Effect of some organic solvents on oxidative phosphorylation in rat liver mitochondria: Choice of organic solvents

Cumulative Deleterious Effects of Tetrahydrocannabinoid (THC) and Ethanol on Mitochondrial Respiration and Reactive Oxygen Species Production Are Enhanced in Old Isolated Cardiac Mitochondria

Delta 9 tetrahydrocannabinol (THC), the main component of cannabis, has adverse effects on the cardiovascular system, but whether concomitant ethanol (EtOH) and aging modulate its toxicity is unknown. We investigated dose responses of THC and its vehicle, EtOH, on mitochondrial respiration and reactive oxygen production in both young and old rat cardiac mitochondria (12 and 90 weeks). THC dose-dependently impaired mitochondrial respiration in both groups, and such impairment was enhanced in aged rats (-97.5 ± 1.4% vs. -75.6 ± 4.0% at 2 × 10-5 M, and IC50: 0.7 ± 0.05 vs. 1.3 ± 0.1 × 10-5 M, p < 0.01, for old and young rats, respectively). The EtOH-induced decrease in mitochondrial respiration was greater in old rats (-50.1 ± 2.4% vs. -19.8 ± 4.4% at 0.9 × 10-5 M, p < 0.0001). Further, mitochondrial hydrogen peroxide (H2O2) production was enhanced in old rats after THC injection (+46.6 ± 5.3 vs. + 17.9 ± 7.8%, p < 0.01, at 2 × 10-5 M). In conclusion, the deleterious cardiac effects of THC were enhanced with concomitant EtOH, particularly in old cardiac mitochondria, showing greater mitochondrial respiration impairment and ROS production. These data improve our knowledge of the mechanisms potentially involved in cannabis toxicity, and likely support additional caution when THC is used by elderly people who consume alcohol.

Borate reduces experimental supra-celiac aortic clamping-induced oxidative stress in lung and kidney, but fails to prevent organ damage

Background

This study aims to investigate the effects of 2-aminoethoxydiphenyl borate (2-APB) on aortic clamping-induced lung and kidney tissue oxidation, tissue inflammation, and histological damage in a rat model.

Methods

A total of 28 adult female Wistar albino rats were randomly allocated to four equal groups: Control group, ischemia-reperfusion group, dimethyl sulfoxide group, and 2-APB group. Animals in the control group underwent median laparotomy. In the remaining groups, supra-celiac aorta was clamped for 45 min and, then, reperfusion was constituted for 60 min. The 2-APB (2 mg/kg) was administered before clamping. The remaining groups received saline (ischemia-reperfusion group) or dimethyl sulfoxide (dimethyl sulfoxide group). Kidney and lung tissue samples were harvested at the end of reperfusion.

Results

Aortic occlusion caused increased tissue total oxidant status and reduced total antioxidant status and glutathione levels in the ischemia-reperfusion and dimethyl sulfoxide groups. Tissue interleukin-1 beta and tumor necrosis factor-alpha levels, nuclear factor kappa beta activation, and histological damage severity scores were also higher in these groups. The 2-APB treatment eliminated the increase in total oxidant status and the decrease in total antioxidant status and glutathione levels. It also caused a decrease in the interleukin-1 beta levels, although it did not significantly alter the tumor necrosis factor-alpha levels, nuclear factor kappa beta immunoreactivity, and histological damage scores.

Conclusion

Borate exerted a beneficial antioxidant effect as evidenced by reduced oxidative stress; however, it did not inhibit nuclear factor kappa beta activation and prevent histological damage in supra-celiac aortic clamping-induced kidney and lung injury in rats.

Exposure to marine benthic dinoflagellate toxins may lead to mitochondrial dysfunction

Even though marine dinoflagellates are important primary producers, many toxic species may alter the natural equilibrium of aquatic ecosystems and even generate human intoxication incidents, as they are the major causative agents of harmful algal blooms. In order to deepen the knowledge regarding benthic dinoflagellate adverse effects, the present study aims to clarify the influence of Gambierdiscus excentricus strain UNR-08, Ostreopsis cf. ovata strain UNR-03 and Prorocentrum lima strain UNR-01 crude extracts on rat mitochondrial energetic function and permeability transition pore (mPTP) induction. Our results, expressed in number of dinoflagellate cell toxic compounds tested in a milligram of mitochondrial protein, revealed that 934 cells mg prot-1 of G. excentricus, and 7143 cells mg prot-1 of both O. cf. ovata and P. lima negatively affect mitochondrial function, including by decreasing ATP synthesis-related membrane potential variations. Moreover, considerably much lower concentrations of dinoflagellate extracts (117 cells mg prot-1 of G. excentricus, 1429 cells mg prot-1 of O. cf. ovata and 714 cells mg prot-1 of P. lima) produced mPTP-induced swelling in Ca2+-loaded isolated mitochondria. The present study clearly demonstrates the toxicity of G. excentricus, O. cf. ovata and P. lima extracts at the mitochondrial level, which may lead to mitochondrial failure and consequent cell toxicity, and that G. excentricus always provide much more severe effects than O. cf. ovata and P. lima.

Electroacupuncture pretreatment alleviates myocardial injury through regulating mitochondrial function

Background

Electroacupuncture is well known for its advantageous neuroanalgesic and therapeutic effects on myocardial ischemia–reperfusion injury. The purpose of the present research was to verify whether electroacupuncture can alleviate bupivacaine-induced myocardial injury.

Methods

Specific pathogen-free Wistar rats were used to establish the bupivacaine-induced myocardial injury model. Western blot, PCR, transmission electron microscope and enzyme-linked immunosorbent (ELISA) methods were used to evaluate bupivacaine-induced structure injury and dysfunction of the mitochondria as well as the alleviating effects of lipid emulsion, acupoint injection, and electroacupuncture pre-treatment of the oxidase stress response.

Results

Bupivacaine caused structural damage, degradation, and swelling of mitochondria. Furthermore, it reduced adenosine triphosphate (ATP) synthesis and impaired energy metabolism in the mitochondria. Structural and functional impairment of the mitochondria was alleviated via lipid emulsion injection, acupoint injection, and electroacupuncture pre-treatment. Electroacupuncture pre-treatment of PC6 yielded a greater alleviating effect than others approaches. Following electroacupuncture pre-treatment of PC6 point, the number of mitochondria increased; apoptosis was reduced, enzymatic activity of cytochrome C oxidase (COX) and superoxide dismutase and expression of uncoupling protein 2, voltage-dependent anion channel 1, and Bcl 2 were upregulated and SLC25A6, MDA levels were downregulated. Additionally, our findings indicated that electroacupuncture pre-treatment of PC6 point exerted an effect on the mitochondria via the mitochondrial-transcription-factor-A/nuclear-respiratory-factor-1/proliferator-activated-receptor-gamma-coactivator-1 pathway.

Conclusion

The present study revealed that electroacupuncture pre-treatment of PC6 could effectively alleviate bupivacaine-induced myocardial mitochondrial damage, thereby providing a theoretical basis for clinical studies and applications of this treatment method.

Propofol improves colonic but impairs hepatic mitochondrial function in tissue homogenates from healthy rats

Evidence suggests that propofol infusion syndrome (PRIS) is caused by an altered mitochondrial function. The aim of this study was to examine the effects of propofol and the vehicle MCT on mitochondrial function in hepatic and colonic tissue. Mitochondrial oxygen consumption was determined in colon and liver homogenates after incubation with buffer (control), propofol (50, 75, 100, 500  μM) or the carrier substances DMSO and MCT. State 2 (substrate-dependent) and state 3 (ADP-dependent respiration) were assessed. RCI (respiratory control index) - an indicator for coupling between electron transport chain system (ETS) and oxidative phosphorylation (OXPHOS) and ADP/O ratio - a parameter for efficacy of OXPHOS were calculated. Data were presented as % of control. In hepatic mitochondria, 500  μM propofol reduced RCI formulation-independently (propofol/MCT 500 μM: complex I: 66.3 ± 8.7%*, complex II: 75.5 ± 9.2%*; propofol/DMSO 500 μM: complex I: 29.1 ± 8.8%*, complex II: 49.3 ± 15.5%*). 75  μM Propofol/MCT reduced ADP/O for complex I (73.5 ± 27.3%*). DMSO did not affect hepatic mitochondria whereas MCT reduced RCI for complex II (87.2 ± 9.8%*) and ADP/O for complex I (93.7 ± 31.7%*). In colon 50  μM Propofol/MCT increased RCI for complex I and II (complex I: 127.2 ± 10.7%*, complex II: 136.8 ± 33.9%*) and 100  μM Propofol/MCT for complex I (131.4 ± 18.7%*). 500  μM Propofol/DMSO increased ADP/O for complex I (139.4 ± 41.4%*). DMSO did not affect RCI but increased ADP/O for both complexes (complex I: 119.9 ± 25.8%*, complex II: 110.2 ± 14.2%*). MCT increased RCI for complex I (123.0 ± 31.6%*). In hepatic mitochondria propofol uncoupled ETS from OXPHOS formulation-independently and propofol/MCT reduced efficacy of OXPHOS. In colonic mitochondria, propofol/MCT strengthened the coupling and propofol/DMSO enhanced the efficacy of OXPHOS.

Ameliorative role of camel whey protein and rosuvastatin on induced dyslipidemia in mice

The incidence of obesity is rapidly increasing throughout the world. Dyslipidemia is a major risk factor for a number of chronic diseases, including diabetes and cardiovascular diseases. This work presents a novel approach to study the activity of camel whey protein (WP) with antioxidant and anti-inflammatory properties as a cheap dietary protein substance extracted from camel milk to produce satiety and help in building muscles. Mice model suffering from dyslipidemia as a result of feeding on high fat-cholesterol diet for 8 weeks were administrated with either camel WP and/or rosuvastatin for 4 weeks. Dyslipidemia revealed significant increase in anthropometrical measurements, levels of glucose, insulin, cholesterol, triglycerides, low-density lipoprotein, total leucocyte count, inflammatory cytokines and reactive oxygen species, accompanied by a significant elevation in activating transcription factor-3 and inducible nitric oxide synthase expressions. These alterations were correlated with a profound reduction in high-density lipoprotein, peroxisome proliferator-activated receptor alpha and adiponectin along with a decrease in liver and muscle mitochondrial proteins. Rosuvastatin treatment to mice suffering from dyslipidemia in combination with camel WP for 4 weeks ameliorated these parameters. Notably, animals treated with both camel WP and rosuvastatin exhibited a remarkable decrease in the incidence of dyslipidemia. In addition, camel WP succeeded to overcome the therapeutic drawback posed from rosuvastatin therapy alone with minimal side effects.

Mitochondrial morphology and function impaired by dimethyl sulfoxide and dimethyl Formamide

In this work, the effects of two non-ionic, non-hydroxyl organic solvents, dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) on the morphology and function of isolated rat hepatic mitochondria were investigated and compared. Mitochondrial ultrastructures impaired by DMSO and DMF were clearly observed by transmission electron microscopy. Spectroscopic and polarographic results demonstrated that organic solvents induced mitochondrial swelling, enhanced the permeation to H⁺/K⁺, collapsed the potential inner mitochondrial membrane (IMM), and increased the IMM fluidity. Moreover, with organic solvents addition, the outer mitochondrial membrane (OMM) was broken, accompanied with the release of Cytochrome c, which could activate cell apoptosis signaling pathway. The role of DMSO and DMF in enhancing permeation or transient water pore formation in the mitochondrial phospholipid bilayer might be the main reason for the mitochondrial morphology and function impaired. Mitochondrial dysfunctions induced by the two organic solvents were dose-dependent, but the extents varied. Ethanol (EtOH) showed the highest potential damage on the mitochondrial morphology and functions, followed by DMF and DMSO.

Synthesis and characterization of novel carboxymethyl Assam Bora rice starch for the controlled release of cationic anticancer drug based on electrostatic interactions

Carboxymethyl Assam Bora rice starch (CM-ABRS) was chemically synthesized in non-aqueous medium with the optimum degree of substitution (DS) of 1.23, and physicochemically characterized by FT-IR, DSC, XRD, and SEM analysis. Comparative evaluation of CM-ABRS with native starch (ABRS) for powder flow characteristics, swelling index, apparent solubility, rheological properties, textural properties, and mucoadhesive studies were carried out. The aim of the current work was to investigate the potential of CM-ABRS as a novel carrier for the water-soluble chemotherapeutic, doxorubicin hydrochloride (DOX). Formation of drug/polymer complex (DOX-CM-ABRS) via electrostatic interaction has been evaluated for the controlled release of DOX in three different pH media (phosphate-buffered saline (PBS), pH 7.4, 6.8, and 5.5). In vitro drug release studies illustrated faster release of drug in PBS at pH 5.5 as compared to pH 6.8 and pH 7.4, respectively, indicating the importance of pH-sensitive drug release from the DOX-CM-ABRS complex in malignant tissues.

Biochemical alterations in duckweed and algae induced by carrier solvents: Selection of an appropriate solvent in toxicity testing

Carrier solvents are often used in aquatic toxicity testing for test chemicals with hydrophobic properties. However, the knowledge of solvent effects on test organisms remains limited. The present study aimed to determine the biochemical effects of the 4 common solvents methanol, ethanol, acetone, and dimethyl sulfoxide (DMSO) on 2 test species, Lemna minor and Raphidocelis subcapitata, by applying Fourier transform infrared spectroscopy (FTIR) coupled with multivariate analysis to select appropriate solvents for toxicity testing. The results showed biochemical variations associated with solvent treatments at different doses on test species. From the infrared spectra obtained, the structures of lipid membrane and protein phosphorylation in the test species were found to be sensitive to the solvents. Methanol and ethanol mainly affected the protein secondary structure, whereas acetone and DMSO primarily induced alterations in carbohydrates and proteins in the test species. The FTIR results demonstrated that methanol and ethanol showed higher biochemical alterations in the test species than acetone and DMSO, especially at the high doses (0.1 and 1% v/v). Based on the growth inhibition displayed and FTIR spectroscopy, acetone, and DMSO can be used as carrier solvents in toxicity testing when their doses are lower than 0.1% v/v. Environ Toxicol Chem 2017;36:2631-2639. © 2017 SETAC.

Spectroscopic, Polarographic, and Microcalorimetric Studies on Mitochondrial Dysfunction Induced by Ethanol

Liver mitochondria are involved in several important life processes; mitochondrial dysfunction and disorders are implicated in several human diseases. Alcohol permeates all tissues of the body and exerts some intrinsic hepatotoxicity. In this work, our results demonstrated that ethanol caused a series of mitochondria permeability transition pore (MPTP) opening factors such as mitochondrial swelling, increased permeability of H⁺ and K⁺, collapsed membrane potential, and increased membrane fluidity. Furthermore, mitochondrial ultrastructure alternation observed clearly by transmission electron microscopy and the release of Cytochrome c could explain the MPTP opening from another aspect. Moreover, ethanol damaged the mitochondrial respiration system and induced disturbance of mitochondrial energy metabolism which was monitored by polarographic and microcalorimetric methods, respectively. Considered together, these damages may promote both apoptotic and necrotic cell death and contribute to the onset or progression alcohol-induced liver diseases.

Expeditious dissolution dynamic nuclear polarization without glassing agents

The hyperpolarization of metabolic substrates at low temperature using dynamic nuclear polarization (DNP), followed by rapid dissolution and injection into an MRSI or NMR system, allows in vitro or in vivo observation and tracking of biochemical reactions and metabolites in real time. This article describes an elegant approach to sample preparation which is broadly applicable for the rapid polarization of aqueous small-molecule substrate solutions and obviates the need for glassing agents. We demonstrate its utility for solutions of sodium acetate, pyruvate and butyrate. The polarization behavior of substrates prepared using rapid freezing without glassing agents enabled a 1.5-3-fold time savings in polarization buildup, whilst removing the need for toxic glassing agents used as standard for dissolution DNP. The achievable polarization with fully aqueous substrate solutions was equal to that observed using standard approaches and glassing agents. Copyright © 2016 John Wiley & Sons, Ltd.

Mitochondrial toxicity of selective COX-2 inhibitors via inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria

Cyclooxygenase-2 (COX-2) inhibitors (coxibs) are non-steroidal anti-inflammatory drugs (NSAIDs) designed to selectively inhibit COX-2. However, drugs of this therapeutic class are associated with drug induced liver injury (DILI) and mitochondrial injury is likely to play a role. The effects of selective COX-2 inhibitors on inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria were investigated. The order of potency of inhibition of ATP synthesis was: lumiracoxib (IC50: 6.48 ± 2.74 μM)>celecoxib (IC50: 14.92 ± 6.40 μM)>valdecoxib (IC50: 161.4 ± 28.6 μM)>rofecoxib (IC50: 238.4 ± 79.2 μM)>etoricoxib (IC50: 405.1 ± 116.3 μM). Mechanism based inhibition of ATP synthesis (Kinact 0.078 min(-1) and KI 21.46 μM and Kinact/KI ratio 0.0036 min(-1)μM(-1)) was shown by lumiracoxib and data suggest that the opening of the MPT pore may not be the mechanism of toxicity. A positive correlation (with r(2)=0.921) was observed between the potency of inhibition of ATP synthesis and the log P values. The in vitro metabolism of coxibs in rat liver mitochondria yielded for each drug substance a major single metabolite and identified a hydroxy metabolite with each of the coxibs and these metabolites did not alter the inhibition profile of ATP synthesis of the parent compound. The results suggest that coxibs themselves could be involved in the hepatotoxic action through inhibition of ATP synthesis.

Mitochondrial toxicity of diclofenac and its metabolites via inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria: Possible role in drug induced liver injury (DILI)

Diclofenac is a widely prescribed NSAID, which by itself and its reactive metabolites (Phase-I and Phase-II) may be involved in serious idiosyncratic hepatotoxicity. Mitochondrial injury is one of the mechanisms of drug induced liver injury (DILI). In the present work, an investigation of the inhibitory effects of diclofenac (Dic) and its phase I [4-hydroxy diclofenac (4'-OH-Dic) and 5-hydroxy diclofenac (5-OH-dic)] and Phase-II [diclofenac acyl glucuronide (DicGluA) and diclofenac glutathione thioester (DicSG)] metabolites, on ATP synthesis in rat liver mitochondria was carried out. A mechanism based inhibition of ATP synthesis is exerted by diclofenac and its metabolites. Phase-I metabolite (4'-OH-Dic) and Phase-II metabolites (DicGluA and DicSG) showed potent inhibition (2-5 fold) of ATP synthesis, where as 5-OH-Dic, one of the Phase-I metabolite, was a less potent inhibitor as compared to Dic. The calculated kinetic constants of mechanism based inhibition of ATP synthesis by Dic showed maximal rate of inactivation (Kinact) of 2.64 ± 0.15 min(-1) and half maximal rate of inactivation (KI) of 7.69 ± 2.48 μM with Kinact/KI ratio of 0.343 min(-1) μM(-1). Co-incubation of mitochondria with Dic and reduced GSH exhibited a protective effect on Dic mediated inhibition of ATP synthesis. Our data from this study strongly indicate that Dic as well as its metabolites could be involved in the hepato-toxic action through inhibition of ATP synthesis.

Inhibition of ATP synthesis by fenbufen and its conjugated metabolites in rat liver mitochondria

Fenbufen is an arylpropionic acid derivative belonging to the group of non-steroidal anti-inflammatory drugs (NSAIDs). Even though fenbufen is considered a safe drug, some adverse reactions including hepatic events have been reported. To investigate whether mitochondrial damage could be involved in the drug induced liver injury (DILI) by fenbufen, the inhibitory effect of fenbufen and its conjugated metabolites on oxidative phosphorylation (ATP synthesis) in rat liver mitochondria was investigated. Fenbufen glucuronide (F-GlcA), fenbufen-N-acetyl cysteine-thioester (F-NAC) and fenbufen-S-glutathione thioester (F-SG) were found to be more potent inhibitors compared to parent fenbufen (F), whereas fenbufen-O-carnitine (F-carn), fenbufen-glycine (F-gly) and fenbufen-N-acetyl lysine amide (F-NAL) were less potent compared to fenbufen. Fenbufen-CoA thioester (F-CoA) was equally potent as fenbufen in inhibiting ATP synthesis. Fenbufen showed time and concentration dependent inhibition of ATP synthesis with Kinact of 4.4 min(-1) and KI of 0.88 μM and Kinact/KI ratio of 5.01 min(-1) μM(-1). Data show that fenbufen did not act through opening MPT pore, nor did incubation of mitochondria with reduced GSH and fenbufen show any protective effect on fenbufen mediated inhibition of oxidative phosphorylation. Inclusion of NADPH in mitochondrial preparations with fenbufen did not modulate the inhibitory effects, suggesting no role of CYP mediated oxidative metabolites on the ATP synthesis in isolated mitochondria. The results from the present experiments provide evidence that fenbufen and its metabolites could be involved in mitochondrial toxicity through inhibition of ATP synthesis.

Doxorubicin-loaded polypeptide nanorods based on electrostatic interactions for cancer therapy

An amphiphilic anionic polypeptide, methoxypolyethylene glycol-poly (glutamic acid) (mPEG-PGA), was synthesized, characterized and evaluated as a nanocarrier for the cationic anticancer drug doxorubicin hydrochloride (DOX·HCl). The complex self-assembled into nanorods in aqueous solutions via electrostatic interactions and exhibited a superior drug loading content (50.8%) and drug loading efficiency (90.2%). The average major axis of the drug-loaded nanorods was approximately 300nm, as determined by transmission electron microscopy. An in vitro release assay showed that drug-loaded nanorods exhibited pH-sensitivity and sustained release. Haemolysis assays demonstrated that the polypeptide was haemocompatible, and the polypeptide drug carrier significantly reduced the haemolysis ratio of DOX·HCl. The pharmacokinetics study showed that DOX-loaded nanorods significantly prolonged the resident time in blood. An in vitro cytotoxicity study and cellular uptake assays demonstrated that the DOX-loaded nanorods resulted in higher cell proliferation inhibition and a higher level of tumour cell uptake in A549 cells than with free DOX·HCl. The prolonged circulation and enhanced antitumor efficacy of DOX-loaded nanorods shows promise for efficient cancer chemotherapy.

Cancer stem cell theory and the warburg effect, two sides of the same coin?

Over the last 100 years, many studies have been performed to determine the biochemical and histopathological phenomena that mark the origin of neoplasms. At the end of the last century, the leading paradigm, which is currently well rooted, considered the origin of neoplasms to be a set of genetic and/or epigenetic mutations, stochastic and independent in a single cell, or rather, a stochastic monoclonal pattern. However, in the last 20 years, two important areas of research have underlined numerous limitations and incongruities of this pattern, the hypothesis of the so-called cancer stem cell theory and a revaluation of several alterations in metabolic networks that are typical of the neoplastic cell, the so-called Warburg effect. Even if this specific “metabolic sign” has been known for more than 85 years, only in the last few years has it been given more attention; therefore, the so-called Warburg hypothesis has been used in multiple and independent surveys. Based on an accurate analysis of a series of considerations and of biophysical thermodynamic events in the literature, we will demonstrate a homogeneous pattern of the cancer stem cell theory, of the Warburg hypothesis and of the stochastic monoclonal pattern; this pattern could contribute considerably as the first basis of the development of a new uniform theory on the origin of neoplasms. Thus, a new possible epistemological paradigm is represented; this paradigm considers the Warburg effect as a specific “metabolic sign” reflecting the stem origin of the neoplastic cell, where, in this specific metabolic order, an essential reason for the genetic instability that is intrinsic to the neoplastic cell is defined.