Microsomal Monooxygenase Research Articles

INFLUENCE OF SODIUM GLUTAMATE ON REACTIVE OXYGEN AND NITROGEN SPECIES PRODUCTION IN KIDNEY TISSUES OF RATS UNDER ACUTE DESYNCHRONIZATION AND LIPOPOLYSACCHARIDE-INDUCED SYSTEMIC INFLAMMATORY RESPONSE

The study investigated the effect of sodium glutamate on the production of reactive oxygen and nitrogen species (ROS/RNS) in kidney tissues of rats under conditions of acute desynchronization (AD) and lipopolysaccharide (LPS)-induced systemic inflammatory response (SIR) and, thus, contributed to a deeper understanding of the mechanisms involved in the development of renal dysfunction under these conditions. The experiment was conducted on 21 male Wistar rats (210-230 g), randomly divided into three groups: intact animals, a group exposed to AD modeling under LPS-induced systemic inflammatory response (Group II), and a group (Group 3) exposed to AD modeling under LPS-induced systemic inflammatory response, who received sodium glutamate in a dose of 20 mg/kg. The administration of sodium glutamate significantly increased the generation rate of the superoxide anion radical by 13.8% through microsomal monooxygenases, by 8.7% through the mitochondrial respiratory chain, and by 7.7% through leukocyte NADPH oxidase compared to Group 2. However, sodium glutamate did not affect the total NO synthase activity or the activity of its constitutive and inducible isozymes in the kidney homogenate compared to Group 2. The uncoupling index of constitutive NO synthases in kidney tissues also remained unchanged under the administration of sodium glutamate, but the peroxynitrites were 20.5% higher, and S-nitrosothiols were 11.6% higher, than in group 2. The findings indicate that sodium glutamate significantly increases oxidative-nitrosative stress in rat kidney tissues under AD and LPS-induced SIR, resulting in excessive ROS/RNS formation.

Immobilization of Membrane-Associated Protein Complexes on SERS-Active Nanomaterials for Structural and Dynamic Characterization.

Exploring the structural basis of membrane proteins is significant for a deeper understanding of protein functions. In situ analysis of membrane proteins and their dynamics, however, still challenges conventional techniques. Here we report the first attempt to immobilize membrane protein complexes on surface-enhanced Raman scattering (SERS)-active supports, titanium dioxide-coated silver (Ag@TiO2) nanoparticles. Biocompatible immobilization of microsomal monooxygenase complexes is achieved through lipid fission and fusion. SERS activity of the Ag@TiO2 nanoparticles enables in situ monitoring of protein-protein electron transfer and enzyme catalysis in real time. Through SERS fingerprints of the monooxygenase redox centers, the correlations between these protein-ligand interactions and reactive oxygen species generation are revealed, providing novel insights into the molecular mechanisms underlying monooxygenase-mediated apoptotic regulation. This study offers a novel strategy to explore structure-function relationships of membrane protein complexes and has the potential to advance the development of novel reactive oxygen species-inducing drugs for cancer therapy.

Вплив кверцетину на показники оксидативнонітрозативного стресу в тканинах нирок щурів за умов гострого десинхронозу та ліпополісахаридіндукованої системної запальної відповіді

The relevance of this study stems from the growing interest in the impact of acute desynchronosis (AD) on oxidative disorders and the insufficiently studied effect of flavonoids on these processes in kidney tissue. This study investigates the effect of quercetin on oxidative and nitrosative stress in rat kidney homogenate under AD and 3 lipopolysaccharide (LPS)-induced systemic inflammatory response (SIR). The animals were randomly divided into five groups: group 1 served as the control, group 2 underwent LPS-induced SIR modeling for 8 weeks, group 3 experienced AD reproduction by shifting the light-dark cycle 6 hours earlier for 7 days, group 4 underwent AD modeling during the last week of LPS-induced SIR, and rats in group 5 were administered a water-soluble form of quercetin (corvitin) intragastrically was administered at a dose of 200 mg/kg (20 mg/kg in terms of quercetin) daily during the AD modeling against LPS-induced SIR. It was found that the modeling of LPS-induced oxidative stress and AD significantly increased the rate of superoxide anion radical production in kidney homogenate by microsomal monooxygenases and NO synthase (NOS), mitochondrial respiratory chain, leukocyte NADPH oxidase, inducible NOS activity, and decreased the activity of the constitutive NOS isoform and its coupling index. Under AD modeling, the rate of superoxide anion radical production by leukocyte NADPH oxidase, total and inducible NOS activity was significantly lower compared with LPS-induced SIR. When modeling AD against the background of LPS-induced SIR, the production of superoxide anion radical by microsomes, mitochondria and leukocyte NADPH oxidase exceeded the respective results of group 2 by 15.9%, 16.0% and 38.5%, and group 3 by 24.4%, 17.5% and 74.6%. The inducible NOS activity was 22.9% higher compared to the value of group 2 and 93.4% higher in group 3, the concentration of peroxynitrites of alkali and alkaline earth metals was 35.5% higher than the respective parameters of group 2 and 57.9% higher than in group 3. Administration of quercetin during AD modeling and LPS-induced oxidative stress significantly reduced the rate of superoxide anion radical production by microsomal monooxygenases by 17.1%, mitochondrial respiratory chain by 31.2%, leukocyte NADPH oxidase by 19.4%, total and inducible NOS activity by 50.4% and 55.5%, respectively; the concentration of peroxynitrites of alkali and alkaline earth metals diminished by 41.4% compared to the value of group 4. It has been concluded that the administration of quercetin significantly reduces the signs of oxidative-nitrosative stress in the kidney homogenate of rats.

Comparative Analysis of Bioelectrocatalytic Cytochrome P450 3A4 Systems

This article describes the approaches developed by the authors with the aim to increase the efficiency of electro enzymatic reactions catalyzed by cytochrome P450 3A4. A comparative analysis of cytochrome P450 3A4 systems was carried out during the formation of the functional complexes hemoprotein-flavin nucleotides as low-molecular models of NAD(P)H-dependent cytochrome P450 reductase. The formation of a productive enzyme-substrate complex before the stage ofaccepting electrons from the modified electrode was studied from the electocatalytic viewpoint. Incorporation of the enzyme into nanopores of different nature on the electrode (2D-3D transition) was also studied. The results on the electrochemical reduction of bactosomes as the functionally active models of the microsomal monooxygenase system are also considered. The electrochemical and electrocatalytic parameters of cytochrome P450 3A4 were compared for different models of the electrocatalytic generation of metabolites.

In Situ and Real-Time Monitoring of Mitochondria-Endoplasmic Reticulum Crosstalk in Apoptosis via Surface-Enhanced Resonance Raman Spectroscopy.

The crosstalk between mitochondria and endoplasmic reticula plays a crucial role in apoptotic pathways in which reactive oxygen species (ROS) produced by microsomal monooxygenase (MMO) are believed to accelerate cytochrome c release. Herein, we successfully demonstrate the potential of surface-enhanced resonance Raman spectroscopy (SERRS) for monitoring MMO-derived ROS formation and ROS-mediated cytochrome c release. Silver nanoparticles coated with nickel shells are used as both Raman signal enhancers and electron donors for cytochrome c. SERRS of cytochrome c is found to be sensitive to ROS, allowing for in situ probing of ROS formation with a cell death inducer. Label-free evaluation of ROS-induced apoptosis is achieved by SERRS-based monitoring of cytochrome c release in living cells. This study verifies the capability of SERRS for label-free, in situ, and real-time monitoring of the mitochondria-endoplasmic reticulum crosstalk in apoptosis and provides a novel strategy for the rational design and screening of ROS-inducing drugs for cancer treatment.

Effects of acaricides on the activities of monooxygenases in bovine liver microsomes.

Organophosphates (OPs), pyrethrins and fipronil, are acaricides commonly used in cattle, mainly as pour on formulations. Scant information is available on their potential interactions with hepatic xenobiotic metabolizing enzymes. This work aimed to evaluate in vitro the potential inhibitory effects of widely employed acaricides on catalytic activities mediated by hepatic cytochrome P450 (CYP) and flavin-monooxygenase (FMO) enzymes in cattle. Bovine (n = 4) liver microsomes were incubated in the absence (control assays) and in presence of different OPs (fenthion, chlorpyrifos, ethion, diazinon and dichlorvos), fipronil and cypermethrin at 0.1-100 μm. Five oxidative enzyme activities were assayed by spectrofluorimetric or HPLC methods: 7-ethoxyresorufin O-deethylase (for CYP1A1), methoxyresorufin O-demethylase (for CYP1A2), benzyloxyresorufin O-debenzylase (for CYP2B), testosterone 6-beta hydroxylase (for CYP3A) and benzydamine N-oxidase (for FMO). All acaricides, particularly phosphorothionate-containing OPs, inhibited to some extent more than one enzyme activity. The most frequent inhibitor was fenthion, which inhibited (p < .05) all enzyme activities tested (from 22% at 1 μm to 72% at 100 μm). However, low inhibitory potencies (IC50s higher than 7 μm) of all acaricides studied were observed against the catalytic activities assayed. Therefore, the risk of in vivo metabolic interactions due to inhibition of monooxygenases would be low under common husbandry conditions.

EFFECT OF CURCUMIN ON THE DEVELOPMENT OF OXIDATIVE-NITROSATIVE STRESS IN THE LIVER TISSUES OF RATS EXPOSED TO MODELED METABOLIC SYNDROME UNDER ROUND-THE-CLOCK LIGHTING

The aim of this study is to evaluate the effect of curcumin, a natural polyphenol, on indicators of oxidative-nitrosative stress in the liver of rats exposed to modeled metabolic syndrome (MS) under 24-hour lighting. The experiments were performed on 21 Wistar male white rats weighing 215-255 g. The animals were divided into 3 groups of 7 animals in each. The animals of the 1st group (control I) were kept on a standard vivarium diet and an ordered alternation of light / dark periods. The rats of the 2nd group were used for modeling diet-induced MS (a 2-month carbohydrate-lipid diet including 20% aqueous fructose solution for drinking and appropriate food) under the 24-hour lighting (control II). The rats of the 3rd group received curcumin (Sigma-Aldrich, Inc., USA) intragastrically through a gavage in a dose of 200 mg/kg daily during the 24-hour lighting exposure. We investigated the liver homogenate of rats to assess the rate of generation of the superoxide anion radical (•О), the activity of total NO synthase (NOS), its constitutive and inducible isoforms (cNOS, iNOS), and the content of peroxynitrites of alkali and alkaline earth metals. The administration of curcumin under the experimental conditions significantly suppresses the •О production in liver tissues by microsomal monooxygenases and NOS by 40.1%, by the mitochondrial respiratory chain by 34.4%, and by leukocyte NADPH oxidase by 32.1%; the activity of NOS and iNOS by 39.0% and 41.6%, the concentration of peroxynitrites of alkaline and alkaline earth metals by 23.8 compared to the values in the 2nd group. The activity of cNOS under these conditions was 2.79 times higher than the respective results in the II control, and the coupling index of this isoenzyme was 4.3 times higher. The main conclusion that can be drawn is that the administration of curcumin in the rat model of MS under the round-the-clock lighting significantly reduces the signs of oxidative-nitrosative stress in the liver tissues.

Electron transfer between cytochrome c and microsomal monooxygenase generates reactive oxygen species that accelerates apoptosis

Generation of reactive oxygen species (ROS) are possibly induced by the crosstalk between mitochondria and endoplasmic reticula, which is physiologically important in apoptosis. Cytochrome c (Cyt c) is believed to play a crucial role in such signaling pathway by interrupting the coupling within microsomal monooxygenase (MMO). In this study, the correlation of ROS production with the electron transfer between Cyt c and the MMO system is investigated by resonance Raman (RR) spectroscopy. Binding of Cyt c to MMO is found to induce the production of ROS, which is quantitatively determined by the in-situ RR spectroscopy reflecting the interactions of Cyt c with generated ROS. The amount of ROS that is produced from isolated endoplasmic reticulum depends on the redox state of the Cyt c, indicating the important role of oxidized Cyt c in accelerating apoptosis. The role of electron transfer from MMO to Cyt c in the apoptotic mitochondria-endoplasmic reticulum pathway is accordingly proposed. This study is of significance for a deeper understanding of how Cyt c regulates apoptotic pathways through the endoplasmic reticulum, and thus may provide a rational basis for the design of antitumor drugs for cancer therapy.

Вплив епігалокатехін-3-галату та кверцетину на утворення активних форм кисню та азоту в печінці щурів за умов їх цілодобового освітлення та утримання на вуглеводно-ліпідній дієті

The purpose of this study is to investigate the effects of bioflavonoids, epigallocatechin-3-gallate (EGCG) and quercetin, on the production of reactive oxygen and nitrogen species in the liver of rats under round-the-clock light exposure with an intensity of 1500 lux for 30 days while being kept on carbohydrate-lipid diet (20% fructose solution and appropriate food) for 60 days. In the liver tissues, the rate of the superoxide anion production by NADPH-dependent electron transport chains (microsomal monooxygenases and constitutive uncoupled NO synthases) increased by 1.93 times, by the mitochondrial respiratory chain by 1.89 times, and it was doubled by leukocyte NADPH-oxidase. The total activity of NO synthase was increased by 2.35 times, the activity of its inducible isoform increased by 2.57 times, and the concentration of alkali and alkaline earth metals peroxynitrites elevated by 1.68 times. Administration of bioflavonoids-epigallocatechin-3-gallate and quercetinsignificantly restrained the rate of superoxide anion production in the liver tissues by microsomal monooxygenases and NO synthase by 39.1 and 40.1%, by the mitochondrial respiratory chain by 37.2 and 34.4%, by leukocyte NADPH-oxidase by 35.0 and 32.1%, respectively. Epigallocatechin-3-gallate and quercetin inhibited the total activity of NO-synthase by 46.7 and 36.2%, the activity of its inducible isoform by 49.6 and 39,0%, increased the activity of the constitutive isoenzyme NO-synthase by 2.9 times and its coupling index by 4.5 and 4.7 times. Additionally, administration of these bioflavonoids lowered the concentration of peroxynitrites of alkali and alkaline earth metals by 30.5 and 34.3% compared to the respective values obtained in the group of rats, which did not receive the bioflavonoids, but were exposed to light and carbohydrate-lipid-rich diet. We suggest that epigallocatechin3-gallate and quercetin in the above experimental conditions are effective means to restrain the formation of reactive oxygen and nitrogen species in the liver tissue.

POLYPHENOLS AS A MEANS TO CORRECT OXIDATIVE-NITROSATIVE STRESS IN SKELETAL MUSCLES OF RATS UNDER EXPERIMENTAL METABOLIC SYNDROME

The studies were carried out on 35 Wistar white male rats weighing 215-255 g, divided into 5 groups: intact animals (group 1, control I); animals of other groups exposed to round-the-clock illumination (1500 lux during the last 30 days of the experiment) and kept on a carbohydrate-lipid diet (60 days) daily received 1 ml of a 20% aqueous fructose solution (group 2, "placebo", control II), epigallocatechin-3-gallate (group 3, a daily dose of 40 mg/kg), quercetin (group 4, a daily dose of 200 mg/kg), and resveratrol (group 5, a daily dose of 5 mg/kg). The substances were administered intragastrically. Polyphenols were injected together with carbohydrates, a 20% aqueous fructose solution, which increases their solubility and bioavailability. Modelled metabolic syndrome (MS) manifested the development of signs of oxidative-nitrosative stress in the muscles of the thigh: an increase in the superoxide anion radical generation by NADPHand NADHdependent electron transport systems (by microsomal monooxygenases and NO-synthase, by the mitochondrial respiratory chain); elevation in the activity of NO-synthase due to its inducible isoenzyme, and peroxynitrite concentration. The administration of polyphenols (epigallocatechin-3-gallate, quercetin, and resveratrol) over the MS modelling has been found out as an effective means to restrain the signs of oxidative-nitrosative stress in the muscles of the thigh that is confirmed by a decrease in the production of superoxide anion radicals by NADPHand NADH-dependent electron transport systems and constitutive isoform of NO-synthase, by lowered activity of NO-synthase due to its inducible isoform and a fall in the concentration of peroxynitrites. Thus, the capability of bioflavonoids and resveratrol to restrict oxidative-nitrosative stress in skeletal muscles under experimental conditions gives grounds to investigate them as safe and effective means in the therapy and prevention of metabolic syndrome associated with the impact of such factors as the modern "Western diet" and the light regime impairment.

Ліпополісахаридіндукована системна запальна відповідь обтяжує розвиток окисно-нітрозативного стресу в слинних залозах щурів при їх алкогольному ураженні

We addressed the role of lipopolysaccharide (LPS)-induced systemic inflammatory response (SIR) in the development of oxidative-nitrosative stress in the salivary glands of rats under the influence of alcohol. Ethanol (40%) at the dose of 24 mg/kg was administered intraperitoneally (ip) twice per day for 14 days. SIR was induced by ip administration of LPS (Salmonella typhi) at the dose 0.4 mg/kg for 1 week followed by a weekly LPS administration for 7 weeks. We found that long-term administration of ethanol in the back- ground of LPS-induced SIR increased the circulating level of proinflammatory markers (TNFa, IL-6) and C-reactive protein and this increase exceeded the respective values when LPS and alcohol were administered separately. Under these conditions, in submandibular salivary glands, the superoxide anion production by mitochondria respiratory chain was increased by 25.9 and 30.5%, by microsomal monooxygenases and NO synthase by 19.0 and 27,1%, by phagocyte NADPH-oxidase by 29.5 and 30.0%. The activity of inducible NO-synthase increased by 15.5 and 83.6%, the concentration of peroxynitrites of alkali and alkali-earth metals elevated by 32.5 and 58, 3%, and S- nitrosothiols raised by 20.2 and 22.7%. These changes were accompanied by a decrease in α-amylase activity and the aquaporin-5 concentration that impairs water and protein excretion by salivary glands. We conclude that adminis- tration of ethanol in the background of LPS-induced SIR results in more pronounced development of oxidative- nitrosative stress in the submandibular salivary glands and more marked dysfunction compared to separate use of LPS and alcohol.

Biological profile of medical response in alcoholic patients of different ethnic groups in Siberia

IntroductionThe individual sensitivity of a person to the effects of alcohol is defined as the possibility of adaptive reactions, which are controlled by various factors associated in their manifestation with characteristics in various ethnic populations.ObjectivesTo determine biological profile of medical response in alcoholic patients of different ethnic groups.Methods168 alcoholic men, aged 17 to 62 years were examined. For the therapeutic correction of withdrawal and post-withdrawal symptoms of patients from two different ethnic groups (Tatars and Russians in Siberia), the original anticonvulsant galodif (M-chloro-benzhydrylurea) was used. Pharmacokinetic parameters were calculated a model-independent method of statistical moments: half-life (T1/2,h), total clearance (Clt,ml/min), average time of the residual drug in the body (MRI,h), average elimination time (MET,h), the area under the pharmacokinetic curve (AUC, μg/ml).ResultsGalodif causes a reduction in almost half T1/2, a significant decrease in the average time of the residual drug in the body MRI, and the average elimination time MET. Overall clearance increased. Under the influence of the course with Galodif, antipyrine elimination intensified, which indicates the induction of the cytochrome P-450 system of microsomal liver monooxygenases in Russian alcoholic patients. Galodif causes a reduction of almost five-fold T1/2, a significant decrease MRI and MET. Activation of oxidative metabolism of xenobiotics in Tatar alcoholic patients is more significant.ConclusionsThe increased sensitivity of P-450 cytochrome system to anticonvulsants action with inductive detoxification properties reflects differences in adaptive mechanisms in human from various ethnic groups, what is significant in the therapy.DisclosureNo significant relationships.

Influence of cranioskeltal trauma, complicated with blood loss, on the bile-forming function of liver during the early period of traumatic disease among rats with different resistance to hypoxia and its correction

Introduction. The development of multiorgan dysfunction and insufficiency is one of the serious complications of severe multiple and combined lesions. In their pathogenesis, a key role is played by secondary lesions of organs remote from the site of direct injury, which is caused by the systemic response of the body to inflammation and is a characteristic feature of traumatic disease. As a model of the development of organ damage in experimental polytrauma, the biliary function of liver is often investigated. However, the features of systemic disorders, in particular, the biliary function of liver, in conditions of severe skeletal injury, depending on the resistance to hypoxia, have not been studied enough.Purpose: to determine the dynamics of biliary function of liver in case of cranioskeletal trauma complicated with blood loss among rats with different resistance to hypoxia during the early period of traumatic disease and to evaluate the effectiveness of thiocetam in the correction of identified disorders.Materials and methods. 108 nonlinear white male rats weighing 180-200 g were used in the experiments. Previously, individual resistance to hypoxia was determined, rats were divided into two groups: with high- and low-resistance (HR and LR) animals to hypoxia. Subsequently, HR and LR rats were divided into 4 groups: one control and three experimental. Under conditions of thiopentale sodium anesthesia (40 mg kg-1) the first experimental group HR and LR of rats was had cranioskeletal trauma, the second - acute blood loss in the amount of 20-22% of circulating blood volume, the third experimental group after application of cranioskeletal injuries and acute blood loss in order to correct HR and LR-rats were thrown Thiocetam intraperitoneally, dose 250 mg kg-1 of body weight 1 time per day. Animals of the control and experimental groups in 1, 3 and 7 days after injury were catheterized the common bile duct, collected bile, in which the content of total bile acids was determined.It was found out that laboratory white rats, which are genetically different in resistance to hypoxia, also differ in the intensity of biliary function of liver. Among HR rats, the bile content of total bile acids was higher than that among LR rats. Under the influence of cranioskeletal injury, the bile content of total bile acids decreased among both HR and LR rats. Despite the lower initial content of total bile acids in the bile of LR rats, under the influence of cranioskeletal trauma in this group, the degree of the studied indicator reduction was significantly greater than among HR rats, indicating greater sensitivity of LR rats to pathogens of traumatic disease, which lead to damage to the microsomal monooxygenase system of hepatocytes. Under the conditions of acute blood loss additional modeling, the disorders were more visible, but the result was statistically significant only among LR rats in 3 days of the experiment. In addition, LR rats had a greater degree of reduction of the studied indicator in 3 and 7 days of the experiment. Under the influence of seven-day-usage of Thiocetam in the groups of LR and HR rats with cranioskeletal trauma, the violation of total bile acids content in the bile became significantly lower compared to animals without correction. A similar result was found under conditions of additional acute blood loss. Under these conditions, the degree of increase of total bile acids content in the bile was greater among LR rats than among HR rats, which indicates a higher efficiency of Thiocetam among LR rats.Conclusions: 1. The content of total bile acids in the bile among intact HR-rats is significantly higher than among LR-rats. Under the influence of cranioskeletal trauma, the content of total bile acids in the bile is reduced compared to the control, but the degree of reduction is significantly greater among LR rats after 7 days of the experiment. Complication of cranioskeletal injury with acute blood loss causes a significantly greater reduction in the bile content of total bile acids among LR rats compared with HR rats after 3 and 7 days of the experiment. The use of Thiocetam is accompanied by a decrease of liver biliary dysfunction, which is more visible among LR rats with acute blood loss.

Towards understanding transfluthrin efficacy in a pyrethroid-resistant strain of the malaria vector Anopheles funestus with special reference to cytochrome P450-mediated detoxification

Malaria vector control interventions rely heavily on the application of insecticides against anopheline mosquitoes, in particular the fast-acting pyrethroids that target insect voltage-gated sodium channels (VGSC). Frequent applications of pyrethroids have resulted in resistance development in the major malaria vectors including Anopheles funestus, where resistance is primarily metabolic and driven by the overexpression of microsomal cytochrome P450 monooxygenases (P450s). Here we examined the pattern of cross-resistance of the pyrethroid-resistant An. funestus strain FUMOZ-R towards transfluthrin and multi-halogenated benzyl derivatives, permethrin, cypermethrin and deltamethrin in comparison to the susceptible reference strain FANG. Transfluthrin and two multi-fluorinated derivatives exhibited micromolar potency - comparable to permethrin - to functionally expressed dipteran VGSC in a cell-based cation influx assay. The activity of transfluthrin and its derivatives on VGSC was strongly correlated with their contact efficacy against strain FUMOZ-R, although no such correlation was obtained for the other pyrethroids due to their rapid detoxification by the resistant strain. The low resistance levels for transfluthrin and derivatives in strain FUMOZ-R were only weakly synergized by known P450 inhibitors such as piperonyl butoxide (PBO), triflumizole and 1-aminobenzotriazole (1-ABT). In contrast, deltamethrin toxicity in FUMOZ-R was synergized > 100-fold by all three P450 inhibitors. The biochemical profiling of a range of fluorescent resorufin and coumarin compounds against FANG and FUMOZ-R microsomes identified 7-benzyloxymethoxy-4-trifluoromethylcoumarin (BOMFC) as a highly sensitive probe substrate for P450 activity. BOMFC was used to develop a fluorescence-based high-throughput screening assay to measure the P450 inhibitory action of potential synergists. Azole fungicides prochloraz and triflumizole were identified as extremely potent nanomolar inhibitors of microsomal P450s, strongly synergizing deltamethrin toxicity in An. funestus. Overall, the present study contributed to the understanding of transfluthrin efficacy at the molecular and organismal level and identified azole compounds with potential to synergize pyrethroid efficacy in malaria vectors.

Can a Recently Developed Pig Model Be Used for In Vivo Metabolism Studies of 7-Azaindole-Derived Synthetic Cannabinoids? A Study Using 5F-MDMB-P7AICA.

New psychoactive substances (NPS), especially synthetic cannabinoids (SC) remain a public health concern. Due to ethical reasons, systematic controlled human studies to elucidate their toxicodynamics and/or toxicokinetics are usually not possible. However, such knowledge is necessary, for example, for determination of screening targets and interpretation of clinical and forensic toxicological data. In the present study, the feasibility of the pig model as an alternative for human in vivo metabolism studies of SC was investigated. For this purpose, the metabolic pattern of the SC methyl-2-{[1-(5-fluoropentyl)-1H-pyrrolo[2,3-b]pyridine-3-carbonyl]amino}-3,3-dimethylbutanoate (5F-MDMB-P7AICA) was elucidated in pig urine following inhalative administration (dosage: 200 µg/kg of body weight). The results were compared with human and pig liver microsomal assays and literature. In addition, different incubations with isolated cytochrome-P450 (CYP) monooxygenases were conducted to identify the involved isozymes. In total, nine phase I and three phase II metabolites were identified in pig urine. The most abundant reactions were ester hydrolysis, ester hydrolysis combined with glucuronidation and ester hydrolysis combined with hydroxylation at the tert-butyl moiety. The parent compound was only found up to 1 h after administration in pig urine. The metabolite formed after hydroxylation and glucuronidation was detectable for 2 h, the one formed after ester hydrolyzation and defluorination for 4 h after administration. All other metabolites were detected during the whole sampling time. The most abundant metabolites were also detected using both microsomal incubations and monooxygenase screenings revealed that CYP3A4 catalyzed most reactions. Finally, pig data showed to be in line with published human data. To conclude, the main metabolites recommended in previous studies as urinary targets were confirmed by using pig urine. The used pig model seems therefore to be a suitable alternative for in vivo metabolism studies of 7-azaindole-derived SC.

Comparison of Various Aryl-Dithiolethiones and Aryl-Dithiolones As Hydrogen Sulfide Donors in the Presence of Rat Liver Microsomes.

It has been reported that microsomal metabolism of ADT (5-(p-methoxyphenyl)-3H-1,2-dithiole-3-thione, anetholedithiolethione, Sulfarlem) and ADO (5-(p-methoxyphenyl)-3H-1,2-dithiole-3-one, anetholedithiolone) led to formation of H2S mainly derived from oxidations catalyzed by cytochrome P450-dependent monooxygenases and that ADO was a better H2S donor than ADT under these conditions. This article compares the H2S donor abilities of 18 dithiolethione and dithiolone analogs of ADT and ADO upon incubation with rat liver microsomes. It shows that, for all the studied compounds, maximal H2S formation was obtained after incubation with microsomes and NADPH and that this formation greatly decreased in the presence of N-benzylimidazole, a known inhibitor of cytochrome P450. This indicates that H2S formation from all the studied compounds requires, as previously observed in the case of ADT and ADO, oxidations catalyzed by cytochrome P450-dependent monooxygenases. Under these conditions, the studied dithiolones were almost always better H2S donors than the corresponding dithiolethiones. Interestingly, the best H2S yields (up to 75%) were observed in microsomal oxidation of ADO and its close analogs, pCl-Ph-DO and Ph-DO, in the presence of glutathione (GSH), whereas only small amounts of H2S were formed in microsomal incubations of those compounds with GSH but in the absence of NADPH. A possible mechanism for this effect of GSH is proposed on the basis of results obtained from reactions of GSH with 5-(p-methoxyphenyl)-3H-1,2-dithiole-3-one-1-sulfoxide, the ADO metabolite involved in H2S formation in microsomal oxidation of ADO. SIGNIFICANCE STATEMENT: A series of 18 dithiolethiones and dithiolones were compared for their ability to form hydrogen sulfide (H2S) in oxidations catalyzed by microsomal monooxygenases. The studied dithiolones were better H2S donors than the corresponding dithiolethiones, and the addition of glutathione to the incubations strongly increased H2S formation. A possible mechanism for this effect of GSH is proposed on the basis of results obtained from reactions of GSH with 5-(p-methoxyphenyl)-3H-1,2-dithiole-3-one-1-sulfoxide, a metabolite of the choleretic and sialologic drug Sulfarlem.

Biosensor selection of small compounds, modulating a complex formation between cytochrome P450s and NADPH-dependent P450 oxidoreductase

The study of the effect of low-molecular-weight compounds (substrates, endogenous metabolites, drugs and xenobiotics) on the kinetic and equilibrium parameters of functionally significant binary protein-protein interactions (PPIs) is of both fundamental and clinical importance. The surface plasmon resonance (SPR) is the method of the first choice for studying PPIs. Earlier, SPR analysis revealed the modulating effect of steroidal substrates on the affinity of interactions between steroidogenic microsomal cytochromes P450 (CYP) and their redox partner (cytochrome b5). In this work, we have shown the suitability of the experimental approach for assessing the selective effect of the cofactor NADPH on the interaction between cytochromes CYP3A4 or CYP2E1 with NADPH-dependent P450 oxidoreductase (CPR). Experiments have shown that the CYP3A4/CPR complex is not modulated by NADPH, while the dissociation rate of the CYP2E1/CPR complex in the presence of NADPH significantly decreased: the koff values in the absence and presence of NADPH were (3.6 ± 0.2) • 10-3 s-1 and (3.8 ± 0.2) • 10-4 s-1, respectively. Thus, in the presence of NADPH, an increase in the affinity of CYP2E1/CPR complex formation by approximately one order of magnitude was observed, while NADPH did not affect the kon value of this complex. Co-injection of NADPH at the CYP2E1/CPR complex preformed in the absence of NADPH had minor influence on the koff values (&lt;10%). This suggests a stabilizing role of NADPH for the CYP2E1/CPR complex formation. Thus, the use of our approach made it possible to assess the effect of the main electron supplier for the microsomal cytochrome P450 monooxygenase system on the kinetic rate constants of CYP/CPR complexes.

Viral-mediated gene delivery of TMBIM6 protects the neonatal brain via disruption of NPR-CYP complex coupled with upregulation of Nrf-2 post-HI

BackgroundOxidative stress, inflammation, and endoplasmic reticulum (ER) stress play a major role in the pathogenesis of neonatal hypoxic-ischemic (HI) injury. ER stress results in the accumulation of unfolded proteins that trigger the NADPH-P450 reductase (NPR) and the microsomal monooxygenase system which is composed of cytochrome P450 members (CYP) generating reactive oxygen species (ROS) as well as the release of inflammatory cytokines.We explored the role of Bax Inhibitor-1 (BI-1) protein, encoded by the Transmembrane Bax inhibitor Motif Containing 6 (TMBIM6) gene, in protection from ER stress after HI brain injury. BI-1 may attenuate ER stress-induced ROS production and release of inflammatory mediators via (1) disruption of the NPR-CYP complex and (2) upregulation of Nrf-2, a redox-sensitive transcription factor, thus promoting an increase in anti-oxidant enzymes to inhibit ROS production. The main objective of our study is to evaluate BI-1’s inhibitory effects on ROS production and inflammation by overexpressing BI-1 in 10-day-old rat pups.MethodsTen-day-old (P10) unsexed Sprague-Dawley rat pups underwent right common carotid artery ligation, followed by 1.5 h of hypoxia. To overexpress BI-1, rat pups were intracerebroventricularly (icv) injected at 48 h pre-HI with the human adenoviral vector-TMBIM6 (Ad-TMBIM6). BI-1 and Nrf-2 silencing were achieved by icv injection at 48 h pre-HI using siRNA to elucidate the potential mechanism. Percent infarcted area, immunofluorescent staining, DHE staining, western blot, and long-term neurobehavior assessments were performed.ResultsOverexpression of BI-1 significantly reduced the percent infarcted area and improved long-term neurobehavioral outcomes. BI-1’s mediated protection was observed to be via inhibition of P4502E1, a major contributor to ROS generation and upregulation of pNrf-2 and HO-1, which correlated with a decrease in ROS and inflammatory markers. This effect was reversed when BI-1 or Nrf-2 were inhibited.ConclusionsOverexpression of BI-1 increased the production of antioxidant enzymes and attenuated inflammation by destabilizing the complex responsible for ROS production. BI-1’s multimodal role in inhibiting P4502E1, together with upregulating Nrf-2, makes it a promising therapeutic target.

Mechanism of H2S Formation from the Metabolism of Anetholedithiolethione and Anetholedithiolone by Rat Liver Microsomes.

The drug anetholedithiolethione (ADT) and its analogs have been extensively used as H2S donors. However, the mechanism of H2S formation from ADT under biologic conditions remains almost completely unknown. This article shows that only small amounts of H2S are formed during incubation of ADT and of its metabolite anetholedithiolone (ADO) with rat liver cytosol or with rat liver microsomes (RLM) in the absence of NADPH, indicating that H2S formation under these conditions is of hydrolytic origin only to a minor extent. By contrast, much greater amounts of H2S are formed upon incubation of ADT and ADO with RLM in the presence of NADPH and dioxygen, with a concomitant formation of H2S and para-methoxy-acetophenone (pMA). Moreover, H2S and pMA formation under those conditions are greatly inhibited in the presence of N-benzyl-imidazole indicating the involvement of cytochrome P450-dependent monooxygenases. Mechanistic studies show the intermediate formation of the ADT-derived 1,2-dithiolium cation and of the ADO sulfoxide during microsomal metabolism of ADT and ADO, respectively. This article proposes the first detailed mechanisms for the formation of H2S from microsomal metabolism of ADT and ADO in agreement with those data and with previously published data on the metabolism of compounds involving a C=S bond. Finally, this article shows for the first time that ADO is a better H2S donor than ADT under those conditions. SIGNIFICANCE STATEMENT: Incubation of anetholedithiolethione (ADT) or its metabolite anetholedithiolone (ADO) in the presence of rat liver microsomes, NADPH, and O2 leads to H2S. This article shows for the first time that this H2S formation involves several steps catalyzed by microsomal monooxygenases and that ADO is a better H2S donor than ADT. We propose the first detailed mechanisms for the formation of H2S from the microsomal metabolism of ADT and ADO.

A large-scale comparative analysis of affinity, thermodynamics and functional characteristics of interactions of twelve cytochrome P450 isoforms and their redox partners

The aim of the present work was to establish the thermodynamic and functional differences in the protein-protein interactions between the components of the P450-dependent mitochondrial (mit) and microsomal (mic) monooxygenase systems using 12 different isoforms of cytochromes P450 and two redox partners, NADPH-dependent cytochrome P450 reductase (CPR) and adrenodoxin (Adx). Comparative analysis of the affinity, thermodynamics, enzymatic activity and the ability for one-electron reduction has been carried out. The study of protein-protein interactions to determine the equilibrium dissociation constants (Kd) was performed using surface plasmon resonance (SPR) biosensor Biacore 3000. We demonstrated that CPR and Adx interacted with both, micCYPs and mitCYPs, with different affinities (Kd values ranged from 0.01 to 2 μM). All complexes of microsomal (micCYP) and mitochondrial (mitCYP) cytochrome P450 with redox partners can be divided into three groups depending on the prevalent role of either enthalpy or entropy contribution. About 90% of CYP/redox partner complexes were entropy-driven, while the contribution of enthalpy and entropy differed significantly in case of mitCYP/Adx complexes. The CYP11A1/Adx complex was enthalpy-driven, while CYP11B1/Adx and CYP11B2/Adx complexes were entropy-driven. Thermodynamic discrimination of mitCYPs/Adx complexes is likely associated with the different functional impact of CYP11A1 and CYP11B. The exception was the enthalpy-entropy-driven (mixed type) CYP21A2/Adx complex. CPR and Adx were able to transfer the first electron to micCYPs while mitCYPs demonstrated high specificity to Adx. Productive catalysis for mitCYPs observed only in the presence of Adx/AdR pair, while in case of steroidogenic micCYPs (CYP17A1, CYP19A1, and CYP21A2) it was found either in the presence of a CPR or an Adx/AdR pair. From the evolutionary point of view, the type 1 electron transport system (mitCYPs, Adx and NADPH-dependent adrenodoxin reductase (AdR)) increased the specialization of protein-protein interactions (PPI) significantly, which was accompanied by an increase in the specificity of electron transfer. In contrast, the evolution of the type 2 electron transport system (micCYPs and CPR) led to an increase in versatility of PPI as demonstrated for steroidogenic microsomal cytochrome P450s. Our data enhance the current understanding of molecular recognition and summarize qualitative and thermodynamic characteristics of protein-protein interactions in the P450-dependent mitochondrial and microsomal monooxygenase systems.