Heteroaryl substituted bis-trifluoromethyl carbinols as malonyl-CoA decarboxylase inhibitors

Myocardial metabolism in diabetic cardiomyopathy: potential therapeutic targets

SIGNIFICANCE

Cardiovascular complications in diabetes are particularly serious and represent the primary cause of morbidity and mortality in diabetic patients. Despite early observations of cardiac dysfunction in diabetic humans, cardiomyopathy unique to diabetes has only recently been recognized.

RECENT ADVANCES

Research has focused on understanding the pathogenic mechanisms underlying the initiation and development of diabetic cardiomyopathy. Emerging data highlight the importance of altered mitochondrial function as a major contributor to cardiac dysfunction in diabetes. Mitochondrial dysfunction occurs by several mechanisms involving altered cardiac substrate metabolism, lipotoxicity, impaired cardiac insulin and glucose homeostasis, impaired cellular and mitochondrial calcium handling, oxidative stress, and mitochondrial uncoupling.

CRITICAL ISSUES

Currently, treatment is not specifically tailored for diabetic patients with cardiac dysfunction. Given the multifactorial development and progression of diabetic cardiomyopathy, traditional treatments such as anti-diabetic agents, as well as cellular and mitochondrial fatty acid uptake inhibitors aimed at shifting the balance of cardiac metabolism from utilizing fat to glucose may not adequately target all aspects of this condition. Thus, an alternative treatment such as resveratrol, which targets multiple facets of diabetes, may represent a safe and promising supplement to currently recommended clinical therapy and lifestyle changes.

FUTURE DIRECTIONS

Elucidation of the mechanisms underlying the initiation and progression of diabetic cardiomyopathy is essential for development of effective and targeted treatment strategies. Of particular interest is the investigation of alternative therapies such as resveratrol, which can function as both preventative and mitigating agents in the management of diabetic cardiomyopathy.

Crystal structures of malonyl-coenzyme A decarboxylase provide insights into its catalytic mechanism and disease-causing mutations

Malonyl-coenzyme A decarboxylase (MCD) is found from bacteria to humans, has important roles in regulating fatty acid metabolism and food intake, and is an attractive target for drug discovery. We report here four crystal structures of MCD from human, Rhodopseudomonas palustris, Agrobacterium vitis, and Cupriavidus metallidurans at up to 2.3 Å resolution. The MCD monomer contains an N-terminal helical domain involved in oligomerization and a C-terminal catalytic domain. The four structures exhibit substantial differences in the organization of the helical domains and, consequently, the oligomeric states and intersubunit interfaces. Unexpectedly, the MCD catalytic domain is structurally homologous to those of the GCN5-related N-acetyltransferase superfamily, especially the curacin A polyketide synthase catalytic module, with a conserved His-Ser/Thr dyad important for catalysis. Our structures, along with mutagenesis and kinetic studies, provide a molecular basis for understanding pathogenic mutations and catalysis, as well as a template for structure-based drug design.

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Structures of human and bacterial MCDs were determined at up to 2.3 Å resolution

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Distinct tetrameric and dimeric MCD oligomerizations were observed

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Unexpected homology to the GNAT superfamily gives insights into catalytic mechanism

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The structures provide the molecular basis for the disease-causing mutations in MCD

Targeting fatty acid and carbohydrate oxidation--a novel therapeutic intervention in the ischemic and failing heart

Cardiac ischemia and its consequences including heart failure, which itself has emerged as the leading cause of morbidity and mortality in developed countries are accompanied by complex alterations in myocardial energy substrate metabolism. In contrast to the normal heart, where fatty acid and glucose metabolism are tightly regulated, the dynamic relationship between fatty acid β-oxidation and glucose oxidation is perturbed in ischemic and ischemic-reperfused hearts, as well as in the failing heart. These metabolic alterations negatively impact both cardiac efficiency and function. Specifically there is an increased reliance on glycolysis during ischemia and fatty acid β-oxidation during reperfusion following ischemia as sources of adenosine triphosphate (ATP) production. Depending on the severity of heart failure, the contribution of overall myocardial oxidative metabolism (fatty acid β-oxidation and glucose oxidation) to adenosine triphosphate production can be depressed, while that of glycolysis can be increased. Nonetheless, the balance between fatty acid β-oxidation and glucose oxidation is amenable to pharmacological intervention at multiple levels of each metabolic pathway. This review will focus on the pathways of cardiac fatty acid and glucose metabolism, and the metabolic phenotypes of ischemic and ischemic/reperfused hearts, as well as the metabolic phenotype of the failing heart. Furthermore, as energy substrate metabolism has emerged as a novel therapeutic intervention in these cardiac pathologies, this review will describe the mechanistic bases and rationale for the use of pharmacological agents that modify energy substrate metabolism to improve cardiac function in the ischemic and failing heart. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.

3D-QSAR studies on malonyl coenzyme A decarboxylase inhibitors

Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on a series of Malonyl Co-A decarboxylase (MCD) inhibitors (Cheng et al. J. Med. Chem.2006, 49, 1517-1525 and Cheng et al. Bioorg. Med. Chem. Lett.2006, 16, 695-700). These inhibitors have shown protective action on the ischemic heart by inhibiting fatty acid oxidation. The CoMFA model produced statistically significant results, with the cross-validated and conventional correlation coefficients being 0.544 and 0.986, respectively. The best results were obtained by combining steric, electrostatic, hydrophobic, and H-bond acceptor fields in CoMSIA, in which case the respective cross-validated and conventional correlation coefficients were 0.551 and 0.918. The predictive ability of CoMFA and CoMSIA, determined using a test set of 24 compounds, gave predictive correlation coefficients of 0.718 and 0.725, respectively. The information obtained from CoMFA and CoMSIA 3D contour maps may be of utility in the design of more potent MCD inhibitors.

Novel trifluoroacetophenone derivatives as malonyl-CoA decarboxylase inhibitors

A series of trifluoroacetophenone derivatives were prepared and evaluated as malonyl-CoA decarboxylase (MCD) inhibitors. Some of the 'reverse amide' analogs were found to be potent inhibitors of MCD enzyme activity. The trifluoroacetyl group may interact with the MCD active site as the hydrate in a similar fashion to the hexafluoroisopropanol analogs reported previously. Adding electron-withdrawing groups to the phenyl ring stabilizes the hydrated species and enhances this interaction.

Malonyl-CoA Decarboxylase Inhibition as a Novel Approach to Treat Ischemic Heart Disease

INTRODUCTION

During and following cardiac ischemia the levels of circulating fatty acids are elevated, resulting in fatty acid oxidation dominating as a source of oxidative metabolism at the expense of pyruvate oxidation. A decrease in the levels of myocardial malonyl-CoA (an endogenous inhibitor of mitochondrial fatty acid uptake) contributes to these high fatty acid oxidation rates. Low pyruvate oxidation rates during and following ischemia results in the accumulation of metabolic byproducts (lactate and protons) that leads to impaired cardiac function, decreased cardiac efficiency, and increased myocardial tissue injury.

METHODOLOGY

One approach to increasing pyruvate oxidation during and following ischemia is to inhibit fatty acid oxidation, which results in an improvement of both cardiac function and cardiac efficiency. A novel approach to decreasing fatty acid oxidation and increasing pyruvate oxidation is to increase myocardial levels of malonyl-CoA. This can be achieved by pharmacologically inhibiting malonyl-CoA decarboxylase (MCD), the principal enzyme involved in the degradation of cardiac malonyl-CoA.

RESULTS

Studies with either genetic deletion of MCD in the mouse or with novel MCD inhibitors show that decreased MCD activity increases cardiac malonyl-CoA, resulting in an inhibition of fatty acid oxidation and a stimulation of pyruvate oxidation.

CONCLUSION

The beneficial effects of MCD inhibition on cardiac function and cardiac efficiency suggest that this approach could be an effective means to treat ischemic heart disease.