In-vitro metabolic profiling study of potential topoisomerase inhibitors 'pyrazolines' in RLMs by mass spectrometry

Simvastatin: In Vitro Metabolic Profiling of a Potent Competitive HMG-CoA Reductase Inhibitor

Simvastatin (SV) is a semisynthetic derivative of lovastatin (LV), which is biosynthetically produced from the fungus Aspergillus terreus and has a high log p value (log p = 4.39)and thus high hepatic extraction and high efficacy in controlling cholesterol synthesis. The current study was undertaken to investigate the metabolic profile of SV using various mass spectrometry (MS) platforms. Metabolic profiling was studied in in vitro models, rat liver microsomes (RLMs), and isolated perfused rat liver hepatocytes (RLHs) using both ion trap and triple quadruple LC–MS/MS systems. A total of 29 metabolites were identified. Among them, three types of SV-related phase-I metabolites, namely exomethylene simvastatin acid (exomethylene SVA), monohydroxy SVA, and dihydrodiol SVA, were identified as new in RLMs. No phase-II metabolites were identified while incubating with RLHs.

Galeon: A Biologically Active Molecule with In Silico Metabolite Prediction, In Vitro Metabolic Profiling in Rat Liver Microsomes, and In Silico Binding Mechanisms with CYP450 Isoforms

Galeon, a natural cyclic-diarylheptanoid (CDH), which was first isolated from Myrica gale L., is known to have potent cytotoxicity against A549 cell lines, anti-tubercular activity against Mycobacterium tuberculosis H37Rv, chemo-preventive potential, and moderate topoisomerase inhibitory activity. Here, in silico metabolism and toxicity prediction of galeon by CYP450, in vitro metabolic profiling study in rat liver microsomes (RLMs), and molecular interactions of galeon-CYP450 isoforms were performed. An in silico metabolic prediction study showed demethyl and mono-hydroxy galeon were the metabolites with the highest predictability. Among the predicted metabolites, mono-hydroxy galeon was found to have plausible toxicities such as skin sensitization, thyroid toxicity, chromosome damage, and carcinogenicity. An in vitro metabolism study of galeon, incubated in RLMs, revealed eighteen Phase-I metabolites, nine methoxylamine, and three glutathione conjugates. Identification of possible metabolites and confirmation of their structures were carried out using ion-trap tandem mass spectrometry. In silico docking analysis of galeon demonstrated significant interactions with active site residues of almost all CYP450 isoforms.