Structure elucidation of the designer drug N -(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-(5-fluoropentyl)-3-(4-fluorophenyl)-pyrazole-5-carboxamide and the relevance of predicted 13 C NMR shifts - a case study

In vitro characterization of the pyrazole-carrying synthetic cannabinoid receptor agonist 5F-3,5-AB-PFUPPYCA and its structural analogs

The synthetic cannabinoid receptor agonist (SCRA) market is undergoing important changes since the enactment of the 2021 class-wide generic SCRA ban in China, one of the most important source countries for new psychoactive substances (NPS). Recently, various compounds with new structural features, synthesized to bypass this legislation, have entered the recreational drug market. Certain monocyclic pyrazole-carrying "FUPPYCA" SCRAs have been sporadically detected since 2015 without gaining further popularity. However, as evidenced by their recent detection in Scottish prisons, 5F-3,5-AB-PFUPPYCA and 3,5-ADB-4en-PFUPPYCA have re-emerged, potentially triggered by the new legislative ban. The aim of this study was to characterize the in vitro intrinsic CB₁ and CB₂ receptor activation potential of 5F-3,5-AB-PFUPPYCA and 3,5-ADB-4en-PFUPPYCA, as well as 4 analogs (5F-3,5-ADB-PFUPPYCA, 3,5-AB-CHMFUPPYCA, 5,3-AB-CHMFUPPYCA and 5,3-ADB-4en-PFUPPYCA) using live cell β-arrestin 2 recruitment assays. Most analogs were essentially inactive at either CB₁ or CB₂, with only 3,5-AB-CHMFUPPYCA, 5,3-AB-CHMFUPPYCA and 5,3-ADB-4en-PFUPPYCA showing a limited activation potential at CB₁. Furthermore, the importance of the position of the tail structure was demonstrated, with 5,3 regioisomers being more active than their 3,5 analogs. Moreover, all compounds exhibited antagonistic behavior at both receptors, which may be associated with their structural resemblance to cannabinoid antagonists and inverse agonists. Although the 3,5 regioisomers of these "FUPPYCA" SCRAs circumvent the Chinese ban, it is unlikely that these SCRAs will pose a major threat to public health, given the lack of pronounced CB receptor activity.

Modern approaches to the development of synthetic cannabinoid receptor probes

The endocannabinoid system, which spans the central and peripheral nervous systems and regulates many biologic processes, is an important target for probe discovery and medications development. Whereas the earliest endocannabinoid receptor probes were derivatives of the non-selective phytocannabinoids isolated from Cannabis species, modern drug discovery techniques have expanded the definitions of what constitutes a CB1R or CB2R cannabinoid receptor ligand. This review highlights recent advances in synthetic cannabinoid receptor chemistry and pharmacology. We provide examples of new CB1R- and CB2R-selective probes, and discuss rational approaches to the design of peripherally-restricted agents. We also describe structural classes of positive- and negative allosteric modulators (PAMs and NAMs) of CB1R and CB2R. Finally, we introduce new opportunities for cannabinoid receptor probe development that have emerged in recent years, including biased agonists that may lead to medications lacking adverse effects.

Synthetic cannabinoid receptor agonists: Analytical profiles and development of QMPSB, QMMSB, QMPCB, 2F-QMPSB, QMiPSB, and SGT-233

A diverse assortment of molecules designed to explore the cannabinoid receptor system and considered new psychoactive substances (NPS) have become known as synthetic cannabinoid receptor agonists (SCRAs). One group of SCRAs that has received little attention involves those exhibiting sulfamoyl benzoate, sulfamoyl benzamide, and N-benzoylpiperidine based structures. In this study, quinolin-8-yl 4-methyl-3-(piperidine-1-sulfonyl)benzoate (QMPSB), quinolin-8-yl 4-methyl-3-(morpholine-4-sulfonyl)benzoate (QMMSB), quinolin-8-yl 4-methyl-3-(piperidine-1-carbonyl)benzoate (QMPCB, SGT-11), quinolin-8-yl 3-(4,4-difluoropiperidine-1-sulfonyl)-4-methylbenzoate (2F-QMPSB, QMDFPSB, SGT-13), quinolin-8-yl 4-methyl-3-[(propan-2-yl)sulfamoyl]benzoate (QMiPSB, SGT-46), and 3-(4,4-difluoropiperidine-1-sulfonyl)-4-methyl-N-(2-phenylpropan-2-yl)benzamide (SGT-233) were extensively characterized (including data on impurities). The analytical profiles may be useful to researchers and scientists who deal with the emergence of NPS during forensic and clinical investigations. The detection of QMPSB was first published in 2016 but it is worth noting that Stargate International, a company originally formed to develop harm reduction solutions, were involved in the investigation and development of these six compounds for potential release between 2011 and early 2014. Whilst information on the prevalence of use of these particular compounds at the present time is limited, one of the key outcomes of the research performed by Stargate International reviewed here was to set the stage for the quinolin-8-yl ester head group that ultimately led to hybridization with an N-alkyl-1H-indole core to give SGT-21 and SGT-32, which became later known as PB-22 (QMPSB/JWH-018 hybrid) and BB-22, respectively, thus, opening the door to a range of SCRAs carrying the quinolin-8-yl head group from about 2012 onwards.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

The Chemistry and Pharmacology of Synthetic Cannabinoid Receptor Agonist New Psychoactive Substances: Evolution

Synthetic cannabinoid receptor agonists (SCRAs) are the largest and most structurally diverse class of new psychoactive substances (NPS). Although the earliest SCRA NPS were simply repurposed from historical academic manuscripts or pharmaceutical patents describing cannabinoid ligands, recent examples bear hallmarks of rational design. SCRA NPS manufacturers have applied traditional medicinal chemistry strategies (such as molecular hybridization, bioisosteric replacement, and scaffold hopping) to existing cannabinoid templates in order to generate new molecules that circumvent structure-based legislation. Most SCRAs potently activate cannabinoid type 1 and type 2 receptors (CB₁ and CB₂, respectively), with the former contributing to the psychoactivity of these substances. SCRAs are generally more toxic than the Δ⁹-tetrahydrocannabinol (Δ⁹-THC) found in cannabis, and this may be due to ligand bias, metabolism, or off-target activity. This chapter will chart the evolution of recently identified SCRA NPS chemotypes, as well as their putative manufacturing by-products and thermolytic degradants, and describe structure-activity relationships within each class.

The 2-alkyl-2H-indazole regioisomers of synthetic cannabinoids AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA are possible manufacturing impurities with cannabimimetic activities

Indazole-derived synthetic cannabinoids (SCs) featuring an alkyl substituent at the 1-position and l-valinamide at the 3-carboxamide position (e.g., AB-CHMINACA) have been identified by forensic chemists around the world, and are associated with serious adverse health effects. Regioisomerism is possible for indazole SCs, with the 2-alkyl-2H-indazole regioisomer of AB-CHMINACA recently identified in SC products in Japan. It is unknown whether this regiosiomer represents a manufacturing impurity arising as a synthetic byproduct, or was intentionally synthesized as a cannabimimetic agent. This study reports the synthesis, analytical characterization, and pharmacological evaluation of commonly encountered indazole SCs AB-CHMINACA, AB-FUBINACA, AB-PINACA, 5F-AB-PINACA and their corresponding 2-alkyl-2H-indazole regioisomers. Both regioisomers of each SC were prepared from a common precursor, and the physical properties, ¹H and ¹³C nuclear magnetic resonance spectroscopy, gas chromatography-mass spectrometry, and ultraviolet-visible spectroscopy of all SC compounds are described. Additionally, AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA were found to act as high potency agonists at CB₁ (EC₅₀ = 2.1-11.6 nM) and CB₂ (EC₅₀ = 5.6-21.1 nM) receptors in fluorometric assays, while the corresponding 2-alkyl-2H-indazole regioisomers demonstrated low potency (micromolar) agonist activities at both receptors. Taken together, these data suggest that 2-alkyl-2H-indazole regioisomers of AB-CHMINACA, AB-FUBINACA, AB-PINACA, and 5F-AB-PINACA are likely to be encountered by forensic chemists and toxicologists as the result of improper purification during the clandestine synthesis of 1-alkyl-1H-indazole regioisomers, and can be distinguished by differences in gas chromatography-mass spectrometry fragmentation pattern.

In vitro metabolism of the synthetic cannabinoid 3,5-AB-CHMFUPPYCA and its 5,3-regioisomer and investigation of their thermal stability

Recently, the pyrazole-containing synthetic cannabinoid N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-(cyclohexylmethyl)-3-(4-fluorophenyl)-1H-pyrazole-5-carboxamide (3,5-AB-CHMFUPPYCA) has been identified as a 'research chemical' both in powdered form and as an adulterant present in herbal preparations. Urine is the most common matrix used for abstinence control and the extensive metabolism of synthetic cannabinoids requires implementation of targeted analysis. The present study describes the investigation of the in vitro phase I metabolism of 3,5-AB-CHMFUPPYCA and its regioisomer 5,3-AB-CHMFUPPYCA using pooled human liver microsomes. Metabolic patterns of both AB-CHMFUPPYCA isomers were qualitatively similar and dominated by oxidation of the cyclohexylmethyl side chain. Biotransformation to monohydroxylated metabolites of high abundance confirmed that these species might serve as suitable targets for urine analysis. Furthermore, since synthetic cannabinoids are commonly administered by smoking and because some metabolites can also be formed as thermolytic artefacts, the stability of both isomers was assessed under smoking conditions. Under these conditions, pyrolytic cleavage of the amide bond occurred that led to approximately 3 % conversion to heat-induced degradation products that were also detected during metabolism. These artefactual 'metabolites' could potentially bias in vivo metabolic profiles after smoking and might have to be considered for interpretation of metabolite findings during hair analysis. This might be relevant to the analysis of hair samples where detection of metabolites is generally accepted as a strong indication of drug use rather than a potential external contamination. Copyright © 2016 John Wiley & Sons, Ltd.