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The ergoline d-lysergic acid diethylamide (LSD) is one of the most potent psychedelic drugs. 1-Acetyl-LSD (ALD-52), a derivative of LSD containing an acetyl group on the indole nitrogen, also produces psychedelic effects in humans and has about the same potency as LSD. Recently, several other 1-acyl-substitued LSD derivatives, including 1-propanoyl-LSD (1P-LSD) and 1-butanoyl-LSD (1B-LSD), have appeared as designer drugs. Although these compounds are assumed to act as prodrugs for LSD, studies have not specifically tested this prediction. The present investigation was conducted to address the gap of information about the pharmacological effects and mechanism-of-action of 1-acyl-substituted LSD derivatives. Competitive binding studies and calcium mobilization assays were performed to assess the interaction of ALD-52, 1P-LSD, and 1B-LSD with serotonin 5-HT2 receptor subtypes. A receptorome screening was performed with 1B-LSD to assess its binding to other potential targets. Head twitch response (HTR) studies were performed in C57BL/6J mice to assess in vivo activation of 5-HT2A (the receptor thought to be primarily responsible for hallucinogenesis). Finally, liquid chromatography/ion-trap mass spectrometry (LC/MS) was used to quantify plasma levels of LSD in Sprague-Dawley rats treated with ALD-52 and 1P-LSD. 1-Acyl-substitution reduced the affinity of LSD for most monoamine receptors, including 5-HT2A sites, by one to two orders of magnitude. Although LSD acts as an agonist at 5-HT2 subtypes, ALD-52, 1P-LSD and 1B-LSD have weak efficacy or act as antagonists in Ca2+-mobilization assays. Despite the detrimental effect of 1-acyl substitution on 5-HT2A affinity and efficacy, 1-acyl-substitued LSD derivatives induce head twitches in mice with relatively high potency. High levels of LSD were detected in the plasma of rats after subcutaneous administration of ALD-52 and 1P-LSD, demonstrating these compounds are rapidly and efficiently deacylated in vivo. These findings are consistent with the prediction that ALD-52, 1P-LSD and 1B-LSD serve as prodrugs for LSD. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

RationaleThe lysergamide lysergic acid diethylamide (LSD) is a prototypical classical hallucinogen with remarkably high potency. LSD remains a popular recreational drug but is also becoming an important research tool for medical and neuroscience studies. Recently, several lysergamides that are close structural analogs of LSD have been sold as recreational drugs, which suggests that further studies are needed to explore the pharmacological properties of these compounds.ObjectiveIn this present investigation, another LSD congener, N-ethyl-N-cyclopropyl lysergamide (ECPLA), which to date has not been marketed as a recreational substance, was evaluated for its pharmacological features relative to those previously reported for LSD. The experiments focused on interactions with the 5-HT2A receptor, which is responsible for mediating the psychedelic effects of LSD and other hallucinogens.MethodsCompetitive binding assays were performed to measure the affinity of ECPLA for 27 monoamine receptors. The ability of ECPLA to activate human 5-HT2 receptor subtypes was assessed using calcium mobilization assays. Head twitch response (HTR) studies were conducted in C57BL/6J mice to determine whether ECPLA activates 5-HT2A receptors in vivo. Two other N-alkyl substituted lysergamides, N-methyl-N-isopropyl lysergamide (MIPLA) and N-methyl-N-propyl lysergamide (LAMPA), were also tested in the HTR paradigm for comparative purposes.ResultsECPLA has high affinity for most serotonin receptors, α2-adrenoceptors, and D2-like dopamine receptors. Additionally, ECPLA was found to be a potent, highly efficacious 5-HT2A agonist for Gq-mediated calcium flux. Treatment with ECPLA induced head twitches in mice with a median effective dose (ED50) of 317.2 nmol/kg (IP), which is ~ 40% of the potency observed previously for LSD. LAMPA (ED50 = 358.3 nmol/kg) was virtually equipotent with ECPLA in the HTR paradigm whereas MIPLA (ED50 = 421.7 nmol/kg) was slightly less potent than ECPLA.ConclusionsThese findings demonstrate that the pharmacological properties of ECPLA, MIPLA, and LAMPA are reminiscent of LSD and other lysergamide hallucinogens.

In recent years, rigid analogs of phenylalkylamine hallucinogens have appeared as recreational drugs. Examples include 2-(8-bromo-2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b']difuran-4-yl)ethan-1-amine (2C-B-FLY) and 1-(8-bromobenzo[1,2-b;4,5-b']difuran-4-yl)-2-aminopropane (Bromo-DragonFLY, DOB-DFLY). Although some rigid compounds such as DOB-DFLY reportedly have higher potency than their non-rigid counterparts, it is not clear whether the same is true for 2C-B-FLY and other tetrahydrobenzodifurans. In the present study, the head twitch response (HTR), a 5-HT2A receptor-mediated behavior induced by serotonergic hallucinogens, was used to assess the effects of 2,5-dimethoxy-4-bromoamphetamine (DOB) and its α-desmethyl homologue 2,5-dimethoxy-4-bromophenethylamine (2C-B), as well as their benzodifuranyl and tetrahydrobenzodifuranyl analogs, in C57BL/6J mice. DOB (ED50 = 0.75 μmol/kg) and 2C-B (ED50 = 2.43 μmol/kg) induced the HTR. The benzodifurans DOB-DFLY (ED50 = 0.20 μmol/kg) and 2C-B-DFLY (ED50 = 1.07 μmol/kg) had significantly higher potency than DOB and 2C-B, respectively. The tetrahydrobenzodifurans DOB-FLY (ED50 = 0.67 μmol/kg) and 2C-B-FLY (ED50 = 1.79 μmol/kg), by contrast, were approximately equipotent with their non-rigid counterparts. Three novel tetrahydrobenzodifurans (2C-I-FLY, 2C-E-FLY and 2C-EF-FLY) were also active in the HTR assay but had relatively low potency. In summary, the in vivo potency of 2,5-dimethoxyphenylalkylamines is enhanced when the 2- and 5-methoxy groups are incorporated into aromatic furan rings, whereas potency is not altered if the methoxy groups are incorporated into dihydrofuran rings. The potency relationships for these compounds in mice closely parallel the human hallucinogenic data. The high potency of DOB-DFLY is probably linked to the presence of two structural features (a benzodifuran nucleus and an α-methyl group) known to enhance the potency of phenylalkylamine hallucinogens.

Lysergic acid diethylamide (LSD) is perhaps one of the best-known psychoactive substances and many structural modifications of this prototypical lysergamide have been investigated. Several lysergamides were recently encountered as 'research chemicals' or new psychoactive substances (NPS). Although lysergic acid morpholide (LSM-775) appeared on the NPS market in 2013, there is disagreement in the literature regarding the potency and psychoactive properties of LSM-775 in humans. The present investigation attempts to address the gap of information that exists regarding the analytical profile and pharmacological effects of LSM-775. A powdered sample of LSM-775 was characterized by X-ray crystallography, nuclear magnetic resonance spectroscopy (NMR), gas chromatography mass spectrometry (GC-MS), high mass accuracy electrospray MS/MS, high performance liquid chromatography (HPLC) diode array detection, HPLC quadrupole MS, and GC solid-state infrared analysis. Screening for receptor affinity and functional efficacy revealed that LSM-775 acts as a nonselective agonist at 5-HT1A and 5-HT2A receptors. Head twitch studies were conducted in C57BL/6J mice to determine whether LSM-775 activates 5-HT2A receptors and produces hallucinogen-like effects in vivo. LSM-775 did not induce the head twitch response unless 5-HT1A receptors were blocked by pretreatment with the antagonist WAY-100,635 (1 mg/kg, subcutaneous). These findings suggest that 5-HT1A activation by LSM-775 masks its ability to induce the head twitch response, which is potentially consistent with reports in the literature indicating that LSM-775 is only capable of producing weak LSD-like effects in humans.

Preclinical investigations have shown that N‐ethyl‐N‐isopropyllysergamide (EIPLA) exhibits lysergic acid diethylamide (LSD)‐like properties, which suggests that it might show psychoactive effects in humans. EIPLA is also an isomer of N6‐ethylnorlysergic acid N,N‐diethylamide (ETH‐LAD), a lysergamide known to produce psychedelic effects in humans that emerged as a research chemical. EIPLA was subjected to analysis by various forms of mass spectrometry, chromatography (GC, LC), nuclear magnetic resonance (NMR) spectroscopy, and GC condensed‐phase infrared spectroscopy. The most straightforward differentiation between EIPLA and ETH‐LAD included the evaluation of mass spectral features that reflected the structural differences (EIPLA: N6‐methyl and N‐ethyl‐N‐isopropylamide group; ETH‐LAD: N6‐ethyl and N,N‐diethylamide group). Proton NMR analysis of blotter extracts suggested that EIPLA was detected as the base instead of a salt, and two blotter extracts suspected to contain EIPLA revealed the detection of 96.9 ± 0.5 μg (RSD: 0.6%) and 85.8 ± 2.8 μg base equivalents based on LC–MS analysis. The in vivo activity of EIPLA was evaluated using the mouse head‐twitch response (HTR) assay. Similar to LSD and other serotonergic psychedelics, EIPLA induced the HTR (ED50 = 234.6 nmol/kg), which was about half the potency of LSD (ED50 = 132.8 nmol/kg). These findings are consistent with the results of previous studies demonstrating that EIPLA can mimic the effects of known psychedelic drugs in rodent behavioral models. The dissemination of analytical data for EIPLA was deemed justifiable to aid future forensic and clinical investigations. [ABSTRACT FROM AUTHOR]

The development of novel lysergamides continues to occur, based on both the needs of psychedelic medicine and commercial interest in new recreational substances. The present study continues the authors' research on novel lysergamides and describes the analytical profile of 1‐cyclopropanoyl‐AL‐LAD (IUPAC name: 1‐(cyclopropanecarbonyl)‐N,N‐diethyl‐6‐(prop‐2‐en‐1‐yl)‐9,10‐didehydroergoline‐8β‐carboxamide; 1cP‐AL‐LAD), using various chromatographic, mass spectrometric, and spectroscopic methods. Analysis of a powdered sample of 1cP‐AL‐LAD, obtained from an online vendor, by high performance liquid chromatography‐electrospray ionization‐quadrupole time‐of‐flight mass spectrometry in full scan/AutoMS/MS mode revealed the detection of 17 impurities based on high‐resolution tandem mass spectral data; tentative determination of their identity was based on mass spectral grounds alone, though detection of AL‐LAD and 1P‐AL‐LAD was confirmed using available reference standards. Other tentative compound identifications included 1‐acetyl‐AL‐LAD and several other substances potentially reflecting oxidation of the N6‐allyl group as well as other positions on the ergoline ring system. These data may assist those interested in the chemistry of lysergamides. Finally, 1cP‐AL‐LAD was also detected in samples of "blotters" sold online for recreational use. [ABSTRACT FROM AUTHOR]

Lysergic acid diethylamide (LSD) is known to induce powerful psychoactive effects in humans, which cemented its status as an important tool for clinical research. A range of analogues and derivatives has been investigated over the years, including those classified as new psychoactive substances. This study presents the characterization of the novel lysergamide N,N‐diethyl‐1‐propanoyl‐6‐(prop‐2‐en‐1‐yl)‐9,10‐didehydroergoline‐8β‐carboxamide (1P‐AL‐LAD) using various mass spectrometric, gas‐ and liquid chromatographic and spectroscopic methods. In vitro metabolism studies using pooled human liver microsomes (pHLM) confirmed that 1P‐AL‐LAD converted to AL‐LAD as the most abundant metabolite consistent with the hypothesis that 1P‐AL‐LAD may act as a prodrug. Fourteen metabolites were detected in total; metabolic reactions included hydroxylation of the core lysergamide ring structure or the N6‐allyl group, formation of dihydrodiol metabolites, N‐dealkylation, N1‐deacylation, dehydrogenation, and combinations thereof. The in vivo behavioral activity of 1P‐AL‐LAD was evaluated using the mouse head twitch response (HTR), a 5‐HT2A‐mediated head movement that serves as a behavioral proxy in rodents for human hallucinogenic effects. 1P‐AL‐LAD induced a dose‐dependent increase in HTR counts with an inverted U‐shaped dose–response function, similar to lysergic acid diethylamide (LSD), psilocybin, and other psychedelics. Following intraperitoneal injection, the median effective dose (ED50) for 1P‐AL‐LAD was 491 nmol/kg, making it almost three times less potent than AL‐LAD (174.9 nmol/kg). Previous studies have shown that N1‐substitution disrupts the ability of lysergamides to activate the 5‐HT2A receptor; based on the in vitro metabolism data, 1P‐AL‐LAD may induce the HTR because it acts as a prodrug and is metabolized to AL‐LAD after administration to mice. [ABSTRACT FROM AUTHOR]

The psychopharmacological properties of the psychedelic drug lysergic acid diethylamide (LSD) have attracted the interest of several generations of scientists. While further explorations involving novel LSD‐type compounds are needed to assess their potential as medicinal drugs, the emergence of novel derivatives as recreational drugs has also been observed. 1‐Valeroyl‐LSD (also known as 1‐valeryl‐LSD, 1‐pentanoyl‐LSD, 1V‐LSD, or "Valerie") is a new N1‐acylated LSD derivative that recently appeared on the online market, and it could be viewed as a higher homolog of ALD‐52, 1P‐LSD, and 1B‐LSD. The present study included the analytical characterization and involved various methods of mass spectrometry (MS), gas and liquid chromatography (GC and LC), nuclear magnetic resonance (NMR) spectroscopy, GC–solid‐state infrared (GC‐sIR) analysis, and Raman spectroscopy. The in vivo activity of 1V‐LSD was assessed using the mouse head‐twitch response (HTR), a 5‐HT2A‐mediated head movement that serves as a behavioral proxy in rodents for human hallucinogenic effects. Similar to LSD and other psychedelic drugs, the HTR induced by 1V‐LSD was dose dependent, and the median effective dose for 1V‐LSD was 373 nmol/kg, which was about a third of the potency of LSD (ED50 = 132.8 nmol/kg). Lysergamides containing the N1‐substituent typically act as weak partial agonists at the 5‐HT2A receptor and are believed to serve as prodrugs for LSD. 1V‐LSD is also likely to be hydrolyzed to LSD and serve as a prodrug, but studies to assess the biotransformation and receptor pharmacology of 1V‐LSD should be performed to fully elucidate its mechanism of action. [ABSTRACT FROM AUTHOR]

Lysergic acid diethylamide (LSD) is a potent psychoactive substance that has attracted great interest in clinical research. As the pharmacological exploration of LSD analogs continues to grow, some of those analogs have appeared on the street market. Given that LSD analogs are uncontrolled in many jurisdictions, it is important that these analogs be differentiated from LSD. This report presents the analysis of blotters found to contain the N‐methyl‐N‐isopropyl isomer of LSD (MIPLA), and techniques to differentiate it from LSD and the N‐methyl‐N‐propyl isomer (LAMPA) under routine conditions. Gas chromatography (GC)‐solid phase infrared spectroscopy was particularly helpful. GC‐electron ionization‐tandem mass spectrometry of the m/z 72 iminium ion also provided sufficient information to distinguish the three isomers on mass spectral grounds alone, where chromatographic separation proved challenging. Derivatization with 2,2,2‐trifluoro‐N,N‐bis (trimethylsilyl)acetamide (BSTFA) also led to improved GC separation. Liquid chromatography single quadrupole mass spectrometry (LC‐Q‐MS) and in‐source collision‐induced dissociation allowed for the differentiation between MIPLA and LAMPA based on distinct m/z 239 ion ratios when co‐eluting. An alternative LC‐MS/MS method improved the separation between all three lysergamides, but LSD was found to co‐elute with iso‐LSD. However, a comparison of ion ratios recorded for transitions at m/z 324.2 > 223.2 and m/z 324.2 > 208.2 facilitated their differentiation. The analysis of two blotters by LC‐Q‐MS revealed the presence of 180 and 186 μg MIPLA per blotter. These procedures may be used to avoid inadvertent misidentification of MIPLA or LAMPA as LSD. [ABSTRACT FROM AUTHOR]

Recent investigations have shown that N‐ethyl‐N‐cyclopropyl lysergamide (ECPLA) produces LSD‐like behavioral effects in mice, which suggests that it may act as a hallucinogen in humans. Although the use of ECPLA as a recreational drug has been limited, key analytical data that can be used to detect ECPLA are required for future forensic and clinical investigations. ECPLA is an isomer of (2′S,4′S)‐lysergic acid 2,4‐dimethylazetidide (LSZ), a lysergamide that emerged as a recreational drug in 2013. Several analytical approaches were examined, including single‐ and tandem mass spectrometry platforms at low and high resolution, gas‐ and liquid chromatography (GC, LC), nuclear magnetic resonance spectroscopy (NMR), and GC condensed‐phase infrared spectroscopy (GC‐sIR). ECPLA and LSZ could be differentiated by NMR, GC‐sIR, GC, and LC‐based methods. The electron ionization mass spectra of ECPLA and LSZ contained ion clusters typically observed with related lysergamides such as m/z 150–155, m/z 177–182, m/z 191–197, m/z 205–208, and m/z 219–224. One of the significant differences in abundance related to these clusters included ions at m/z 196 and m/z 207/208. The base peaks were detected at m/z 221 in both cases followed by the retro‐Diels‐Alder fragment at m/z 292. Minor but noticeable differences between the two isomers could also be seen in the relative abundance of m/z 98 and m/z 41. Electrospray ionization mass spectra included lysergamide‐related ions at m/z 281, 251, 223, 208, 197, 180, and 140. LSZ (but not ECPLA) showed product ions at m/z 267 and m/z 98 under the conditions used. [ABSTRACT FROM AUTHOR]

1‐Propanoyl‐lysergic acid diethylamide (1P‐LSD) appeared as a non‐controlled alternative to LSD a few years ago. Although evidence is beginning to emerge from in vitro and animal studies that 1P‐LSD might serve as a prodrug for LSD, an equivalent evaluation in humans is unavailable. Controlled oral and intravenous self‐administrations of 100 μg 1P‐LSD hemitartrate are reported in two human volunteers followed by analyses of urine and serum samples using a fully validated LC–MS/MS method. Psychometric evaluations included assessment of selected subjective drug effects and administration of the Five‐Dimensions of Altered States of Consciousness rating scale (5D‐ASC). In serum and urine, oral administrations of 1P‐LSD only led to the detection of LSD reflecting biphasic elimination with a terminal elimination half‐life of approx. t1/2 = 6.4 h. 1P‐LSD could be detected for only up to 4.16 h in serum and 2.7 h in urine following intravenous administration, whereas LSD was detected in all serum samples (last sampling after approx. 24 h) and up to 80 h in urine. LSD showed first order elimination kinetics with an approx. t1/2 = 5.7 h, whereas 1P‐LSD showed a rapid decrease in concentration within the first hour followed by a slower decrease, most probably due to hydrolysis. The bioavailability of LSD after oral ingestion of 1P‐LSD was close to 100%. The psychosensory effects of 1P‐LSD and their time course were comparable to those seen after uptake of LSD in other studies which further supports the prodrug hypothesis. The 5D‐ASC scores were higher after oral compared with intravenous administration of 1P‐LSD. [ABSTRACT FROM AUTHOR]

Lysergic acid diethylamide (LSD) is a prototypical serotonergic psychedelic drug and the subject of many clinical investigations. In recent years, a range of lysergamides has emerged with the production of some being inspired by the existing scientific literature. Others, for example various 1‐acyl substituted lysergamides, did not exist before their appearance as research chemicals. 1‐Cylopropanoyl‐LSD (1CP‐LSD) has recently emerged as a new addition to the group of lysergamide‐based designer drugs and is believed to be psychoactive in humans. In this investigation, 1CP‐LSD was subjected to detailed analytical characterizations including various mass spectrometry (MS) platforms, gas and liquid chromatography, nuclear magnetic resonance spectroscopy, solid phase and GC condensed phase infrared spectroscopy. Analysis by GC–MS also revealed the detection of artificially induced degradation products. Incubation of 1CP‐LSD with human serum led to the formation of LSD, indicating that it may act as a prodrug for LSD in vivo, similar to other 1‐acyl substituted lysergamides. The analysis of blotters and pellets is also included. 1CP‐LSD also induces the head‐twitch response (HTR) in C57BL/6 J mice, indicating that it produces an LSD‐like behavioural profile. 1CP‐LSD induced the HTR with an ED50 = 430.0 nmol/kg which was comparable to 1P‐LSD (ED50 = 349.6 nmol/kg) investigated previously. Clinical studies are required to determine the potency and profile of the effects produced by 1CP‐LSD in humans. [ABSTRACT FROM AUTHOR]

The psychedelic properties of lysergic acid diethylamide (LSD) have captured the imagination of researchers for many years and its rediscovery as an important research tool is evidenced by its clinical use within neuroscientific and therapeutic settings. At the same time, a number of novel LSD analogs have recently emerged as recreational drugs, which makes it necessary to study their analytical and pharmacological properties. One recent addition to this series of LSD analogs is 1‐butanoyl‐LSD (1B‐LSD), a constitutional isomer of 1‐propanoyl‐6‐ethyl‐6‐nor‐lysergic acid diethylamide (1P‐ETH‐LAD), another LSD analog that was described previously. This study presents a comprehensive analytical characterization of 1B‐LSD employing nuclear magnetic resonance spectroscopy (NMR), low‐ and high‐resolution mass spectrometry platforms, gas‐ and liquid chromatography (GC and LC), and GC‐condensed phase and attenuated total reflection infrared spectroscopy analyses. Analytical differentiation of 1B‐LSD from 1P‐ETH‐LAD was straightforward. LSD and other serotonergic hallucinogens induce the head‐twitch response (HTR) in rats and mice, which is believed to be mediated largely by 5‐HT2A receptor activation. HTR studies were conducted in C57BL/6J mice to assess whether 1B‐LSD has LSD‐like behavioral effects. 1B‐LSD produced a dose‐dependent increase in HTR counts, acting with ~14% (ED50 = 976.7 nmol/kg) of the potency of LSD (ED50 = 132.8 nmol/kg). This finding suggests that the behavioral effects of 1B‐LSD are reminiscent of LSD and other serotonergic hallucinogens. The possibility exists that 1B‐LSD serves as a pro‐drug for LSD. Further investigations are warranted to confirm whether 1B‐LSD produces LSD‐like psychoactive effects in humans. [ABSTRACT FROM AUTHOR]

The psychoactive properties of lysergic acid diethylamide (LSD) have fascinated scientists across disciplines and the exploration of other analogues and derivatives has been motivated by deepening the understanding of ligand-receptor interactions at the molecular level as well as by the search for new therapeutics. Several LSD congeners have appeared on the new psychoactive substances (NPS) market in the form of blotters or powders. Examples include 1-propionyl-LSD (1P-LSD), AL-LAD, and LSZ. The absence of analytical data for novel compounds is a frequent challenge encountered in clinical and toxicological investigations. Two newly emerging lysergamides, namely N6-ethyl-6-norlysergic acid diethylamide (ETH-LAD) and 1P-ETH-LAD, were characterized by gas chromatography-mass spectrometry (GC-MS), low and high mass accuracy electrospray MS(/MS), GC solid-state infrared analysis, high performance liquid chromatography diode array detection as well as nuclear magnetic resonance spectroscopy. Limited analytical data for ETH-LAD were previously available, whereas information about 1P-ETH-LAD has not previously been encountered in the scientific literature. This study extends the characterization of lysergamides distributed on the NPS market, which will help to make analytical data available to clinicians, toxicologists, and other stakeholders who are likely to encounter these substances. The analysis of a test incubation of 1P-ETH-LAD with human serum at 37°C by LC single quadrupole MS at various time points (0-6 h, once per hour and one measurement after 24 h) revealed the formation of ETH-LAD, suggesting that 1P-ETH-LAD might serve as a pro-drug. 1P-ETH-LAD was still detectable in serum after 24 h. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Lysergic acid N, N-diethylamide (LSD) is perhaps one of the most intriguing psychoactive substances known and numerous analogs have been explored to varying extents in previous decades. In 2013, N6-allyl-6-norlysergic acid diethylamide (AL-LAD) and (2' S,4' S)-lysergic acid 2,4-dimethylazetidide (LSZ) appeared on the 'research chemicals'/new psychoactive substances (NPS) market in both powdered and blotter form. This study reports the analytical characterization of powdered AL-LAD and LSZ tartrate samples and their semi-quantitative determination on blotter paper. Included in this study was the use of nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), low and high mass accuracy electrospray MS(/MS), high performance liquid chromatography diode array detection and GC solid-state infrared analysis. One feature shared by serotonergic psychedelics, such as LSD, is the ability to mediate behavioural responses via activation of 5-HT2A receptors. Both AL-LAD and LSZ displayed LSD-like responses in male C57BL/6 J mice when employing the head-twitch response (HTR) assay. AL-LAD and LSZ produced nearly identical inverted-U-shaped dose-dependent effects, with the maximal responses occurring at 200 µg/kg. Analysis of the dose responses by nonlinear regression confirmed that LSZ (ED50 = 114.2 nmol/kg) was equipotent to LSD (ED50 = 132.8 nmol/kg) in mice, whereas AL-LAD was slightly less potent (ED50 = 174.9 nmol/kg). The extent to which a comparison in potency can be translated directly to humans requires further investigation. Chemical and pharmacological data obtained from NPS may assist research communities that are interested in various aspects related to substance use and forensic identification. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

1-Propionyl- d-lysergic acid diethylamide hemitartrate (1P-LSD) has become available as a 'research chemical' in the form of blotters and powdered material. This non-controlled derivative of d-lysergic acid diethylamide (LSD) has previously not been described in the published literature despite being closely related to 1-acetyl-LSD (ALD-52), which was developed in the 1950s. This study describes the characterization of 1P-LSD in comparison with LSD using various chromatographic and mass spectrometric methods, infrared and nuclear magnetic resonance spectroscopy. An important feature common to LSD and other serotonergic hallucinogens is that they produce 5-HT2A-receptor activation and induce the head-twitch response (HTR) in rats and mice. In order to assess whether 1P-LSD displays LSD-like properties and activates the 5-HT2A receptor, male C57BL/6 J mice were injected with vehicle (saline) or 1P-LSD (0.025-0.8 mg/kg, IP) and HTR assessed for 30 min using magnetometer coil recordings. It was found that 1P-LSD produced a dose-dependent increase in HTR counts, and that it had ~38% (ED50 = 349.6 nmol/kg) of the potency of LSD (ED50 = 132.8 nmol/kg). Furthermore, HTR was abolished when 1P-LSD administration followed pretreatment with the selective 5-HT2A receptor antagonist M100907 (0.1 mg/kg, SC), which was consistent with the concept that the behavioural response was mediated by activation of the 5-HT2A receptor. These results indicate that 1P-LSD produces LSD-like effects in mice, consistent with its classification as a serotonergic hallucinogen. Nevertheless, the extent to which 1P-LSD might show psychoactive effects in humans similar to LSD remains to be investigated. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract In recent years, rigid analogs of phenylalkylamine hallucinogens have appeared as recreational drugs. Examples include 2-(8-bromo-2,3,6,7-tetrahydrobenzo[1,2- b :4,5- b ′]difuran-4-yl)ethan-1-amine (2C-B-FLY) and 1-(8-bromobenzo[1,2 -b ;4,5 -b' ]difuran-4-yl)-2-aminopropane (Bromo-DragonFLY, DOB-DFLY). Although some rigid compounds such as DOB-DFLY reportedly have higher potency than their non-rigid counterparts, it is not clear whether the same is true for 2C-B-FLY and other tetrahydrobenzodifurans. In the present study, the head twitch response (HTR), a 5-HT 2A receptor-mediated behavior induced by serotonergic hallucinogens, was used to assess the effects of 2,5-dimethoxy-4-bromoamphetamine (DOB) and its α-desmethyl homologue 2,5-dimethoxy-4-bromophenethylamine (2C-B), as well as their benzodifuranyl and tetrahydrobenzodifuranyl analogs, in C57BL/6J mice. DOB (ED 50 = 0.75 μmol/kg) and 2C-B (ED 50 = 2.43 μmol/kg) induced the HTR. The benzodifurans DOB-DFLY (ED 50 = 0.20 μmol/kg) and 2C-B-DFLY (ED 50 = 1.07 μmol/kg) had significantly higher potency than DOB and 2C-B, respectively. The tetrahydrobenzodifurans DOB-FLY (ED 50 = 0.67 μmol/kg) and 2C-B-FLY (ED 50 = 1.79 μmol/kg), by contrast, were approximately equipotent with their non-rigid counterparts. Three novel tetrahydrobenzodifurans (2C-I-FLY, 2C-E-FLY and 2C-EF-FLY) were also active in the HTR assay but had relatively low potency. In summary, the in vivo potency of 2,5-dimethoxyphenylalkylamines is enhanced when the 2- and 5-methoxy groups are incorporated into aromatic furan rings, whereas potency is not altered if the methoxy groups are incorporated into dihydrofuran rings. The potency relationships for these compounds in mice closely parallel the human hallucinogenic data. The high potency of DOB-DFLY is probably linked to the presence of two structural features (a benzodifuran nucleus and an α-methyl group) known to enhance the potency of phenylalkylamine hallucinogens. Highlights • The hallucinogens 2C-B and DOB induced head twitches in mice. • Tethering the methoxy groups into a benzodifuran nucleus increased potency. • Tethering the methoxy groups into a tetrahydrobenzodifuran nucleus did not alter potency. • The benzodifuran hallucinogen Bromo-DragonFLY was highly potent in mice. [ABSTRACT FROM AUTHOR]

The ergoline d -lysergic acid diethylamide (LSD) is one of the most potent psychedelic drugs. 1-Acetyl-LSD (ALD-52), a derivative of LSD containing an acetyl group on the indole nitrogen, also produces psychedelic effects in humans and has about the same potency as LSD. Recently, several other 1-acyl-substitued LSD derivatives, including 1-propanoyl-LSD (1P-LSD) and 1-butanoyl-LSD (1B-LSD), have appeared as designer drugs. Although these compounds are assumed to act as prodrugs for LSD, studies have not specifically tested this prediction. The present investigation was conducted to address the gap of information about the pharmacological effects and mechanism-of-action of 1-acyl-substituted LSD derivatives. Competitive binding studies and calcium mobilization assays were performed to assess the interaction of ALD-52, 1P-LSD, and 1B-LSD with serotonin 5-HT 2 receptor subtypes. A receptorome screening was performed with 1B-LSD to assess its binding to other potential targets. Head twitch response (HTR) studies were performed in C57BL/6J mice to assess in vivo activation of 5-HT 2A (the receptor thought to be primarily responsible for hallucinogenesis). Finally, liquid chromatography/ion-trap mass spectrometry (LC/MS) was used to quantify plasma levels of LSD in Sprague-Dawley rats treated with ALD-52 and 1P-LSD. 1-Acyl-substitution reduced the affinity of LSD for most monoamine receptors, including 5-HT 2A sites, by one to two orders of magnitude. Although LSD acts as an agonist at 5-HT 2 subtypes, ALD-52, 1P-LSD and 1B-LSD have weak efficacy or act as antagonists in Ca2+-mobilization assays. Despite the detrimental effect of 1-acyl substitution on 5-HT 2A affinity and efficacy, 1-acyl-substitued LSD derivatives induce head twitches in mice with relatively high potency. High levels of LSD were detected in the plasma of rats after subcutaneous administration of ALD-52 and 1P-LSD, demonstrating these compounds are rapidly and efficiently deacylated in vivo. These findings are consistent with the prediction that ALD-52, 1P-LSD and 1B-LSD serve as prodrugs for LSD. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'. • N 1-Substituted LSD derivatives such as ALD-52 are potent hallucinogens in humans. • N 1-Substitution markedly reduces the efficacy of LSD at the 5-HT 2A receptor. • ALD-52 and 1P-LSD are metabolized to LSD in rats. • N 1-Substituted LSD derivatives likely act as prodrugs. [ABSTRACT FROM AUTHOR]