Report on a New Opioid NPS: Chemical and in Vitro Functional Characterization of A

Journal of Analytical Toxicology, 2021;45:134–140 doi: 10.1093/jat/bkaa066 Advance Access Publication Date: 6 June 2020 Article Article Report on a New Opioid NPS: Chemical and In Vitro Functional Characterization of a Structural Isomer of the MT-45 Derivative Downloaded from https://academic.oup.com/jat/article/45/2/134/5854565 by guest on 24 March 2021 Diphenpipenol Annelies Cannaert 1,†, Fabian Hulpia 2,†, Martijn Risseeuw 2, Katleen Van Uytfanghe 1, Eric Deconinck3, Serge Van Calenbergh 2, Peter Blanckaert 4 and Christophe Stove 1,* 1Laboratory of Toxicology, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium, 2Laboratory for Medicinal Chemistry, Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium, 3Section of Medicines and Health Products, Scientific Direction Chemical and Physical Health Risks, Sciensano, Juliette Wytsmanstraat 14, 9050 Brussels, Belgium, and 4Belgian Early Warning System Drugs, Substance Use and Related Disorders, Sciensano, Juliette Wytsmanstraat 14, 9050 Brussels, Belgium *Author to whom correspondence should be addressed. Email: [email protected] †Equally contributed. Abstract In this paper, the identification and full characterization of a novel non-fentanyl opioid sourced online, which is a member of the 1-substituted-4-(1,2-diphenylethyl)piperazine derivatives related to MT-45, is reported. The sample was sold under the name “diphenpipenol,” (3-[2-[4-(2-methoxyphenyl)piperazin-1-yl]-2-phenylethyl]phenol), although extensive NMR analysis showed that the product obtained was actually a diphenpipenol structural isomer, (2-[4-(2- methoxyphenyl)piperazin-1-yl]-1,2-diphenylethanol). Liquid chromatography time-of-flight mass spectrometry identified an exact mass for the protonated molecule of m/z 389.2264, with two prominent fragment ions (m/z 91.0567 and 150.0937), which were not reported in earlier literature describing MT-45 derivatives. The chemical characterization was finalized by gas chromatography– mass spectrometry, high-performance liquid chromatography diode array detector and Fourier- transform infrared spectroscopy analyses. This product is a clear example of the trend that new non-fentanyl opioids are reappearing on the recreational drug market to escape the recent changes in (inter)national legislation concerning fentanyl analogues. Although in this particular case, the product’s potency and efficacy were relatively low, other new non-fentanyl opioids might possess stronger potencies and therefore pose greater health risks for ignorant users. The fact that the product was sold under the wrong name further demonstrates the well-known problematic issue of a mismatch between the adverted and true identity, confirming the irregularities of the online new psychoactive substances market. © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected] 134 New NPS Opioid: Diphenpipenol Isomer 135 Introduction Sample preparation The sample (a white homogenous powder), sold as diphenpipenol, In the last decade, there has been a progressive increase in the number was obtained during routine online monitoring of drug markets, of new psychoactive substances (NPS). These substances comprise performed continuously in the framework of the functioning of the a wide variety of drugs, such as synthetic cannabinoids, stimulants, Belgian Early Warning System Drugs (BEWSD). It was provided in a benzodiazepines and opioids. Synthetic opioids are narcotic anal- clear plastic unmarked ziplock bag, which was sealed in an aluminum gesics, and some of them are widely used in human medicine, but pouch, unmarked as well. It was used, as provided, after short-term they can also lead to abuse and may produce dependence. While storage in the freezer (range minus 20◦C—minus 30◦C) for analysis. currently playing a relatively small role in the NPS market, many new For all the chromatographic analyses and the determination of the opioids are highly potent substances that can pose a serious threat to biological activity, 5.15 mg of the powder was dissolved in 0.5 mL of individual and public health (1, 2). methanol as a stock solution. For NMR analysis, a sample (9.0 mg) From 2009 to 2018, 49 new synthetic opioids have been detected was dissolved in DMSO-d (∼0.75 mL). For the optical rotation on Europe’s drug market (1). The majority (n = 34) of these are 6 analysis, a sample (9.0 mg) was dissolved in 2.0 mL MeOH. fentanyl derivatives. Their popularity can be explained by their relatively simple synthesis in addition to excellent online precursor Downloaded from https://academic.oup.com/jat/article/45/2/134/5854565 by guest on 24 March 2021 availability (3). More recently, the implementation of new national Instrumentation and international legislation has resulted in a shift, away from the Liquid chromatography time-of-flight mass spectrometry, gas fentanyl-type opioids, toward synthetic opioids from the “others” chromatography–mass spectrometry and high-performance category (examples include 2F-viminol, 2-Me-AP-237, isotonitazene, liquid chromatography diode array detector U-47700) (4–6). For liquid chromatography time-of-flight mass spectrometry This paper reports on the identification and full character- (LC–QTOF–MS), chromatographic separation was accomplished ization of a novel non-fentanyl opioid sourced online: 2-[4-(2- with an Agilent 1290 Infinity LC system and a Phenomenex Kinetex methoxyphenyl)piperazin-1-yl]-1,2-diphenylethanol, a structural iso- C18-column (2.6 µm, 3 x 50 mm), maintained at 30◦C. The high- mer of diphenpipenol (3-[2-[4-(2-methoxyphenyl)piperazin-1-yl]-2- resolution mass spectrometry (HRMS) system was a 5600+ QTOF phenylethyl]phenol), an NPS opioid and member of the 1-substituted- from Sciex, with an electrospray ionization (ESI) source and Analyst 4-(1,2-diphenylethyl)piperazine derivatives related to MT-45 TF 1.7.1 software, from the same provider. The LC–HRMS analysis (Figure 1). MT-45 (1-cyclohexyl-4-(1,2-diphenylethyl)piperazine) is was performed using the same settings as those described (5, 15), a synthetic opioid investigated as an analgesic in the 1970s (7–9) obtaining a TOF-MS full scan combined with a data-dependent which has reappeared on the recreational drug market in 2013 (10). acquisition of product ion spectra. For gas chromatography–mass Since 2016, MT-45 is listed in Schedule I of the 1961 Convention (11, spectrometry (GC–MS), one µL of a 1/10 dilution of the stock 12). Interestingly, the product sourced online was wrongly sold under solution was injected on an Agilent 7890A GC system (Agilent HP-5- the name diphenpipenol, which is a structural analogue of MT-45. MS column, 30 m × 0.25 mm i.d. × 0.25 µm) coupled to a 5975 XL While it has been reported that MT-45 has a comparable analgesic mass-selective detector operated by MSD Chemstation software, as potency to morphine in animal models, diphenpipenol showed a has been described (5). For the HPLC–DAD (high-performance liquid much stronger effect (up to 105 times compared to morphine for the chromatography diode array detector), reversed-phase separation most potent S-enantiomer) (7, 13). Extensive NMR analysis showed was performed on a LaChrom HPLC system from Merck-Hitachi that the product obtained was a structural isomer of diphenpipenol (Tokyo, Japan), using a Merck Purospher® Star RP-8 endcapped (the difference lies in the position of the hydroxyl group, Figure 1). column (5 µm, 125 mm x 4.6 mm) fitted with a Merck Purospher® This isomer has up to now only been mentioned once in literature Star RP-8 endcapped guard column (5 µm, 4 mm x 4 mm), as has (14), and no information on the potency of this compound has been been described (5). Detection was done by a diode array detector reported before. (DAD), monitoring a wavelength from 220 to 350 nm with a slit of 1 nm, a spectral bandwidth of 1 nm and a spectral interval of 200 ms, as described before (5). Materials and Methods Materials Fourier-transform infrared spectroscopy analysis All reagents used during the analyses were at least of HPLC Fourier-transform infrared spectroscopy (FT–IR) spectra were grade. For NMR analysis, deuterated dimethyl sulfoxide (DMSO- recorded using a Nicolet iS10 FT–IR spectrometer (Thermo Fisher d6, 99.8%) was purchased from Eurisotop (Saint-Aubin, FR). Scientific, Waltham, USA), equipped with a Smart iTR accessory Hydromorphone was purchased as hydromorphone HCl from and a deuterated triglycine sulphate detector. The infrared spectrum − Fagron (Nazareth, Belgium). Fentanyl was obtained as a free base was subsequently recorded from 4000 to 400 cm 1 with a spectral − from LGC Chemicals (Wesel, Germany). MT-45 was a kind gift resolution of 4 cm 1 and 32 co-added scans. Spectral data were from Prof. Volker Auwärter and was originally purchased from obtained using the OMNIC Software version 8.3 (Thermo Fisher Cayman Chemical Company (Ann Arbor, MI, USA). Dulbecco’s Scientific, Madison, USA) as described before (5). Modified Eagle’s Medium (DMEM; GlutaMAXTM), Opti-MEM® I Reduced Serum Medium, Penicillin-Streptomycin (5.000 U/mL) Nuclear magnetic resonance spectroscopy (NMR) and amphotericin B (250 µg/mL) were purchased from Thermo NMR measurements were performed on a Bruker Avance® Neo Fisher Scientific (Pittsburg, PA, USA). Fetal bovine serum (FBS) (400 MHz) spectrometer, operated at room temperature (25◦C). and poly-d-lysine were supplied by Sigma Aldrich (Overijse, Chemical shifts (δ) are reported in ppm, and spectra are referenced Belgium). The Nano-Glo® Live Cell reagent, which was used for to the residual solvent peak signal. Coupling constants are given in the readout of the bioassay, was procured from Promega (Madison, Hz. Copies of the relevant 1H-, 13C-NMR and 2D NMR spectra are WI, USA). included in the Supplementary Data. 136 Cannaert et al. Figure 1.

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