIV drug associated with severe idiosyncratic reactions elicited by toxic metabolites, with women at increased risk. As such, NVP is a good model to assess sex-dimorphic metabolism. The aim of this study was to perform a comparative profiling of NVP biotransformation in rat intestine and liver and evaluate whether or not it is organ- and sex-dependent. Therefore, nevirapine-containing solutions were perfused through the intestine, in a specially designed chamber, or incubated with liver slices, from male and female Wistar rats. The levels of NVP and its Phase I metabolites were quantified by HPLC-UV. Liver incubation experiments yielded the metabolites 2-, 3-, 8-, and 12-OH-NVP, being 12-OH-NVP and 2-OH-NVP the major metabolites in males and females, respectively. Inter-sex differences in the metabolic profile were also detected in the intestine perfusion experiments. Herein, the metabolites 3- and 12-OH-NVP were only found in male rats, whereas 2-OH-NVP levels were higher in females, both in extraluminal (p<0.01) and intraluminal media. The metabolite 8-OH-NVP was not detected in the intraluminal media from either males or females. In this study, important inter-sex differences were detected in both organs, providing further clues to the sex-dimorphic profile of NVP toxicity. Moreover, an extra-hepatic contribution to NVP biotransformation was observed, strengthening the relevance of the intestinal contribution in the biotransformation of orally taken-drugs.

Metabolite Identification of Myricetin in Rats Using HPLC Coupled with ESI-MS

Myricetin, a naturally occurring flavonol, shows multifarious pharmacological activities, e.g., antidiabetic, antioxidant, anti-inflammatory, antitumor, and liver protection effects. In order to obtain an understanding of the myricetin’s metabolism in vivo, a rapid and sensitive method by high-performance liquid chromatography coupled with electrospray-ionization mass spectrometry (HPLC-MSn) techniques was employed to investigate the biotransformation in rats after oral administration of myricetin. Recognition and structural exposition of the metabolites were operated by comparing the changes in molecular mass (ΔM) and MSn spectra with the parent drug. As a result, the parent compound and seven metabolites were found in rat plasma, urine, and feces. In addition, besides 3,5-dihydroxyphenylacetic acid (M1) and 3,4,5-trihydroxyphenylacetic acid (M2), five other compounds were first discovered in the metabolite research of myricetin. These results indicated that, besides ring-fission, there were methylate (M3, M4, M5) and glucuronide (M6, M7) biotransformations of myricetin occurring in vivo.

The inability of tapeworm Hymenolepis diminuta and fluke Dicrocoelium dendriticum to metabolize praziquantel

Biotransformation enzymes can, to a certain extent, protect parasitic worms against the toxic effects of anthelmintics and can contribute to drug-resistance development. The objective of our work was (1) to find and identify phase I and II metabolites of the anthelmintic praziquantel (PZQ) formed by the lancet fluke (Dicrocoelium dendriticum) and the rat tapeworm (Hymenolepis diminuta) and (2) to compare PZQ metabolites in helminths with PZQ biotransformation in rat as host species. Ultra high performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) was used for this purpose. During in vitro incubations, mitochondria-like and microsomes-like fractions (prepared from homogenates of adult worms or from rat liver homogenate) were incubated with 10 and 100μM PZQ. Liquid/liquid extraction was used for samples during in vitro experiments. In the ex vivo study, living D. dendriticum and H. diminuta adults were incubated in RPMI-1640 medium in the presence of 50nM or 100nM PZQ for 24h. After incubation, the worms were removed from the medium and homogenized. Homogenates of worms, medium from the incubation of worms or rat hepatocytes and rat urine (collected during 24h after oral PZQ administration) were separately extracted using solid-phase extraction.The results showed that both D. dendriticum and H. diminuta enzymatic systems are not able to metabolize PZQ. On the other hand, thirty one different phase I and four phase II PZQ metabolites were detected in rat samples using UHPLC/MS/MS analyses. These results show that our experimental helminths, as the members of tapeworm and fluke groups of parasites, are not able to deactivate PZQ, and that the biotransformation enzymes of the studied helminths do not contribute to PZQ-resistance.

Three Major Metabolites of Mulberroside A in Rat Intestinal Contents and Feces

Mulberroside A, a major stilbene constituent of MORUS ALBA L. (Moraceae), displays significant antitussive and antiasthmatic effects in animals. As part of our ongoing research on its biotransformation in rats, mulberroside A was orally administered to rats, and the metabolites in the gastrointestinal contents and feces were investigated. Three major metabolites were isolated from the feces of rats and identified as oxyresveratrol-2- O- beta- D-glucopyranoside ( 1), oxyresveratrol-3'- O- beta- D-glucopyranoside ( 2), and oxyresveratrol ( 3) on the basis of chemical and spectroscopic evidence. The three metabolites were also detected in the small intestinal contents of rats following oral administration of mulberroside A. These findings suggest that mulberroside A is metabolized prior to absorption into the body.

Isolation and Identification of Urinary Metabolites of Berberine in Rats and Humans

The urinary metabolites of berberine, an isoquinoline alkaloid isolated from several Chinese herbal medicines, were investigated in rats and humans. Using macroporous adsorption resin chromatography, open octadecyl silane column chromatography and preparative high-performance liquid chromatography, we isolated seven metabolites (HM1-HM7) from human urine and five metabolites (RM1-RM5) from rat urine after oral administration. Their structures were elucidated by enzymatic deconjugation and analyses of mass spectrometry, (1)H NMR, and nuclear Overhauser effect spectroscopy spectra. Besides the three known metabolites demethyleneberberine-2-O-sulfate (HM1 and RM3), jatrorrhizine-3-O-sulfate (HM5), and thalifendine (RM5), six new metabolites were identified, namely, jatrorrhizine-3-O-beta-D-glucuronide (HM2), thalifendine-10-O-beta-D-glucuronide (HM3), berberrubine-9-O-beta-D-glucuronide (HM4 and RM2), 3,10-demethylpalmatine-10-O-sulfate (HM6 and RM4), columbamin-2-O-beta-D-glucuronide (HM7), and demethyleneberberine-2,3-di-O-beta-D-glucuronide (RM1). These findings suggest that berberine undergoes similar biotransformation in rats and humans. Possible metabolic pathways of berberine in rats and humans are proposed.

High-pressure liquid chromatographic analysis for identification of in vitro and in vivo metabolites of 4-phenethyl-5-[4-(1-(2-hydroxyethyl)-3,5-dimethyl-4-pyrazolylazo)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thione in rats

All azo colorants whose metabolism can liberate a carcinogenic arylamine, are suspected of having carcinogenic potential. Therefore, a new azo compound 4-phenethyl-5-[4-(1-(2-hydroxyethyl)-3,5-dimethyl-4-pyrazolylazo)phenyl]-2,4-dihydro-3H-1,2,4-triazole-3-thione (substrate) was prepared to investigate its in vitro and in vivo biotransformation in rats by HPLC. Chromatographic separation of substrate and its metabolites was performed using a Chromasil C(18) column. The mobile phase consisted of acetonitrile and water in a linear gradient system. From the biotransformation of this compound, the reduction metabolite 4-(2-phenethyl)-5-(4-aminophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione was identified by comparing it to reference standard by HPLC-DAD. In the in vivo study, identification of the unknown peak which was the N-acetylation metabolite was confirmed by LC-MS spectrometry. Besides this, the azo compound was reduced to its corresponding amine in intestinal and cytosolic parts. In addition, oxidation of the methyl group and the phenyl ring, and reduction of azo group to hydrazo were identified in the cytosolic part using LC-MS.

Characterization of enzymes responsible for biotransformation of the new antileukotrienic drug quinlukast in rat liver microsomes and in primary cultures of rat hepatocytes.

The promising new drug quinlukast, 4-(4-(quinoline-2'-yl-methoxy)phenylsulphanyl)benzoic acid (VUFB 19363), is under investigation for its anti-inflammatory and anti-asthmatic effects. The main metabolite of quinlukast identified in incubations of rat microsomal fraction, and in primary culture of rat hepatocytes, is quinlukast sulfoxide (M2). Also, several other metabolites of quinlukast were found: two dihydrodiol derivatives (M3, M5) and quinlukast sulfone (M4). This study was conducted to characterize the enzymes involved in quinlukast biotransformation in rat in-vitro. Primary cultures of rat hepatocytes were treated with inducers of different cytochrome P450s (CYPs) for 48 h. Quinlukast (100 microM) was incubated for 24 h in a primary culture of induced or control hepatocytes. The effects of CYP inhibitors, ketoconazole, methylpyrazole, metyrapone and alpha-naphthoflavone (2, 10, 50 microM), on quinlukast metabolism were tested in induced and control hepatocytes. Significant induction of M2 (6 times), M5 (twice) and M3 (by 50%) formation by dexamethasone and strong concentration-dependent inhibition by ketoconazole indicated that CYP3A participates in formation of these metabolites. CYP1A catalyses formation of metabolite M3 mainly, as beta-naphthoflavone induced (10 times) production of M3 and a strong inhibitory effect of alpha-naphthoflavone on its formation was observed. A significant inhibitory effect of quinlukast (2, 10, 50 microM) on ethoxyresorufin, methoxyresorufin and benzyloxyresorufin O-dealkylase activity was observed as well.

The influence of L-carnitine on methanol biotransformation in rats

There persists a need for potent and safe inhibitors of alcohol dehydrogenase (ADH), to effectively treat methanol poisoning by slowing its rate of biotransformation to there toxic products, formaldehyde and formic acid. Only a few former papers have reported on the significant effectiveness of L-carnitine in treating ethanol poisoning as well as alcohol abuse. As are no reports on the effectiveness of L-carnitine in treating methanol poisoning till now, the current studies were conducted to investigate the influence of L-carnitine on both oxydative metabolism and elimination of methanol in rats. Male Sprague-Dawley rats, aged 3 months with the body weight of 200-230 g were divided into 6 groups at random, with two of the groups considered to be control. Rats were given drinking water (control) or methanol in two different doses of 3220 mg/kg b.m. or 6440 mg/kg b.m. intragastrically and 0.9% NaCl (control) or 6.2 mmol/kg b.m. of L-carnitine intraperitionelly. Within 96 hours after the administration of methanol and 0.9% NaCl or L-carnitine, the urine was collected and then the animals were decapitated. To determine methanol there were taken blood samples for clot, and to determine carnitine and its derivatives blood was taken into heparinized test tubes. During the autopsy liver was also secured. In all the experimental time points stated the methanol concentrations in blood, urine and liver homogenate were determined by a head-space gas chromatography.

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.

Minimal effect of acute experimental hepatitis induced by lipopolysaccharide/ d-galactosamine on biotransformation in rats

When administered with d-galactosamine, lipopolysaccharide endotoxins produce a good experimental animal model of hepatitis. This galactosamine plus endotoxin model has been used widely, but the acute effect of this fixed combination of two chemicals on hepatic and extrahepatic biotransformation has not been determined. Therefore, either 2 or 4 hr after a single intraperitoneal dose of 300 mg/kg galactosamine plus 30 μg/kg lipopolysaccharide was administered, serum, liver, kidney, intestine, and spleen were collected. Serum enzymes (alanine and aspartate aminotransferases, sorbitol dehydrogenase, and γ-glutamyltranspeptidase) were elevated dramatically 2 and 4 hr after treatment. Cytochrome P450 monooxygenase activity toward benzo-[a]pyrene was increased in kidney 4 hr after treatment, whereas dealkylation of 7-methoxycoumarin or 7-ethoxyresorufin was unchanged in any tissue at either time point. An increase in UDP-glucuronosyltransferase activity toward 4-methylumbelliferone and 4-hydroxybiphenyl was noted in the intestine. Conjugation of 1-chloro-2,4-dinitrobenzene with glutathione was increased in intestine and spleen 2 hr after treatment. γ-Glutamyltranspeptidase activity was unaltered in all tissues studied. Reduced glutathione concentrations were increased significantly by different amounts depending on which organs were studied 2 or 4 hr after treatment. These results indicate that galactosamine/lipopolysaccharide-induced liver injury is not accompanied by major effects on the examined biotransformation reactions.

Preparation of N-methoxycarbonyl-N′-[2-nitro-4(5)-propylthiophenyl]thiourea as prodrugs of albendazole

N-methoxycarbonyl-N′-(2-nitro-4-propylthiophenyl)thiourea and N-methoxycarbonyl-N′-(2-nitro-5-propylthiophenyl)thiourea, prodrugs of albendazole, have been synthesized. The biotransformation in rats, after oral administration of these prodrugs to albendazole and albendazole sulphoxide, is described.

Cyclic Peptides from Higher Plants. XXVIII. Antitumor Activity and Hepatic Microsomal Biotransformation of Cyclic Pentapeptides, Astins, from Aster tataricus.

Antitumor activities on Sarcoma 180A of a series of cyclic pentapeptides, astins, isolated from the roots of Aster tataricus, were examined. The activities on various congeners of the dichlorinated proline residues prepared by chemical conversion and a hepatic microsomal biotransformation in rats suggested that 1,2-cis dichlorinated proline residues of astins A, B and C play an important role in the antitumor activity of astins.

Acid reaction products of indole-3-carbinol and their effects on cytochrome P450 and phase II enzymes in rat and monkey hepatocytes

The effects of three acid condensation products of indole-3-carbinol (I3C), i.e. 3,3'-diindolylmethane (DIM), 5,6,11,12,17,18-hexahydrocyclonona[1,2- b:4,5- b:7,8- b]tri-indole (CTI) and 2,3-bis[3-indolylmethyl]indole (BII), on cytochrome P450 and phase II enzymes were studied in primary cultures of rat and cynomolgus monkey liver cells. In rat hepatocytes all three indole derivatives dose-relatedly induced the ethoxyresorufin O-dealkylation (EROD) activity (to 24-fold) and 7α- hydroxylation of testosterone (to 4-fold), whereas all three decreased the 16α- and 2α-testosterone hydroxylation (DIM to 60%, CTI and BII to a mere 5% of the control cells). Treatment of monkey hepatocytes with DIM and BII enhanced the EROD activity to 6- and 9-fold, respectively. Furthermore, BII decreased the 6β-hydroxylation of testosterone (to 60% of the untreated cultures) in monkey cells. Phase II enzymes were also affected. In rat hepatocytes DIM, CTI and BII enhanced DT-diaphorase (DTD) (= NAD(P)H-quinone reductase) activity, and DIM and BII the glucuronidation of 1-naphthol. In monkey cells BII only enhanced DTD, and no changes were observed in the glucuronidation of 1- naphthol after treatment with either DIM or BII. The indole derivatives did not affect glutathione S- transferase activity and sulfation of 1-naphthol in either rat or monkey hepatocytes. These results identify two novel acid condensation products of I3C, CTI and BII, as potent compounds in affecting biotransformation in rat as well as in monkey hepatocytes.