Thymoquinone reduces mitochondrial damage and death of cardiomyocytes induced by clozapine

Comparative Study of the Protective Effects of Citral, Thymoquinone, and Silymarin on Methotrexate-induced Cardiotoxicity in Rats

Objectives

Methotrexate (MTX), an immunosuppressant and anti-cancer medication, can harm the heart. The goal of the current investigation was to assess the cardiotoxicity caused by MTX and the potential cardioprotective properties of silymarin, citral, and thymoquinone as antioxidants.

Methods

Forty-eight rats were divided into six groups, which included control, MTX, cosolvent, citral, thymoquinone, and silymarin groups. At the end of the study, the rats were anesthetized (ketamine and xylazine) and killed using CO2. Their blood samples were collected to measure the enzymatic activities of creatine kinase-myoglobin binding (CK-MB), creatine phosphokinase (CPK), and lactate dehydrogenase (LDH). Also, the heart tissue was sampled to determine the antioxidant capacity and examine the histopathology.

Results

The findings revealed that the activity of CPK, CK-MB, and LDH enzymes significantly reduced in the thymoquinone treatment group compared to the MTX group (p < 0.05). On the other hand, total antioxidant capacity was significantly increased in the thymoquinone group compared to the MTX group (p < 0.05). The pathological modifications (i.e. severe congestion, edema fluid, the presence of inflammatory cells around the blood vessels, mild to moderate hemorrhaging between cardiac muscle fibers) were seen in the MTX group. The treatment groups, particularly thymoquinone, did not experience any appreciable pathological changes.

Conclusion

The thymoquinone was found to have the strongest protective effect against the heart damage caused by MTX.

Modeling drug-induced mitochondrial toxicity with human primary cardiomyocytes

Mitochondrial toxicity induced by therapeutic drugs is a major contributor for cardiotoxicity, posing a serious threat to pharmaceutical industries and patients' lives. However, mitochondrial toxicity testing is not incorporated into routine cardiac safety screening procedures. To accurately model native human cardiomyocytes, we comprehensively evaluated mitochondrial responses of adult human primary cardiomyocytes (hPCMs) to a nucleoside analog, remdesivir (RDV). Comparison of their response to human pluripotent stem cell-derived cardiomyocytes revealed that the latter utilized a mitophagy-based mitochondrial recovery response that was absent in hPCMs. Accordingly, action potential duration was elongated in hPCMs, reflecting clinical incidences of RDV-induced QT prolongation. In a screen for mitochondrial protectants, we identified mitochondrial ROS as a primary mediator of RDV-induced cardiotoxicity. Our study demonstrates the utility of hPCMs in the detection of clinically relevant cardiac toxicities, and offers a framework for hPCM-based high-throughput screening of cardioprotective agents.

Antioxidant Thymoquinone and Its Potential in the Treatment of Neurological Diseases

Oxidative stress is one of the main pathogenic factors of neuron damage in neurodegenerative processes; this makes it an important therapeutic target to which the action of neuroprotectors should be directed. One of these drugs is thymoquinone. According to modern data, this substance has a wide range of pharmacological activity, including neuroprotective, which was demonstrated in experimental modeling of various neurodegenerative diseases and pathological conditions of the brain. The neuroprotective effect of thymoquinone is largely due to its antioxidant ability. Currently available data show that thymoquinone is an effective means to reduce the negative consequences of acute and chronic forms of cerebral pathology, leading to the normalization of the content of antioxidant enzymes and preventing an increase in the level of lipid peroxidation products. Antioxidant properties make this substance a promising basis for the development of prototypes of therapeutic agents aimed at the treatment of a number of degenerative diseases of the central nervous system.

Evaluation of Conventional and Hyaluronic Acid-Coated Thymoquinone Liposomes in an In Vitro Model of Dry Eye

Dry eye disease (DED) is a common ocular disorder characterized by an inadequate lubrication of the eye by tears leading to inflammation and the alteration of the ocular surface. Current treatments are often limited due to their side effects and ineffectiveness. Thymoquinone (TQ) is a natural compound present in the essential oil of Nigella sativa L., with anti-inflammatory and antioxidant activities. In this study, conventional and hyaluronic acid-coated liposomes were developed to improve TQ activity at ocular level. In the present study, the cytoprotective effects of TQ or TQ liposomes were assessed against oxidative and inflammatory processes in human corneal epithelial cells (HCE-2). Hyperosmolarity conditions (450 mOsm) were used as a model of DED. Interleukin-1β (IL-1β), Interleukin-6 (IL-6) and tumor necrosis factor (TNFα) were quantified by quantitative real-time polymerase chain reaction (RT-qPCR); COX-2 and Phospho-NF-κB p65 (p-p65) by Western blotting (WB). Moreover, the mitochondrial reactive oxygen species (mtROS) levels were measured by MitoSOX assay. The hyperosmotic treatment induced a significant increase of the proinflammatory genes and proteins expression that were significantly decreased in the liposomes-treated cells. The coincubation with hyaluronic acid-coated liposomes significantly reverted the increase of mtROS production, evidently stimulated by the hyperosmotic stress. Our data suggest that TQ-loaded liposomes have potential as a therapeutic agent in dry eye disease, improving the TQ efficacy.

Exploring the possible mitoprotective and neuroprotective potency of thymoquinone, betanin, and vitamin D against cytarabine-induced mitochondrial impairment and neurotoxicity in rats' brain

It has been suggested that cytarabine (Ara-C) induces toxicity via mitochondrial dysfunction and oxidative stress. Therefore, we hypothesized that mitochondrial protective agents and antioxidants can reduce cytarabine-induced neurotoxicity. For this purpose, 48 male Wistar rats were assigned into eight equal groups include control group, Ara-C (70 mg/kg, i.p.) group, Ara-C plus betanin (25 mg/kg, i.p.) group, Ara-C plus vitamin D (500 U/kg, i.p.) group, Ara-C plus thymoquinone (0.5 mg/kg, i.p.) group, betanin group, vitamin group, and thymoquinone group. The activity of acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), the concentrations of antioxidants (reduced glutathione and oxidized glutathione), oxidative stress (malondialdehyde) biomarkers, mitochondrial toxicity parameters as well as histopathological alteration in brain tissues were measured. Our results demonstrated that Ara-C exposure significantly declines the brain enzymes activity (AChE and BChE), levels of antioxidant biomarkers (GSH), and mitochondrial functions, but markedly elevate the levels of oxidative stress biomarkers (MDA) and mitochondrial toxicity. Almost all of the previously mentioned parameters (especially mitochondrial toxicity) were retrieved by betanin, vitamin D, and thymoquinone compared to Ara-C group. These findings conclusively indicate that betanin, vitamin D, and thymoquinone administration provide adequate protection against Ara-C-induced neurotoxicity through modulations of oxidative, antioxidant activities, and mitochondrial protective (mitoprotective) effects.

Role of Oxidative Stress and Reactive Metabolites in Cytotoxicity & Mitotoxicity of Clozapine, Diclofenac and Nifedipine in CHO-K1 Cells In Vitro

BACKGROUND

CHO-K1 cells were used as in vitro model to explore mechanisms of cytotoxicity of the test drugs.

AIM

To provide in vitro data on toxicity mechanisms of clozapine, diclofenac and nifedipine.

OBJECTIVE

Cytotoxic mechanisms of clozapine (CLZ), diclofenac (DIC) and nifedipine (NIF) were studied in CHO-K1 cells in vitro. All three drugs induce adverse reactions in some patients with partially unknown mechanisms.

METHODS

Following the determination of time- and dose-dependency of cytotoxicity by the MTT test, cytoplasmic membrane integrity was explored by the LDH leakage test. Both end-points were further examined in the presence of soft and hard nucleophilic agents, glutathione (GSH) and potassium cyanide (KCN), respectively, and either individual or general cytochrome P450 (CYP) inhibitors, whether CYPcatalysed formation of electrophilic metabolites play a role in the observed cytotoxicity and membrane damage. The generation of reactive metabolites during the incubations was also explored. Formation of malondialdehyde (MDA) and oxidation of dihydrofluorescein (DCFH) were monitored whether peroxidative membrane damage and oxidative stress take place in cytotoxicity. Incubations were also conducted in the presence of chelating agents of EDTA or DTPA to explore any possible role of metals in cytotoxicity by facilitating electron transfer in redox reactions. Finally, mitochondrial membrane oxidative degradation and permeability transition pore (mPTP) induction by the drugs were tested as markers of mitochondrial damage.

RESULTS

The presence of an individual or combined nucleophilic agents significantly diminished CLZand NIF-induced cytotoxicities, while the presence of both agents paradoxically increased DIC-induced cytotoxicity by a factor of three with the reason remaining unknown. The presence of GSH significantly increased DIC-induced membrane damage too. Prevention of membrane damage by the hard nucleophile KCN suggests the generation of a hard electrophile upon DIC and GSH interaction. The presence of CYP2C9 inhibitor sulfaphenazole significantly diminished DIC-induced cytotoxicity, probably by preventing the formation of 4-hydroxylated metabolite of DIC, which further converts to an electrophilic reactive intermediate. Among the chelating agents, EDTA caused a marginal decrease in CLZ-induced cytotoxicity, while DIC-induced cytotoxicity was amplified by a factor of five. Both reactive and stable metabolites of CLZ could be detected in the incubation medium of CLZ with CHO-K1 cells, which are known to have low metabolic capacity. All three drugs caused a significant increase in cytoplasmic oxidative stress by means of DCFH oxidation, which was confirmed by increased MDA from cytoplasmic as well as mitochondrial membranes. The addition of GSH paradoxically and significantly increased DICinduced MDA formation, in parallel with the increase in membrane damage when DIC and GSH combined.

CONCLUSION

Our results suggested that the soft electrophilic nitrenium ion of CLZ is not responsible for the observed in vitro toxicities, and this may originate from a relatively low amount of the metabolite due to the low metabolic capacity of CHO-K1. A hard electrophilic intermediate may contribute to cellular membrane damage incubated with DIC, while a soft electrophilic intermediate seems to exacerbate cell death by a mechanism other than membrane damage. A significant decrease in cytotoxicity of NIF by GSH and KCN suggested that both soft and hard electrophiles contribute to NIF-induced cytotoxicity. All three drugs induced peroxidative cytoplasmic membrane damage, while only DIC and NIF induced peroxidative mitochondrial membrane damage, which suggested mitochondrial processes may contribute to adverse effects of these drugs in vivo.

Bioactivation and Reactivity Research Advances - 2021 year in review

This year's review on bioactivation and reactivity began as a part of the annual review on biotransformation and bioactivation led by Cyrus Khojasteh (Khojasteh et al., 2021, 2020, 2019, 2018, 2017; Baillie et al., 2016). Increased contributions from experts in the field led to the development of a stand alone edition for the first time this year focused specifically on bioactivation and reactivity. Our objective for this review is to highlight and share articles which we deem influential and significant regarding the development of covalent inhibitors, mechanisms of reactive metabolite formation, enzyme inactivation, and drug safety. Based on the selected articles, we created two sections: (1) reactivity and enzyme inactivation, and (2) bioactivation mechanisms and safety (Table 1). Several biotransformation experts have contributed to this effort from academic and industry settings.

Assessing Drug-Induced Mitochondrial Toxicity in Cardiomyocytes: Implications for Preclinical Cardiac Safety Evaluation

Drug-induced cardiotoxicity not only leads to the attrition of drugs during development, but also contributes to the high morbidity and mortality rates of cardiovascular diseases. Comprehensive testing for proarrhythmic risks of drugs has been applied in preclinical cardiac safety assessment for over 15 years. However, other mechanisms of cardiac toxicity have not received such attention. Of them, mitochondrial impairment is a common form of cardiotoxicity and is known to account for over half of cardiovascular adverse-event-related black box warnings imposed by the U.S. Food and Drug Administration. Although it has been studied in great depth, mitochondrial toxicity assessment has not yet been incorporated into routine safety tests for cardiotoxicity at the preclinical stage. This review discusses the main characteristics of mitochondria in cardiomyocytes, drug-induced mitochondrial toxicities, and high-throughput screening strategies for cardiomyocytes, as well as their proposed integration into preclinical safety pharmacology. We emphasize the advantages of using adult human primary cardiomyocytes for the evaluation of mitochondrial morphology and function, and the need for a novel cardiac safety testing platform integrating mitochondrial toxicity and proarrhythmic risk assessments in cardiac safety evaluation.

Protective Effect of Curcumin, Chrysin and Thymoquinone Injection on Trastuzumab-Induced Cardiotoxicity via Mitochondrial Protection

Mitochondrial dysfunction may lead to cardiomyocyte death in trastuzumab (TZM)-induced cardiotoxicity. Accordingly, this study was designed to evaluate the mitochondrial protective effects of curcumin, chrysin and thymoquinone alone in TZM-induced cardiotoxicity in the rats. Forty-eight male adult Wistar rats were divided into eight groups: control group (normal saline), TZM group (2.5 mg/kg I.P. injection, daily), TZM + curcumin group (10 mg/kg, I.P. injection, daily), TZM + chrysin (10 mg/kg, I.P. injection, daily), TZM + thymoquinone (0.5 mg/kg, I.P. injection, daily), curcumin group (10 mg/kg, I.P. injection, daily), chrysin group (10 mg/kg, I.P. injection, daily) and thymoquinone group (10 mg/kg, I.P. injection, daily). Blood and tissue were collected on day 11 and used for assessment of creatine phosphokinase, lactate dehydrogenase (LDH), troponin, malondialdehyde (MDA) amount, glutathione levels and mitochondrial toxicity parameters. TZM increased mitochondrial impairments (reactive oxygen species formation, mitochondrial swelling, mitochondrial membrane potential collapse and decline in succinate dehydrogenase activity) and histopathological alterations (hypertrophy, enlarged cell, disarrangement, myocytes degeneration, infiltration of fat in some areas, hemorrhage and focal vascular thrombosis) in rat heart. As well as TZM produced a significant increase in the level of CK, LDH, troponin, MDA, glutathione disulfide. In most experiments, the co-injection of curcumin, chrysin and thymoquinone with TZM restored the level of CK, LDH, troponin, MDA, GSH, mitochondrial impairments and histopathological alterations. The study revealed the cardioprotective effects of curcumin, chrysin and thymoquinone against TZM-induced cardiotoxicity which could be attributed to their antioxidant and mitochondrial protection activities.