title: Studies on drug metabolism by fungi colonizing decomposing human cadavers. Part II: biotransformation of five model drugs by fungi isolated from post-mortem material.
abstract: The present study investigated the in vitro metabolic capacity of 28 fungal strains isolated from post-mortem material towards five model drugs: amitriptyline, metoprolol, mirtazapine, promethazine, and zolpidem. Each fungal strain was incubated at 25 °C for up to 120 h with each of the five models drugs. Cunninghamella elegans was used as positive control. Aliquots of the incubation mixture were centrifuged and 50 μL of the supernatants were diluted and directly analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with product ion scanning. The remaining mixture was analyzed by full scan gas chromatography-mass spectrometry (GC-MS) after liquid-liquid extraction and acetylation. The metabolic activity was evaluated through the total number of detected metabolites (NDM) produced in each model and fungal strains and the percentage of parent drug remaining (%RPD) after up to five days of incubation. All the tested fungal strains were capable of forming mammalian phase I metabolites. Fungi from the normal fungal flora of the human body such as Candida sp., Geotrichum candidum, and Trichosporon asahii) formed up to seven metabolites at %RPD values greater than 52% but no new fungal metabolites (NFM). In contrast, some airborne fungal strains like Bjerkandera adusta, Chaetomium sp, Coriolopsis sp., Fusarium solani and Mucor plumbeus showed NDM values exceeding those of the positive control, complete metabolism of the parent drug in some models and formation of NFM. NFM (numbers in brackets) were detected in four of the five model drugs: amitriptyline (18), metoprolol (4), mirtazapine (8), and zolpidem (2). The latter NFM are potential candidates for marker substances indicating post-mortem fungal metabolism.
authors.affiliation: Institute of Forensic Medicine, Jena University Hospital, Fürstengraben 23, D-07743, Jena, Germany; Department of Pharmacy, National University, A.A. 14490, Bogotá D.C., Colombia.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Martínez-Ramírez
authors.forename: Grit
authors.initials: G
authors.lastname: Walther
authors.forename: Frank T
authors.initials: FT
authors.lastname: Peters
mesh_terms: D000639:Amitriptyline / Q000378:metabolism*; D001711:Biotransformation; D002102:Cadaver; D005658:Fungi / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D008790:Metoprolol / Q000378:metabolism*; D008803:Mianserin / Q000031:analogs & derivatives* / Q000378:metabolism; D000078785:Mirtazapine; D011398:Promethazine / Q000378:metabolism*; D011725:Pyridines / Q000378:metabolism*; D000077334:Zolpidem
chemical_list: D011725:Pyridines; D000639:Amitriptyline; D008803:Mianserin; D000077334:Zolpidem; D000078785:Mirtazapine; D011398:Promethazine; D008790:Metoprolol
keywords: GC-MS; LC-ESI-MS/MS; drug metabolism; fungi; post-mortem material