ABSTRACT
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. The results obtained provide guidance for the design of CoQ10 analogues with improved activity compared to that of idebenone (1), the latter of which is undergoing evaluation in the clinic as a therapeutic agent.
Subject(s)
Electron Transport/drug effects , Mitochondria/drug effects , Ubiquinone/analogs & derivatives , Animals , Cattle , Cell Line , Cell Line, Tumor , Cytoprotection , Electron Transport/physiology , Humans , Leukemia/metabolism , Leukemia/pathology , Membrane Potential, Mitochondrial/drug effects , Mitochondria/metabolism , Oxygen Consumption/drug effects , Reactive Oxygen Species/metabolism , Retinal Ganglion Cells/cytology , Retinal Ganglion Cells/drug effects , Retinal Ganglion Cells/metabolism , Structure-Activity Relationship , Ubiquinone/chemistry , Ubiquinone/metabolism , Ubiquinone/pharmacologyABSTRACT
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. The compounds were more effective than idebenone in neurodegenerative disease cells. These novel pyrimidinol derivatives were also shown to augment ATP levels in coenzyme Q(10)-deficient human lymphocytes. The more lipophilic side chains attached to the pyrimidinol redox core in these compounds resulted in less inhibition of the electron transport chain and improved antioxidant activity.
Subject(s)
Antioxidants/chemistry , Mitochondria/metabolism , Neuroprotective Agents/chemistry , Pyrimidines/chemistry , Ubiquinone/analogs & derivatives , Adenosine Triphosphate/metabolism , Animals , Antioxidants/chemical synthesis , Antioxidants/toxicity , Cattle , Cell Line , Cell Survival/drug effects , Drug Design , Glutathione/metabolism , Humans , Lymphocytes/drug effects , Lymphocytes/metabolism , Mitochondria/enzymology , Multienzyme Complexes/antagonists & inhibitors , Multienzyme Complexes/metabolism , NADH, NADPH Oxidoreductases/antagonists & inhibitors , NADH, NADPH Oxidoreductases/metabolism , Neurodegenerative Diseases/metabolism , Neurodegenerative Diseases/pathology , Neuroprotective Agents/chemical synthesis , Neuroprotective Agents/toxicity , Pyrimidines/chemical synthesis , Pyrimidines/toxicity , Reactive Oxygen Species/metabolism , Ubiquinone/chemical synthesis , Ubiquinone/chemistry , Ubiquinone/genetics , Ubiquinone/metabolism , Ubiquinone/toxicityABSTRACT
The one-pot construction of functionalized α'-methoxy-γ-pyrones is detailed. Starting from α,α'-dimethoxy-γ-pyrone, molecular diversity is attained by a regio- and stereoselective desymmetrization using allyllithium followed by vinylogous aldol reaction. Mechanistic considerations including density functional theory calculations and insightful experiments have been gathered to shed light on this complex multistep process. To illustrate the versatility of this methodology, some of the molecules prepared were evaluated for their ability to inhibit NADH-oxidase and NADH-ubiquinone oxidoreductase. In the process, a potent new inihibitor of NADH-oxidase activity (IC(50) 44 nM) was identified.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Mitochondria/drug effects , NADH, NADPH Oxidoreductases/antagonists & inhibitors , Pyrones/chemical synthesis , Pyrones/pharmacology , Enzyme Inhibitors/chemistry , Mitochondria/physiology , Molecular Structure , NADH, NADPH Oxidoreductases/metabolism , Pyrones/chemistry , Quantum Theory , StereoisomerismABSTRACT
Arabidopsis (Arabidopsis thaliana) plants were grown in a hydroponic culture system for 7 to 14 d in the absence or presence of 75 microM Cd or 75 microM Cu. The Cu treatment resulted in visual leaf symptoms, together with anthocyanin accumulation and loss of turgor. Pronounced lipid peroxidation, which was detected by autoluminescence imaging and malondialdehyde titration, was observed in Cu-treated leaves. The Cd treatment also resulted in loss of leaf pigments but lipid peroxidation and oxidative stress were less pronounced than in the leaves exposed to Cu. Analysis of low-molecular-weight chloroplast and cytosolic antioxidants (ascorbate, glutathione, tocopherols, carotenoids) and antioxidant enzymes (thiol-based reductases and peroxidases) revealed relatively few responses to metal exposure. However, there was a marked increase in vitamin E (alpha-tocopherol) in response to Cd and Cu treatments. Ascorbate increased significantly in Cu-exposed leaves. Other antioxidants either remained stable or decreased in response to metal stress. Transcripts encoding enzymes of the vitamin E biosynthetic pathway were increased in response to metal exposure. In particular, VTE2 mRNA was enhanced in Cu- and Cd-treated plants, while VTE5 and hydroxylpyruvate dioxygenase (HPPD) mRNAs were only up-regulated in Cd-treated plants. Consistent increases in HPPD transcripts and protein were observed. The vitamin E-deficient (vte1) mutant exhibited an enhanced sensitivity towards both metals relative to the wild-type (WT) control. Unlike the vte1 mutants, which showed enhanced lipid peroxidation and oxidative stress in the presence of Cu or Cd, the ascorbate-deficient (vtc2) mutant showed WT responses to metal exposure. Taken together, these results demonstrate that vitamin E plays a crucial role in the tolerance of Arabidopsis to oxidative stress induced by heavy metals such as Cu and Cd.
