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

Selective Functionalization of Antimycin A Through an <i>N</i>‑Transacylation Reaction

Acylation of 3-(<i>N</i>-formylamino)­salicylic acids resulted in transacylation with loss of the formyl moiety. The reaction proceeds through a bis-<i>N</i>-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. The selective cytotoxicity of some of these derivatives toward cultured A549 human lung epithelial adenocarcinoma cells, in comparison with WI-38 normal human lung fibroblasts, illustrates one application of this transacylation reaction

An Optimized Pyrimidinol Multifunctional Radical Quencher

A series of aza analogues (<b>4</b>–<b>9</b>) of the experimental neuroprotective drug idebenone (<b>1</b>) 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 <b>3</b> improved its antioxidant and cytoprotective properties. Compounds <b>4</b>–<b>9</b>, having the same redox core, exhibited a range of antioxidant activities, reflecting side chain differences. Compounds having side chains extending 14–16 atoms from the pyrimidinol ring (<b>6</b>, <b>7</b>, and <b>9</b>) were potent antioxidants. They were superior to idebenone and more active than <b>3</b>, <b>4</b>, <b>5</b>, and <b>8</b>. Optimized analogue <b>7</b> and its acetate (<b>7a</b>) are of interest in defining potential therapeutic agents capable of blocking oxidative stress, maintaining mitochondrial membrane integrity, and augmenting ATP levels. Compounds with such properties may find utility in treating mitochondrial and neurodegenerative diseases such as FRDA and Alzheimer’s disease

Selective Functionalization of Antimycin A Through an <i>N</i>‑Transacylation Reaction

Acylation of 3-(<i>N</i>-formylamino)­salicylic acids resulted in transacylation with loss of the formyl moiety. The reaction proceeds through a bis-<i>N</i>-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. The selective cytotoxicity of some of these derivatives toward cultured A549 human lung epithelial adenocarcinoma cells, in comparison with WI-38 normal human lung fibroblasts, illustrates one application of this transacylation reaction

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. Further, we demonstrate that this mito­chondrially localized enzymatic activity can be exploited both for selective NIR imaging of mito­chondria and for mito­chondrial targeting by activating a mito­chondrial poison specifically within that organelle. This constitutes a new mechanism for mito­chondrial imaging and targeting. These findings represent the first use of mito­chondrial enzyme activity to unmask agents for mito­chondrial fluorescent imaging and therapy, which may prove to be more broadly applicable

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

IntroductionWe 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.MethodsHippocampal tissues from 44 non-AD controls (NC), 10 amnestic MCI, and 18 AD cases were analyzed on Affymetrix Hg-U133 plus 2.0 arrays.ResultsThe microarray data revealed significant down regulation in OXPHOS genes in AD, particularly those encoded in the nucleus. In contrast, there was up regulation of the same gene(s) in MCI subjects compared to AD and ND cases. No significant differences were observed in mtDNA genes identified in the array between AD, ND, and MCI subjects except one mt-ND6.DiscussionOur findings suggest that restoration of the expression of nuclear-encoded OXPHOS genes in aging could be a viable strategy for blunting AD progression

"Novel idebenone analogs block Shc\u2019s access to insulin receptor to improveinsulin 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. By high-throughput screening, idebenone was isolated as the first small molecule 'Shc Blocker'. Idebenone blocks p52Shc's access to Insulin Receptor to increase insulin sensitivity. In this work the avidity of 34 novel idebenone analogs and 3 metabolites to bind p52Shc, and to block the interaction of p52Shc with the Insulin receptor was tested. Our hypothesis was that if an idebenone analog bound and blocked p52Shc's access to insulin receptor better than idebenone, it should be a more effective insulin sensitizing agent than idebenone itself. Of 34 analogs tested, only 2 both bound p52Shc more tightly and/or blocked the p52Shc-Insulin Receptor interaction more effectively than idebenone. Of those 2 only idebenone analog #11 was a superior insulin sensitizer to idebenone. Also, the long-lasting insulin-sensitizing potency of idebenone in rodents over many hours had been puzzling, as the parent molecule degrades to metabolites within 1\u2009h. We observed that two of the idebenone\u2019s three metabolites are insulin sensitizing almost as potently as idebenone itself, explaining the persistent insulin sensitization of this rapidly metabolized molecule. These results help to identify key SAR\u2009=\u2009structure-activity relationship requirements for more potent small molecule Shc inhibitors as Shc-targeted insulin sensitizers for type 2 diabetes

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. By high-throughput screening, idebenone was isolated as the first small molecule 'Shc Blocker'. Idebenone blocks p52Shc's access to Insulin Receptor to increase insulin sensitivity. In this work the avidity of 34 novel idebenone analogs and 3 metabolites to bind p52Shc, and to block the interaction of p52Shc with the Insulin receptor was tested. Our hypothesis was that if an idebenone analog bound and blocked p52Shc's access to insulin receptor better than idebenone, it should be a more effective insulin sensitizing agent than idebenone itself. Of 34 analogs tested, only 2 both bound p52Shc more tightly and/or blocked the p52Shc-Insulin Receptor interaction more effectively than idebenone. Of those 2 only idebenone analog #11 was a superior insulin sensitizer to idebenone. Also, the long-lasting insulin-sensitizing potency of idebenone in rodents over many hours had been puzzling, as the parent molecule degrades to metabolites within 1 h. We observed that two of the idebenone's three metabolites are insulin sensitizing almost as potently as idebenone itself, explaining the persistent insulin sensitization of this rapidly metabolized molecule. These results help to identify key SAR = structure-activity relationship requirements for more potent small molecule Shc inhibitors as Shc-targeted insulin sensitizers for type 2 diabetes