Investigating the ability of the microbial model Cunninghamella elegans for the metabolism of synthetic tryptamines

Fungal-Mediated Biotransformation of the Plant Growth Regulator Forchlorfenuron by Cunninghamella elegans

The synthetic cytokinin forchlorfenuron (FCF), while seemingly presenting relatively low toxicity for mammalian organisms, has been the subject of renewed scrutiny in the past few years due to its increasing use in fruit crops and potential for bioaccumulation. Despite many toxicological properties of FCF being known, little research has been conducted on the toxicological effects of its secondary metabolites. Given this critical gap in the existing literature, understanding the formation of relevant FCF secondary metabolites and their association with mammalian metabolism is essential. To investigate the formation of FCF metabolites in sufficient quantities for toxicological studies, a panel of four fungi were screened for their ability to catalyze the biotransformation of FCF. Of the organisms screened, Cunninghamella elegans (ATCC 9245), a filamentous fungus, was found to convert FCF to 4-hydroxyphenyl-forchlorfenuron, the major FCF secondary metabolite identified in mammals, after 26 days. Following the optimization of biotransformation conditions using a solid support system, media screening, and inoculation with a solid pre-formed fungal mass of C. elegans, this conversion time was significantly reduced to 7 days-representing a 73% reduction in total reaction time as deduced from the biotransformation products and confirmed by LC-MS, NMR spectroscopic data, as well as a comparison with synthetically prepared metabolites. Our study provides the first report of the metabolism of FCF by C. elegans. These findings suggest that C. elegans can produce FCF secondary metabolites consistent with those produced via mammalian metabolism and could be used as a more efficient, cost-effective, and ethical alternative for producing those metabolites in useful quantities for toxicological studies.

The role of microorganisms in the biotransformation of psychoactive substances and its forensic relevance: a critical interdisciplinary review

Microorganisms are widespread on the planet being able to adapt, persist, and grow in diverse environments, either rich in nutrient sources or under harsh conditions. The comprehension of the interaction between microorganisms and drugs is relevant for forensic toxicology and forensic chemistry, elucidating potential pathways of microbial metabolism and their implications. Considering the described scenario, this paper aims to provide a comprehensive and critical review of the state of the art of interactions amongst microorganisms and common drugs of abuse. Additionally, other drugs of forensic interest are briefly discussed. This paper outlines the importance of this area of investigation, covering the intersections between forensic microbiology, forensic chemistry, and forensic toxicology applied to drugs of abuse, and it also highlights research potentialities.

Key points

Microorganisms are widespread on the planet and grow in a myriad of environments.Microorganisms can often be found in matrices of forensic interest.Drugs can be metabolized or produced (e.g. ethanol) by microorganisms.

An O-Demethylation Metabolite of Rabeprazole Sulfide by Cunninghamella blakesleeana 3.970 Biotransformation

To explore the potential metabolites from rabeprazole sulfide, seven strains of filamentous fungi were screened for their biotransformation abilities. Among these strains, Cunninghamella blakesleeana 3.970 exhibited the best result. Four different culture media were screened in order to identify the most optimal for subsequent research. Single factors such as the initial pH of culture media, culture time, inoculation volume, and media volume were individually investigated to provide the optimum biotransformation conditions. Then, an orthogonal optimization process using a five-factor, four-level L16(45) experiment was designed and performed. Finally, when the substrate concentration is 3 g/L, one major metabolite was detected with a transformation rate of 72.4%. Isolated by semipreparative HPLC, this metabolite was further detected by ESI-MS and NMR. The final data analysis indicated that the metabolite is O-demethylation rabeprazole sulfide.

Biomedical Research on Substances of Abuse: The Italian Case Study

Substances of abuse have the potential to cause addiction, habituation or altered consciousness. Most of the research on these substances focuses on addiction, and is carried out through observational and clinical studies on humans, or experimental studies on animals. The transposition of the EU Directive 2010/63 into Italian law in 2014 (IT Law 2014/26) includes a ban on the use of animals for research on substances of abuse. Since then, in Italy, public debate has continued on the topic, while the application of the Article prohibiting animal research in this area has been postponed every couple of years. In the light of this debate, we briefly review a range of methodologies - including animal and non-animal, as well as patient or population-based studies - that have been employed to address the biochemical, neurobiological, toxicological, clinical and behavioural effects of substances of abuse and their dependency. We then discuss the implications of the Italian ban on the use of animals for such research, proposing concrete and evidence-based solutions to allow scientists to pursue high-quality basic and translational studies within the boundaries of the regulatory and legislative framework.

Systematic characterization of metabolic profiles of ingenol in rats by UPLC-Q/TOF-MS and NMR in combination with microbial biotransformation

Ingenol, as the precursor of the marketed drug ingenol mebutate, has been proven to have a variety of bioactivities. The purpose of this study was to identify the metabolites of ingenol using ultra-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-Q/TOF-MS) combined with UNIFI software. Plasma, urine and fecal samples of rats were obtained and analyzed. A total of 18 metabolites were detected and identified in rat, including five phase II metabolites (M14-M18). Moreover, as microbial biotransformation is helpful to obtain sufficient reference standards of metabolites, the co-culture of ingenol with the fungus Cunninghamella elegans bio-110930 was also studied and yielded 4 phase I metabolites, in which reference standards of three metabolites were further obtained by preparative scale biotransformation. By matching their retention times, accurate masses, and fragment ions with metabolites in rat, the structures of three metabolites (M2, M3 and M4) were unambiguously confirmed by NMR technology. The results revealed that C. elegans bio-110930 functioned as an appropriate model to mimic and prepare phase I metabolism of ingenol in vivo to a certain extent. It also revealed that hydroxylation, oxygenation, sulfonation, and glucuronidation were the major metabolic pathways of ingenol. Furthermore, the first systematic metabolic study of ingenol is of great significance to elucidate the metabolites and metabolic pathways in vivo, which is helpful to predict metabolites of ingenol in humans, understand the elimination mechanism of ingenol, and clarify its effectiveness and toxicity.

Can the Intake of a Synthetic Tryptamine be Detected Only by Blood Plasma Analysis? A Clinical Toxicology Case Involving 4-HO-MET

Tryptamines represent a group of hallucinogenic new psychoactive substances with increasing prevalence. Unfortunately, only limited data concerning their toxicology and bioanalysis is available as tryptamines are not included in routine screening procedures in many laboratories. In order to expand the current knowledge, we report a non-fatal clinical toxicology case involving the synthetic tryptamine 4-HO-MET (4-hydroxy-N-methyl-N-ethyl-tryptamine, 3-{2-[ethyl(methyl)amino]ethyl}-1H-indol-4-ol, metocin, or methylcybin). Only blood was available and our systematic blood plasma screening approaches based on gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC) coupled to low-resolution linear ion trap mass spectrometry (ITMSn) or high-resolution tandem mass spectrometry (HRMS/MS) were conducted. The ingestion of the synthetic tryptamine 4-HO-MET could be revealed by blood plasma analysis using both LC-based systematic screening approaches, but not using GC-MS. Furthermore, the detection of metabolites, which may be used to confirm an intake of the parent compound 4-HO-MET, was only successful using LC-HRMS/MS most probably due to its increased sensitivity compared to LC-ITMSn. A total of four metabolites were detected in blood including N-demethyl-, oxo-, and hydroxy-4-HO-MET, as well as the N-oxide. Finally, LC-HRMS/MS analysis revealed a plasma concentration of 193 ng/mL for 4-HO-MET using the standard addition method. The presented data may help clinical and forensic toxicologists with the interpretation of future cases involving synthetic tryptamines, especially if only blood samples are available.

Recent trends in drugs of abuse metabolism studies for mass spectrometry-based analytical screening procedures

The still increasing number of drugs of abuse, particularly the so-called new psychoactive substances (NPS), poses an analytical challenge for clinical and forensic toxicologists but also for doping control. NPS usually belong to various classes such as synthetic cannabinoids, phenethylamines, opioids, or benzodiazepines. Like other xenobiotics, NPS undergo absorption, distribution, metabolism, and excretion processes after consumption, but only very limited data concerning their toxicokinetics and safety properties is available once they appear on the market. The inclusion of metabolites in mass spectral libraries is often crucial for the detection of NPS especially in urine screening approaches. Authentic human samples may represent the gold standard for identification of metabolites but are often not available and clinical studies cannot be performed due to ethical concerns. However, numerous alternative in vitro and in vivo models are available. This trends article will give an overview on selected models, discuss current studies, and highlight recent developments.

Untargeted Metabolic Profiling of 4-Fluoro-Furanylfentanyl and Isobutyrylfentanyl in Mouse Hepatocytes and Urine by Means of LC-HRMS

The diffusion of new psychoactive substances (NPS) is highly dynamic and the available substances change over time, resulting in forensic laboratories becoming highly engaged in NPS control. In order to manage NPS diffusion, efficient and innovative legal responses have been provided by several nations. Metabolic profiling is also part of the analytical fight against NPS, since it allows us to identify the biomarkers of drug intake which are needed for the development of suitable analytical methods in biological samples. We have recently reported the characterization of two new analogs of fentanyl, i.e., 4-fluoro-furanylfentanyl (4F-FUF) and isobutyrylfentanyl (iBF), which were found for the first time in Italy in 2019; 4F-FUF was identified for the first time in Europe and was notified to the European Early Warning System. The goal of this study was the characterization of the main metabolites of both drugs by in vitro and in vivo experiments. To this end, incubation with mouse hepatocytes and intraperitoneal administration to mice were carried out. Samples were analyzed by means of liquid chromatography-high resolution mass spectrometry (LC-HRMS), followed by untargeted data evaluation using Compound Discoverer software with a specific workflow, designed for the identification of the whole metabolic pattern, including unexpected metabolites. Twenty metabolites were putatively annotated for 4-FFUF, with the dihydrodiol derivative appearing as the most abundant, whereas 22 metabolites were found for iBF, which was mainly excreted as nor-isobutyrylfentanyl. N-dealkylation of 4-FFUF dihydrodiol and oxidation to carbonyl metabolites for iBF were also major biotransformations. Despite some differences, in general there was a good agreement between in vitro and in vivo samples.

Monitoring metabolism of synthetic cannabinoid 4F-MDMB-BINACA via high-resolution mass spectrometry assessed in cultured hepatoma cell line, fungus, liver microsomes and confirmed using urine samples

Purpose

A tert-leucinate derivative synthetic cannabinoid, methyl (2S)-2-([1-(4-fluorobutyl)-1H-indazole-3-carbonyl]amino)-3,3-dimethylbutanoate (4F-MDMB-BINACA, 4F-MDMB-BUTINACA or 4F-ADB) is known to adversely impact health. This study aimed to evaluate the suitability of three different modes of monitoring metabolism: HepG2 liver cells, fungus Cunninghamella elegans (C. elegans) and pooled human liver microsomes (HLM) for comparison with human in-vivo metabolism in identifying suitable urinary marker(s) for 4F-MDMB-BINACA intake.

Methods

Tentative structure elucidation of in-vitro metabolites was performed on HepG2, C. elegans and HLM using liquid chromatography–tandem mass spectrometry and high-resolution mass spectrometry analysis. In-vivo metabolites obtained from twenty authentic human urine samples were analysed using liquid chromatography–Orbitrap mass spectrometry.

Results

Incubation with HepG2, C. elegans and HLM yielded nine, twenty-three and seventeen metabolites of 4F-MDMB-BINACA, respectively, formed via ester hydrolysis, hydroxylation, carboxylation, dehydrogenation, oxidative defluorination, carbonylation or reaction combinations. Phase II metabolites of glucosidation and sulfation were also exclusively identified using C. elegans model. Eight in-vivo metabolites tentatively identified were mainly products of ester hydrolysis with or without additional dehydrogenation, N-dealkylation, monohydroxylation and oxidative defluorination with further oxidation to butanoic acid. Metabolites with intact terminal methyl ester moiety, i.e., oxidative defluorination with further oxidation to butanoic acid, were also tentatively identified.

Conclusions

The in-vitro models presented proved useful in the exhaustive metabolism studies. Despite limitations, HepG2 identified the major 4F-MDMB-BINACA ester hydrolysis metabolite, and C. elegans demonstrated the capacity to produce a wide variety of metabolites. Both C. elegans and HLM produced all the in-vivo metabolites. Ester hydrolysis and ester hydrolysis plus dehydrogenation 4F-MDMB-BINACA metabolites were recommended as urinary markers for 4F-MDMB-BINACA intake.

Metabolism of synthetic cathinones through the zebrafish water tank model: a promising tool for forensic toxicology laboratories

Purpose

The aim of this study was to identify in vivo phase I metabolites of five psychoactive substances: N-ethylpentylone, ethylone, methylone, α-PVP and 4-CDC, using the in house developed experimental set-up zebrafish (Danio rerio) water tank (ZWT). High-resolution mass spectrometry allowed for metabolite identification. A pilot study of reference standard collection of N-ethylpentylone from the water tank was conducted.

Methods

ZWT consisted in 8 fish placed in a 200 mL recipient-containing water for a single cathinone. Experiments were performed in triplicate. Water tank samples were collected after 8 h and pretreated through solid-phase extraction. Separation and accurate-mass spectra of metabolites were obtained using liquid chromatography–high resolution tandem mass spectrometry.

Results

Phase I metabolites of α-PVP were identified, which were formed involving ketone reduction, hydroxylation, and 2″-oxo-pyrrolidine formation. The lactam derivative was the major metabolite observed for α-PVP in ZWT. N-Ethylpentylone and ethylone were transformed into phase I metabolites involving reduction, hydroxylation, and dealkylation. 4-CDC was transformed into phase I metabolites, reported for the first time, involving N-dealkylation, N,N-bis-dealkylation and reduction of the ketone group, the last one being the most intense after 8 h of the experiment.

Conclusions

ZWT model indicated to be very useful to study the metabolism of the synthetic cathinones, such as N-ethylpentylone, ethylone, α-PVP and 4-CDC. Methylone seems to be a potent CYP450 inhibitor in zebrafish. More experiments are needed to better evaluate this issue. Finally, this approach was quite simple, straightforward, extremely low cost, and fast for “human-like” metabolic studies of synthetic cathinones.