- Structure effect relationships of amiodarone analogues on the inhibition of thyroxine deiodination
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Objectives: Amiodarone (AMI) has proven to be a potent anti-arrhythmic compound. Due to the structural similarity between AMI and thyroid hormone, it is possible that the drug could inhibit the activity of the 5'-thyroxine- deiodinase. Methods: AMI analogues resulting from (1) dealkylation, (2) deiodination and (3) deamination were synthesised and used as inhibitors in an in vitro biotransformation reaction of thyroxine (T4) to 3,3',5'- triiodothyronine (T3). Using high-performance liquid chromatography and ultraviolet detection for quantifying T3, it was found that the 5'-T4 deiodinase type I was involved in the reaction. On separate occasions, AMI or an AMI analogue was added to the reaction as an inhibitor. Results: All studied AMI analogues inhibited 5'-T4 deiodination competitively (K(i) value range 25-360 μM). In the concentration range of 1-1000 μM, AMI and its N- desethylated, deiodinated analogues inhibited 5'-T4 deiodination very weakly. AMI analogues with a hydroxyl group at the 4-position were strong inhibitors. Moreover, diiodo-AMI analogues inhibited 5'-T4 deiodination more strongly than their corresponding monoiodo- or deiodinated derivatives. Conclusion: It is likely that the degraded products of AMI could be responsible for thyroid dysfunction toxicosis in AMI therapy.
- Ha,Stieger,Grassi,Altorfer,Follath
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- Comparative analysis of in vivo and in silico toxicity evaluation of the organoiodine compounds towards D. magna using multivariate chemometric approach: A study on the example of amiodarone phototransformation products
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In the present study the photochemical fate of organoiodine compound – amiodarone was performed. The drug turned out to be highly susceptible to UV–Vis irradiation, especially in the presence of humic substances and organic matrix. Qualitative LC-MS analysis revealed formation of twelve – mainly previously unreported – transformation products (TPs). Four major TPs were submitted to the toxicity analysis with the use of D. magna. All of the tested TPs presented higher toxic potential than the parent compound. The phenolic TPs were approximately 100 times more toxic than amiodarone. Toxic properties of the major TPs resulted in steadily increasing toxic potential of the photo-generated mixture over the time of irradiation. Moreover, the experimental toxicity data, concerning the TPs, were compared with results estimated by 6 in silico models with the use of a multivariate chemometric analysis. The results showed that the applied computational methods were able neither to correctly predict toxic properties of the studied compounds, nor the trends in change of their toxic parameters. Additional validation of in silico models ability to predict toxicity of iodinated organic compounds showed that the studied computational methods do not present sufficient prediction ability. Therefore their estimations concerning organoiodines should be verified using experimental tests.
- Skibiński, Robert,Trawiński, Jakub
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- Trace amine-associated receptor 1 (TAAR1) is activated by amiodarone metabolites
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Amiodarone (Cordarone, Wyeth-Ayerst Pharmaceuticals) is a clinically available drug used to treat a wide variety of cardiac arrhythmias. We report here the synthesis and characterization of a panel of potential amiodarone metabolites that have significant structural similarity to thyroid hormone and its metabolites the iodothyronamines. Several of these amiodarone derivatives act as specific agonists of the G protein-coupled receptor (GPCR) trace amine-associated receptor 1 (TAAR1). This result demonstrates a novel molecular target for amiodarone derivatives with potential clinical significance.
- Snead, Aaron N.,Miyakawa, Motonori,Tan, Edwin S.,Scanlan, Thomas S.
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supporting information; experimental part
p. 5920 - 5922
(2009/05/31)
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