ABSTRACT
Multiple changes in metabolic levels could be useful for understanding physiological toxicity. To explore further risk factors for the convulsions induced by the interaction of nonsteroidal anti-inflammatory and new quinolone antimicrobial drugs, the effect of sparfloxacin, enoxacin, and felbinac on fatty acid metabolism and glucose concentrations in the liver, brain, and blood of rats was investigated. The levels of long-chain acyl-CoAs (C(18:1) and C(20:4)) in the liver and brain were decreased at the onset of convulsions induced by the coadministration of enoxacin with felbinac. Then, glucose concentrations in the liver and blood were decreased, whereas they were increased in a dose-dependant manner in the brain. However, the formation of acyl-CoAs and glucose levels in the liver, brain, and blood was not significantly influenced by enoxacin, felbinac, and sparfloxacin alone, respectively. The disturbance of both fatty acid metabolism and glucose levels might be associated with the increased susceptibility to convulsions, which may contribute to further understanding of the toxic effects associated with these drugs.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/toxicity , Enoxacin/toxicity , Fatty Acids/metabolism , Fluoroquinolones/toxicity , Glucose/metabolism , Phenylacetates/toxicity , Animals , Brain/drug effects , Brain/metabolism , Chromatography, Liquid , Liver/drug effects , Liver/metabolism , Male , Rats , Rats, Wistar , Spectrometry, Mass, Electrospray Ionization , Tandem Mass SpectrometryABSTRACT
OBJECTIVES: Fatty acid metabolism is controlled not only by the acyl-coenzyme A (CoA) synthetases but by some enzymes in the ß-oxidation cycle. Medium-chain and long-chain acyl-CoA esters are key metabolites in fatty acid metabolism. We have developed an enzymatic assay method for determining chain shortening of the acyl-CoAs via ß-oxidation from palmitic and octanoic acids in liver mitochondria. We have evaluated the assay method for detecting whether drugs influence the activation or the ß-oxidation of fatty acids. METHODS: Liver mitochondria were used for investigating the effect of drugs on fatty acid metabolism. The drugs selected were salicylic acid, diclofenac, valproic acid and paracetamol. Each acyl-CoA formed was analysed by liquid chromatography-tandem mass spectrometry. KEY FINDINGS: After less than 5 min of incubation, the levels of acyl-CoAs reflected the acyl-CoA synthetase activity, whereas after 60-min incubation they reflected the activity of some enzymes in the ß-oxidation cycle. Salicylic acid, diclofenac and valproic acid inhibited the medium-chain acyl-CoA synthetases, whereas valproic acid only exhibited a weak inhibitory activity toward the ß-oxidation of the medium-chain fatty acids. In the case of long-chain fatty acid metabolism, salicylic acid and diclofenac inhibited both the activation and ß-oxidation, whereas valproic acid was a weak inhibitor for only the ß-oxidation activity. Paracetamol showed hardly any influence on the metabolism of medium-chain and long-chain fatty acids. CONCLUSIONS: These findings suggest that salicylic acid, diclofenac, valproic acid and paracetamol exert a different influence on fatty acid metabolism depending on the length of the acyl chain. This assay allows sensitive and selective analysis for predicting the pathways by which drugs exert a greater influence over fatty acid metabolism.
Subject(s)
Fatty Acids/metabolism , Lipid Metabolism/drug effects , Mitochondria, Liver/metabolism , Acetaminophen/pharmacology , Analgesics, Non-Narcotic/pharmacology , Animals , Anti-Infective Agents/pharmacology , Anti-Inflammatory Agents, Non-Steroidal/analysis , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Chromatography, Liquid/methods , Coenzyme A Ligases/antagonists & inhibitors , Coenzyme A Ligases/metabolism , Diclofenac/metabolism , Diclofenac/pharmacology , Enzyme Inhibitors/pharmacology , Fatty Acids/antagonists & inhibitors , Fatty Acids/pharmacology , Male , Mice , Mice, Mutant Strains , Mitochondria, Liver/drug effects , Mitochondria, Liver/enzymology , Oxidation-Reduction , Salicylic Acid/pharmacology , Tandem Mass Spectrometry/methods , Valproic Acid/pharmacologyABSTRACT
Medium-chain and long-chain acyl-CoA esters are key metabolites in fatty acid metabolism. Effects of salicylic acid on the in vivo formation of acyl-CoAs in mouse liver and brain were investigated. Further, inhibition of the medium-chain and long-chain acyl-CoA synthetases by salicylic acid and diclofenac was determined in mouse liver and brain mitochondria. Acyl-CoA esters were analyzed by liquid chromatography-tandem mass spectrometry. The amounts of medium-chain acyl-CoAs (C(6), C(8) and C(10)) were less than long-chain acyl-CoAs (C(16:0), C(18:0), C(18:1) and C(20:4)) in both liver and brain. The administration of salicylic acid decreased the levels of both the medium-chain (C(6), C(8) and C(10)) and long-chain acyl-CoAs (C(16:0), C(18:0), C(18:1) and C(20:4)) in liver. In brain, however, only long-chain acyl-CoAs were decreased. The level of salicylyl-CoA detected in brain was about 12% of that in liver. Salicylic acid had a strong inhibitory activity (IC(50) = 0.1 mm) for the liver mitochondrial formation of hexanoyl-CoA from hexanoic acid, whereas diclofenac was weak (IC(50) = 4.4 mm). In contrast, diclofenac (IC(50) = 1.4 mm) inhibited the liver mitochondrial long-chain acyl-CoA synthetases more potently than salicylic acid (IC(50) = 25.5 mm). Similar inhibitory activities for the acyl-CoA synthetases were obtained in the case of the brain and liver mitochondria, except for the weak inhibition of brain medium-chain acyl-CoA synthetases by salicylic acid (IC(50) = 1.8 mm). These findings suggest that salicylic acid and diclofenac exhibit different mechanisms of inhibition of fatty acid metabolism depending on the length of the acyl chain and tissues, and they may contribute to the further understanding of the toxic effects associated with these drugs.