Structural pharmacology and therapeutic potential of 5-methoxytryptamines.

Psychedelic substances such as lysergic acid diethylamide (LSD) and psilocybin show potential for the treatment of various neuropsychiatric disorders1-3. These compounds are thought to mediate their hallucinogenic and therapeutic effects through the serotonin (5-hydroxytryptamine (5-HT)) receptor 5-HT2A (ref. 4). However, 5-HT1A also plays a part in the behavioural effects of tryptamine hallucinogens5, particularly 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), a psychedelic found in the toxin of Colorado River toads6. Although 5-HT1A is a validated therapeutic target7,8, little is known about how psychedelics engage 5-HT1A and which effects are mediated by this receptor. Here we map the molecular underpinnings of 5-MeO-DMT pharmacology through five cryogenic electron microscopy (cryo-EM) structures of 5-HT1A, systematic medicinal chemistry, receptor mutagenesis and mouse behaviour. Structure-activity relationship analyses of 5-methoxytryptamines at both 5-HT1A and 5-HT2A enable the characterization of molecular determinants of 5-HT1A signalling potency, efficacy and selectivity. Moreover, we contrast the structural interactions and in vitro pharmacology of 5-MeO-DMT and analogues to the pan-serotonergic agonist LSD and clinically used 5-HT1A agonists. We show that a 5-HT1A-selective 5-MeO-DMT analogue is devoid of hallucinogenic-like effects while retaining anxiolytic-like and antidepressant-like activity in socially defeated animals. Our studies uncover molecular aspects of 5-HT1A-targeted psychedelics and therapeutics, which may facilitate the future development of new medications for neuropsychiatric disorders.

Pharmaco-toxicological effects of the novel tryptamine hallucinogen 5-MeO-MiPT on motor, sensorimotor, physiological, and cardiorespiratory parameters in mice-from a human poisoning case to the preclinical evidence.

RATIONALE: The 5-methoxy-N-methyl-N-isopropyltryptamine (5-MeO-MiPT, known online as "Moxy") is a new psychedelic tryptamine first identified on Italian national territory in 2014. Its hallucinogen effects are broadly well-known; however, only few information is available regarding its pharmaco-toxicological effects. OBJECTIVES: Following the seizure of this new psychoactive substances by the Arm of Carabinieri and the occurrence of a human intoxication case, in the current study we had the aim to characterize the in vivo acute effects of systemic administration of 5-MeO-MiPT (0.01-30 mg/kg i.p.) on sensorimotor (visual, acoustic, and overall tactile) responses, thermoregulation, and stimulated motor activity (drag and accelerod test) in CD-1 male mice. We also evaluated variation on sensory gating (PPI, prepulse inhibition; 0.01-10 mg/kg i.p.) and on cardiorespiratory parameters (MouseOx and BP-2000; 30 mg/kg i.p.). Lastly, we investigated the in silico ADMET (absorption, distribution, metabolism, excretion, toxicity) profile of 5-MeO-MiPT compared to 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) and N,N-dimethyltryptamine (DMT). RESULTS: This study demonstrates that 5-MeO-MiPT dose-dependently inhibits sensorimotor and PPI responses and, at high doses, induces impairment of the stimulated motor activity and cardiorespiratory changes in mice. In silico prediction shows that the 5-MeO-MiPT toxicokinetic profile shares similarities with 5-MeO-DIPT and DMT and highlights a cytochrome risk associated with this compound. CONCLUSIONS: Consumption of 5-MeO-MiPT can affect the ability to perform activities and pose a risk to human health status, as the correspondence between the effects induced in mice and the symptoms occurred in the intoxication case suggests. However, our findings suggest that 5-MeO-MiPT should not be excluded from research in the psychiatric therapy field.

Nontargeted metabolomic insights into the behavioral effects of 5-MeO-MiPT in zebrafish (Danio rerio).

5-Methoxy-N-methyl-N-isopropyltryptamine (5-MeO-MiPT) is a novel psychoactive substance exhibiting a tryptamine structure. Despite its increasing prevalence, the environmental impact of 5-MeO-MiPT remains unexplored. Our prior investigation revealed that 5-MeO-MiPT induced inhibited spontaneous movement and prompted anxiety-like behavior in adult zebrafish-a validated toxicological model. To elucidate this phenomenon and establish a correlation between metabolomics and behavioral changes induced by 5-MeO-MiPT, zebrafish were administered varying drug concentrations. Zebrafishes were subjected to injections of different 5-MeO-MiPT concentrations. Subsequent metabolomic analysis of endogenous metabolites affected by the drug unveiled substantial variations in metabolic levels between the control group and the drug-injected cohorts. A total of 22 distinct metabolites emerged as potential biomarkers. Further scrutiny identified seven pathways significantly influenced by 5-MeO-MiPT. A focused exploration into amino acid metabolism, lipid metabolism, and energy metabolism unveiled that the metabolic repercussions of 5-MeO-MiPT on zebrafish resulted in observable brain damage. Notably, the study identified a consequential disruption in the liver-brain pathway. The comprehensive metabolomic approach employed herein effectively discerned the impact of 5-MeO-MiPT on zebrafish metabolism. This approach also shed light on the mechanism underpinning the anxiety-like behavior observed in zebrafish post-drug injection. Specifically, our findings indicate that 5-MeO-MiPT induces brain damage, particularly within the liver-brain pathway.

Dual actions of 5-MeO-DIPT at the serotonin transporter and serotonin 5-HT1A receptor in the mouse striatum and prefrontal cortex.

AIMS: 5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is a synthetic orally active hallucinogenic tryptamine analogue. The present study examined whether the effects of 5-MeO-DIPT involve the serotonin transporter (SERT) and serotonin 5-hydroxytryptamine-1A (5-HT1A ) receptor in the striatum and prefrontal cortex (PFC). METHODS: We investigated the effects of 5-MeO-DIPT on extracellular 5-HT (5-HTex ) and dopamine (DAex ) levels in the striatum and PFC in wildtype and SERT knockout (KO) mice using in vivo microdialysis, and for comparison the effects of the 5-HT1A receptor antagonist WAY100635 and the 5-HT1A receptor agonist 8-OH-DPAT on 5-HTex . RESULTS: 5-MeO-DIPT decreased 5-HTex levels in the striatum, but not PFC. In SERT-KO mice, 5-MeO-DIPT did not affect 5-HTex levels in the striatum or PFC. In the presence of WAY100635, 5-MeO-DIPT substantially increased 5-HTex levels, suggesting that 5-MeO-DIPT acts on SERT and these effects are masked by its 5-HT1A actions in the absence of WAY100635. 8-OH-DPAT decreased 5-HTex levels in the striatum and PFC in wildtype mice. WAY100635 antagonized the 8-OH-DPAT-induced decrease in 5-HTex levels. In SERT-KO mice, 8-OH-DPAT did not decrease 5-HTex levels in the striatum and PFC. 5-MeO-DIPT dose-dependently increased DAex levels in the PFC, but not striatum, in wildtype and SERT-KO mice. The increase in DAex levels that was induced by 5-MeO-DIPT was not antagonized by WAY100635. CONCLUSION: 5-MeO-DIPT influences both 5-HTex and DAex levels in the striatum and PFC. 5-MeO-DIPT dually acts on SERT and 5-HT1A receptors so that elevations in 5-HTex levels produced by reuptake inhibition are limited by actions of the drug on 5-HT1A receptors.

Role of peripheral 5-HT5A receptors in 5-HT-induced cardiac sympatho-inhibition in type 1 diabetic rats.

5-HT inhibits cardiac sympathetic neurotransmission in normoglycaemic rats, via 5-HT1B, 5-HT1D and 5-HT5A receptor activation. Since type 1 diabetes impairs the cardiac sympathetic innervation leading to cardiopathies, this study aimed to investigate whether the serotonergic influence on cardiac noradrenergic control is altered in type 1 diabetic rats. Diabetes was induced in male Wistar rats by streptozotocin (50 mg/kg, i.p.). Four weeks later, the rats were anaesthetized, pithed and prepared for producing tachycardic responses by electrical preganglionic stimulation (C7-T1) of the cardioaccelerator sympathetic outflow or i.v. noradrenaline bolus injections. Immunohistochemistry was performed to study 5-HT1B, 5-HT1D and 5-HT5A receptor expression in the stellate ganglion from normoglycaemic and diabetic rats. In the diabetic group, i) i.v. continuous infusions of 5-HT induced a cardiac sympatho-inhibition that was mimicked by the 5-HT1/5A agonist 5-carboxamidotryptamine (without modifying noradrenaline-induced tachycardia), but not by the agonists indorenate (5-HT1A), CP 93,129 (5-HT1B), PNU 142633 (5-HT1D), or LY344864 (5-HT1F); ii) SB 699551 (5-HT5A antagonist; i.v.) completely reversed 5-CT-induced cardiac sympatho-inhibition; and iii) 5-HT5A receptors were more expressed in the stellate ganglion compared to normoglycaemic rats. These results show the prominent role of the peripheral 5-HT5A receptors prejunctionally inhibiting the cardiac sympathetic drive in type 1 diabetic rats.

Development of an LC-MS/MS method for determining 5-MeO-DIPT in dried urine spots and application to forensic cases.

PURPOSE: The dried urine spots (DUSs) technique is increasing continuously as an easy sampling method for monitoring substance abuse due to its advantages of stability and convenience regarding transport and storage. 5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is a new type of tryptamine hallucinogen, the use of which has been banned in many countries. And according to the previous research, 5-MeO-DIPT is not stable in urine. In order to improve its stability, an LC-MS/MS method for determining 5-MeO-DIPT in DUSs was developed. METHOD: 10 µl urine was spotted on Whatman FTATM classic card, then extracted with 200 µl methanol, and liquid chromatography-tandem mass spectrometry in positive ion multiple reaction monitoring mode was utilized for analysis. RESULTS: The LOD and LLOQ of the method were 0.1 ng/ml and 0.2 ng/ml, respectively. The accuracy and precision were 98.2%-103.9% and 2.7%-8.5%, respectively. It was found that the stability of 5-MeO-DIPT in DUSs was better than the stability of 5-MeO-DIPT in urine stored at 25 °C. Moreover, this method was also applied to detect 5-MeO-DIPT in the urine of individuals known to have used 5-MeO-DIPT. It was found that the concentrations of 5-MeO-DIPT were 0.3-2.3 ng/ml, which were lower than those obtained via GC-Orbitrap-MS. The small volume of urine required (10 µl), combined with the simplicity of the analytical technique, makes this an useful procedure for the screening of drug of abuse.

Determination of 5-MeO-DIPT in Human Urine Using Gas Chromatography Coupled with High-Resolution Orbitrap Mass Spectrometry.

5-Methoxy-N,N-Diisopropyltryptamine (5-MeO-DIPT) is a designer hallucinogen derived from tryptamine and its use has been banned by many countries. In this study, a qualitative and quantitative method was developed for determining 5-MeO-DIPT in urine by gas chromatography high-resolution mass spectrometry. 5-hydroxy-N,N-diisopropyltryptamine (5-OH-DIPT) and 5-methoxy-N-isopropyltryptamine (5-MeO-IPT) were identified as 5-MeO-DIPT metabolites in abusers' urine. 5-MeO-DIPT was extracted from urine by liquid-liquid extraction with ethyl acetate under alkaline conditions. The extract was analyzed by GC-Orbitrap-MS in full scan mode with a resolution of 60,000 full width at half maxima (FWHM). The linear range of this method was 2-300 ng/mL with r > 0.99, and the limit of detection was 1 ng/mL. The accuracy and precision were 93-108.7% and 3.1-10.3%, respectively. This method is simple and sensitive. It has been successfully used to detect 5-MeO-DIPT in drug abusers' urine, which showed that the concentrations of 5-MeO-DIPT were between 1 and 2.8 ng/mL. 5-OH-DIPT and 5-MeO-IPT, two urinary major metabolites of 5-MeO-DIPT, were identified in urine samples from 5-MeO-DIPT users. Furthermore, the stability of 5-MeO-DIPT in human urine was investigated. It was discovered that the concentration of 5-MeO-DIPT in urine decreased by 22.8, 33.2 and 38.2% after samples were stored for 24 h at 25°C, 5 days at 4°C and 7 days at 4°C, respectively. And 5-MeO-DIPT in urine were stable after they were stored for 30 days at -20°C. Therefore, it is recommended that urine should be stored under freezing conditions before performing 5-MeO-DIPT analysis.

Application of hair analysis to document illegal 5-methoxy-N,N-dissopropyltrptamine (5-MeO-DiPT) use.

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DiPT) is a designer hallucinogen that is a synthetic tryptamine derivative. It is highly abused and is involved in criminal activities because of its psychotropic properties. Herein, we presented an UHPLC-MS/MS method allowing for the qualitative and quantitative determination of 5-MeO-DiPT in human hair. The hair was first decontaminated and then cut into pieces. Thirty milligrams of hair samples was pulverized below 4°C in the presence of 0.5mL deionized water containing 0.1% formic acid. After centrifuging twice, 5µL of supernatant was injected into the LC-MS/MS system. A T3 column (100mm×2.1mm, 1.8µm) was used, and mobile phases consisted of 20mmol/L ammonium acetate, 5% acetonitrile and 0.1% formic acid in water (solvent A) and acetonitrile (solvent B). The gradient elution was used at a flow rate of 0.3mL/min. The resulting calibration curve for 5-MeO-DiPT was y=281.50213x+0.00231 (R2=0.992), the limit of detection (LOD) was 0.05pg/mg, and the lower limit of quantification (LLOQ) was 0.1pg/mg. The accuracy was between 92.1% and 105.6%, and the intra- and interday precision, recovery and matrix effect were acceptable. The validated method was successfully used in 106 real cases, and the concentration of 5-MeO-DiPT in hair samples of these suspected users was 0.2-7532.5pg/mg. These cases present data to document illegal 5-MeO-DiPT use.

5-HT2 receptor binding, functional activity and selectivity in N-benzyltryptamines.

The last fifteen years have seen the emergence and overflow into the drug scene of "superpotent" N-benzylated phenethylamines belonging to the "NBOMe" series, accompanied by numerous research articles. Although N-benzyl substitution of 5-methoxytryptamine is known to increase its affinity and potency at 5-HT2 receptors associated with psychedelic activity, N-benzylated tryptamines have been studied much less than their phenethylamine analogs. To further our knowledge of the activity of N-benzyltryptamines, we have synthesized a family of tryptamine derivatives and, for comparison, a few 5-methoxytryptamine analogs with many different substitution patterns on the benzyl moiety, and subjected them to in vitro affinity and functional activity assays vs. the human 5-HT2 receptor subtypes. In the binding (radioligand displacement) studies some of these compounds exhibited only modest selectivity for either 5-HT2A or 5-HT2C receptors suggesting that a few of them, with affinities in the 10-100 nanomolar range for 5-HT2A receptors, might presumably be psychedelic. Unexpectedly, their functional (calcium mobilization) assays reflected very different trends. All of these compounds proved to be 5-HT2C receptor full agonists while most of them showed low efficacy at the 5-HT2A subtype. Furthermore, several showed moderate-to-strong preferences for activation of the 5-HT2C subtype at nanomolar concentrations. Thus, although some N-benzyltryptamines might be abuse-liable, others might represent new leads for the development of therapeutics for weight loss, erectile dysfunction, drug abuse, or schizophrenia.

Trends in DMT and other tryptamine use among young adults in the United States.

BACKGROUND AND OBJECTIVES: The popularity of tryptamines such as N,N-dimethyltryptamine (DMT) appears to be increasing in the United States (US), but epidemiologic literature on prevalence of use is scant. This paper aims to determine trends in prevalence and correlates of past-year tryptamine use among a nationally representative sample of young adults in the US. METHODS: Participants in the National Survey on Drug Use and Health survey were queried about past-year use of tryptamines-specifically DMT, α-methyltryptamine (AMT), and 5-MeO-DIPT ("Foxy"). Data were examined from young adults (ages 18-25), years 2007-2014 (N = 144,787). Linear trends in prevalence of past-year tryptamine use were examined in the full sample and stratified by specific demographic and drug use characteristics. RESULTS: Tryptamine use is rare, but increased from .2% in 2007/08 to .7% in 2013/14, a 273% relative increase (p < .001). While prevalence increased among all demographic groups, prevalence was substantially higher among individuals who use other drugs. In particular, between 2007/08 and 2013/14, prevalence of tryptamine use increased among past-year ecstasy users (from 2.1% to 10.0%) and LSD users (from 7.0% to 15.5%) (ps < .01). Prevalence of tryptamine use tended to be higher among lifetime and past-year users of psychedelic drugs compared to users of non-psychedelic drugs. CONCLUSION: While tryptamine use is not prevalent in the general young adult population, prevalence is increasing. Users of various other drugs-particularly drugs with psychedelic effects-report higher prevalence of tryptamine use. SCIENTIFIC SIGNIFICANCE: Users of other drugs can be targeted when disseminating information about tryptamines to ensure user safety. (Am J Addict 2018;27:578-585).

The effect of repeated-intermittent exposure to 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) during adolescence on learning and memory in adult rats.

BACKGROUND: According to the European Drug Report, the use of novel psychoactive substances (NPS) is constantly growing. NPS are widely abused by human adolescent subjects. 5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is one of the most frequently used hallucinogenic NPS. 5-MeO-DIPT intoxication results in hallucinations, vomiting, and tachycardia. Long-term exposure to 5-MeO-DIPT was reported to lead to development of post-hallucinogenic perception disorder. The aim of the present study was to determine whether repeated-intermittent administration of 5-MeO-DIPT during adolescence affects learning and memory in adult rats. METHODS: Rats were treated with 5-MeO-DIPT in a dose of 2.5mg/kg from 30 to 33 and 37 to 40 Postnatal Day (PND). The experiments were conducted when the animals reached 90 PND. The effect of 5-MeO-DIPT on cognitive functions was assessed using the novel object recognition, open field, and serial pattern learning (SPL) tests. RESULTS: Repeated-intermittent exposure to 5-MeO-DIPT during adolescence decreased the number of crossings in the open field test at adulthood. Moreover, 5-MeO-DIPT treatment impaired adult rats' learning in the SPL test. There was no change in the novel object recognition test. CONCLUSIONS: The present results show that the performance of adult rats treated with 5-MeO-DIPT during adolescence was impaired in the open field test, which indicates the attenuated exploratory activity. 5-MeO-DIPT treatment undermined adult rats' performance in the serial pattern learning test, suggesting impairment of long term memory and cognitive flexibility. The present study showed that the exposure to 5-MeO-DIPT during adolescence might lead to long-lasting behavioral changes which persisted long after the exposure period.

Metabolism of the tryptamine-derived new psychoactive substances 5-MeO-2-Me-DALT, 5-MeO-2-Me-ALCHT, and 5-MeO-2-Me-DIPT and their detectability in urine studied by GC-MS, LC-MSn , and LC-HR-MS/MS.

Many N,N-dialkylated tryptamines show psychoactive properties and were encountered as new psychoactive substances. The aims of the presented work were to study the phase I and II metabolism and the detectability in standard urine screening approaches (SUSA) of 5-methoxy-2-methyl-N,N-diallyltryptamine (5-MeO-2-Me-DALT), 5-methoxy-2-methyl-N-allyl-N-cyclohexyltryptamine (5-MeO-2-Me-ALCHT), and 5-methoxy-2-methyl-N,N-diisopropyltryptamine (5-MeO-2-Me-DIPT) using gas chromatography-mass spectrometry (GC-MS), liquid chromatography coupled with multistage accurate mass spectrometry (LC-MSn ), and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS). For metabolism studies, urine was collected over a 24 h period after administration of the compounds to male Wistar rats at 20 mg/kg body weight (BW). Phase I and II metabolites were identified after urine precipitation with acetonitrile by LC-HR-MS/MS. 5-MeO-2-Me-DALT (24 phase I and 12 phase II metabolites), 5-MeO-2-Me-ALCHT (24 phase I and 14 phase II metabolites), and 5-MeO-2-Me-DIPT (20 phase I and 11 phase II metabolites) were mainly metabolized by O-demethylation, hydroxylation, N-dealkylation, and combinations of them as well as by glucuronidation and sulfation of phase I metabolites. Incubations with mixtures of pooled human liver microsomes and cytosols (pHLM and pHLC) confirmed that the main metabolic reactions in humans and rats might be identical. Furthermore, initial CYP activity screenings revealed that CYP1A2, CYP2C19, CYP2D6, and CYP3A4 were involved in hydroxylation, CYP2C19 and CYP2D6 in O-demethylation, and CYP2C19, CYP2D6, and CYP3A4 in N-dealkylation. For SUSAs, GC-MS, LC-MSn , and LC-HR-MS/MS were applied to rat urine samples after 1 or 0.1 mg/kg BW doses, respectively. In contrast to the GC-MS SUSA, both LC-MS SUSAs were able to detect an intake of 5-MeO-2-Me-ALCHT and 5-MeO-2-Me-DIPT via their metabolites following 1 mg/kg BW administrations and 5-MeO-2-Me-DALT following 0.1 mg/kg BW dosage. Copyright © 2017 John Wiley & Sons, Ltd.

Proposal of 5-methoxy-N-methyl-N-isopropyltryptamine consumption biomarkers through identification of in vivo metabolites from mice.

New psychoactive substances (NPS) are a new breed of synthetically produced substances designed to mimic the effects of traditional illegal drugs. Synthetic cannabinoids and synthetic cathinones are the two most common groups, which try to mimic the effects of the natural compounds 9Δ-tetrahydrocannabinol and cathinone, respectively. Similarly, synthetic tryptamines are designer compounds which are based on the compounds psilocin, N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine found in some mushrooms. One of the most important tryptamine compounds found in seizures is 5-methoxy-N,N-diisopropyltryptamine, which has been placed as controlled substance in USA and some European countries. The control of this compound has promoted the rising of another tryptamine, the 5-methoxy-N-methyl-N-isopropyltryptamine, which at the time of writing this article has not been banned yet. So, it is undeniable that this new substance should be monitored. 5-methoxy-N-methyl-N-isopropyltryptamine has been reported by the Spanish Early Warning System and detected in our laboratory in two pill samples purchased in a local smart shop. This has promoted the need of stablishing consumption markers for this compound in consumers' urine. In the present work, the metabolism and pharmacokinetic of 5-methoxy-N-methyl-N-isopropyltryptamine has been studied by an in vivo approach, using adult male mice of the inbred strain C57BLJ/6. The use of ultra-high performance liquid chromatography coupled to high resolution mass spectrometry allowed the identification of four metabolites. After the pharmacokinetic study in serum and urine, the O-demethylated metabolite and the non-metabolised parent compound are proposed as consumption markers in hydrolysed urine. Data reported in this work will help hospitals and forensic laboratories to monitor the consumption and potential intoxication cases related to this tryptamine.

Neurotoxic Effects of 5-MeO-DIPT: A Psychoactive Tryptamine Derivative in Rats.

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT, 'foxy') is one of the most popular tryptamine hallucinogens in the illicit drug market. It produces serious adverse effects, but its pharmacological profile is not well recognized. In vitro data have shown that 5-MeO-DIPT acts as a potent serotonin transporter (SERT) inhibitor and displays high affinity at serotonin 5-HT1A, 5-HT2A, and 5-HT2C receptors. In this study, using microdialysis in freely moving rats, we examined the effect of 5-MeO-DIPT on dopamine (DA), serotonin (5-HT), and glutamate release in the rat striatum, nucleus accumbens, and frontal cortex. In search of a possible neurotoxic effect of 5-MeO-DIPT, we measured DA and 5-HT tissue content in the above rat brain regions and also determined the oxidative DNA damage with the comet assay. Moreover, we tested drug-elicited head-twitch response and a forepaw treading induced by 8-OH-DPAT. 5-MeO-DIPT at doses of 5, 10, and 20 mg/kg increased extracellular DA, 5-HT, and glutamate level but the differences in the potency were found between brain regions. 5-MeO-DIPT increased 5-HT and decreased 5-HIAA tissue content which seems to result from SERT inhibition. On the other hand, a decrease in DA, DOPAC, and HVA tissue contents suggests possible adaptive changes in DA turnover or damage of DA terminals by 5-MeO-DIPT. DNA single and double-strand breaks persisted up to 60 days after the treatment, indicating marked neurotoxicity of 5-MeO-DIPT. The induction of head-twitch response and potentiation of forepaw treading induced by 8-OH-DPAT indicate that hallucinogenic activity seems to be mediated through the stimulation of 5-HT2A and 5-HT1A receptors by 5-MeO-DIPT.

N-Benzyl-5-methoxytryptamines as Potent Serotonin 5-HT2 Receptor Family Agonists and Comparison with a Series of Phenethylamine Analogues.

A series of N-benzylated-5-methoxytryptamine analogues was prepared and investigated, with special emphasis on substituents in the meta position of the benzyl group. A parallel series of several N-benzylated analogues of 2,5-dimethoxy-4-iodophenethylamine (2C-I) also was included for comparison of the two major templates (i.e., tryptamine and phenethylamine). A broad affinity screen at serotonin receptors showed that most of the compounds had the highest affinity at the 5-HT2 family receptors. Substitution at the para position of the benzyl group resulted in reduced affinity, whereas substitution in either the ortho or the meta position enhanced affinity. In general, introduction of a large lipophilic group improved affinity, whereas functional activity often followed the opposite trend. Tests of the compounds for functional activity utilized intracellular Ca(2+) mobilization. Function was measured at the human 5-HT2A, 5-HT2B, and 5-HT2C receptors, as well as at the rat 5-HT2A and 5-HT2C receptors. There was no general correlation between affinity and function. Several of the tryptamine congeners were very potent functionally (EC50 values from 7.6 to 63 nM), but most were partial agonists. Tests in the mouse head twitch assay revealed that many of the compounds induced the head twitch and that there was a significant correlation between this behavior and functional potency at the rat 5-HT2A receptor.

Prolonged delusional state triggered by repeated ingestion of aromatic liquid in a past 5-methoxy-N, N-diisopropyltryptamine abuser.

A 30-year-old Japanese man with no previous psychiatric history presented to our facility with delusions, which had been ongoing for 2 months. Upon further interview, he confided that he had a past history of recurrent 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT or "Foxy") abuse, as well as a recent history of recurrent ingestion of a legal aromatic liquid used as a recreational drug. After this episode, his condition improved and he did not follow up at subsequent appointments. However, 6 months later, he suffered a relapse of prolonged delusions after again ingesting a recreational aromatic liquid. An evaluation of the chronological sequence of the patient's condition revealed that ingestion of these aromatic liquids, which can be purchased easily on the Internet, likely triggered the patient's delusional episodes. We speculate that the patient's recurrent abuse of 5-MeO-DIPT caused sensitization (or reverse tolerance), thus prolonging his delusions. Sensitization is the amplification of a response following repeated administrations of a stimulus. 5-MeO-DIPT is a popular drug of abuse, and it is highly probable that a large number of past 5-MeO-DIPT users are currently sensitized. This is an important latent factor underlying subsequent episode of drug-induced psychosis. Psychiatrists should consider the possibility of 5-MeO-DIPT sensitization when evaluating patients with acute psychoses.

Assessment of the pharmacological properties of 5-methoxyindole derivatives at 5-HT4 receptors.

OBJECTIVES: The aim was to examine the biological activity of 5-methoxytryptamine derivatives at the 5-hydroxytryptamine (5-HT)(4) receptor to explore the effect of substitution on the aliphatic amine of the 5-methoxyamine scaffold. METHODS: Three compounds were tested for affinity at the 5-HT(4) receptor by radioligand binding and functional activity using guinea-pig ileum and human colon circular muscle preparations and also in the mouse whole gut transit test. KEY FINDINGS: The three compounds all had agonist properties at the 5-HT(4) receptor but their efficacy differed in the different functional tests. Compound 3 had the highest affinity for the 5-HT(4) receptor and was a full agonist at relaxing human colon circular muscle with efficacy closest to 5-HT. Compounds 1 and 2 were partial agonists in this assay with lower efficacies; compound 2 was a full agonist in the guinea-pig ileum assay whereas compound 3 was a partial agonist. Compounds 1 and 2 also showed activity in the mouse gut transit assay while compound 3 had no activity. CONCLUSIONS: Of the compounds tested, compound 3 was the most promising 5-HT(4) receptor agonist and the results highlight the value of using human tissue in functional tests when assessing compounds for potential activity.

The recreational tryptamine 5-MeO-DALT (N,N-diallyl-5-methoxytryptamine): a brief review.

5-MeO-DALT (N,N-diallyl-5-methoxytryptamine) is a psychoactive substance, sold primarily over the Internet as a 'research chemical' or 'plant food'. Although details for the synthesis of this tryptamine have been available since 2004, its use as a hallucinogenic drug has been reported only occasionally in on-line user fora. It is controlled in only a few countries world-wide. There is little scientifically-based literature on the pharmacological, physiological, psychopharmacological, toxicological and epidemiological characteristics of 5-MeO-DALT. Here we review what is known about these aspects. We also report what we believe to be the first death involving the use of this substance. The case involved a man in his mid-20s who died in mid-2010. The coroner concluded that the deceased "died from injuries sustained after being hit by a lorry whilst under the influence of 5-MeODALT". It is critical that any other cases, including non-fatal instances, are documented so that a scientific evidence-base can be established for this drug.

A quantitative method for simultaneous determination of 5-methoxy-N,N-diisopropyltryptamine and its metabolites in urine using liquid chromatography-electrospray ionization-tandem mass spectrometry.

5-Methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) is a designer hallucinogen derived from tryptamine and is reportedly abused and involved in criminal activities. For the detection of 5-MeO-DIPT use, a liquid chromatography-tandem mass spectrometric method for 5-MeO-DIPT and its metabolites, 5-hydroxy-N,N-diisopropyltryptamine (5-OH-DIPT) and 5-methoxy-N,N-isopropyltryptamine (5-MeO-IPT) was developed and validated in rat urine. The urine samples were pretreated by protein precipitation with acetonitrile and introduced into a BDS HYPERSIL C(18) column (50 × 2.0 mm, 5 µm) for chromatographic separation. Mobile phases consisted of methanol, water, and 1% formic acid, and gradient elution was used at a flow rate of 0.2 mL/min. For the MS detection, multiple-reaction monitoring analysis was adopted. The linear range was 0.01-10 µg/mL, and the lower limit of quantification was 10 ng/mL for all analytes. The intra- and interday accuracies and precisions met the criteria (<15%). The developed method was successfully applied to the drug-treated rat urine.

5-methoxy-N,N-di(iso)propyltryptamine hydrochloride (Foxy)-induced cognitive deficits in rat after exposure in adolescence.

Foxy or Methoxy Foxy (5-methoxy-N,N-di(iso)propyltryptamine hydrochloride; 5-MeO-DIPT) is rapidly gaining popularity among recreational users as a hallucinogenic "designer drug." Unfortunately, much remain unknown about the consequences of its use on neuropsychological development or behavior. During one of two adolescent periods, the rats were given repeated injections of 5 mg/kg or 20 mg/kg of 5-MeO-DIPT or a corresponding volume of isotonic saline. After the animals reached adulthood, they were trained and tested on a number of tasks designed to assess the impact of 5-MeO-DIPT, if any, on spatial memory, presumably involving declarative memory systems as well as a nonspatial task that is considered sensitive to disruptions in nondeclarative memory. Both the 5-MeO-DIPT- and saline-treated rats were able to master spatial navigation tests where the task included a single goal location and all groups performed comparably on these phases of training and testing. Regardless of exposure level during adolescence, the performance of the drug-treated rats was markedly inferior to that of the control animals on a task where the goal was moved to a new location and on a response learning task, suggesting a lack of flexibility in adapting their responses to changing task demands. Detected reductions in serotonin activity in the forebrain similar to the effects of extensively investigated compounds such as methylenedioxymethamphetamine (MDMA), suggest that 5-MeO-DIPT may produce its adverse effects by compromising serotonergic systems in the brain.