Structure-Activity Relationship Study of Psychostimulant Synthetic Cathinones Reveals Nanomolar Antagonist Potency of α-Pyrrolidinohexiophenone at Human Muscarinic M2 Receptors

Low-triggering-potential electrochemiluminescence based on mental-organic frameworks encapsulation of ruthenium for synthetic cathinone detection by coupling photonic crystal light-scattering signal amplification of covalent-organic frameworks

Developing effective electrochemiluminescence (ECL) platforms is always an essential concern in highly sensitive bioanalysis. In this work, a low-triggering-potential ECL sensor was designed for detecting synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV) based on a dual-signal amplification strategy. Initially, a probe was created by integrating Ruthenium into the hollow porphyrin-based MOF (PCN-222) structure to decrease the excitation potential and enhance ECL performance without external co-reaction accelerators. Additionally, for the first time, photonic crystals (PCs) assembled from covalent organic frameworks (COFs) were employed to amplify the ECL signal, thereby increasing the photon flux and the loading capacity of the ECL emitter to enhance sensitivity of the sensor. In the presence of the target MDPV, the aptamer labeled with Ferrocene (Fc) experienced conformational changes, causing Fc to approach the luminophore and resulting in ECL quenching. This effect was attributed to aptamer's conformational changes induced by the target, directly correlating with the target concentration. The constructed sensor showed good linearity with the target MDPV concentration, covering a dynamic range from 1.0 × 10-14 to 1.0 × 10-6 g/L and achieved an ultra-low detection limit of 4.79 × 10-15 g/L. This work employed dual amplification strategies to enhance ECL signals effectively, providing a novel method for developing highly responsive and bioactive sensors.

Toxicological Investigation of a Case Series Involving the Synthetic Cathinone α-Pyrrolidinohexiophenone (α-PHP) and Identification of Phase I and II Metabolites in Human Urine

α-Pyrrolidinohexiophenone (α-PHP) is a derivative of the class of α-pyrrolidinophenones, a subgroup of synthetic cathinones. These substances are the second most abused drugs of new psychoactive substances. Here, we report the toxicological investigation of a series of 29 authentic forensic and clinical cases with analytically confirmed intake of α-PHP including two cases of drug testing in newborns using meconium. The age range of subjects where serum samples were available was 23-51 years (median 39.5), and 90% were male. Serum α-PHP concentrations, determined by a validated LC-MS-MS method, showed a high variability ranging from 1 to 83 ng/mL (mean, 40 ng/mL; median, 36 ng/mL). Comprehensive toxicological analysis revealed co-consumption of other psychotropic drugs in almost all cases with frequent occurrence of opiates (60%), benzodiazepines (35%), cannabinoids (30%), and cocaine (20%). Hence, forensic and clinical symptoms like aggressive behavior, sweating, delayed physical response, and impaired balance could not be explained by the abuse of α-PHP alone but rather by poly-intoxications. Liquid chromatography-quadrupole time-of-flight mass spectrometry and gas chromatography-mass spectrometry were used to investigate the metabolism of α-PHP in vivo using authentic human urine samples. Altogether, 11 phase I metabolites and 5 phase II glucuronides could be identified by this approach. Apart from the parent drug, most abundant findings in urine were the metabolites dihydroxy-pyrrolidinyl-α-PHP and dihydro-α-PHP and, to a lesser extent, 2'-oxo-dihydro-α-PHP and 2'-oxo-α-PHP. Monitoring of these metabolites along with the parent drug in forensic and clinical toxicology could unambiguously prove the abuse of the novel designer drug α-PHP.

Dual-binding domain electrochemiluminescence biosensing platform with self-checking function for sensitive detection of synthetic cathinone in e-cigarettes

Current single signal electrochemiluminescence (ECL) sensors are susceptible to false positive or false negative phenomena due to experimental conditions. Therefore, sensors with "self-checking" function are attracting democratic attention. In quick succession, a highly sensitive single-cathode dual ECL signal aptasensor with self-checking function to improve the shortcomings mentioned above was designed. This aptasensor used In-based metal-organic framework (MIL-68) as load and stabilizer to effectively attenuate the aggregation-induced quenching (ACQ) effect of porphyrin derivatives (Sn-TCPP) while improve ECL stability. The introduction of cooperative-binding split-aptamers" (CBSAs) aptamers increased the specificity of the aptasensor and its unique double-binding domains detection accelerated the detection efficiency. When analyzing 3,4-methylenedioxypyrovalerone (MDPV), we could calculate two concentrations based on the strength of ECL 1 and ECL 2. If the concentrations are the same, the result would be obtained; if not, it should be retested. Depending on the above operation, the results achieve self-check. It was found that the designed aptasensor could quantify the concentration of MDPV between 1.0 × 10^-12 g/L and 1.0 × 10^-6 g/L with the limit of detection (LOD) of 1.4 × 10^-13 g/L and 2.0 × 10^-13 g/L, respectively (3 σ/slope). This study not only improves the detection technology of MDPV, but also explores the dual-signal detection of porphyrin for the first time and enriches the definition of self-checking sensor.

A narrative review of the neuropharmacology of synthetic cathinones-Popular alternatives to classical drugs of abuse

OBJECTIVE

To review the literature on the neuropharmacology of synthetic cathinones.

METHODS

A comprehensive literature search was carried out across multiple databases (mainly PubMed, World Wide Web, and Google Scholar) using relevant keywords.

RESULTS

Cathinones exhibit a broad toxicological profile, mimicking the effects of a wide variety of 'classic drugs' such as 3,4-methylenedioxymethamphetamine (MDMA), methamphetamine and cocaine. Even small structural changes affect their interactions with key proteins. This article reviews existing knowledge of the mechanisms of action of cathinones at the molecular level, and key findings from research on their structure-activity relationship. The cathinones are also classified according to their chemical structure and neuropharmacological profiles.

CONCLUSIONS

Synthetic cathinones represent one of the most numerous and widespread groups among new psychoactive substances. Initially developed for therapeutic purposes, they quickly started to be used recreationally. With a rapidly increasing number of new agents entering the market, structure-activity relationship studies are valuable for assessing and predicting the addictive potential and toxicity of new and potential future substances. The neuropharmacological properties of synthetic cathinones are still not fully understood. A full elucidation of the role of some key proteins, including organic cation transporters, requires detailed studies.

A new synthetic cathinone: 3,4-EtPV or 3,4-Pr-PipVP? An unsuccessful attempt to circumvent the German legislation on new psychoactive substances

Synthetic cathinones comprise psychostimulants with desired effects like euphoria, increased vigilance, appetite suppression, and-mainly depending on certain structural features-entactogenic properties. 3,4-EtPV (1-(bicyclo[4.2.0]octa-1,3,5-trien-3-yl)-2-(pyrrolidin-1-yl)pentan-1-one) was first mentioned in an online drug forum in September 2021, where its imminent synthesis was announced. The goal was to produce a legal alternative to the phenylethylamines already banned by the German NpSG. In February and June 2022, two samples labeled with the name and molecular structure of 3,4-EtPV were analyzed. The molecular structure of the obviously mislabeled compound was elucidated and comprehensively characterized within the ADEBAR project. The synthetic cathinone identified differed from the declared 3,4-EtPV by a 3,4-propylene bridge instead of a 3,4-ethylene bridge and a piperidine ring instead of a pyrrolidine ring. The short name 3,4-Pr-PipVP (3,4-propylene-2-(1-piperidinyl)valerophenone) was suggested as a semisystematic name in collaboration with the European Monitoring Centre for Drugs and Drug Addiction. Herein, the results of the analyses are discussed and will enable forensic laboratories to update their databases quickly and identify 3,4-Pr-PipVP confidently. 3,4-Pr-PipVP is already scheduled under the German NpSG. This study highlights that there are ongoing efforts to deliberately circumvent generic definitions given, for example, in the German NpSG and that (unintentional?) mislabeling can be an issue. The end user purchasing substances online can never be sure that the material actually supplied will be the one ordered, and he might receive an illicit drug instead of an uncontrolled one. Furthermore, the purity is always unknown, creating health risks due to unexpected effects and potencies.

Prenatal cyanuric acid exposure induced spatial learning impairments associated with alteration of acetylcholine-mediated neural information flow at the hippocampal CA3-CA1 synapses of male rats

Cyanuric acid (CA) is reported to induce nephrotoxicity but its toxic effect is not fully known. Prenatal CA exposure causes neurodevelopmental deficits and abnormal behavior in spatial learning ability. Dysfunction of the acetyl-cholinergic system in neural information processing is correlated with spatial learning impairment and was found in the previous reports of CA structural analogue melamine. To further investigate the neurotoxic effects and the potential mechanism, the acetylcholine (ACh) level was detected in the rats which were exposed to CA during the whole of gestation. Local field potentials (LFPs) were recorded when rats infused with ACh or cholinergic receptor agonist into hippocampal CA3 or CA1 region were trained in the Y-maze task. We found the expression of ACh in the hippocampus was significantly reduced in dose-dependent manners. Intra-hippocampal infusion of ACh into the CA1 but not the CA3 region could effectively mitigate learning deficits induced by CA exposure. However, activation of cholinergic receptors did not rescue the learning impairments. In the LFP recording, we found that the hippocampal ACh infusions could enhance the values of phase synchronization between CA3 and CA1 regions in theta and alpha oscillations. Meanwhile, the reduction in the coupling directional index and the strength of CA3 driving CA1 in the CA-treated groups was also reversed by the ACh infusions. Our findings are consistent with the hypothesis and provide the first evidence that prenatal CA exposure induced spatial learning defect is attributed to the weakened ACh-mediated neuronal coupling and NIF in the CA3-CA1 pathway.

A review of synthetic cathinones emerging in recent years (2019-2022)

Purpose

The emergence of novel psychoactive substances (NPS) has been being a continuous and evolving problem for more than a decade. Every year, dozens of new, previously unknown drugs appear on the illegal market, posing a significant threat to the health and lives of their users. Synthetic cathinones are one of the most numerous and widespread groups among NPS. The purpose of this work was to identify and summarize available data on newly emerging cathinones in very recent years.

Methods

Various online databases such as PubMed, Google Scholar, but also databases of government agencies including those involved in early warning systems, were used in search of reports on the identification of newly emerging synthetic cathinones. In addition, threads on various forums created by users of these drugs were searched for reports on the effects of these new substances.

Results

We have identified 29 synthetic cathinones that have been detected for the first time from early 2019 to mid-2022. We described their structures, known intoxication symptoms, detected concentrations in biological material in poisoning cases, as well as the countries and dates of their first appearance. Due to the lack of studies on the properties of the novel compounds, we compared data on the pharmacological profiles of the better-known synthetic cathinones with available information on the newly emerged ones. Some of these new agents already posed a threat, as the first cases of poisonings, including fatal ones, have been reported.

Conclusions

Most of the newly developed synthetic cathinones can be seen as analogs and replacements for once-popular compounds that have been declining in popularity as a result of legislative efforts. Although it appears that some of the newly emerging cathinones are not widely used, they may become more popular in the future and could become a significant threat to health and life. Therefore, it is important to continue developing early warning systems and identifying new compounds so that their widespread can be prevented.

Activity of Mitragyna speciosa ("Kratom") Alkaloids at Serotonin Receptors

Kratom alkaloids have mostly been evaluated for their opioid activity but less at other targets that could contribute to their physiological effects. Here, we investigated the in vitro and in vivo activity of kratom alkaloids at serotonin receptors (5-HTRs). Paynantheine and speciogynine exhibited high affinity for 5-HT1ARs and 5-HT2BRs, unlike the principal kratom alkaloid mitragynine. Both alkaloids produced antinociceptive properties in rats via an opioid receptor-independent mechanism, and neither activated 5-HT2BRs in vitro. Paynantheine, speciogynine, and mitragynine induced lower lip retraction and antinociception in rats, effects blocked by a selective 5-HT1AR antagonist. In vitro functional assays revealed that the in vivo 5-HT1AR agonistic effects may be due to the metabolites 9-O-desmethylspeciogynine and 9-O-desmethylpaynantheine and not the parent compounds. Both metabolites did not activate 5-HT2BR, suggesting low inherent risk of causing valvulopathy. The 5-HT1AR agonism by kratom alkaloids may contribute to the mood-enhancing effects associated with kratom use.

Molecular Mechanisms of Action of Novel Psychoactive Substances (NPS). A New Threat for Young Drug Users with Forensic-Toxicological Implications

Novel psychoactive substances (NPS) represent a severe health risk for drug users. Even though the phenomenon has been growing since the early 2000s, the mechanisms of action of NPS at the receptors and beyond them are still scarcely understood. The aim of the present study was to provide a systematic review of the updated knowledge regarding the molecular mechanisms underlying the toxicity of synthetic opioids, cannabinoids, cathinones, and stimulants. The study was conducted on the PubMed database. Study eligibility criteria included relevance to the topic, English language, and time of publication (2010–2020). A combined Mesh and free-text protocols search was performed. Study selection was performed on the title/abstract and, in doubtful cases, on the full texts of papers. Of the 580 records identified through PubMed searching and reference checking, 307 were excluded by title/abstract and 78 additional papers were excluded after full-text reading, leaving a total of 155 included papers. Molecular mechanisms of synthetic opioids, synthetic cannabinoids, stimulants, psychedelics, and hallucinogens were reviewed and mostly involved both a receptor-mediated and non-receptor mediated cellular modulation with multiple neurotransmitters interactions. The molecular mechanisms underlying the action of NPS are more complex than expected, with a wide range of overlap among activated receptors and neurotransmitter systems. The peculiar action profile of single compounds does not necessarily reflect that of the structural class to which they belong, accounting for possible unexpected toxic reactions.