desmosterol and zymostenol

We have earlier reported that amiodarone, a potent and commonly used antiarrhythmic drug increases serum desmosterol, the last precursor of cholesterol, in 20 cardiac patients by an unknown mechanism.. Here, we extended our study to a large number of cardiac patients of heterogeneous diagnoses, evaluated the effects of combining amiodarone and statins (inhibitors of cholesterol synthesis at the rate-limiting step of hydroxy-methyl-glutaryl CoA reductase) on desmosterol levels and investigated the mechanism(s) by which amiodarone interferes with the metabolism of desmosterol using in vitro studies.. We report in a clinical case-control setting of 236 cardiac patients (126 with and 110 without amiodarone treatment) that amiodarone medication is accompanied by a robust increase in serum desmosterol levels independently of gender, age, body mass index, cardiac and other diseases, and the use of statins. Lipid analyses in patient samples taken before and after initiation of amiodarone therapy showed a systematic increase of desmosterol upon drug administration, strongly arguing for a direct causal link between amiodarone and desmosterol accumulation. Mechanistically, we found that amiodarone resulted in desmosterol accumulation in cultured human cells and that the compound directly inhibited the 24-dehydrocholesterol reductase (DHCR24) enzyme activity.. These novel findings demonstrate that amiodarone blocks the cholesterol synthesis pathway by inhibiting DHCR24, causing a robust accumulation of cellular desmosterol in cells and in the sera of amiodarone-treated patients. It is conceivable that the antiarrhythmic potential and side effects of amiodarone may in part result from inhibition of the cholesterol synthesis pathway.

Topics: Amiodarone; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Case-Control Studies; Cells, Cultured; Cholesterol; Desmosterol; Female; Humans; Lipids; Male; Middle Aged; Nerve Tissue Proteins; Oxidoreductases Acting on CH-CH Group Donors

We developed a simple and robust liquid chromatographic/mass spectrometric method (LC-MS) for the quantitative analysis of 10 sterols from the late part of cholesterol synthesis (zymosterol, dehydrolathosterol, 7-dehydrodesmosterol, desmosterol, zymostenol, lathosterol, FFMAS, TMAS, lanosterol, and dihydrolanosterol) from cultured human hepatocytes in a single chromatographic run using a pentafluorophenyl (PFP) stationary phase. The method also avails on a minimized sample preparation procedure in order to obtain a relatively high sample throughput. The method was validated on 10 sterol standards that were detected in a single chromatographic LC-MS run without derivatization. Our developed method can be used in research or clinical applications for disease-related detection of accumulated cholesterol intermediates. Disorders in the late part of cholesterol synthesis lead to severe malformation in human patients. The developed method enables a simple, sensitive, and fast quantification of sterols, without the need of extended knowledge of the LC-MS technique, and represents a new analytical tool in the rising field of cholesterolomics.

Topics: Cholecalciferol; Cholesterol; Chromatography, Liquid; Desmosterol; Fluorobenzenes; Gene Deletion; Hep G2 Cells; Hepatocytes; Humans; Lanosterol; Mass Spectrometry; Phenols; Reproducibility of Results; Sterols

The hypocholesterolaemic effect of pravastatin 40 mg and lovastatin 40 mg daily has been compared in patients with familial hypercholesterolaemia (FH). Administration of the two drugs was separated by a three-month washout period. The reduction in total serum cholesterol after 1,2 and 4 weeks of treatment was similar after pravastatin (-23%, -32% and -32%) and lovastatin (-23%, -30% and -31%). The serum concentrations of LDL cholesterol were similarly reduced, whilst triglycerides, other lipoproteins, cholestanol and squalene were not altered. The reductions in the serum levels of the cholesterol precursor sterols, delta 8-cholesterol, desmosterol and lathosterol were not significantly different after either drug. The lack of difference suggests that cholesterol synthesis was equally inhibited by the two agents. In addition, the serum content of the plant sterols campesterol and sitosterol tended to be equally increased. The comparability of the increases suggests that the absorption and biliary elimination of the two sterols were equally affected by the two statins. Thus, no difference was found between the effects of pravastatin and lovastatin on the serum levels and metabolic precursors of cholesterol in FH during four weeks of treatment.

Topics: Adult; Aged; Cholesterol; Cholesterol, LDL; Desmosterol; Female; Humans; Hyperlipoproteinemia Type II; Isomerism; Lovastatin; Male; Middle Aged; Phytosterols; Pravastatin; Sitosterols; Triglycerides