Antiferroptotic Activity of Phenothiazine Analogues: A Novel Therapeutic Strategy for Oxidative Stress Related Disease.

Ferroptosis is an iron-catalyzed, nonapoptotic form of regulated necrosis that has been implicated in the pathological cell death associated with various disorders including neurodegenerative diseases (e.g., Friedreich's ataxia (FRDA), Alzheimer's disease, and Parkinson's disease), stroke, and traumatic brain injury.

Novel idebenone analogs block Shc's access to insulin receptor to improve insulin sensitivity.

There has been little innovation in identifying novel insulin sensitizers. Metformin, developed in the 1920s, is still used first for most Type 2 diabetes patients. Mice with genetic reduction of p52Shc protein have improved insulin sensitivity and glucose tolerance.

An assay for DNA polymerase β lyase inhibitors that engage the catalytic nucleophile for binding.

DNA polymerase β (Pol β) repairs cellular DNA damage. When such damage is inflicted upon the DNA in tumor cells treated with DNA targeted antitumor agents, Pol β thus diminishes their efficacy. Accordingly, this enzyme has long been a target for antitumor therapy.

Double-component diazeniumdiolate derivatives as anti-cancer agents.

In this study, we synthesized a series of double-component O-aryl diazeniumdiolate (DDNO) derivatives, of which each molecule can release up to four nitric oxide molecules. These compounds showed cytotoxic activities to cancer cells, such as human leukemia, breast cancer and lung cancer. Among them, compound 1 (DDNO-1) showed the highest specific activity to human leukemia cells.

Multifunctional radical quenchers as potential therapeutic agents for the treatment of mitochondrial dysfunction.

Mitochondrial dysfunction is associated with a wide range of human diseases, including neurodegenerative diseases, and is believed to cause or contribute to the etiology of these diseases. These disorders are frequently associated with increased levels of reactive oxygen species. One of the design strategies for therapeutic intervention involves the development of novel small molecules containing redox cores, which can scavenge reactive oxygen radicals and selectively block oxidative damage to the mitochondria.

Phenothiazine antioxidants increase mitochondrial biogenesis and frataxin levels in Friedreich's ataxia cells.

Friedreich's ataxia (FRDA) is a progressive neurodegenerative disease that is linked to transcriptional repression of the nuclear FXN gene encoding the essential mitochondrial protein frataxin (FXN). Compounds that increase frataxin levels may enable effective therapeutic intervention for blunting disease progression. Recently, we showed that lipophilic methylene violet (MV) and methylene blue (MB) analogues both conferred benefit to cultured FRDA cells in several regards, including ROS suppression, maintenance of mitochondrial membrane potential and increased ATP production.

Chemical synthesis of lipophilic methylene blue analogues which increase mitochondrial biogenesis and frataxin levels.

As part of an ongoing program to develop potential therapeutic agents for the treatment of the neurodegenerative disease Friedreich׳s ataxia (FRDA), we have prepared a number of lipophilic methylene blue analogues. Some of these compounds significantly increase mitochondrial biogenesis and frataxin levels in cultured Friedreich's ataxia cells [1]. This data article describes the chemical synthesis and full physicochemical characterization of the new analogues.

Lipophilic methylene blue analogues enhance mitochondrial function and increase frataxin levels in a cellular model of Friedreich's ataxia.

Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder resulting from reduced expression of the protein frataxin (FXN). Although its function is not fully understood, frataxin appears to help assemble iron sulfur clusters; these are critical for the function of many proteins, including those needed for mitochondrial energy production. Finding ways to increase FXN levels has been a major therapeutic strategy for this disease.

Oligomeric amyloid β preferentially targets neuronal and not glial mitochondrial-encoded mRNAs.

Introduction: Our laboratories have demonstrated that accumulation of oligomeric amyloid β (OAβ) in neurons is an essential step leading to OAβ-mediated mitochondrial dysfunction.

Methods: Alzheimer's disease (AD) and matching control hippocampal neurons, astrocytes, and microglia were isolated by laser-captured microdissection from the same subjects, followed by whole-transcriptome sequencing. Complementary in vitro work was performed in OAβ-treated differentiated SH-SY5Y, followed by the use of a novel CoQ analogue for protection.

Lipophilic methylene violet analogues as modulators of mitochondrial function and dysfunction.

In an effort to identify methylene blue analogues having improved antioxidant activity, a series of new methylene violet analogues have been designed and synthesized. The analogues were prepared following a synthetic route that is more efficient than the previously reported methods, both in terms of yield and purity of the final products. The route involves the Smiles rearrangement as one of the crucial steps.

Inhibition of Human Cancer Cell Growth by Analogues of Antimycin A.

In a recent study, several new derivatives of antimycin A (AMA) were produced by means of a novel transacylation reaction, and these were shown to mediate selective toxicity toward cultured A549 human lung epithelial adenocarcinoma cells, as compared with WI-38 normal human lung fibroblasts. The purpose of our study was to investigate whether the analogues all expressed their cytotoxicity by the same mechanism. This was done by studying the effects of the compounds in several types of cell lines.

Influence of substituent heteroatoms on the cytoprotective properties of pyrimidinol antioxidants.

Recently, we described the optimization of novel pyrimidinol-based antioxidants as potential therapeutic molecules for targeting mitochondrial diseases. That study focused on improving the potency and metabolic stability of pyrimidinol antioxidants. This led us to consider the possibility of altering the positions of the exocyclic alkoxy and alkylamino substituents on the pyrimidinol scaffold.

Nuclear but not mitochondrial-encoded oxidative phosphorylation genes are altered in aging, mild cognitive impairment, and Alzheimer's disease.

Introduction: We have comprehensively described the expression profiles of mitochondrial DNA and nuclear DNA genes that encode subunits of the respiratory oxidative phosphorylation (OXPHOS) complexes (I-V) in the hippocampus from young controls, age matched, mild cognitively impaired (MCI), and Alzheimer's disease (AD) subjects.

Methods: Hippocampal tissues from 44 non-AD controls (NC), 10 amnestic MCI, and 18 AD cases were analyzed on Affymetrix Hg-U133 plus 2.0 arrays.

Optimization of pyrimidinol antioxidants as mitochondrial protective agents: ATP production and metabolic stability.

Previously we described a novel series of pyrimidinol antioxidants and their structural optimization as potential therapeutic agents for neurodegenerative and mitochondrial disorders. Our initial lead compound was a potent antioxidant in vitro, but was subsequently found to exhibit poor stability to oxidative metabolism. The current study focused on balancing potency with metabolic stability through structural modification, and involved modifications at positions 2 and 4 of the pyrimidinol redox core, likely sites of oxidative metabolism.

Mitochondrial Nitroreductase Activity Enables Selective Imaging and Therapeutic Targeting.

Nitroreductase (NTR) activities have been known for decades, studied extensively in bacteria and also in systems as diverse as yeast, trypanosomes, and hypoxic tumors. The putative bacterial origin of mitochondria prompted us to explore the possible existence of NTR activity within this organelle and to probe its behavior in a cellular context. Presently, by using a profluorescent near-infrared (NIR) dye, we characterize the nature of NTR activity localized in mammalian cell mitochondria.

Selective Functionalization of Antimycin A Through an N-Transacylation Reaction.

Acylation of 3-(N-formylamino)salicylic acids resulted in transacylation with loss of the formyl moiety. The reaction proceeds through a bis-N-acylated intermediate, which undergoes facile deformylation. This transacylation reaction has been employed for the site-specific functionalization of the mitochondrial poison antimycin A, affording several novel derivatives.

Novel antioxidants protect mitochondria from the effects of oligomeric amyloid beta and contribute to the maintenance of epigenome function.

Alzheimer's disease is associated with metabolic deficits and reduced mitochondrial function, with the latter due to the effects of oligomeric amyloid beta peptide (AβO) on the respiratory chain. Recent evidence has demonstrated reduction of epigenetic markers, such as DNA methylation, in Alzheimer's disease. Here we demonstrate a link between metabolic and epigenetic deficits via reduction of mitochondrial function which alters the expression of mediators of epigenetic modifications.

Cytoprotective pyridinol antioxidants as potential therapeutic agents for neurodegenerative and mitochondrial diseases.

As part of our ongoing efforts to identify compounds having potential utility in treating neurodegenerative and mitochondrial disorders, a series of pyridinol analogues have been prepared. The synthetic route employed for the preparation of the new analogues is different, and considerably more efficient, than that used in previously reported studies. The new route yields a pair of pyridinol regioisomers that can be readily separated and evaluated.

An optimized pyrimidinol multifunctional radical quencher.

A series of aza analogues (4-9) of the experimental neuroprotective drug idebenone (1) have been prepared and evaluated for their ability to attenuate oxidative stress induced by glutathione depletion and to compensate for the decrease in oxidative phosphorylation efficiency in cultured Friedreich's ataxia (FRDA) fibroblasts and lymphocytes and also coenzyme Q10-deficient lymphocytes. Modification of the redox core of the previously reported 3 improved its antioxidant and cytoprotective properties. Compounds 4-9, having the same redox core, exhibited a range of antioxidant activities, reflecting side chain differences.

A structurally simplified analogue of geldanamycin exhibits neuroprotective activity.

The syntheses of a structurally simplified geldanamycin analogue 2 and two related compounds are described. Compound 2 conferred cytoprotection and quenched ROS and lipid peroxidation in a dose-dependent manner in Friedreich's ataxia (FRDA) lymphocytes at low micromolar concentrations. It also prevented ROS-induced damage of cellular lipid membranes and maintained the mitochondrial membrane potential of FRDA lymphocytes.

Effects of alkyl side chain modification of coenzyme Q10 on mitochondrial respiratory chain function and cytoprotection.

The effect of the alkyl side chain length of coenzyme Q10 on mitochondrial respiratory chain function has been investigated by the use of synthetic ubiquinone derivatives. Three analogues (3, 4 and 6) were identified that exhibited significantly improved effects on mitochondrial oxygen consumption and mitochondrial membrane potential, and also conferred significant cytoprotection on cultured mammalian cells in which glutathione had been depleted by treatment with diethyl maleate. The analogues also exhibited lesser inhibition of the electron transport chain than idebenone.

Effects of cytoprotective antioxidants on lymphocytes from representative mitochondrial neurodegenerative diseases.

Two new aza analogues of the neuroprotective agent idebenone have been synthesized and characterized. Their antioxidant activity, and ability to augment ATP levels have been evaluated in several different cell lines having suboptimal mitochondrial function. Both compounds were found to be good ROS scavengers, and to protect the cells from oxidative stress induced by glutathione depletion.

Synthesis and biological activities of N-(3-carboxylpropyl)-5-amino-2-hydroxy-3-tridecyl-1,4-benzoquinone and analogues.

The synthesis of benzoquinone natural product 2 and three analogues is described. The synthesized compounds were tested for their ability to protect Friedreich's ataxia (FRDA) lymphocytes from induced oxidative stress. One of the analogues (3) conferred cytoprotection in a dose-dependent manner in FRDA lymphocytes at micromolar concentrations.

Analysis of the structural and mechanistic factors in antioxidants that preserve mitochondrial function and confer cytoprotection.

Selected pyridinol analogues of the experimental neuroprotective drug idebenone have been synthesized and evaluated as antioxidants capable of preserving mitochondrial function. The compounds, having a different redox core but the same side chain as idebenone, exhibited a range of potencies, reflecting differences in their structures. The results obtained provide guidance in the design of such analogues with improved properties.

Simplified bicyclic pyridinol analogues protect mitochondrial function.

Bicyclic pyridinol antioxidants have been reported to suppress the autoxidation of methyl linoleate more effectively than α-tocopherol in benzene solution. A few novel lipophilic analogues have recently been synthesized by conjugating a pyridinol core with the phytyl side chain of α-tocopherol; these have been shown to possess potent antioxidant activity. However, the complexity of the synthetic routes has hampered their further development.