Neuroprotective Effects of Mitochondria-Targeted Plastoquinone and Thymoquinone in a Rat Model of Brain Ischemia/Reperfusion Injury

Therapeutic potential of thymoquinone and its nanoformulations in neuropsychological disorders: a comprehensive review on molecular mechanisms in preclinical studies

Thymoquinone (THQ) and its nanoformulation (NFs) have emerged as promising candidates for the treatment of neurological diseases due to their diverse pharmacological properties, which include anti-inflammatory, antioxidant, and neuroprotective effects. In this study, we conducted an extensive search across reputable scientific websites such as PubMed, ScienceDirect, Scopus, and Google Scholar to gather relevant information. The antioxidant and anti-inflammatory properties of THQ have been observed to enhance the survival of neurons in affected areas of the brain, leading to significant improvements in behavioral and motor dysfunctions. Moreover, THQ and its NFs have demonstrated the capacity to restore antioxidant enzymes and mitigate oxidative stress. The primary mechanism underlying THQ's antioxidant effects involves the regulation of the Nrf2/HO-1 signaling pathway. Furthermore, THQ has been found to modulate key components of inflammatory signaling pathways, including toll-like receptors (TLRs), nuclear factor-κB (NF-κB), interleukin 6 (IL-6), IL-1β, and tumor necrosis factor alpha (TNFα), thereby exerting anti-inflammatory effects. This comprehensive review explores the various beneficial effects of THQ and its NFs on neurological disorders and provides insights into the underlying mechanisms involved.

Neuroprotective effects of dantrolene in neurodegenerative disease: Role of inhibition of pathological inflammation

Neurodegenerative diseases (NDs) refer to a group of diseases in which slow, continuous cell death is the main pathogenic event in the nervous system. Most NDs are characterized by cognitive dysfunction or progressive motor dysfunction. Treatments of NDs mainly target alleviating symptoms, and most NDs do not have disease-modifying drugs. The pathogenesis of NDs involves inflammation and apoptosis mediated by mitochondrial dysfunction. Dantrolene, approved by the US Food and Drug Administration, acts as a RyRs antagonist for the treatment of malignant hyperthermia, spasticity, neuroleptic syndrome, ecstasy intoxication and exertional heat stroke with tolerable side effects. Recently, dantrolene has also shown therapeutic effects in some NDs. Its neuroprotective mechanisms include the reduction of excitotoxicity, apoptosis and neuroinflammation. In summary, dantrolene can be considered as a potential therapeutic candidate for NDs.

Targeting Mitochondria for Cancer Treatment

There is an increasing accumulation of data on the exceptional importance of mitochondria in the occurrence and treatment of cancer, and in all lines of evidence for such participation, there are both energetic and non-bioenergetic functional features of mitochondria. This analytical review examines three specific features of adaptive mitochondrial changes in several malignant tumors. The first feature is characteristic of solid tumors, whose cells are forced to rebuild their energetics due to the absence of oxygen, namely, to activate the fumarate reductase pathway instead of the traditional succinate oxidase pathway that exists in aerobic conditions. For such a restructuring, the presence of a low-potential quinone is necessary, which cannot ensure the conventional conversion of succinate into fumarate but rather enables the reverse reaction, that is, the conversion of fumarate into succinate. In this scenario, complex I becomes the only generator of energy in mitochondria. The second feature is the increased proliferation in aggressive tumors of the so-called mitochondrial (peripheral) benzodiazepine receptor, also called translocator protein (TSPO) residing in the outer mitochondrial membrane, the function of which in oncogenic transformation stays mysterious. The third feature of tumor cells is the enhanced retention of certain molecules, in particular mitochondrially directed cations similar to rhodamine 123, which allows for the selective accumulation of anticancer drugs in mitochondria. These three features of mitochondria can be targets for the development of an anti-cancer strategy.

Intranasal delivery of mitochondria targeted neuroprotective compounds for traumatic brain injury: screening based on pharmacological and physiological properties

Targeting drugs to the mitochondrial level shows great promise for acute and chronic treatment of traumatic brain injury (TBI) in both military and civilian sectors. Perhaps the greatest obstacle to the successful delivery of drug therapies is the blood brain barrier (BBB). Intracerebroventricular and intraparenchymal routes may provide effective delivery of small and large molecule therapies for preclinical neuroprotection studies. However, clinically these delivery methods are invasive, and risk inadequate exposure to injured brain regions due to the rapid turnover of cerebral spinal fluid. The direct intranasal drug delivery approach to therapeutics holds great promise for the treatment of central nervous system (CNS) disorders, as this route is non-invasive, bypasses the BBB, enhances the bioavailability, facilitates drug dose reduction, and reduces adverse systemic effects. Using the intranasal method in animal models, researchers have successfully reduced stroke damage, reversed Alzheimer's neurodegeneration, reduced anxiety, improved memory, and delivered neurotrophic factors and neural stem cells to the brain. Based on literature spanning the past several decades, this review aims to highlight the advantages of intranasal administration over conventional routes for TBI, and other CNS disorders. More specifically, we have identified and compiled a list of most relevant mitochondria-targeted neuroprotective compounds for intranasal administration based on their mechanisms of action and pharmacological properties. Further, this review also discusses key considerations when selecting and testing future mitochondria-targeted drugs given intranasally for TBI.

Quinones as Neuroprotective Agents

Quinones can in principle be viewed as a double-edged sword in the treatment of neurodegenerative diseases, since they are often cytoprotective but can also be cytotoxic due to covalent and redox modification of biomolecules. Nevertheless, low doses of moderately electrophilic quinones are generally cytoprotective, mainly due to their ability to activate the Keap1/Nrf2 pathway and thus induce the expression of detoxifying enzymes. Some natural quinones have relevant roles in important physiological processes. One of them is coenzyme Q₁₀, which takes part in the oxidative phosphorylation processes involved in cell energy production, as a proton and electron carrier in the mitochondrial respiratory chain, and shows neuroprotective effects relevant to Alzheimer's and Parkinson's diseases. Additional neuroprotective quinones that can be regarded as coenzyme Q₁₀ analogues are idobenone, mitoquinone and plastoquinone. Other endogenous quinones with neuroprotective activities include tocopherol-derived quinones, most notably vatiquinone, and vitamin K. A final group of non-endogenous quinones with neuroprotective activity is discussed, comprising embelin, APX-3330, cannabinoid-derived quinones, asterriquinones and other indolylquinones, pyrroloquinolinequinone and its analogues, geldanamycin and its analogues, rifampicin quinone, memoquin and a number of hybrid structures combining quinones with amino acids, cholinesterase inhibitors and non-steroidal anti-inflammatory drugs.

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.

Thymoquinone in Ocular Neurodegeneration: Modulation of Pathological Mechanisms via Multiple Pathways

Thymoquinone is a naturally occurring compound and is the major component of Nigella sativa, also known as black seed or black cumin. For centuries thymoquinone has been used especially in the Middle East traditionally to treat wounds, asthma, allergies, fever, headache, cough, hypertension, and diabetes. Studies have suggested beneficial effects of thymoquinone to be attributed to its antioxidant, antibacterial, anti-oxidative stress, anti-inflammatory, and neuroprotective properties. Recently, there has been a surge of interest in thymoquinone as a treatment for neurodegeneration in the brain, such as that seen in Alzheimer’s (AD) and Parkinson’s diseases (PD). In vitro and in vivo studies on animal models of AD and PD suggest the main neuroprotective mechanisms are based on the anti-inflammatory and anti-oxidative properties of thymoquinone. Neurodegenerative conditions of the eye, such as Age-related Macular Degeneration (AMD) and glaucoma share at least in part similar mechanisms of neuronal cell death with those occurring in AD and PD. This review aims to summarize and critically analyze the evidence to date of the effects and potential neuroprotective actions of thymoquinone in the eye and ocular neurodegenerations.

The effects of different herbals on the rat hippocampus exposed to electromagnetic field for one hour during the prenatal period

The purpose of this study was to highlight the possible effects on the hippocampus of the electromagnetic field (EMF) emitted by mobile phones, and to investigate whether these potential effects can be reduced using various antioxidant substances. Twenty-seven female Wistar albino rats were divided into nine equal groups, each containing three pregnant rats aged 8-10 weeks and weighing 200-250 gr. The EMF groups were exposed to 900 Megahertz (MHz) EMF for 1 h (hr) a day for 21 days. No EMF exposure was applied to the Cont and also the groups given only Garcinia kola (GK), Momordica charantia (MC), and thymoquinone (TQ). The Sham group was kept in the polycarbonate EMF exposure system, but was not exposed to EMF. Four weeks after birth, rat pups were subjected to behavioural tests. Brain tissue samples were evaluated using histological, stereological, functional, and immunohistochemical methods. The numbers of pyramidal neurons in the rat cornu ammonis (CA) were determined using the optical fractionator method. Superoxide dismutase (SOD) and catalase (CAT) enzyme activities in the blood samples were also evaluated. The analysis data indicated that total pyramidal neuron numbers were decreased significantly in the CA of the EMF (1 hr) group (p < 0.01). Our results also showed that the protective effect of MC was more potent than that of the other antioxidant substances (p < 0.01). A 900 MHz EMF can cause deleterious changes in the brain. It can also be suggested that GK, MC and TQ are capable of reducing these adverse effects.

Harnessing the mitochondrial integrity for neuroprotection: Therapeutic role of piperine against experimental ischemic stroke

Ischemic stroke (IS) is a rapidly increasing global burden and is associated with severe neurological decline and mortality. There is urgent requirement of the efforts, aimed to identify therapeutic strategies that are effective in clinic to promote significant recovery from IS. Studies have shown that mitochondria mediated neuroprotection can be a competent target against ischemic damage. Therefore, we examined whether mitochondrial impairment is regulated by Piperine (PIP), an alkaloid of Piper Longum, which has neuroprotective activity against ischemic brain injury. In this study, transient middle cerebral artery occlusion (tMCAO) surgery was performed on male Wistar rats for 90 min followed by 22.5 h of reperfusion for mimicking the IS condition. This study consisted of three groups: sham, tMCAO and tMCAO + PIP (10 mg/kg b.wt., p.o/day for 15 days), and studied for behavioral tests, infarct volume, brain pathological changes, mitochondrial dysfunction, inflammation alongwith cell survival status. PIP pre-treatment showed reduction in neurological alterations and infarct volume. In addition, PIP pre-treatment suppressed the mitochondrial dysfunction and might have anti-apoptotic potential by preventing Cytochrome c (Cyt c) release from mitochondria to cytoplasm and caspase 3 activation. It also regulates pro-apoptotic, Bax and anti-apoptotic, Bcl-2 proteins accompanied by glial fibrillary acidic protein (GFAP) positive cells in cortex region. Quantitative Reverse transcription-polymerase chain reaction (qRT-PCR) results also showed that PIP reduced the expression of pro-inflammatory protein, interleukin-1 β (IL-1β) and enhanced cell survival by restoring the activity of brain derived neurotrophic factor (BDNF) and its transcription protein, cAMP response element binding protein (CREB). Taken together, PIP reduced the mitochondrial dysfunction, neurological impairment, and enhanced neuronal survival. In conclusion, our findings reinforce PIP as an effective neuroprotective agent and provide important evidence about its role as a potential target to serve as a promising therapy for treatment of IS.

Thymoquinone protects against cardiac mitochondrial DNA loss, oxidative stress, inflammation and apoptosis in isoproterenol-induced myocardial infarction in rats

INTRODUCTION

Myocardial infarction (MI) is an ischemic life-threatening disease with exaggerated oxidative stress state that vigorously damages the cardiomyocyte membrane and subcellular structures, including the vital mitochondrial DNA (mtDNA). The mtDNA is responsible for the proper functionality of the mitochondria, which are abundant in cardiomyocytes due to their dynamic nature and energy production requirements. Furthermore, oxidative stress triggers an inflammatory cascade and eventual apoptosis, which exacerbates cardiac injuries and dysfunction.

AIM

The present study used an isoproterenol (ISP)-induced MI rat model to investigate the role of the main active constituent of Nigella Sativa seeds, thymoquinone (TQ), in preserving the cardiac mtDNA content and ameliorating oxidative stress, inflammation, and apoptosis.

METHODS

Rats in the (TQ + ISP) group were pre-treated with TQ (20 mg/kg/day) for 21 days before the MI induction using ISP (85 mg/kg/day). In addition, negative control and ISP groups were included in the study for comparison. A histopathological examination was performed and serum cardiac parameters (cTnI and LDH) were assessed. In addition, mtDNA content, oxidative stress parameters (MDA, GSH, SOD, GPx, and CAT), inflammatory mediators (IL-6, IL-1β, and TNF-α), and apoptosis markers (BAX, Bcl2, and caspase-3) were detected.

RESULTS

The results showed that pre- and co-treatment with TQ in the (TQ + ISP) group reversed the histoarchitecture changes, caused a significant decrease in serum cardiac markers, oxidative stress markers, inflammatory cytokines, the apoptosis process, and preserved the cardiac mtDNA content.

CONCLUSION

TQ is a cardioprotective agent with an extended effect on preserving the cardiac mtDNA content, in addition to its powerful antioxidant, anti-inflammatory, and anti-apoptotic action.

The Effect of Thymoquinone on the Characteristics of the Brain Extracellular Space in Transient Middle Cerebral Artery Occlusion Rats

The extracellular space (ECS) is the space between the neurons and the capillaries in the brain. The volume fraction (α) and the tortuosity (λ) are the main parameters used to describe its characteristics. Thymoquinone has been proved to possess anti-oxidant and anti-inflammatory activity. In this study, we used a gadolinium-diethylenetriaminepentacetate (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) system to determine the effects of thymoquinone on ECS parameters in transient middle cerebral artery occlusion rats (tMCAO) to prove the neuroprotective effect of thymoquinone on brain tissue damage caused by ischemic stroke. Neurological examinations, 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H&E) staining and assaying of ECS parameters using MRI were performed 24 h after surgery. We found that thymoquinone could improve the behavioural performance by neurological examinations. TTC staining indicated that thymoquinone significantly decreased the percentage of hemi-cerebral infarction. Also, H&E staining showed that thymoquinone could inhibit the neuron necrosis in the hippocampal CA1 region. We found that thymoquinone treatment could inhibit the changes in ECS diffusion parameters, which might prove that thymoquinone might protect brain tissue damage caused by ischemic stroke. Thymoquinone can protect the brain against cerebral ischemia-reperfusion injury, effectively ameliorate abnormalities in characteristics of ECS and decrease cerebral infarction in tMCAO rats.

Energy, Entropy and Quantum Tunneling of Protons and Electrons in Brain Mitochondria: Relation to Mitochondrial Impairment in Aging-Related Human Brain Diseases and Therapeutic Measures

Adult human brains consume a disproportionate amount of energy substrates (2-3% of body weight; 20-25% of total glucose and oxygen). Adenosine triphosphate (ATP) is a universal energy currency in brains and is produced by oxidative phosphorylation (OXPHOS) using ATP synthase, a nano-rotor powered by the proton gradient generated from proton-coupled electron transfer (PCET) in the multi-complex electron transport chain (ETC). ETC catalysis rates are reduced in brains from humans with neurodegenerative diseases (NDDs). Declines of ETC function in NDDs may result from combinations of nitrative stress (NS)-oxidative stress (OS) damage; mitochondrial and/or nuclear genomic mutations of ETC/OXPHOS genes; epigenetic modifications of ETC/OXPHOS genes; or defects in importation or assembly of ETC/OXPHOS proteins or complexes, respectively; or alterations in mitochondrial dynamics (fusion, fission, mitophagy). Substantial free energy is gained by direct O2-mediated oxidation of NADH. Traditional ETC mechanisms require separation between O2 and electrons flowing from NADH/FADH2 through the ETC. Quantum tunneling of electrons and much larger protons may facilitate this separation. Neuronal death may be viewed as a local increase in entropy requiring constant energy input to avoid. The ATP requirement of the brain may partially be used for avoidance of local entropy increase. Mitochondrial therapeutics seeks to correct deficiencies in ETC and OXPHOS.

An Angiopep2-PAPTP Construct Overcomes the Blood-Brain Barrier. New Perspectives against Brain Tumors

A developing family of chemotherapeutics—derived from 5-(4-phenoxybutoxy)psoralen (PAP-1)—target mitochondrial potassium channel mtKv1.3 to selectively induce oxidative stress and death of diseased cells. The key to their effectiveness is the presence of a positively charged triphenylphosphonium group which drives their accumulation in the organelles. These compounds have proven their preclinical worth in murine models of cancers such as melanoma and pancreatic adenocarcinoma. In in vitro experiments they also efficiently killed glioblastoma cells, but in vivo they were powerless against orthotopic glioma because they were completely unable to overcome the blood-brain barrier. In an effort to improve brain delivery we have now coupled one of these promising compounds, PAPTP, to well-known cell-penetrating and brain-targeting peptides TAT_48–61 and Angiopep-2. Coupling has been obtained by linking one of the phenyl groups of the triphenylphosphonium to the first amino acid of the peptide via a reversible carbamate ester bond. Both TAT_48–61 and Angiopep-2 allowed the delivery of 0.3–0.4 nmoles of construct per gram of brain tissue upon intravenous (i.v.) injection of 5 µmoles/kg bw to mice. This is the first evidence of PAPTP delivery to the brain; the chemical strategy described here opens the possibility to conjugate PAPTP to small peptides in order to fine-tune tissue distribution of this interesting compound.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

p62-Nrf2-p62 Mitophagy Regulatory Loop as a Target for Preventive Therapy of Neurodegenerative Diseases

Turnover of the mitochondrial pool due to coordinated processes of mitochondrial biogenesis and mitophagy is an important process in maintaining mitochondrial stability. An important role in this process is played by the Nrf2/ARE signaling pathway, which is involved in the regulation of the expression of genes responsible for oxidative stress protection, regulation of mitochondrial biogenesis, and mitophagy. The p62 protein is a multifunctional cytoplasmic protein that functions as a selective mitophagy receptor for the degradation of ubiquitinated substrates. There is evidence that p62 can positively regulate Nrf2 by binding to its negative regulator, Keap1. However, there is also strong evidence that Nrf2 up-regulates p62 expression. Thereby, a regulatory loop is formed between two important signaling pathways, which may be an important target for drugs aimed at treating neurodegeneration. Constitutive activation of p62 in parallel with Nrf2 would most likely result in the activation of mTORC1-mediated signaling pathways that are associated with the development of malignant neoplasms. The purpose of this review is to describe the p62-Nrf2-p62 regulatory loop and to evaluate its role in the regulation of mitophagy under various physiological conditions.

Riding the tiger - physiological and pathological effects of superoxide and hydrogen peroxide generated in the mitochondrial matrix

Elevated mitochondrial matrix superoxide and/or hydrogen peroxide concentrations drive a wide range of physiological responses and pathologies. Concentrations of superoxide and hydrogen peroxide in the mitochondrial matrix are set mainly by rates of production, the activities of superoxide dismutase-2 (SOD2) and peroxiredoxin-3 (PRDX3), and by diffusion of hydrogen peroxide to the cytosol. These considerations can be used to generate criteria for assessing whether changes in matrix superoxide or hydrogen peroxide are both necessary and sufficient to drive redox signaling and pathology: is a phenotype affected by suppressing superoxide and hydrogen peroxide production; by manipulating the levels of SOD2, PRDX3 or mitochondria-targeted catalase; and by adding mitochondria-targeted SOD/catalase mimetics or mitochondria-targeted antioxidants? Is the pathology associated with variants in SOD2 and PRDX3 genes? Filtering the large literature on mitochondrial redox signaling using these criteria highlights considerable evidence that mitochondrial superoxide and hydrogen peroxide drive physiological responses involved in cellular stress management, including apoptosis, autophagy, propagation of endoplasmic reticulum stress, cellular senescence, HIF1α signaling, and immune responses. They also affect cell proliferation, migration, differentiation, and the cell cycle. Filtering the huge literature on pathologies highlights strong experimental evidence that 30-40 pathologies may be driven by mitochondrial matrix superoxide or hydrogen peroxide. These can be grouped into overlapping and interacting categories: metabolic, cardiovascular, inflammatory, and neurological diseases; cancer; ischemia/reperfusion injury; aging and its diseases; external insults, and genetic diseases. Understanding the involvement of mitochondrial matrix superoxide and hydrogen peroxide concentrations in these diseases can facilitate the rational development of appropriate therapies.

Thymoquinone as a Potential Neuroprotector in Acute and Chronic Forms of Cerebral Pathology

Thymoquinone is one of the main active components of the essential oil from black cumin (Nigella sativa) seeds. Thymoquinone exhibits a wide range of pharmacological activities, including neuroprotective action demonstrated in the models of brain ischemia/reperfusion, Alzheimer's and Parkinson's diseases, and traumatic brain injury. The neuroprotective effect of thymoquinone is mediated via inhibition of lipid peroxidation, downregulation of proinflammatory cytokines, maintenance of mitochondrial membrane potential, and prevention of apoptosis through inhibition of caspases-3, -8, and -9. Thymoquinone-based mitochondria-targeted antioxidants are accumulated in the mitochondria and exhibit neuroprotective properties in nanomolar concentrations. Thymoquinone reduces the negative effects of acute and chronic forms of brain pathologies. The mechanisms of the pharmacological action of thymoquinone and its chemical derivatives require more comprehensive studying. In this paper, we formulated the prospects of application of thymoquinone and thymoquinone-based drugs in the therapy of neurodegenerative diseases.

Mitochondria-targeted triphenylphosphonium-based compounds do not affect estrogen receptor α

BACKGROUND

Targeting negatively charged mitochondria is often achieved using triphenylphosphonium (TPP) cations. These cationic vehicles may possess biological activity, and a docking study indicates that TPP-moieties may act as modulators of signaling through the estrogen receptor α (ERα). Moreover, in vivo and in vitro experiments revealed the estrogen-like effects of TPP-based compounds. Here, we tested the hypothesis that TPP-based compounds regulate the activity of ERα.

METHODS

We used ERa-positive and ERα-negative human breast adenocarcinoma cell lines (MCF-7 and MDA-MB-231, respectively). Cell proliferation was measured using a resazurin cell growth assay and a real-time cell analyzer assay. Cell cycle progression was analyzed using flow cytometry. Real-time PCR was used to assess mRNA expression of endogenous estrogen-responsive genes. Luciferase activity was measured to evaluate transcription driven by estrogen-responsive promoters in cells transfected with an estrogen response element (ERE)3-luciferase expression vector.

RESULTS

The TPP-based molecules SkQ1 and C12TPP, as well as the rhodamine-based SkQR1, did not increase the proliferation or alter the cell cycle progression of MCF-7 cells. In contrast, 17β estradiol increased the proliferation of MCF-7 cells and the proportion of cells in the S/G2/M-phases of the cell cycle. TPP-based compounds did not affect the induction of transcription of an ERE-luciferase expression vector in vitro, and SkQ1 did not alter the levels of expression of estrogen-dependent genes encoding GREB1, TFF1, COX6, and IGFBP4.

CONCLUSION

TPP-based compounds do not possess properties typical of ERα agonists.

Triphenylphosphonium (TPP)-Based Antioxidants: A New Perspective on Antioxidant Design

Mitochondrial oxidative damage and dysfunction contribute to a wide range of human diseases. Considering the limitation of conventional antioxidants and that mitochondria are the main source of reactive oxygen species (ROS) which induce oxidative damage, mitochondria-targeted antioxidants which can selectively block mitochondrial oxidative damage and prevent various types of cell death have been widely developed. As a lipophilic cation, triphenylphosphonium (TPP) has been commonly used in designing mitochondria-targeted antioxidants. Conjugated with the TPP moiety, antioxidants can achieve more than 1000-fold higher mitochondrial concentration depending on cell membrane potentials and mitochondrial membrane potentials. Herein we discuss the deficiencies of conventional antioxidants and the advantages of mitochondrial targeting, and review various types of TPP-based mitochondria-targeted antioxidants. These provide theoretical and background support for the design of new anti-oxidant.

Therapeutic Effect of the Mitochondria-Targeted Antioxidant SkQ1 on the Culture Model of Multiple Sclerosis

Multiple sclerosis (MS) is a heterogeneous autoimmune disease of unknown etiology characterized by inflammation, demyelination, and axonal degeneration that affects both the white and gray matter of CNS. Recent large-scale epidemiological and genomic studies identified several genetic and environmental risk factors for the disease. Among them are environmental factors of infectious origin, possibly causing MS, which include Epstein-Barr virus infection, reactivation of some endogenous retrovirus groups, and infection by pathogenic bacteria (mycobacteria, Chlamydia pneumoniae, and Helicobacter pylori). However, the nature of the events leading to the activation of immune cells in MS is mostly unknown and there is no effective therapy against the disease. Amazingly, whatever the cause of the disease, signs of damage to the nerve tissue with MS lesions were the same as with infectious leprosy, while in the latter case nitrozooxidative stress was suggested as the main cause of the nerve damage. With this in mind and following the hypothesis that excessive production of mitochondrial reactive oxygen species critically contributes to MS pathogenesis, we studied the effect of mitochondria-targeted antioxidant SkQ1 in an in vitro MS model of the primary oligodendrocyte culture of the cerebellum, challenged with lipopolysaccharide (LPS). SkQ1 was found to accumulate in the mitochondria of oligodendrocytes and microglial cells, and it was also found to prevent LPS-induced inhibition of myelin production in oligodendrocytes. The results implicate that mitochondria-targeted antioxidants could be promising candidates as components of a combined therapy for MS and related neurological disorders.

Mitochondrial Damage and Mitochondria-Targeted Antioxidant Protection in LPS-Induced Acute Kidney Injury

Induced and frequently unwanted alterations in the mitochondrial structure and functions are a key component of the pathological cascade in many kidney pathologies, including those associated with acute damage. One of the principal pathogenic elements causing mitochondrial dysfunction in Acute Kidney Injury (AKI) is oxidative stress. After ischemia and nephrotoxic action of drugs, sepsis and systemic inflammation are the most frequent causes of AKI. As the kidney suffers from oxidative stress during sepsis, one of the most promising approaches to alleviate such damaging consequences is the use of antioxidants. Considering administration of lipopolysaccharide (LPS) as a model of sepsis, we demonstrate that the mitochondria of neonatal renal tissue are severely affected by LPS-induced AKI, with pathological ultrastructural changes observed in both the mitochondria of the renal tubular epithelium and the vascular endothelium. Upon mitochondrial damage, we evaluated the effect of the mitochondria-targeted antioxidant plastoquinol decylrhodamine 19 (SkQR1) on the development of acute renal failure in newborn rats associated with systemic inflammation induced by the administration of LPS. We found that SkQR1 administration 3 h before LPS led to decreased urinal expression of the AKI marker neutrophil gelatinase-associated lipocalin 2 (NGAL), in addition to a decrease in urea and creatinine levels in the blood. Additionally, an observed impairment of proliferative activity in the neonatal kidney caused by LPS treatment was also prevented by the treatment of rat pups with SkQR1. Thus, one of the key events for renal tissue damage in neonatal sepsis is an alteration in the structure and function of the mitochondria and the mitochondria-targeted antioxidant SkQR1 is an effective nephroprotective agent, which protects the neonatal kidney from sepsis-induced AKI.

Mechanism and Treatment Related to Oxidative Stress in Neonatal Hypoxic-Ischemic Encephalopathy

Hypoxic ischemic encephalopathy (HIE) is a type of neonatal brain injury, which occurs due to lack of supply and oxygen deprivation to the brain. It is associated with a high morbidity and mortality rate. There are several therapeutic strategies that can be used to improve outcomes in patients with HIE. These include cell therapies such as marrow mesenchymal stem cells (MSCs) and umbilical cord blood stem cells (UCBCs), which are being incorporated into the new protocols for the prevention of ischemic brain damage. The focus of this review is to discuss the mechanism of oxidative stress in HIE and summarize the current available treatments for HIE. We hope that a better understanding of the relationship between oxidative stress and HIE will provide new insights on the potential therapy of this devastating condition.

SkQ1 Controls CASP3 Gene Expression and Caspase-3-Like Activity in the Brain of Rats under Oxidative Stress

Here, we studied the effect of the mitochondria-targeted antioxidant SkQ1 (plastoquinone cationic derivative) on the CASP3 gene expression and caspase-3 activity in rat cerebral cortex and brain mitochondria under normal conditions and in oxidative stress induced by hyperbaric oxygenation (HBO). Under physiological conditions, SkQ1 administration (50 nmol/kg, 5 days) did not affect the CASP3 gene expression and caspase-3-like activity in the cortical cells, as well as caspase-3-like activity in brain mitochondria, but caused a moderate decrease in the content of primary products of lipid peroxidation (LPO) and an increase in the reduced glutathione (GSH) level. HBO-induced oxidative stress (0.5 MPa, 90 min) was accompanied by significant upregulation of CASP3 mRNA and caspase-3-like activity in the cerebral cortex, activation of the mitochondrial enzyme with simultaneous decrease in the GSH content, increase in the glutathione reductase activity, and stimulation of LPO. Administration of SkQ1 before the HBO session maintained the basal levels of the CASP3 gene expression and enzyme activity in the cerebral cortex cells and led to the normalization of caspase-3-like activity and redox parameters in brain mitochondria. We hypothesize that SkQ1 protects brain cells from the HBO-induced oxidative stress due to its antioxidant activity and stimulation of antiapoptotic mechanisms.

Neuroprotective Effects of Mitochondria-Targeted Plastoquinone in a Rat Model of Neonatal Hypoxic⁻Ischemic Brain Injury

Neonatal hypoxia⁻ischemia is one of the main causes of mortality and disability of newborns. To study the mechanisms of neonatal brain cell damage, we used a model of neonatal hypoxia⁻ischemia in seven-day-old rats, by annealing of the common carotid artery with subsequent hypoxia of 8% oxygen. We demonstrate that neonatal hypoxia⁻ischemia causes mitochondrial dysfunction associated with high production of reactive oxygen species, which leads to oxidative stress. Targeted delivery of antioxidants to the mitochondria can be an effective therapeutic approach to treat the deleterious effects of brain hypoxia⁻ischemia. We explored the neuroprotective properties of the mitochondria-targeted antioxidant SkQR1, which is the conjugate of a plant plastoquinone and a penetrating cation, rhodamine 19. Being introduced before or immediately after hypoxia⁻ischemia, SkQR1 affords neuroprotection as judged by the diminished brain damage and recovery of long-term neurological functions. Using vital sections of the brain, SkQR1 has been shown to reduce the development of oxidative stress. Thus, the mitochondrial-targeted antioxidant derived from plant plastoquinone can effectively protect the brain of newborns both in pre-ischemic and post-stroke conditions, making it a promising candidate for further clinical studies.

Mitochondrial abnormalities in Parkinson's disease and Alzheimer's disease: can mitochondria be targeted therapeutically?

Mitochondrial abnormalities have been identified as a central mechanism in multiple neurodegenerative diseases and, therefore, the mitochondria have been explored as a therapeutic target. This review will focus on the evidence for mitochondrial abnormalities in the two most common neurodegenerative diseases, Parkinson's disease and Alzheimer's disease. In addition, we discuss the main strategies which have been explored in these diseases to target the mitochondria for therapeutic purposes, focusing on mitochondrially targeted antioxidants, peptides, modulators of mitochondrial dynamics and phenotypic screening outcomes.

Protective Effects of Curcumin Against Ischemia-Reperfusion Injury in the Nervous System

Ischemia-reperfusion injury (I/R injury) is a common feature of ischemic stroke which occurs when blood supply is restored after a period of ischemia. Although stroke is an important cause of death in the world, effective therapeutic strategies aiming at improving neurological outcomes in this disease are lacking. Various studies have suggested the involvement of different mechanisms in the pathogenesis of I/R injury in the nervous system. These mechanisms include oxidative stress, platelet adhesion and aggregation, leukocyte infiltration, complement activation, blood-brain barrier (BBB) disruption, and mitochondria-mediated mechanisms. Curcumin, an active ingredient of turmeric, can affect all these pathways and exert neuroprotective activity culminating in the amelioration of I/R injury in the nervous system. In this review, we discuss the protective effects of curcumin against I/R injury in the nervous system and highlight the studies that have linked biological functions of curcumin and I/R injury improvement.

Mitochondria-Targeted Antioxidant SkQ1 (10-(6´-Plastoquinonyl)decyltriphenylphosphonium Bromide) Inhibits Mast Cell Degranulation in vivo and in vitro

The therapeutic effect of mitochondria-targeted antioxidant 10-(6´-plastoquinonyl)decyltriphenylphosphonium bromide (SkQ1) in experimental models of acute inflammation and wound repair has been shown earlier. It was suggested that the antiinflammatory activity of SkQ1 is related to its ability to suppress inflammatory activation of the vascular endothelium and neutrophil migration into tissues. Here, we demonstrated that SkQ1 inhibits activation of mast cells (MCs) followed by their degranulation and histamine release in vivo and in vitro. Intraperitoneal injections of SkQ1 in the mouse air-pouch model reduced the number of leukocytes in the air-pouch cavity and significantly decreased the histamine content in it, as well as suppressing MC degranulation in the air-pouch tissue. The direct effect of SkQ1 on MCs was studied in vitro in the rat basophilic leukemia RBL-2H3 cell line. SkQ1 inhibited induced degranulation of RBL-2H3 cells. These results suggest that mitochondrial reactive oxygen species are involved in the activation of MCs. It is known that MCs play a crucial role in regulation of vascular permeability by secreting histamine. Suppression of MC degranulation by SkQ1 might be a significant factor in the antiinflammatory activity of this mitochondria-targeted antioxidant.

Neuropharmacological Potential and Delivery Prospects of Thymoquinone for Neurological Disorders

Thymoquinone (TQ) is an active ingredient isolated from Nigella sativa and has various pharmacological activities, such as protection against oxidative stress, inflammation, and infections. In addition, it might be a potential neuropharmacological agent because it exhibits versatile potential for attenuating neurological impairments. It features greater beneficial effects in toxin-induced neuroinflammation and neurotoxicity. In various models of neurological disorders, it demonstrates emergent functions, including safeguarding various neurodegenerative diseases and other neurological diseases, such as stroke, schizophrenia, and epilepsy. TQ also has potential effects in trauma mediating and chemical-, radiation-, and drug-induced central nervous system injuries. Considering the pharmacokinetic limitations, research has concentrated on different TQ novel formulations and delivery systems. Here, we visualize the neuropharmacological potential, challenges, and delivery prospects of TQ, specifically focusing on neurological disorders along with its chemistry, pharmacokinetics, and toxicity.

Hemopexin promotes angiogenesis via up-regulating HO-1 in rats after cerebral ischemia-reperfusion injury

BACKGROUND

Ischemia-reperfusion (I/R) is a critical pathophysiological change of ischemic stroke. Heme-oxygenase-1 (HO-1) is a rate-limiting enzyme of eliminating excessive free heme by combining with hemopexin (HPX), a plasma protein contributing to alleviating infarct size due to ischemia stroke. This study was to investigate whether HPX could improve angiogenesis after cerebral ischemia-reperfusion via up-regulating HO-1.

METHODS

Rats were randomly divided into five groups: sham, MCAO, MCAO + Vehicle, MCAO + HPX and MCAO + HPX + protoporphyrin IX (ZnPPIX, an HO-1 inhibitor). Cerebral I/R was induced by MCAO. Saline, vehicle, HPX and HPX + ZnPPIX were respectively given to MCAO group, MCAO + Vehicle group, MCAO + HPX group and MCAO + HPX + ZnPPIX group at the moment after reperfusion by intracerebroventricular injection. Neurological behavioral scores(NBS) was assessed at 24 h and 7d after I/R. Real-time polymerase chain reaction (RT-PCR) was used to analyze the mRNA level of HO-1. Angiogenesis in penumbra area was assessed by immunofluorescence detection at 7d after I/R. Serum endothelial nitric oxide synthase (eNOS) was assessed by enzyme linked immunosorbent assay (ELISA) at 24 h and 7d after I/R.

RESULTS

Compared with sham group, the NBS and the mRNA levels of HO-1 at 24 h and 7d after I/R in MCAO group decreased notably (P < 0.05), the new vessel density in ischemia penumbra increased notably at 7d after I/R (P < 0.05), the serum eNOS level increased at 24 h and 7d after I/R (P < 0.05). MCAO group and MCAO + Vehicle group showed no significant differences (P > 0.05). In the MCAO + HPX group, compared with MCAO + Vehicle group, the NBS and the mRNA levels of HO-1 increased drastically at 24 h and 7d after I/R (P < 0.05), the new vessel density in ischemia penumbra increased significantly at 7d after I/R (P < 0.05), the serum eNOS level at 24 h and 7d after I/R ascended notably (P < 0.05). Compared with MCAO + HPX group, the NBS assessment, new vessel density and serum eNOS level decreased at corresponding time points after I/R in MCAO + HPX+ ZnPPIX group (P < 0.05).

CONCLUSION

HPX can promote angiogenesis after cerebral ischemia-reperfusion injury in rats via up-regulating HO-1.

Mitochondrial dynamics, mitophagy and biogenesis in neonatal hypoxic-ischaemic brain injury

Hypoxic-ischaemic encephalopathy, resulting from asphyxia during birth, affects 2-3 in every 1000 term infants and depending on severity, brings about life-changing neurological consequences or death. This hypoxic-ischaemia (HI) results in a delayed neural energy failure during which the majority of brain injury occurs. Currently, there are limited treatment options and additional therapies are urgently required. Mitochondrial dysfunction acts as a focal point in injury development in the immature brain. Not only do mitochondria become permeabilised, but recent findings implicate perturbations in mitochondrial dynamics (fission, fusion), mitophagy and biogenesis. Mitoprotective therapies may therefore offer a new avenue of intervention for babies who suffer lifelong disabilities due to birth asphyxia.

An antioxidant specifically targeting mitochondria delays progression of Alzheimer's disease-like pathology

Mitochondrial aberrations are observed in human Alzheimer's disease (AD) and in medical conditions that increase the risk of this disorder, suggesting that mitochondrial dysfunction may contribute to pathophysiology of AD. Here, using OXYS rats that simulate key characteristics of sporadic AD, we set out to determine the role of mitochondria in the pathophysiology of this disorder. OXYS rats were treated with a mitochondria-targeted antioxidant SkQ1 from age 12 to 18 months, that is, during active progression of AD-like pathology in these animals. Dietary supplementation with SkQ1 caused this compound to accumulate in various brain regions, and it was localized mostly to neuronal mitochondria. Via improvement of structural and functional state of mitochondria, treatment with SkQ1 alleviated the structural neurodegenerative alterations, prevented the neuronal loss and synaptic damage, increased the levels of synaptic proteins, enhanced neurotrophic supply, and decreased amyloid-β1-42 protein levels and tau hyperphosphorylation in the hippocampus of OXYS rats, resulting in improvement of the learning ability and memory. Collectively, these data support that mitochondrial dysfunction may play a key role in the pathophysiology of AD and that therapies with target mitochondria are potent to normalize a wide range of cellular signaling processes and therefore slow the progression of AD.

Humanin analogue, S14G-humanin, has neuroprotective effects against oxygen glucose deprivation/reoxygenation by reactivating Jak2/Stat3 signaling through the PI3K/AKT pathway

Stroke, characterized by a disruption of blood supply to the brain, is a major cause of morbidity and mortality worldwide. Although humanin, a 24-amino acid polypeptide, has been identified to have multiple neuroprotective functions, the level of humanin in plasma has been demonstrated to decrease with age, which likely limits the effects against stroke injury. A potent humanin analogue, S14G-humanin (HNG), generated by replacement of Ser14 with glycine, has been demonstrated to have 1,000-fold stronger biological activity than humanin. The present study established an in vitro oxygen glucose deprivation/reoxygenation (OGD/R) model using SH-SY5Y neuroblastoma cells to mimic the in vivo ischemia/reperfusion injury in stroke. Adding HNG (0-10 µg/l) to SH-SY5Y cells to different extents blocked OGD/R-induced reduction of cell viability and antioxidative capacity, as well as decreased the elevated apoptosis rate induced by OGD/R, with the most evident effects at 1 µg/l HNG. Janus kinase 2 (Jak2)/signal transducer and activator of transcription 3 (Stat3) signaling was attenuated in OGD/R processes, yet reactivated with HNG treatment. FLLL32 (5 µM), a specific inhibitor of the signal, abolished effects of HNG on anti-apoptosis and antioxidation in OGD/R processes. Co-treatment with HNG and FLLL32 failed to interrupt upregulation of cytochrome c, B-cell lymphoma 2-associated X protein and cleaved caspase-3 provoked by OGD/R. Similar to FLLL32, Jak2/Stat3 signaling activated by HNG was also repressed by inhibitor of phosphoinositide 3-kinase (PI3K; 10 µM LY294002) or protein kinase B (AKT; 5 µM MK-2206 2HCl). These data collectively indicated that HNG has neuroprotective effects against OGD/R by reactivating Jak2/Stat3 signaling through the PI3K/AKT pathway, suggesting that HNG may be a promising agent in the management of stroke.

A synthetic cell permeable antioxidant protects neurons against acute oxidative stress

Excessive reactive oxygen species (ROS) can damage proteins, lipids, and DNA, which result in cell damage and death. The outcomes can be acute, as seen in stroke, or more chronic as observed in age-related diseases such as Parkinson’s disease. Here we investigate the antioxidant ability of a novel synthetic flavonoid, Proxison (7-decyl-3-hydroxy-2-(3,4,5-trihydroxyphenyl)-4-chromenone), using a range of in vitro and in vivo approaches. We show that, while it has radical scavenging ability on par with other flavonoids in a cell-free system, Proxison is orders of magnitude more potent than natural flavonoids at protecting neural cells against oxidative stress and is capable of rescuing damaged cells. The unique combination of a lipophilic hydrocarbon tail with a modified polyphenolic head group promotes efficient cellular uptake and moderate mitochondrial enrichment of Proxison. Importantly, in vivo administration of Proxison demonstrated effective and well tolerated neuroprotection against cell loss in a zebrafish model of dopaminergic neurodegeneration.

Mitochondria-Targeted Triphenylphosphonium-Based Compounds: Syntheses, Mechanisms of Action, and Therapeutic and Diagnostic Applications

Mitochondria are recognized as one of the most important targets for new drug design in cancer, cardiovascular, and neurological diseases. Currently, the most effective way to deliver drugs specifically to mitochondria is by covalent linking a lipophilic cation such as an alkyltriphenylphosphonium moiety to a pharmacophore of interest. Other delocalized lipophilic cations, such as rhodamine, natural and synthetic mitochondria-targeting peptides, and nanoparticle vehicles, have also been used for mitochondrial delivery of small molecules. Depending on the approach used, and the cell and mitochondrial membrane potentials, more than 1000-fold higher mitochondrial concentration can be achieved. Mitochondrial targeting has been developed to study mitochondrial physiology and dysfunction and the interaction between mitochondria and other subcellular organelles and for treatment of a variety of diseases such as neurodegeneration and cancer. In this Review, we discuss efforts to target small-molecule compounds to mitochondria for probing mitochondria function, as diagnostic tools and potential therapeutics. We describe the physicochemical basis for mitochondrial accumulation of lipophilic cations, synthetic chemistry strategies to target compounds to mitochondria, mitochondrial probes, and sensors, and examples of mitochondrial targeting of bioactive compounds. Finally, we review published attempts to apply mitochondria-targeted agents for the treatment of cancer and neurodegenerative diseases.

Thymoquinone Attenuates Brain Injury via an Anti-oxidative Pathway in a Status Epilepticus Rat Model

AIM

Status epilepticus (SE) results in the generation of reactive oxygen species (ROS), which contribute to seizure-induced brain injury. It is well known that oxidative stress plays a pivotal role in status epilepticus (SE). Thymoquinone (TQ) is a bioactive monomer extracted from black cumin (Nigella sativa) seed oil that has anti-inflammatory, anti-cancer, and antioxidant activity in various diseases. This study evaluated the protective effects of TQ on brain injury in a lithium-pilocarpine rat model of SE and investigated the underlying mechanism related to antioxidative pathway.

METHODS

Electroencephalogram and Racine scale were used to value seizure severity. Passive-avoidance test was used to determine learning and memory function. Moreover, anti-oxidative activity of TQ was observed using Western blot and super oxide dismutase (SOD) activity assay.

RESULTS

Latency to SE increased in the TQ-pretreated group compared with rats in the model group, while the total power was significantly lower. Seizure severity measured on the Racine scale was significantly lower in the TQ group compared with the model group. Results of behavioral experiments suggest that TQ may also have a protective effect on learning and memory function. Investigation of the protective mechanism of TQ showed that TQ-pretreatment significantly increased the expression of Nrf2, HO-1 proteins and SOD in the hippocampus.

CONCLUSION

These findings showed that TQ attenuated brain injury induced by SE via an anti-oxidative pathway.

Neuroprotective properties of mitochondria-targeted antioxidants of the SkQ-type

In 2008, using a model of compression brain ischemia, we presented the first evidence that mitochondria-targeted antioxidants of the SkQ family, i.e. SkQR1 [10-(6′-plastoquinonyl)decylrhodamine], have a neuroprotective action. It was shown that intraperitoneal injections of SkQR1 (0.5–1 μmol/kg) 1 day before ischemia significantly decreased the damaged brain area. Later, we studied in more detail the anti-ischemic action of this antioxidant in a model of experimental focal ischemia provoked by unilateral intravascular occlusion of the middle cerebral artery. The neuroprotective action of SkQ family compounds (SkQR1, SkQ1, SkQTR1, SkQT1) was manifested through the decrease in trauma-induced neurological deficit in animals and prevention of amyloid-β-induced impairment of long-term potentiation in rat hippocampal slices. At present, most neurophysiologists suppose that long-term potentiation underlies cellular mechanisms of memory and learning. They consider inhibition of this process by amyloid-β1-42as anin vitromodel of memory disturbance in Alzheimer’s disease. Further development of the above studies revealed that mitochondria-targeted antioxidants could retard accumulation of hyperphosphorylated τ-protein, as well as amyloid-β1-42, and its precursor APP in the brain, which are involved in developing neurodegenerative processes in Alzheimer’s disease.

Parkin Protects against Oxygen-Glucose Deprivation/Reperfusion Insult by Promoting Drp1 Degradation

Ischemic stroke results in severe brain damage and remains one of the leading causes of death and disability worldwide. Effective neuroprotective therapies are needed to reduce brain damage resulting from ischemic stroke. Mitochondria are crucial for cellular energy production and homeostasis. Modulation of mitochondrial function mediates neuroprotection against ischemic brain damage. Dynamin-related protein 1 (Drp1) and parkin play a key role in regulating mitochondrial dynamics. They are potential therapeutic targets for neuroprotection in ischemic stroke. Protective effects of parkin-Drp1 pathway on mitochondria were assessed in a cellular ischemia-reperfusion injury model. Mouse neuroblastoma Neuro2a (N2a) cells were subjected to oxygen-glucose deprivation/reperfusion (OGDR) insult. OGDR induces mitochondrial fragmentation. The expression of Drp1 protein is increased after OGDR insult, while the parkin protein level is decreased. The altered protein level of Drp1 after OGDR injury is mediated by parkin through ubiquitin proteasome system (UPS). Drp1 depletion protects against OGDR induced mitochondrial damage and apoptosis. Meanwhile, parkin overexpression protects against OGDR induced apoptosis and mitochondrial dysfunction, which is attenuated by increased expression of Drp1. Our data demonstrate that parkin protects against OGDR insult through promoting degradation of Drp1. This neuroprotective potential of parkin-Drp1 pathway against OGDR insult will pave the way for developing novel neuroprotective agents for cerebral ischemia-reperfusion related disorders.

Role of Mitochondria in Cerebral Vascular Function: Energy Production, Cellular Protection, and Regulation of Vascular Tone

Mitochondria not only produce energy in the form of ATP to support the activities of cells comprising the neurovascular unit, but mitochondrial events, such as depolarization and/or ROS release, also initiate signaling events which protect the endothelium and neurons against lethal stresses via pre-/postconditioning as well as promote changes in cerebral vascular tone. Mitochondrial depolarization in vascular smooth muscle (VSM), via pharmacological activation of the ATP-dependent potassium channels on the inner mitochondrial membrane (mitoKATP channels), leads to vasorelaxation through generation of calcium sparks by the sarcoplasmic reticulum and subsequent downstream signaling mechanisms. Increased release of ROS by mitochondria has similar effects. Relaxation of VSM can also be indirectly achieved via actions of nitric oxide (NO) and other vasoactive agents produced by endothelium, perivascular and parenchymal nerves, and astroglia following mitochondrial activation. Additionally, NO production following mitochondrial activation is involved in neuronal preconditioning. Cerebral arteries from female rats have greater mitochondrial mass and respiration and enhanced cerebral arterial dilation to mitochondrial activators. Preexisting chronic conditions such as insulin resistance and/or diabetes impair mitoKATP channel relaxation of cerebral arteries and preconditioning. Surprisingly, mitoKATP channel function after transient ischemia appears to be retained in the endothelium of large cerebral arteries despite generalized cerebral vascular dysfunction. Thus, mitochondrial mechanisms may represent the elusive signaling link between metabolic rate and blood flow as well as mediators of vascular change according to physiological status. Mitochondrial mechanisms are an important, but underutilized target for improving vascular function and decreasing brain injury in stroke patients. © 2016 American Physiological Society. Compr Physiol 6:1529-1548, 2016.

Generation of reactive oxygen species in the anterior eye segment. Synergistic codrugs of N-acetylcarnosine lubricant eye drops and mitochondria-targeted antioxidant act as a powerful therapeutic platform for the treatment of cataracts and primary open-angle glaucoma

Senile cataract is a clouding of the lens in the aging eye leading to a decrease in vision. Symptoms may include faded colors, blurry vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Cataracts are the cause of half of blindness and 33% of visual impairment worldwide. Cataracts result from the deposition of aggregated proteins in the eye lens and lens fiber cells plasma membrane damage which causes clouding of the lens, light scattering, and obstruction of vision. ROS induced damage in the lens cell may consist of oxidation of proteins, DNA damage and/or lipid peroxidation, all of which have been implicated in cataractogenesis. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can't drain out of the eye. With primary open-angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink. The excessive oxidative damage is a major factor of the ocular diseases because the mitochondrial respiratory chain in mitochondria of the vital cells is a significant source of the damaging reactive oxygen species superoxide and hydrogen peroxide. However, despite the clinical importance of mitochondrial oxidative damage, antioxidants have been of limited therapeutic success. This may be because the antioxidants are not selectively taken up by mitochondria, but instead are dispersed throughout the body, ocular tissues and fluids' moieties. This work is an attempt to integrate how mitochondrial reactive oxygen species (ROS) are altered in the aging eye, along with those protective and repair therapeutic systems believed to regulate ROS levels in ocular tissues and how damage to these systems contributes to age-onset eye disease and cataract formation. Mitochondria-targeted antioxidants might be used to effectively prevent ROS-induced oxidation of lipids and proteins in the inner mitochondrial membrane in vivo. The authors developed and patented the new ophthalmic compositions including N-acetylcarnosine acting as a prodrug of naturally targeted to mitochondria l-carnosine endowed with pluripotent antioxidant activities, combined with mitochondria-targeted rechargeable antioxidant (either MitoVit E, Mito Q or SkQs) as a potent medicine to treat ocular diseases. Such specificity is explained by the fact that developed compositions might be used to effectively prevent ROS-induced oxidation of lipids and proteins in the inner mitochondrial membrane in vivo and outside mitochondria in the cellular and tissue structures of the lens and eye compartments. Mitochondrial targeting of compounds with universal types of antioxidant activity represents a promising approach for treating a number of ROS-related ocular diseases of the aging eye and can be implicated in the management of cataracts and primary open-angle glaucoma.