Ubiquinol-10 is an effective lipid-soluble antioxidant at physiological concentrations

Effects of adenosine triphosphate and coenzyme Q10 on potential hydroxychloroquine-induced retinal damage in rats

This study aimed to investigate biochemically and histopathologically the protective effect of adenosine triphosphate (ATP) and coenzyme Q10 (CoQ10) against potential hydroxychloroquine (HCQ)-induced retinal damage in rats. Twenty-four male albino Wistar-type rats were randomly separated into four groups: healthy (HG), receiving HCQ (HQG), receiving ATP + HCQ (AHQ), and receiving CoQ10 + HCQ (CoQHQ). ATP (4 mg/kg, intraperitoneal) was given to the AHQ, and CoQ10 (10 mg/kg, oral) to the CoQHQ. Rats in the HQG, AHQ, and CoQHQ were given HCQ (120 mg/kg, oral) 1 h after administering ATP and CoQ10. Treatments continued once a day for seven days. On the 8th day, the rats were sacrificed with 50 mg/kg sodium thiopental, and the eyes were removed. Malondialdehyde (MDA), total glutathione (tGSH), superoxide dismutase (SOD), and catalase (CAT), and interleukin-6 (IL-6) levels were measured in the retrieved eye tissues and retinal tissues were assessed histopathologically. An increase in MDA and IL-6 levels and a decrease in tGSH, SOD, and CAT levels were detected in the eye tissues of the HQGcompared to the HG. HCQ-induced changes in oxidant and antioxidant levels were significantly suppressed by ATP and CoQ10 treatment. ATP was more successful than CoQ10 in this inhibition. Severe damage was observed in the eye tissues of the HQG group, whereas the damage was mild in the AHQ and moderate in the CoQHQ. Although both ATP and CoQ10 have the potential to be effective in the prevention of HCQ-induced retinal damage through antioxidative activity, ATP appears to be the more preferable treatment approach.

Advances in kidney disease: pathogenesis and therapeutic targets

Chronic kidney disease (CKD) is a global public health issue characterized by progressive loss of kidney function, of which end-stage kidney disease (ESKD) is the last stage. The global increase in the prevalence of CKD is linked to the increasing prevalence of traditional risk factors, including obesity, hypertension, and diabetes mellitus, as well as metabolic factors, particularly insulin resistance, dyslipidemia, and hyperuricemia. Mortality and comorbidities, such as cardiovascular complications, rise steadily as kidney function deteriorates. Patients who progress to ESKD require long-term kidney replacement therapy, such as transplantation or hemodialysis/peritoneal dialysis. It is currently understood that a crucial aspect of CKD involves persistent, low-grade inflammation. In addition, increased oxidative and metabolic stress, endothelial dysfunction, vascular calcification from poor calcium and phosphate metabolism, and difficulties with coagulation are some of the complex molecular pathways underlying CKD-related and ESKD-related issues. Novel mechanisms, such as microbiome dysbiosis and apolipoprotein L1 gene mutation, have improved our understanding of kidney disease mechanisms. High kidney disease risk of Africa has been linked to APOL1 high-risk alleles. The 3-fold increased risk of ESKD in African Americans compared to European Americans is currently mainly attributed to variants in the APOL1 gene in the chromosome 22q12 locus. Additionally, the role of new therapies such as SGLT2 inhibitors, mineralocorticoid receptor antagonists, and APOL1 channel function inhibitors offers new therapeutic targets in slowing down the progression of chronic kidney disease. This review describes recent molecular mechanisms underlying CKD and emerging therapeutic targets.

Ferroptosis in schizophrenia: Mechanisms and therapeutic potentials (Review)

Schizophrenia, a complex psychiatric disorder, presents with multifaceted symptoms and important challenges in treatment, primarily due to its pathophysiological complexity, which involves oxidative stress and aberrant iron metabolism. Recent insights into ferroptosis, a unique form of iron‑dependent cell death characterized by lipid peroxidation and antioxidant system failures, open new avenues for understanding the neurobiological foundation of schizophrenia. The present review explores the interplay between ferroptosis and schizophrenia, emphasizing the potential contributions of disrupted iron homeostasis and oxidative mechanisms to the pathology and progression of this disease. The emerging evidence linking ferroptosis with the oxidative stress observed in schizophrenia provides a compelling narrative for re‑evaluating current therapeutic strategies and exploring novel interventions targeting these molecular pathways, such as the glutathione peroxidase 4 pathway and the ferroptosis suppressor protein 1 pathway. By integrating recent advances in ferroptosis research, the current review highlights innovative therapeutic potentials, including N‑acetylcysteine, selenium, omega‑3 fatty acids and iron chelation therapy, which could address the limitations of existing treatments and improve clinical outcomes for individuals with schizophrenia.

Mitochondrial-ER Contact Sites and Tethers Influence the Biosynthesis and Function of Coenzyme Q

Coenzyme Q (CoQ) is an essential redox-active lipid that plays a major role in the electron transport chain, driving mitochondrial ATP synthesis. In Saccharomyces cerevisiae (yeast), CoQ biosynthesis occurs exclusively in the mitochondrial matrix via a large protein-lipid complex, the CoQ synthome, comprised of CoQ itself, late-stage CoQ-intermediates, and the polypeptides Coq3-Coq9 and Coq11. Coq11 is suggested to act as a negative modulator of CoQ synthome assembly and CoQ synthesis, as its deletion enhances Coq polypeptide content, produces an enlarged CoQ synthome, and restores respiration in mutants lacking the CoQ chaperone polypeptide, Coq10. The CoQ synthome resides in specific niches within the inner mitochondrial membrane, termed CoQ domains, that are often located adjacent to the endoplasmic reticulum-mitochondria encounter structure (ERMES). Loss of ERMES destabilizes the CoQ synthome and renders CoQ biosynthesis less efficient. Here we show that deletion of COQ11 suppresses the respiratory deficient phenotype of select ERMES mutants, results in repair and reorganization of the CoQ synthome, and enhances mitochondrial CoQ domains. Given that ER-mitochondrial contact sites coordinate CoQ biosynthesis, we used a Split-MAM (Mitochondrial Associated Membrane) artificial tether consisting of an ER-mitochondrial contact site reporter, to evaluate the effects of artificial membrane tethers on CoQ biosynthesis in both wild-type and ERMES mutant yeast strains. Overall, this work identifies the deletion of COQ11 as a novel suppressor of phenotypes associated with ERMES deletion mutants and indicates that ER-mitochondria tethers influence CoQ content and turnover, highlighting the role of membrane contact sites in regulating mitochondrial respiratory homeostasis.

Investigation and determination of CoQ10(H2) and CoQ10(H4) species from black yeast-like fungi and filamentous fungi

Coenzyme Q (CoQ) or ubiquinone functions as an electron transporter in the electron transport system in both prokaryotes and eukaryotes. The isoprenyl side chain of CoQ is modified in some organisms, especially in fungi, for optimal electron transport performance under various conditions. In this study, we investigated the side chain saturated dihydro CoQ (CoQ10(H2)) in Aureobasidium pullulans EXF-150, Sydowia polyspora NBRC 30562, and naturally isolated Plowrightia sp. A37, all of which are melanized Dothideomycetes species within Ascomycota, and also in filamentous fungi Aspergillus oryzae and A. terreus. Plowrightia sp. A37 produced the rarely synthesized tetrahydro type CoQ10(H4), especially in glucose-rich medium, during extended cultivation in contrast to CoQ10(H2) in time-limited cultivation. Using liquid chromatography-mass spectrometry, we identified demethoxyubiquinone-H2 (DMQ(H2)) as an indicative intermediate that suggests that the side chain saturation of CoQ occurs after the formation of DMQ and not always in the last step as previously considered.

Ferroptosis and its role in osteoarthritis: mechanisms, biomarkers, and therapeutic perspectives

Osteoarthritis (OA) is one of the leading causes of disability worldwide, characterized by a complex pathological process involving cartilage degradation, synovial inflammation, and subchondral bone remodeling. In recent years, ferroptosis, a form of programmed cell death driven by iron-dependent lipid peroxidation, has been recognized as playing a critical role in the onset and progression of OA. Investigating the molecular mechanisms of ferroptosis and its involvement in OA may offer novel strategies for diagnosing and treating this disease. This review first outlines the core mechanisms of ferroptosis, with a particular focus on the roles of critical molecules such as Glutathione Peroxidase 4 (GPX4), Transferrin Receptor 1 (TfR1), and Nuclear Receptor Coactivator 4 (NCOA4). Subsequently, this study examines the specific impacts of ferroptosis on the pathophysiology of OA. Building on this, the potential of ferroptosis-related biomarkers for OA diagnosis and treatment is highlighted, along with proposed therapeutic strategies targeting ferroptosis regulation. This review aims to deepen the understanding of ferroptosis mechanisms and advance the clinical application of regulatory therapies for OA.

Nonfunctional coq10 mutants maintain the ERMES complex and reveal true phenotypes associated with the loss of the coenzyme Q chaperone protein Coq10

Coenzyme Q (CoQ) is a redox-active lipid molecule that acts as an electron carrier in the mitochondrial electron transport chain. In Saccharomyces cerevisiae, CoQ is synthesized in the mitochondrial matrix by a multisubunit protein-lipid complex termed the CoQ synthome, the spatial positioning of which is coordinated by the endoplasmic reticulum-mitochondria encounter structure (ERMES). The MDM12 gene encoding the cytosolic subunit of ERMES is coexpressed with COQ10, which encodes the putative CoQ chaperone Coq10, via a shared bidirectional promoter. Deletion of COQ10 results in respiratory deficiency, impaired CoQ biosynthesis, and reduced spatial coordination between ERMES and the CoQ synthome. While Coq10 protein content is maintained upon deletion of MDM12, we show that deletion of COQ10 by replacement with a HIS3 marker results in diminished Mdm12 protein content. Since deletion of individual ERMES subunits prevents ERMES formation, we asked whether some or all of the phenotypes associated with COQ10 deletion result from ERMES dysfunction. To identify the phenotypes resulting solely due to the loss of Coq10, we constructed strains expressing a functionally impaired (coq10-L96S) or truncated (coq10-R147∗) Coq10 isoform using CRISPR-Cas9. We show that both coq10 mutants preserve Mdm12 protein content and exhibit impaired respiratory capacity like the coq10Δ mutant, indicating that Coq10's function is vital for respiration regardless of ERMES integrity. Moreover, the maintenance of CoQ synthome stability and efficient CoQ biosynthesis observed for the coq10-R147∗ mutant suggests these deleterious phenotypes in the coq10Δ mutant result from ERMES disruption. Overall, this study clarifies the role of Coq10 in modulating CoQ biosynthesis.

Understanding coenzyme Q

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid side chain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) but is also required for several other crucial cellular processes. In fact, CoQ appears to be central to the entire redox balance of the cell. Remarkably, its structure and therefore its properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox-active molecule in the ETC and other enzymatic systems, its role as a prooxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common, as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

Unveiling ferroptosis as a promising therapeutic avenue for colorectal cancer and colitis treatment

Ferroptosis is a novel type of regulated cell death (RCD) involving iron accumulation and lipid peroxidation. Since its discovery in 2012, various studies have shown that ferroptosis is associated with the pathogenesis of various diseases. Ferroptotic cell death has also been linked to intestinal dysfunction but can act as either a positive or negative regulator of intestinal disease, depending on the cell type and disease context. The continued investigation of mechanisms underlying ferroptosis provides a wealth of potential for developing novel treatments. Considering the growing prevalence of intestinal diseases, particularly colorectal cancer (CRC) and inflammatory bowel disease (IBD), this review article focuses on potential therapeutics targeting the ferroptotic pathway in relation to CRC and IBD.

Ferroptosis-A Shared Mechanism for Parkinson's Disease and Type 2 Diabetes

Type 2 diabetes (T2D) and Parkinson's disease (PD) are the two most frequent age-related chronic diseases. There are many similarities between the two diseases: both are chronic diseases; both are the result of a decrease in a specific substance-insulin in T2D and dopamine in PD; and both are caused by the destruction of specific cells-beta pancreatic cells in T2D and dopaminergic neurons in PD. Recent epidemiological and experimental studies have found that there are common underlying mechanisms in the pathophysiology of T2D and PD: chronic inflammation, mitochondrial dysfunction, impaired protein handling and ferroptosis. Epidemiological research has indicated that there is a higher risk of PD in individuals with T2D. Moreover, clinical studies have observed that the symptoms of Parkinson's disease worsen significantly after the onset of T2D. This article provides an up-to-date review on the intricate interplay between oxidative stress, reactive oxygen species (ROS) and ferroptosis in PD and T2D. By understanding the shared molecular pathways and how they can be modulated, we can develop more effective therapies, or we can repurpose existing drugs to improve patient outcomes in both disorders.

The Role of Natural Low Molecular Weight Dicarbonyls in Atherogenesis and Diabetogenesis

This review summarises the data from long-term experimental studies and literature data on the role of oxidatively modified low-density lipoproteins (LDL) in atherogenesis and diabetogenesis. It was shown that not "oxidized" (lipoperoxide-containing) LDL, but dicarbonyl-modified LDL are atherogenic (actively captured by cultured macrophages with the help of scavenger receptors), and also cause expression of lectin like oxidized low density lipoprotein receptor 1 (LOX-1) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 (NOX-1) genes in endotheliocytes, which stimulate apoptosis and endothelial dysfunction. The obtained data allowed us to justify new approaches to pharmacotherapy of atherosclerosis and diabetes mellitus.

Ferroptosis in cancer (Review)

Ferroptosis is a type of programmed cell death depending on iron and reactive oxygen species. This unique cell death process has attracted a great deal of attention in the field of cancer research over the past decade. Research on the association of ferroptosis signal pathways and cancer development indicated that targeting ferroptosis has great potential for cancer therapy. In the present study, the latest research progress of ferroptosis was reviewed, focusing on the relationship between ferroptosis and the development of cancer, in order to further promote the clinical application of ferroptosis in cancer.

A guide to ferroptosis, the biological rust of cellular membranes

Unprotected iron can rust due to oxygen exposure. Similarly, in our body, oxidative stress can kill cells in an iron-dependent manner, which can give rise to devastating diseases. This type of cell death is referred to as ferroptosis. Generally, ferroptosis is defined as an iron-catalyzed form of regulated necrosis that occurs through excessive peroxidation of polyunsaturated fatty acids within cellular membranes. This review summarizes how ferroptosis is executed by a rather primitive biochemical process, under tight regulation of lipid, iron, and redox metabolic processes. An overview is given of major classes of ferroptosis inducers and inhibitors, and how to detect ferroptosis. Finally, its detrimental role in disease is briefly discussed.

Ferroptosis: a potential therapeutic target for stroke

Ferroptosis is a form of regulated cell death characterized by massive iron accumulation and iron-dependent lipid peroxidation, differing from apoptosis, necroptosis, and autophagy in several aspects. Ferroptosis is regarded as a critical mechanism of a series of pathophysiological reactions after stroke because of iron overload caused by hemoglobin degradation and iron metabolism imbalance. In this review, we discuss ferroptosis-related metabolisms, important molecules directly or indirectly targeting iron metabolism and lipid peroxidation, and transcriptional regulation of ferroptosis, revealing the role of ferroptosis in the progression of stroke. We present updated progress in the intervention of ferroptosis as therapeutic strategies for stroke in vivo and in vitro and summarize the effects of ferroptosis inhibitors on stroke. Our review facilitates further understanding of ferroptosis pathogenesis in stroke, proposes new targets for the treatment of stroke, and suggests that more efforts should be made to investigate the mechanism of ferroptosis in stroke.

Identification of a targeted ACSL4 inhibitor to treat ferroptosis-related diseases

Ferroptosis is a form of iron-dependent, lipid peroxidation-driven regulatory cell death that has been implicated in the pathogenesis of multiple diseases, including organ injury, ischemia/reperfusion, and neurodegenerative diseases. However, inhibitors that directly and specifically target ferroptosis are not yet available. Here, we identify the compound AS-252424 (AS) as a potent ferroptosis inhibitor through kinase inhibitor library screening. Our results show that AS effectively inhibits lipid peroxidation and ferroptosis in both human and mouse cells. Mechanistically, AS directly binds to the glutamine 464 of ACSL4 to inhibit its enzymatic activity, resulting in the suppression of lipid peroxidation and ferroptosis. By using nanoparticle-based delivery systems, treatment with AS-loaded nanoparticles effectively alleviate ferroptosis-mediated organ injury in mouse models, including kidney ischemia/reperfusion injury and acute liver injury (ALI). Thus, our results identify that AS is a specific and targeted inhibitor of ACSL4 with remarkable antiferroptosis function, providing a potential therapeutic for ferroptosis-related diseases.

The molecular mechanisms and potential drug targets of ferroptosis in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI), caused by the initial interruption and subsequent restoration of coronary artery blood, results in further damage to cardiac function, affecting the prognosis of patients with acute myocardial infarction. Ferroptosis is an iron-dependent, superoxide-driven, non-apoptotic form of regulated cell death that is involved in the pathogenesis of MIRI. Ferroptosis is characterized by the accumulation of lipid peroxides (LOOH) and redox disequilibrium. Free iron ions can induce lipid oxidative stress as a substrate of the Fenton reaction and lipoxygenase (LOX) and participate in the inactivation of a variety of lipid antioxidants including CoQ10 and GPX4, destroying the redox balance and causing cell death. The metabolism of amino acid, iron, and lipids, including associated pathways, is considered as a specific hallmark of ferroptosis. This review systematically summarizes the latest research progress on the mechanisms of ferroptosis and discusses and analyzes the therapeutic approaches targeting ferroptosis to alleviate MIRI.

Ferroptosis in cancer immunity and immunotherapy: Multifaceted interplay and clinical implications

Ferroptosis is a type of cell death characterized by iron-dependent phospholipid peroxidation and reactive oxygen species overproduction. Ferroptosis induces immunogenic cell death and elicits anti-tumor immune responses, playing an important role in cancer immunotherapy. Ferroptosis suppression in cancer cells impairs its immunotherapeutic efficacy. To overcome this issue, ferroptosis inducers (FINs) have been combined with other cancer therapies to create an anti-tumor immune microenvironment. However, the ferroptosis-based crosstalk between immune and tumor cells is complex because oxidative products released by ferroptotic tumor cells impair the functions of anti-tumor immune cells, resulting in immunotherapeutic resistance. In the present article, we have reviewed ferroptosis in tumor and immune cells and summarized the crosstalk between ferroptotic tumor cells and the immune microenvironment. Based on the existing literature, we have further discussed future perspectives on opportunities for combining ferroptosis-targeted therapies with cancer immunotherapies.

Ferroptosis: Emerging Role in Diseases and Potential Implication of Bioactive Compounds

Ferroptosis is a form of cell death that is distinguished from other types of death for its peculiar characteristics of death regulated by iron accumulation, increase in ROS, and lipid peroxidation. In the past few years, experimental evidence has correlated ferroptosis with various pathological processes including neurodegenerative and cardiovascular diseases. Ferroptosis also is involved in several types of cancer because it has been shown to induce tumor cell death. In particular, the pharmacological induction of ferroptosis, contributing to the inhibition of the proliferative process, provides new ideas for the pharmacological treatment of cancer. Emerging evidence suggests that certain mechanisms including the Xc- system, GPx4, and iron chelators play a key role in the regulation of ferroptosis and can be used to block the progression of many diseases. This review summarizes current knowledge on the mechanism of ferroptosis and the latest advances in its multiple regulatory pathways, underlining ferroptosis' involvement in the diseases. Finally, we focused on several types of ferroptosis inducers and inhibitors, evaluating their impact on the cell death principal targets to provide new perspectives in the treatment of the diseases and a potential pharmacological development of new clinical therapies.

Beyond Glucose: The Dual Assault of Oxidative and ER Stress in Diabetic Disorders

Diabetes mellitus, a prevalent global health concern, is characterized by hyperglycemia. However, recent research reveals a more intricate landscape where oxidative stress and endoplasmic reticulum (ER) stress orchestrate a dual assault, profoundly impacting diabetic disorders. This review elucidates the interplay between these two stress pathways and their collective consequences on diabetes. Oxidative stress emanates from mitochondria, where reactive oxygen species (ROS) production spirals out of control, leading to cellular damage. We explore ROS-mediated signaling pathways, which trigger β-cell dysfunction, insulin resistance, and endothelial dysfunction the quintessential features of diabetes. Simultaneously, ER stress unravels, unveiling how protein folding disturbances activate the unfolded protein response (UPR). We dissect the UPR's dual role, oscillating between cellular adaptation and apoptosis, significantly influencing pancreatic β-cells and peripheral insulin-sensitive tissues. Crucially, this review exposes the synergy between oxidative and ER stress pathways. ROS-induced UPR activation and ER stress-induced oxidative stress create a detrimental feedback loop, exacerbating diabetic complications. Moreover, we spotlight promising therapeutic strategies that target both stress pathways. Antioxidants, molecular chaperones, and novel pharmacological agents offer potential avenues for diabetes management. As the global diabetes burden escalates, comprehending the dual assault of oxidative and ER stress is paramount. This review not only unveils the intricate molecular mechanisms governing diabetic pathophysiology but also advocates a holistic therapeutic approach. By addressing both stress pathways concurrently, we may forge innovative solutions for diabetic disorders, ultimately alleviating the burden of this pervasive health issue.

Ferroptosis in Neurological Disease

Iron accumulation in the CNS occurs in many neurological disorders. It can contribute to neuropathology as iron is a redox-active metal that can generate free radicals. The reasons for the iron buildup in these conditions are varied and depend on which aspects of iron influx, efflux, or sequestration that help maintain iron homeostasis are dysregulated. Iron was shown recently to induce cell death and damage via lipid peroxidation under conditions in which there is deficient glutathione-dependent antioxidant defense. This form of cell death is called ferroptosis. Iron chelation has had limited success in the treatment of neurological disease. There is therefore much interest in ferroptosis as it potentially offers new drugs that could be more effective in reducing iron-mediated lipid peroxidation within the lipid-rich environment of the CNS. In this review, we focus on the molecular mechanisms that induce ferroptosis. We also address how iron enters and leaves the CNS, as well as the evidence for ferroptosis in several neurological disorders. Finally, we highlight biomarkers of ferroptosis and potential therapeutic strategies.

Redox-crippled MitoQ potently inhibits breast cancer and glioma cell proliferation: A negative control for verifying the antioxidant mechanism of MitoQ in cancer and other oxidative pathologies

Mitochondria-targeted coenzyme Q10 (Mito-ubiquinone, Mito-quinone mesylate, or MitoQ) was shown to be an effective antimetastatic drug in patients with triple-negative breast cancer. MitoQ, sold as a nutritional supplement, prevents breast cancer recurrence. It potently inhibited tumor growth and tumor cell proliferation in preclinical xenograft models and in vitro breast cancer cells. The proposed mechanism of action involves the inhibition of reactive oxygen species by MitoQ via a redox-cycling mechanism between the oxidized form, MitoQ, and the fully reduced form, MitoQH2 (also called Mito-ubiquinol). To fully corroborate this antioxidant mechanism, we substituted the hydroquinone group (-OH) with the methoxy group (-OCH3). Unlike MitoQ, the modified form, dimethoxy MitoQ (DM-MitoQ), lacks redox-cycling between the quinone and hydroquinone forms. DM-MitoQ was not converted to MitoQ in MDA-MB-231 cells. We tested the antiproliferative effects of both MitoQ and DM-MitoQ in human breast cancer (MDA-MB-231), brain-homing cancer (MDA-MB-231BR), and glioma (U87MG) cells. Surprisingly, DM-MitoQ was slightly more potent than MitoQ (IC50 = 0.26 μM versus 0.38 μM) at inhibiting proliferation of these cells. Both MitoQ and DM-MitoQ potently inhibited mitochondrial complex I-dependent oxygen consumption (IC50 = 0.52 μM and 0.17 μM, respectively). This study also suggests that DM-MitoQ, which is a more hydrophobic analog of MitoQ (logP: 10.1 and 8.7) devoid of antioxidant function and reactive oxygen species scavenging ability, can inhibit cancer cell proliferation. We conclude that inhibition of mitochondrial oxidative phosphorylation by MitoQ is responsible for inhibition of breast cancer and glioma proliferation and metastasis. Blunting the antioxidant effect using the redox-crippled DM-MitoQ can serve as a useful negative control in corroborating the involvement of free radical-mediated processes (e.g., ferroptosis, protein oxidation/nitration) using MitoQ in other oxidative pathologies.

Biosynthesis, Deficiency, and Supplementation of Coenzyme Q

Originally identified as a key component of the mitochondrial respiratory chain, Coenzyme Q (CoQ or CoQ₁₀ for human tissues) has recently been revealed to be essential for many different redox processes, not only in the mitochondria, but elsewhere within other cellular membrane types. Cells rely on endogenous CoQ biosynthesis, and defects in this still-not-completely understood pathway result in primary CoQ deficiencies, a group of conditions biochemically characterised by decreased tissue CoQ levels, which in turn are linked to functional defects. Secondary CoQ deficiencies may result from a wide variety of cellular dysfunctions not directly linked to primary synthesis. In this article, we review the current knowledge on CoQ biosynthesis, the defects leading to diminished CoQ₁₀ levels in human tissues and their associated clinical manifestations.

Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

Oxidative Stress, Antioxidants and Hypertension

As a major cause of morbidity and mortality globally, hypertension remains a serious threat to global public health. Despite the availability of many antihypertensive medications, several hypertensive individuals are resistant to standard treatments, and are unable to control their blood pressure. Regulation of the renin-angiotensin-aldosterone system (RAAS) controlling blood pressure, activation of the immune system triggering inflammation and production of reactive oxygen species, leading to oxidative stress and redox-sensitive signaling, have been implicated in the pathogenesis of hypertension. Thus, besides standard antihypertensive medications, which lower arterial pressure, antioxidant medications were tested to improve antihypertensive treatment. We review and discuss the role of oxidative stress in the pathophysiology of hypertension and the potential use of antioxidants in the management of hypertension and its associated organ damage.

Understanding the mechanistic roles of environmental heavy metal stressors in regulating ferroptosis: adding new paradigms to the links with diseases

Ferroptosis is a new type of iron-dependent cell death induced by a failure of the lipid repair protein GPX4 or the Xc- antiporter, which is essential for glutathione production. Some heavy metals such as arsenic (As), cobalt (Co), cadmium (Cd), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), mercury (Hg) as well as zinc (Zn) are shown to induce ferroptotic cell death involving the generation of oxidative stress, mitochondrial dysfunctioning, lipid peroxidation, and several other cellular etiologies. However, selenium (Se) treatment has been shown to enhance adaptive transcription responses to protect cells from ferroptosis. Heavy metals like Cadmium exposure activated ALK4/5 signaling via Smad3 and Akt signaling which leads to cell death mechanism. Continuous exposure to a small dose of mercury can damage tissues, and methylmercury bind to sulfhydryl proteins and GSH, this elevates oxidative stress, free radical accumulation, glutathione depletion, mitochondrial damage, and inhibited the nuclear factor-κB pathway which leads to ferroptotic cell death. Animals exposed to nickel and cobalt may have increased lipid peroxidation which can induce ferroptosis. Glutathione depletion is caused by Zn intoxication and exposure to manganese. These metals are systemic toxins that have been shown adverse effects on humans. Ferroptosis has recently been related to several pathological disorders, including, Alzheimer's disease, Parkinson's disease, Huntington's disease, as well as cardiovascular disease, and any type of cancer. For these disorders and some heavy metal toxicity, ferroptosis suppression needs to be looked upon as a promising therapeutic choice.

Ferroptosis: roles and molecular mechanisms in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious complication of type 1 and type 2 diabetes, which leads to the aggravation of myocardial fibrosis, disorders involving systolic and diastolic functions, and increased mortality of patients with diabetes through mechanisms such as glycolipid toxicity, inflammatory response, and oxidative stress. Ferroptosis is a form of iron-dependent regulatory cell death that is attributed to the accumulation of lipid peroxides and an imbalance in redox regulation. Increased production of lipid reactive oxygen species (ROS) during ferroptosis promotes oxidative stress and damages myocardial cells, leading to myocardial systolic and diastolic dysfunction. Overproduction of ROS is an important bridge between ferroptosis and DCM, and ferroptosis inhibitors may provide new targets for the treatment of patients with DCM.

Role of Oxidative Stress in Peyronie's Disease: Biochemical Evidence and Experiences of Treatment with Antioxidants

BACKGROUND

Peyronie's disease (PD) is a chronic inflammatory condition affecting adult males, involving the tunica albuginea of the corpora cavernosa of the penis. PD is frequently associated with penile pain, erectile dysfunction, and a secondary anxious-depressive state. The etiology of PD has not yet been completely elucidated, but local injury is generally recognized to be a triggering factor. It has also been widely proven that oxidative stress is an essential, decisive component in all inflammatory processes, whether acute or chronic. Current conservative medical treatment comprises oral substances, penile injections, and physical therapy.

AIM

This article intends to show how antioxidant therapy is able to interfere with the pathogenetic mechanisms of the disease.

METHOD

This article consists of a synthetic narrative review of the current scientific literature on antioxidant therapy for this disease.

RESULTS

The good results of the antioxidant treatment described above also prove that the doses used were adequate and the concentrations of the substances employed did not exceed the threshold at which they might have interacted negatively with the mechanisms of the redox regulation of tissue.

CONCLUSIONS

We believe new, randomized, controlled studies are needed to confirm the efficacy of treatment with antioxidants. However, we consider the experiences of antioxidant treatment which can already be found in the literature useful for the clinical practice of urologists in the treatment of this chronic inflammatory disease.

Predicting and Understanding the Pathology of Single Nucleotide Variants in Human COQ Genes

Coenzyme Q (CoQ) is a vital lipid that functions as an electron carrier in the mitochondrial electron transport chain and as a membrane-soluble antioxidant. Deficiencies in CoQ lead to metabolic diseases with a wide range of clinical manifestations. There are currently few treatments that can slow or stop disease progression. Primary CoQ₁₀ deficiency can arise from mutations in any of the COQ genes responsible for CoQ biosynthesis. While many mutations in these genes have been identified, the clinical significance of most of them remains unclear. Here we analyzed the structural and functional impact of 429 human missense single nucleotide variants (SNVs) that give rise to amino acid substitutions in the conserved and functional regions of human genes encoding a high molecular weight complex known as the CoQ synthome (or Complex Q), consisting of the COQ3-COQ7 and COQ9 gene products. Using structures of COQ polypeptides, close homologs, and AlphaFold models, we identified 115 SNVs that are potentially pathogenic. Further biochemical characterizations in model organisms such as Saccharomyces cerevisiae are required to validate the pathogenicity of the identified SNVs. Collectively, our results will provide a resource for clinicians during patient diagnosis and guide therapeutic efforts toward combating primary CoQ₁₀ deficiency.

Acute lymphoblastic leukemia necessitates GSH-dependent ferroptosis defenses to overcome FSP1-epigenetic silencing

Ferroptosis is a form of cell death triggered by phospholipid hydroperoxides (PLOOH) generated from the iron-dependent oxidation of polyunsaturated fatty acids (PUFAs). To prevent ferroptosis, cells rely on the antioxidant glutathione (GSH), which serves as cofactor of the glutathione peroxidase 4 (GPX4) for the neutralization of PLOOHs. Some cancer cells can also limit ferroptosis through a GSH-independent axis, centered mainly on the ferroptosis suppressor protein 1 (FSP1). The significance of these two anti-ferroptosis pathways is still poorly understood in cancers from hematopoietic origin. Here, we report that blood-derived cancer cells are selectively sensitive to compounds that block the GSH-dependent anti-ferroptosis axis. In T- and B- acute lymphoblastic leukemia (ALL) cell lines and patient biopsies, the promoter of the gene coding for FSP1 is hypermethylated, silencing the expression of FSP1 and creating a selective dependency on GSH-centered anti-ferroptosis defenses. In-trans expression of FSP1 increases the resistance of leukemic cells to compounds targeting the GSH-dependent anti-ferroptosis pathway. FSP1 over-expression also favors ALL-tumor growth in an in vivo chick chorioallantoic membrane (CAM) model. Hence, our results reveal a metabolic vulnerability of ALL that might be of therapeutic interest.

Dicarbonyl-Dependent Modification of LDL as a Key Factor of Endothelial Dysfunction and Atherosclerotic Vascular Wall Damage

The review presents evidence that the main damage to the vascular wall occurs not from the action of “oxidized” LDL, which contain hydroperoxy acyls in the phospholipids located in their outer layer, but from the action of LDL particles whose apoprotein B-100 is chemically modified with low molecular weight dicarbonyls, such as malondialdehyde, glyoxal, and methylglyoxal. It has been argued that dicarbonyl-modified LDL, which have the highest cholesterol content, are particularly “atherogenic”. High levels of dicarbonyl-modified LDL have been found to be characteristic of some mutations of apoprotein B-100. Based on the reviewed data, we hypothesized a common molecular mechanism underlying vascular wall damage in atherosclerosis and diabetes mellitus. The important role of oxidatively modified LDL in endothelial dysfunction is discussed in detail. In particular, the role of the interaction of the endothelial receptor LOX-1 with oxidatively modified LDL, which leads to the expression of NADPH oxidase, which in turn generates superoxide anion radical, is discussed. Such hyperproduction of ROS can cause destruction of the glycocalyx, a protective layer of endotheliocytes, and stimulation of apoptosis in these cells. On the whole, the accumulated evidence suggests that carbonyl modification of apoprotein B-100 of LDL is a key factor responsible for vascular wall damage leading to atherogenesis and endothelial dysfunction. Possible ways of pharmacological correction of free radical processes in atherogenesis and diabetogenesis are also discussed.

Targeting ferroptosis in ischemia/reperfusion renal injury

Renal I/R injury is a severe medical condition contributing to acute kidney injury (AKI), leading to rapid kidney dysfunction and high mortality rates. It is generally observed during renal transplantation, shock, trauma, and urologic and cardiovascular surgery, for which there is no effective treatment. Cell death and damage are commonly linked to I/R. Cell death triggered by iron-dependent lipid peroxidation, such as ferroptosis, has been demonstrated to have a significant detrimental effect in renal IRI models, making it a new type of cell death currently being researched. Ferroptosis is a nonapoptotic type of cell death that occurs when free iron enters the cell and is a critical component of many biological processes. In ferroptosis-induced renal I/R injury, iron chelators such as Deferasirox, Deferiprone, and lipophilic antioxidants are currently suppressed lipid peroxidation Liproxstatin-1 (Lip-1), Ferrostatin-1 along with antioxidants like vitamin and quercetin. Ferroptosis has been considered a potential target for pharmaceutical intervention to alleviate renal IRI-associated cell damage. Thus, this review emphasized the role of ferroptosis and its inhibition in renal IRI. Also, Pharmacological modulation of ferroptosis mechanism in renal I/R injury has been conferred. Graphical abstract.

Nicotinamide Mononucleotide and Coenzyme Q10 Protects Fibroblast Senescence Induced by Particulate Matter Preconditioned Mast Cells

Particulate matter (PM) pollutants impose a certain degree of destruction and toxicity to the skin. Mast cells in the skin dermis could be activated by PMs that diffuse across the blood vessel after being inhaled. Mast cell degranulation in the dermis provides a kind of inflammatory insult to local fibroblasts. In this study, we evaluated human dermal fibroblast responses to conditioned medium from KU812 cells primed with PM. We found that PM promoted the production of proinflammatory cytokines in mast cells and that the cell secretome induced reactive oxygen species and mitochondrial reactive oxygen species production in dermal fibroblasts. Nicotinamide mononucleotide or coenzyme Q10 alleviated the generation of excessive ROS and mitochondrial ROS induced by the conditioned medium from PM-activated KU812 cells. PM-conditioned medium treatment increased the NF-κB expression in dermal fibroblasts, whereas NMN or Q10 inhibited p65 upregulation by PM. The reduced sirtuin 1 (SIRT 1) and nuclear factor erythroid 2-related Factor 2 (Nrf2) expression induced by PM-conditioned medium was reversed by NMN or Q10 in HDFs. Moreover, NMN or Q10 attenuated the expression of senescent β-galactosidase induced by PM-conditioned KU812 cell medium. These findings suggest that NMN or Q10 ameliorates PM-induced inflammation by improving the cellular oxidative status, suppressing proinflammatory NF-κB, and promoting the levels of the antioxidant and anti-inflammatory regulators Nrf2 and SIRT1 in HDFs. The present observations help to understand the factors that affect HDFs in the dermal microenvironment and the therapeutic role of NMN and Q10 as suppressors of skin aging.

Stimulatory effects of collagen production induced by coenzyme Q10 in cultured skin fibroblasts

Coenzyme Q₁₀ (CoQ₁₀) is a well-known antioxidant and serves as an essential carrier for electron transport and proton translocation in the mitochondrial respiratory chain. CoQ₁₀ has been widely commercially available in Japan as a dietary and health supple­ment since 2001 and it is used for the prevention of lifestyle-related diseases induced by aging. Recently, it was stated that for Japan, which is facing an aging society, CoQ₁₀ has been used in many skincare products. However, the physiological actions of CoQ₁₀ in skin fibroblasts are not fully understood. In this study, we examined the effect of CoQ₁₀ on cultured human skin fibroblast. In this study, CoQ₁₀ treatment increased intracellular CoQ₁₀ level and promoted proliferation of fibroblasts. In addition, CoQ₁₀ increased mRNA expression of type I, IV, VII collagen, elastin, and HSP47, whereas CoQ₁₀ has little effect on mRNA of type II and VIII MMP. These results suggested that CoQ₁₀ has the efficacy that it increases collagen production in skin, thereby there is possible of the anti-aging by CoQ₁₀ in Japan which reached an aging society, so that it might be based on new physiological function by CoQ₁₀.

CYP7A1, NPC1L1, ABCB1, and CD36 Polymorphisms Associated with Coenzyme Q10 Availability Affect the Subjective Quality of Life Score (SF-36) after Long-Term CoQ10 Supplementation in Women

The single nucleotide polymorphisms (SNPs) rs3808607, rs2072183, rs2032582, and rs1761667 are associated with coenzyme Q₁₀ (CoQ₁₀) bioavailability in women after long-term CoQ₁₀ supplementation. However, the beneficial aspects of the association between these SNPs and CoQ₁₀ supplementation remain unknown. We investigated their relationship using the subjective quality of life score SF-36 by reanalyzing previous data from 92 study participants who were receiving ubiquinol (a reduced form of CoQ₁₀) supplementation for 1 year. Two-way repeated-measures analysis of variance revealed a significant interaction between rs1761667 and the SF-36 scores of role physical (p = 0.016) and mental health (p = 0.017) in women. Subgrouping of participants based on the above four SNPs revealed significant interactions between these SNPs and the SF-36 scores of general health (p = 0.045), role emotional (p = 0.008), and mental health (p = 0.019) and increased serum CoQ₁₀ levels (p = 0.008), suggesting that the benefits of CoQ₁₀ supplementation, especially in terms of psychological parameters, are genotype-dependent in women. However, significant interactions were not observed in men. Therefore, inclusion of SNP subgrouping information in clinical trials of CoQ₁₀ supplementation may provide conclusive evidence supporting other beneficial health effects exerted by the association between these SNPs and CoQ₁₀ on women.

A systematic review: metabolomics-based identification of altered metabolites and pathways in the skin caused by internal and external factors

The skin's ability to function optimally is affected by many diverse factors. Metabolomics has a great potential to improve our understanding of the underlying metabolic changes and the affected pathways. Therefore, the objective of this study was to review the current state of the literature and to perform further metabolic pathway analysis on the obtained data. The aim was to gain an overview of the metabolic changes under altered conditions and to identify common and different patterns as a function of the investigated factors. A cross-study comparison of the extracted studies from different databases identified 364 metabolites, whose concentrations were considerably altered by the following factor groups: irradiation, xenobiotics, aging, and skin diseases (mainly psoriasis). Using metabolic databases and pathway analysis tools the individual metabolites were assigned to the corresponding metabolic pathways and the most strongly affected signaling pathways were identified. All factors induced oxidative stress. Thus, antioxidant defense systems, especially coenzyme Q₁₀  (aging) and the glutathione system (irradiation, aging, xenobiotics) were impacted. Lipid metabolism was also impacted by all factors studied. The carnitine shuttle as part of β-oxidation was activated by all factor groups except aging. Glycolysis, Krebs (TCA) cycle and purine metabolism were mainly affected by irradiation and xenobiotics. The pentose phosphate pathway was activated and Krebs cycle was downregulated in response to oxidative stress. In summary, it can be ascertained that mainly energy metabolism, lipid metabolism, antioxidative defense and DNA repair systems were impacted by the factors studied.

Mitochondria-targeted antioxidant supplementation improves 8 km time trial performance in middle-aged trained male cyclists

BACKGROUND

Exercise increases skeletal muscle reactive oxygen species (ROS) production, which may contribute to the onset of muscular fatigue and impair athletic performance. Mitochondria-targeted antioxidants such as MitoQ, which contains a ubiquinone moiety and is targeted to mitochondria through the addition of a lipophilic triphenylphosphonium cation, are becoming popular amongst active individuals as they are designed to accumulate within mitochondria and may provide targeted protection against exercise-induced oxidative stress. However, the effect of MitoQ supplementation on cycling performance is currently unknown. Here, we investigate whether MitoQ supplementation can improve cycling performance measured as time to complete an 8 km time trial.

METHOD

In a randomized, double-blind, placebo-controlled crossover study, 19 middle-aged (age: 44 ± 4 years) recreationally trained (VO_2peak: 58.5 ± 6.2 ml·kg^- 1·min^- 1, distance cycled per week during 6 months prior to study enrollment: 158.3 ± 58.4 km) male cyclists completed 45 min cycling at 70% VO_2peak followed by an 8 km time trial after 28 days of supplementation with MitoQ (20 mg·day^- 1) and a placebo. Free F₂-isoprostanes were measured in plasma samples collected at rest, after 45 min cycling at 70% VO_2peak and after completion of the time trial. Respiratory gases and measures of rating of perceived exertion (RPE) were also collected.

RESULTS

Mean completion time for the time trial was 1.3% faster with MitoQ (12.91 ± 0.94 min) compared to placebo (13.09 ± 0.95 min, p = 0.04, 95% CI [0.05, 2.64], d = 0.2). There was no difference in RPE during the time trial between conditions (p = 0.82) despite there being a 4.4% increase in average power output during the time trial following MitoQ supplementation compared to placebo (placebo; 270 ± 51 W, MitoQ; 280 ± 53 W, p = 0.04, 95% CI [0.49, 8.22], d = 0.2). Plasma F₂-isoprostanes were lower on completion of the time trial following MitoQ supplementation (35.89 ± 13.6 pg·ml^- 1) compared to placebo (44.7 ± 16.9 pg·ml^- 1 p = 0.03).

CONCLUSION

These data suggest that MitoQ supplementation may be an effective nutritional strategy to attenuate exercise-induced increases in oxidative damage to lipids and improve cycling performance.

Ubisol-Q10, a Nanomicellar and Water-Dispersible Formulation of Coenzyme-Q10 as a Potential Treatment for Alzheimer's and Parkinson's Disease

The world continues a desperate search for therapies that could bring hope and relief to millions suffering from progressive neurodegenerative diseases such as Alzheimer’s (AD) and Parkinson’s (PD). With oxidative stress thought to be a core stressor, interests have long been focused on applying redox therapies including coenzyme-Q₁₀. Therapeutic use has failed to show efficacy in human clinical trials due to poor bioavailability of this lipophilic compound. A nanomicellar, water-dispersible formulation of coenzyme-Q₁₀, Ubisol-Q₁₀, has been developed by combining coenzyme-Q₁₀ with an amphiphilic, self-emulsifying molecule of polyoxyethanyl α-tocopheryl sebacate (derivatized vitamin E). This discovery made possible, for the first time, a proper assessment of the true therapeutic value of coenzyme-Q₁₀. Micromolar concentrations of Ubisol-Q₁₀ show unprecedented neuroprotection against neurotoxin exposure in in vitro and in vivo models of neurodegeneration and was extremely effective when delivered either prior to, at the time of, and most significantly, post-neurotoxin exposure. These findings indicate a possible way forward for clinical development due to effective doses well within Federal Drug Administration guidelines. Ubisol-Q₁₀ is a potent mobilizer of astroglia, antioxidant, senescence preventer, autophagy activator, anti-inflammatory, and mitochondrial stabilizer. Here we summarize the work with oil-soluble coenzyme-Q₁₀, its limitations, and focus mainly on efficacy of water-soluble coenzyme-Q₁₀ in neurodegeneration.

Lipid metabolism in cancer: New perspectives and emerging mechanisms

Tumors undergo metabolic transformations to sustain uncontrolled proliferation, avoid cell death, and seed in secondary organs. An increased focus on cancer lipid metabolism has unveiled a number of mechanisms that promote tumor growth and survival, many of which are independent of classical cellular bioenergetics. These mechanisms include modulation of ferroptotic-mediated cell death, support during tumor metastasis, and interactions with the cells of the tumor microenvironment. As such, targeting lipid metabolism for anti-cancer therapies is attractive, with recent work on small-molecule inhibitors identifying compounds to target lipid metabolism. Here, we discuss these topics and identify open questions.

Solubilized ubiquinol for preserving corneal function

Defective cellular metabolism, impaired mitochondrial function, and increased cell death are major problems that adversely affect donor tissues during hypothermic preservation prior to transplantation. These problems are thought to arise from accumulated reactive oxygen species (ROS) inside cells. Oxidative stress acting on the cells of organs and tissues preserved in hypothermic conditions before surgery, as is the case for cornea transplantation, is thought to be a major reason behind cell death prior to surgery and decreased graft survival after transplantation. We have recently discovered that ubiquinol - the reduced and active form of coenzyme Q10 and a powerful antioxidant - significantly enhances mitochondrial function and reduces apoptosis in human donor corneal endothelial cells. However, ubiquinol is highly lipophilic, underscoring the need for an aqueous-based formulation of this molecule. Herein, we report a highly dispersible and stable formulation comprising a complex of ubiquinol and gamma cyclodextrin (γ-CD) for use in aqueous-phase ophthalmic products. Docking studies showed that γ-CD has the strongest binding affinity with ubiquinol compared to α- or β-CD. Complexed ubiquinol showed significantly higher stability compared to free ubiquinol in different aqueous ophthalmic products including Optisol-GS® corneal storage medium, balanced salt solution for intraocular irrigation, and topical Refresh® artificial tear eye drops. Greater ROS scavenging activity was noted in a cell model with high basal metabolism and ROS generation (A549) and in HCEC-B4G12 human corneal endothelial cells after treatment with ubiquinol/γ-CD compared to free ubiquinol. Furthermore, complexed ubiquinol was more effective at lowering ROS, and at far lower concentrations, compared to free ubiquinol. Complexed ubiquinol inhibited lipid peroxidation and protected HCEC-B4G12 cells against erastin-induced ferroptosis. No evidence of cellular toxicity was detected in HCEC-B4G12 cells after treatment with complexed ubiquinol. Using a vertical diffusion system, a topically applied inclusion complex of γ-CD and a lipophilic dye (coumarin-6) demonstrated transcorneal penetrance in porcine corneas and the capacity for the γ-CD vehicle to deliver drug to the corneal endothelium. Using the same model, topically applied ubiquinol/γ-CD complex penetrated the entire thickness of human donor corneas with markedly greater ubiquinol retention in the endothelium compared to free ubiquinol. Lastly, the penetrance of ubiquinol/γ-CD complex was assayed using human donor corneas preserved for 7 days in Optisol-GS® per standard industry practices, and demonstrated higher amounts of ubiquinol retained in the corneal endothelium compared to free ubiquinol. In summary, ubiquinol complexed with γ-CD is a highly stable composition that can be incorporated into a variety of aqueous-phase products for ophthalmic use including donor corneal storage media and topical eye drops to scavenge ROS and protect corneal endothelial cells against oxidative damage.

Primary Coenzyme Q deficiencies: A literature review and online platform of clinical features to uncover genotype-phenotype correlations

Primary Coenzyme Q (CoQ) deficiencies are clinically heterogeneous conditions and lack clear genotype-phenotype correlations, complicating diagnosis and prognostic assessment. Here we present a compilation of all the symptoms and patients with primary CoQ deficiency described in the literature so far and analyse the most common clinical manifestations associated with pathogenic variants identified in the different COQ genes. In addition, we identified new associations between the age of onset of symptoms and different pathogenic variants, which could help to a better diagnosis and guided treatment. To make these results useable for clinicians, we created an online platform (https://coenzymeQbiology.github.io/clinic-CoQ-deficiency) about clinical manifestations of primary CoQ deficiency that will be periodically updated to incorporate new information published in the literature. Since CoQ primary deficiency is a rare disease, the available data are still limited, but as new patients are added over time, this tool could become a key resource for a more efficient diagnosis of this pathology.

Tuning the reduction potentials of benzoquinone through the coordination to Lewis acids

Electron transfer promoted by the coordination of a substrate molecule to a Lewis acid or hydrogen bonding group is a critical step in many biological and catalytic transformations. This computational study investigates the nature of the interaction between benzoquinone and one and two Lewis acids by examining the influence of Lewis acid strength on the ability to alter the two reduction potentials of the coordinated benzoquinone molecule. To investigate this interaction, the coordination of the neutral (Q), singly reduced ([Q]˙-), and doubly reduced benzoquinone ([Q]2-) molecule to eight Lewis acids was analyzed. Coordination of benzoquinone to a Lewis acid became more favorable by 25 kcal mol-1 with each reduction of the benzoquinone fragment. Coordination of benzoquinone to a Lewis acid also shifted each of the reduction potentials of the coordinated benzoquinone anodically by 0.50 to 1.5 V, depending on the strength of the Lewis acid, with stronger Lewis acids exhibiting a larger effect on the reduction potential. Coordination of a second Lewis acid further altered each of the reduction potentials by an additional 0.70 to 1.6 V. Replacing one of the Lewis acids with a proton resulted in the ability to modify the pKa of the protonated Lewis acid-Q/[Q]˙-/[Q]2- adducts by about 10 pKa units, in addition to being able to alter the ability to transfer a hydrogen atom by 10 kcal mol-1, and the capacity to transfer a hydride by about 30 kcal mol-1.

Ferroptosis, radiotherapy, and combination therapeutic strategies

Ferroptosis, an iron-dependent form of regulated cell death driven by peroxidative damages of polyunsaturated-fatty-acid-containing phospholipids in cellular membranes, has recently been revealed to play an important role in radiotherapy-induced cell death and tumor suppression, and to mediate the synergy between radiotherapy and immunotherapy. In this review, we summarize known as well as putative mechanisms underlying the crosstalk between radiotherapy and ferroptosis, discuss the interactions between ferroptosis and other forms of regulated cell death induced by radiotherapy, and explore combination therapeutic strategies targeting ferroptosis in radiotherapy and immunotherapy. This review will provide important frameworks for future investigations of ferroptosis in cancer therapy.

Mitophagy in Human Diseases

Mitophagy is a selective autophagic process, essential for cellular homeostasis, that eliminates dysfunctional mitochondria. Activated by inner membrane depolarization, it plays an important role during development and is fundamental in highly differentiated post-mitotic cells that are highly dependent on aerobic metabolism, such as neurons, muscle cells, and hepatocytes. Both defective and excessive mitophagy have been proposed to contribute to age-related neurodegenerative diseases, such as Parkinson's and Alzheimer's diseases, metabolic diseases, vascular complications of diabetes, myocardial injury, muscle dystrophy, and liver disease, among others. Pharmacological or dietary interventions that restore mitophagy homeostasis and facilitate the elimination of irreversibly damaged mitochondria, thus, could serve as potential therapies in several chronic diseases. However, despite extraordinary advances in this field, mainly derived from in vitro and preclinical animal models, human applications based on the regulation of mitochondrial quality in patients have not yet been approved. In this review, we summarize the key selective mitochondrial autophagy pathways and their role in prevalent chronic human diseases and highlight the potential use of specific interventions.

CYP7A1, NPC1L1, ABCB1, and CD36 Polymorphisms Are Associated with Increased Serum Coenzyme Q10 after Long-Term Supplementation in Women

Coenzyme Q₁₀ (CoQ₁₀), an essential component for energy production that exhibits antioxidant activity, is considered a health-supporting and antiaging supplement. However, intervention-controlled studies have provided variable results on CoQ₁₀ supplementation benefits, which may be attributed to individual CoQ₁₀ bioavailability differences. This study aimed to investigate the relationship between genetic polymorphisms and CoQ₁₀ serum levels after long-term supplementation. CoQ₁₀ levels at baseline and after one year of supplementation (150 mg) were determined, and eight single nucleotide polymorphisms (SNPs) in cholesterol metabolism and CoQ₁₀ absorption, efflux, and cellular uptake related genes were assessed. Rs2032582 (ABCB1) and rs1761667 (CD36) were significantly associated with a higher increase in CoQ₁₀ levels in women. In addition, in women, rs3808607 (CYP7A1) and rs2072183 (NPC1L1) were significantly associated with a higher increase in CoQ₁₀ per total cholesterol levels. Subgroup analyses showed that these four SNPs were useful for classifying high- or low-responder to CoQ₁₀ bioavailability after long-term supplementation among women, but not in men. On the other hand, in men, no SNP was found to be significantly associated with increased serum CoQ₁₀. These results collectively provide novel evidence on the relationship between genetics and CoQ₁₀ bioavailability after long-term supplementation, which may help understand and assess CoQ₁₀ supplementation effects, at least in women.

Regulation of coenzyme Q biosynthesis pathway in eukaryotes

Coenzyme Q (CoQ, ubiquinone/ubiquinol) is a ubiquitous and unique molecule that drives electrons in mitochondrial respiratory chain and an obligatory step for multiple metabolic pathways in aerobic metabolism. Alteration of CoQ biosynthesis or its redox stage are causing mitochondrial dysfunctions as hallmark of heterogeneous disorders as mitochondrial/metabolic, cardiovascular, and age-associated diseases. Regulation of CoQ biosynthesis pathway is demonstrated to affect all steps of proteins production of this pathway, posttranslational modifications and protein-protein-lipid interactions inside mitochondria. There is a bi-directional relationship between CoQ and the epigenome in which not only the CoQ status determines the epigenetic regulation of many genes, but CoQ biosynthesis is also a target for epigenetic regulation, which adds another layer of complexity to the many pathways by which CoQ levels are regulated by environmental and developmental signals to fulfill its functions in eukaryotic aerobic metabolism.

Ubiquinol (reduced coenzyme Q10) as a metabolic resuscitator in post-cardiac arrest: A randomized, double-blind, placebo-controlled trial

INTRODUCTION

Ubiquinol (reduced coenzyme Q10) is essential for adequate aerobic metabolism. The objective of this trial was to determine whether ubiquinol administration in patients resuscitated from cardiac arrest could increase physiological coenzyme Q10 levels, improve oxygen consumption, and reduce neurological biomarkers of injury.

MATERIALS AND METHODS

This was a randomized, double-blind, placebo-controlled trial in patients successfully resuscitated from cardiac arrest. Patients were randomized to receive enteral ubiquinol (300 mg) or placebo every 12 h for up to 7 days. The primary endpoint was total coenzyme Q10 plasma levels at 24 h after enrollment. Secondary endpoints included neuron specific enolase, S100B, lactate, cellular and global oxygen consumption, neurological status, and in-hospital mortality.

RESULTS

Forty-three patients were included in the modified intention-to-treat analysis. Median coenzyme Q10 levels were significantly higher in the ubiquinol group as compared to the placebo group at 24 h (441 [IQR, 215-510] ηg/mL vs. 113 [IQR, 94-208] ηg/mL, P < 0.001). Similar results were observed at 48 and 72 h. There were no differences between the two groups in any of the secondary endpoints. Median neuron specific enolase levels were not different between the two groups at 24 h (16.8 [IQR, 9.5-19.8] ηg/mL vs. 8.2 [IQR, 4.3-19.1] ηg/mL, P = 0.61).

CONCLUSIONS

Administration of enteral ubiquinol increased plasma coenzyme Q10 levels in post-cardiac arrest patients as compared to placebo. There were no differences in neurological biomarkers and oxygen consumption between the two groups.

Prospective study of plasma levels of coenzyme Q10 and lung cancer risk in a low-income population in the Southeastern United States

Background

Coenzyme Q10 (CoQ10) is a ubiquitous molecule in living organisms serving as a cofactor in energy production. Epidemiological studies have reported low CoQ10 levels being associated with an increased risk of various cancers. We conducted the first study to evaluate the association of CoQ10 concentrations with lung cancer risk.

Methods

A nested case‐control study including 201 lung cancer cases and 395 matched controls from the Southern Community Cohort Study was conducted. Plasma CoQ10 levels were measured using high‐performance liquid chromatography with photo‐diode array detection. Conditional logistic regression models were applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between plasma CoQ10 levels and lung cancer risk.

Results

Plasma CoQ10 concentration was inversely associated with the risk of lung cancer. After adjusting for age, sex, race, and socioeconomic status, the OR (95% CI) comparing the third to first tertile was 0.57 (0.36–0.91, P for trend = 0.02). Further adjustments for smoking, alcohol, chronic obstructive pulmonary disease, and body mass index attenuated the point estimate slightly (OR = 0.60, 95% CI = 0.34–1.08, P for trend = 0.11), comparing third to first tertiles. Stratified analyses identified a significant inverse association between plasma CoQ10 levels and lung cancer risk in current smokers, but not in former/never smokers. The association was more evident in cases who were diagnosed within 1 year of blood draw than in cases diagnosed after 1 year.

Conclusions

Low plasma CoQ10 was significantly associated with increased lung cancer risk, particularly among current smokers. The stronger association seen shortly following the blood draw suggests that CoQ10 may be related to disease progression.

Ferroptosis-Related Flavoproteins: Their Function and Stability

Ferroptosis has been described recently as an iron-dependent cell death driven by peroxidation of membrane lipids. It is involved in the pathogenesis of a number of diverse diseases. From the other side, the induction of ferroptosis can be used to kill tumor cells as a novel therapeutic approach. Because of the broad clinical relevance, a comprehensive understanding of the ferroptosis-controlling protein network is necessary. Noteworthy, several proteins from this network are flavoenzymes. This review is an attempt to present the ferroptosis-related flavoproteins in light of their involvement in anti-ferroptotic and pro-ferroptotic roles. When available, the data on the structural stability of mutants and cofactor-free apoenzymes are discussed. The stability of the flavoproteins could be an important component of the cellular death processes.

New avenues for therapy in mitochondrial optic neuropathies

Mitochondrial optic neuropathies are a group of optic nerve atrophies exemplified by the two commonest conditions in this group, autosomal dominant optic atrophy (ADOA) and Leber's hereditary optic neuropathy (LHON). Their clinical features comprise reduced visual acuity, colour vision deficits, centro-caecal scotomas and optic disc pallor with thinning of the retinal nerve fibre layer. The primary aetiology is genetic, with underlying nuclear or mitochondrial gene mutations. The primary pathology is owing to retinal ganglion cell dysfunction and degeneration. There is currently only one approved treatment and no curative therapy is available. In this review we summarise the genetic and clinical features of ADOA and LHON and then examine what new avenues there may be for therapeutic intervention. The therapeutic strategies to manage LHON and ADOA can be split into four categories: prevention, compensation, replacement and repair. Prevention is technically an option by modifying risk factors such as smoking cessation, or by utilising pre-implantation genetic diagnosis, although this is unlikely to be applied in mitochondrial optic neuropathies due to the non-life threatening and variable nature of these conditions. Compensation involves pharmacological interventions that ameliorate the mitochondrial dysfunction at a cellular and tissue level. Replacement and repair are exciting new emerging areas. Clinical trials, both published and underway, in this area are likely to reveal future potential benefits, since new therapies are desperately needed.

Plain language summary

Optic nerve damage leading to loss of vision can be caused by a variety of insults. One group of conditions leading to optic nerve damage is caused by defects in genes that are essential for cells to make energy in small organelles called mitochondria. These conditions are known as mitochondrial optic neuropathies and two predominant examples are called autosomal dominant optic atrophy and Leber's hereditary optic neuropathy. Both conditions are caused by problems with the energy powerhouse of cells: mitochondria. The cells that are most vulnerable to this mitochondrial malfunction are called retinal ganglion cells, otherwise collectively known as the optic nerve, and they take the electrical impulse from the retina in the eye to the brain. The malfunction leads to death of some of the optic nerve cells, the degree of vision loss being linked to the number of those cells which are impacted in this way. Patients will lose visual acuity and colour vision and develop a central blind spot in their field of vision. There is currently no cure and very few treatment options. New treatments are desperately needed for patients affected by these devastating diseases. New treatments can potentially arise in four ways: prevention, compensation, replacement and repair of the defects. Here we explore how present and possible future treatments might provide hope for those suffering from these conditions.