Mechanism of H 2 S Formation from the Metabolism of Anetholedithiolethione and Anetholedithiolone by Rat Liver Microsomes

International audienceThe drug anetholedithiolethione, ADT, and its analogs have been extensively used as H2S donors. However, the mechanism of H2S formation from ADT under biological conditions remains almost completely unknown. This article shows that incubation of ADT or its metabolite anetholedithiolone, ADO, with rat liver microsomes, leads to H2S in the presence of NADPH and O2, and that H2S formation is greatly inhibited by N-benzyl-imidazole, indicating that this formation is mainly catalyzed by cytochrome P450-dependent monooxygenases. It also shows that there is a concomitant formation of H2S and para-methoxy-acetophenone, pMA, during microsomal metabolism of ADT and ADO. This article shows for the first time that ADO is a better H2S donor than ADT under those conditions, and proposes first detailed mechanisms for the formation of H2S from the microsomal metabolism of ADT and ADO

Quantitative analysis of the tumor suppressor dendrogenin A using liquid chromatography tandem mass spectrometry

International audienceDendrogenin A (DDA) was recently identified as a mammalian cholesterol metabolite that displays tumor suppressor and neurostimulating properties at low doses. In breast tumors, DDA levels were found to be decreased compared to normal tissues, evidencing a metabolic deregulation of DDA production in cancers. DDA is an amino-oxysterol that contains three protonatable nitrogen atoms. This makes it physico-chemically different from other oxysterols and it therefore requires specific analytical methods We have previously used a two-step method for the quantification of DDA in biological samples: 1) DDA purification from a Bligh and Dyer extract by RP-HPLC using a 250×4.6mm column, followed by 2) nano-electrospray ionization mass spectrometry (MS) fragmentation to analyze the HPLC fraction of interest. We report here the development a liquid chromatography tandem mass spectrometry method for the analysis of DDA and its analogues. This new method is fast (10min), resolving (peak width <4s) and has a weak carryover (<0.01%). We show that this technique efficiently separates DDA from its C17 isomer and other steroidal alkaloids from the same family establishing a proof of concept for the analysis of this family of amino-oxysterols