The biosynthetic pathway of the hallucinogen mescaline and its heterologous reconstruction.

Mescaline, among the earliest identified natural hallucinogens, holds great potential in psychotherapy treatment. Nonetheless, despite the existence of a postulated biosynthetic pathway for more than half a century, the specific enzymes involved in this process are yet to be identified. In this study, we investigated the cactus Lophophora williamsii (Peyote), the largest known natural producer of the phenethylamine mescaline. We employed a multi-faceted approach, combining de novo whole-genome and transcriptome sequencing with comprehensive chemical profiling, enzymatic assays, molecular modeling, and pathway engineering for pathway elucidation. We identified four groups of enzymes responsible for the six catalytic steps in the mescaline biosynthetic pathway, and an N-methyltransferase enzyme that N-methylates all phenethylamine intermediates, likely modulating mescaline levels in Peyote. Finally, we reconstructed the mescaline biosynthetic pathway in both Nicotiana benthamiana plants and yeast cells, providing novel insights into several challenges hindering complete heterologous mescaline production. Taken together, our study opens up avenues for exploration of sustainable production approaches and responsible utilization of mescaline, safeguarding this valuable natural resource for future generations.

Shared and Distinct Brain Regions Targeted for Immediate Early Gene Expression by Ketamine and Psilocybin.

Psilocybin is a psychedelic with therapeutic potential. While there is growing evidence that psilocybin exerts its beneficial effects through enhancing neural plasticity, the exact brain regions involved are not completely understood. Determining the impact of psilocybin on plasticity-related gene expression throughout the brain can broaden our understanding of the neural circuits involved in psychedelic-evoked neural plasticity. In this study, whole-brain serial two-photon microscopy and light sheet microscopy were employed to map the expression of the immediate early gene, c-Fos, in male and female mice. The drug-induced c-Fos expression following psilocybin administration was compared to that of subanesthetic ketamine and saline control. Psilocybin and ketamine produced acutely comparable elevations in c-Fos expression in numerous brain regions, including anterior cingulate cortex, locus coeruleus, primary visual cortex, central and basolateral amygdala, medial and lateral habenula, and claustrum. Select regions exhibited drug-preferential differences, such as dorsal raphe and insular cortex for psilocybin and the CA1 subfield of hippocampus for ketamine. To gain insights into the contributions of receptors and cell types, the c-Fos expression maps were related to brain-wide in situ hybridization data. The transcript analyses showed that the endogenous levels of Grin2a and Grin2b predict whether a cortical region is sensitive to drug-evoked neural plasticity for both ketamine and psilocybin. Collectively, the systematic mapping approach produced an unbiased list of brain regions impacted by psilocybin and ketamine. The data are a resource that highlights previously underappreciated regions for future investigations. Furthermore, the robust relationships between drug-evoked c-Fos expression and endogenous transcript distributions suggest glutamatergic receptors as a potential convergent target for how psilocybin and ketamine produce their rapid-acting and long-lasting therapeutic effects.

Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor.

Background: Lysergic acid diethylamide (LSD) has agonist activity at various serotonin (5-HT) and dopamine receptors. Despite the therapeutic and scientific interest in LSD, specific receptor contributions to its neurobiological effects remain unknown. Methods: We therefore conducted a double-blind, randomized, counterbalanced, cross-over studyduring which 24 healthy human participants received either (i) placebo+placebo, (ii) placebo+LSD (100 µg po), or (iii) Ketanserin, a selective 5-HT2A receptor antagonist,+LSD. We quantified resting-state functional connectivity via a data-driven global brain connectivity method and compared it to cortical gene expression maps. Results: LSD reduced associative, but concurrently increased sensory-somatomotor brain-wide and thalamic connectivity. Ketanserin fully blocked the subjective and neural LSD effects. Whole-brain spatial patterns of LSD effects matched 5-HT2A receptor cortical gene expression in humans. Conclusions: Together, these results strongly implicate the 5-HT2A receptor in LSD's neuropharmacology. This study therefore pinpoints the critical role of 5-HT2A in LSD's mechanism, which informs its neurobiology and guides rational development of psychedelic-based therapeutics. Funding: Funded by the Swiss National Science Foundation, the Swiss Neuromatrix Foundation, the Usona Institute, the NIH, the NIAA, the NARSAD Independent Investigator Grant, the Yale CTSA grant, and the Slovenian Research Agency. Clinical trial number: NCT02451072

The psychedelic drug LSD alters thinking and perception. Users can experience hallucinations, in which they, for example, see things that are not there. Colors, sounds and objects can appear distorted, and time can seem to speed up or slow down. These changes bear some resemblance to the changes in thinking and perception that occur in certain psychiatric disorders, such as schizophrenia. Studying how LSD affects the brain could thus offer insights into the mechanisms underlying these conditions. There is also evidence that LSD itself could help to reduce the symptoms of depression and anxiety disorders. Preller et al. have now used brain imaging to explore the effects of LSD on the brains of healthy volunteers. This revealed that LSD reduced communication among brain areas involved in planning and decision-making, but it increased communication between areas involved in sensation and movement. Volunteers whose brains showed the most communication between sensory and movement areas also reported the strongest effects of LSD on their thinking and perception. Preller et al. also found that another drug called Ketanserin prevented LSD from altering how different brain regions communicate. It also prevented LSD from inducing changes in thinking and perception. Ketanserin blocks a protein called the serotonin 2A receptor, which is activated by a brain chemical called serotonin that, amongst other roles, helps to regulate mood. By mapping the location of the gene that produces the serotonin 2A receptor, Preller et al. showed that the receptor is present in brain regions that show altered communication after LSD intake, therefore pinpointing the importance of this receptor in the effects of LSD. Psychiatric disorders that produce psychotic symptoms affect vast numbers of people worldwide. Further research into how LSD affects the brain could help us to better understand how such symptoms arise, and may also lead to the development of more effective treatments for a range of mental health conditions.

Enzymatic Synthesis of Psilocybin.

Psilocybin is the psychotropic tryptamine-derived natural product of Psilocybe carpophores, the so-called "magic mushrooms". Although its structure has been known for 60 years, the enzymatic basis of its biosynthesis has remained obscure. We characterized four psilocybin biosynthesis enzymes, namely i) PsiD, which represents a new class of fungal l-tryptophan decarboxylases, ii) PsiK, which catalyzes the phosphotransfer step, iii) the methyltransferase PsiM, catalyzing iterative N-methyl transfer as the terminal biosynthetic step, and iv) PsiH, a monooxygenase. In a combined PsiD/PsiK/PsiM reaction, psilocybin was synthesized enzymatically in a step-economic route from 4-hydroxy-l-tryptophan. Given the renewed pharmaceutical interest in psilocybin, our results may lay the foundation for its biotechnological production.

Δ9-Tetrahydrocannabinol reverses TNFα-induced increase in airway epithelial cell permeability through CB2 receptors.

Despite pharmacological treatment, bronchial hyperresponsiveness continues to deteriorate as airway remodelling persists in airway inflammation. Previous studies have demonstrated that the phytocannabinoid Δ9-tetrahydrocannabinol (THC) reverses bronchoconstriction with an anti-inflammatory action. The aim of this study was to investigate the effects of THC on bronchial epithelial cell permeability after exposure to the pro-inflammatory cytokine, TNFα. Calu-3 bronchial epithelial cells were cultured at air-liquid interface. Changes in epithelial permeability were measured using Transepithelial Electrical Resistance (TEER), then confirmed with a paracellular permeability assay and expression of tight junction proteins by Western blotting. Treatment with THC prevented the TNFα-induced decrease in TEER and increase in paracellular permeability. Cannabinoid CB1 and CB2 receptor-like immunoreactivity was found in Calu-3 cells. Subsequent experiments revealed that pharmacological blockade of CB2, but not CB1 receptor inhibited the THC effect. Selective stimulation of CB2 receptors displayed a similar effect to that of THC. TNFα decreased expression of the tight junction proteins occludin and ZO-1, which was prevented by pre-incubation with THC. These data indicate that THC prevents cytokine-induced increase in airway epithelial permeability through CB2 receptor activation. This highlights that THC, or other cannabinoid receptor ligands, could be beneficial in the prevention of inflammation-induced changes in airway epithelial cell permeability, an important feature of airways diseases.

Chronic treatment with LY341495 decreases 5-HT(2A) receptor binding and hallucinogenic effects of LSD in mice.

Hallucinogenic drugs, such as lysergic acid diethylamide (LSD), mescaline and psilocybin, alter perception and cognitive processes. All hallucinogenic drugs have in common a high affinity for the serotonin 5-HT(2A) receptor. Metabotropic glutamate 2/3 (mGlu2/3) receptor ligands show efficacy in modulating the cellular and behavioral responses induced by hallucinogenic drugs. Here, we explored the effect of chronic treatment with the mGlu2/3 receptor antagonist 2S-2-amino-2-(1S,2S-2-carboxycyclopropan-1-yl)-3-(xanth-9-yl)-propionic acid (LY341495) on the hallucinogenic-like effects induced by LSD (0.24mg/kg). Mice were chronically (21 days) treated with LY341495 (1.5mg/kg), or vehicle, and experiments were carried out one day after the last injection. Chronic treatment with LY341495 down-regulated [(3)H]ketanserin binding in somatosensory cortex of wild-type, but not mGlu2 knockout (KO), mice. Head-twitch behavior, and expression of c-fos, egr-1 and egr-2, which are responses induced by hallucinogenic 5-HT(2A) agonists, were found to be significantly decreased by chronic treatment with LY341495. These findings suggest that repeated blockade of the mGlu2 receptor by LY341495 results in reduced 5-HT(2A) receptor-dependent hallucinogenic effects of LSD.

Metabotropic glutamate mGlu2 receptor is necessary for the pharmacological and behavioral effects induced by hallucinogenic 5-HT2A receptor agonists.

Hallucinogenic drugs, including mescaline, psilocybin and lysergic acid diethylamide (LSD), act at serotonin 5-HT2A receptors (5-HT2ARs). Metabotropic glutamate receptor 2/3 (mGluR2/3) ligands show efficacy in modulating the responses induced by activation of 5-HT2ARs. The formation of a 5-HT2AR-mGluR2 complex suggests a functional interaction that affects the hallucinogen-regulated cellular signaling pathways. Here, we tested the cellular and behavioral effects of hallucinogenic 5-HT2AR agonists in mGluR2 knockout (mGluR2-KO) mice. Mice were intraperitoneally injected with the hallucinogens DOI (2 mg/kg) and LSD (0.24 mg/kg), or vehicle. Head-twitch behavioral response, expression of c-fos, which is induced by all 5-HT2AR agonists, and expression of egr-2, which is hallucinogen-specific, were determined in wild type and mGluR2-KO mice. [(3)H]Ketanserin binding displacement curves by DOI were performed in mouse frontal cortex membrane preparations. Head twitch behavior was abolished in mGluR2-KO mice. The high-affinity binding site of DOI was undetected in mGluR2-KO mice. The hallucinogen DOI induced c-fos in both wild type and mGluR2-KO mice. However, the induction of egr-2 by DOI was eliminated in mGlu2-KO mice. These findings suggest that the 5-HT2AR-mGluR2 complex is necessary for the neuropsychological responses induced by hallucinogens.

Mitochondrial dysfunction and biotransformation of ß-carboline alkaloids, harmine and harmaline, on isolated rat hepatocytes.

The cytotoxic effects and biotransformation of harmine and harmaline, which are known ß-carboline alkaloids and potent hallucinogens, were studied in freshly isolated rat hepatocytes. The exposure of hepatocytes to harmine caused not only concentration (0-0.50mM)- and time (0-3h)-dependent cell death accompanied by the formation of cell blebs and the loss of cellular ATP, reduced glutathione, and protein thiols but also the accumulation of glutathione disulfide. Of the other analogues examined, the cytotoxic effects of harmaline and harmol (a metabolite of harmine) at a concentration of 0.5mM were less than those of harmine. The loss of mitochondrial membrane potential and generation of oxygen radical species in hepatocytes treated with harmine were greater than those with harmaline and harmol. In the oxygen consumption of mitochondria isolated from rat liver, the ratios of state-3/state-4 respiration of these ß-carbolines were decreased in a concentration-dependent manner. In addition, harmine resulted in the induction of the mitochondrial permeability transition (MPT), and the effects of harmol and harmaline were less than those of harmine. At a weakly toxic level of harmine (0.25mM), it was metabolized to harmol and its monoglucuronide and monosulfate conjugates, and the amounts of sulfate rather than glucuronide predominantly increased with time. In the presence of 2,5-dichloro-4-nitrophenol (50µM; an inhibitor of sulfotransferase), harmine-induced cytotoxicity was enhanced, accompanied by decrease in the amount of harmol-sulfate conjugate, due to an increase in the amount of unconjugated harmol and the inhibition of harmine loss. Taken collectively, these results indicate that (a) mitochondria are target organelles for harmine, which elicits cytotoxicity through mitochondrial failure related to the induction of the MPT, mitochondrial depolarization, and inhibition of ATP synthesis; and (b) the toxic effects of harmine are greater than those of either its metabolite harmol or its analogue harmaline, suggesting that the onset of harmine-induced cytotoxicity may depend on the initial and/or residual concentrations of harmine rather than on those of its metabolites.

Involvement of mitochondrial/lysosomal toxic cross-talk in ecstasy induced liver toxicity under hyperthermic condition.

The initial objectives of this study were to evaluate the extent of 3, 4-methylenedioxymethamphetamine (MDMA) induced loss of cell viability (cytotoxicity), induction of reactive oxygen species formation and damage to sub-cellular organelles (e.g. mitochondria/lysosomes) in freshly isolated rat hepatocytes under normothermic conditions (37 degrees C) and to compare the results with the effects obtained under hyperthermic conditions (41 degrees C). MDMA induced cytotoxicity, reactive oxygen species formation, mitochondrial membrane potential decline and lysosomal membrane leakiness in isolated rat hepatocytes at 37 degrees C. A rise in incubation temperature from 37 degrees C to 41 degrees C had an additive/synergic effect on the oxidative stress markers. We observed variations in mitochondrial membrane potential and lysosomal membrane stability that are significantly (P<0.05) higher than those under normothermic conditions. Antioxidants, reactive oxygen species scavengers, lysosomal inactivators, mitochondrial permeability transition (MPT) pore sealing agents, NADPH P450 reductase inhibitor, and inhibitors of reduced CYP2E1 and CYP2D6 prevented all MDMA induced hepatocyte oxidative stress cytotoxicity markers. It is therefore suggested that metabolic reductive activation of MDMA by reduced cytochrome P450s and glutathione could lead to generation of some biological reactive intermediates which could activate reactive oxygen species generation and cause mitochondrial and lysosomal oxidative stress membrane damages. We finally concluded that hyperthermia could potentiate MDMA induced liver toxicity probably through a mitochondrial/lysosomal toxic cross-talk in freshly isolated rat hepatocytes.

Enzymatic-nonenzymatic cellular antioxidant defense systems response and immunohistochemical detection of MDMA, VMAT2, HSP70, and apoptosis as biomarkers for MDMA (Ecstasy) neurotoxicity.

3,4-Methylenedioxymethamphetamine (MDMA)-induced neurotoxicity leads to the formation of quinone metabolities and hydroxyl radicals and then to the production of reactive oxygen species (ROS). We evaluated the effect of a single dose of MDMA (20 mg/kg, i.p.) on the enzymatic and nonenzymatic cellular antioxidant defense system in different areas of rat brain in the early hours (<6 hr) of the administration itself, and we identified the morphological expressions of neurotoxicity induced by MDMA on the vulnerable brain areas in the first 24 hr. The acute administration of MDMA produces a decrease of reduced and oxidized glutathione ratio, and antioxidant enzyme activities were significantly reduced after 3 hr and after 6 hr in frontal cortex. Ascorbic acid levels strongly increased in striatum, hippocampus, and frontal cortex after 3 and 6 hr. High levels of malonaldehyde with respect to control were measured in striatum after 3 and 6 hr and in hippocampus and frontal cortex after 6 hr. An immunohistochemical investigation on the frontal, thalamic, hypothalamic, and striatal areas was performed. A strong positive reaction to the antivesicular monoamine transporter 2 was observed in the frontal section, in the basal ganglia and thalamus. Cortical positivity, located in the most superficial layer was revealed only for heat shock protein 70 after 24 hr.

Engineering and characterization of a mouse/human chimeric anti-phencyclidine monoclonal antibody.

Previously, our laboratory produced a high affinity, anti-phencyclidine (PCP) murine monoclonal antibody (mAb6B5) that also binds other PCP-like arylcyclohexylamines. In this project, mAb6B5 is engineered into a mouse/human chimera (ch-mAb6B5) to assess the feasibility of developing it into a medication for PCP and PCP-like drug abuse. To create ch-mAb6B5, the light and heavy chain constant regions of mAb6B5 were replaced with human kappa and IgG(2) constant regions in order to decrease its potential immunogenicity in humans. To be an effective anti-PCP medication, ch-mAb6B5 must retain the critical immunochemical binding properties of mAb6B5. Expression vectors containing ch-mAb6B5 light chain and heavy chain cDNA were constructed and expressed in the murine myeloma cell line P3X63-Ag8.653. Immunoassays confirm that ch-mAb6B5 is indeed a chimera, composed of mAb6B5's PCP-binding variable domains and human kappa and IgG constant regions. Radioimmunoassays show that ch-mAb6B5 has the same drug-binding profile as mAb6B5. Ch-mAb6B5 and mAb6B5 bind PCP with a K(D) of 0.67 nM and 1.17 nM (respectively) and bind PCP-like arylcyclohexylamines 1-[1-(2-thienyl)cyclohexyl]piperidine and N-ethyl-1-phenylcyclohexylamine with similar specificity. Additionally, ch-mAb6B5 and mAb6B5 have the same calculated isoelectric points and molecular weights, critical properties in antigen-antibody interactions. These data demonstrate that mouse/human ch-mAb6B5, a "more human" version of murine mAb6B5, retains mAb6B5's unique drug-binding properties. This work supports our continued efforts to develop ch-mAb6B5 into a medication for PCP and PCP-like drug abuse - introducing the intriguing possibility of using a single therapeutic mAb for treating a class of abused drugs.

Bioactivation of phencyclidine in rat and human liver microsomes and recombinant P450 2B enzymes: evidence for the formation of a novel quinone methide intermediate.

The hypothesis that the psychological side effects associated with the anesthetic phencyclidine (PCP) may be caused by irreversible binding of PCP or its reactive metabolite(s) to critical macromolecules in the brain has resulted in numerous in vitro studies aimed at characterizing pathways of PCP bioactivation. The studies described herein extend the current knowledge of PCP metabolism and provide details on a previously unknown metabolic activation pathway of PCP. Following incubations with NADPH- and GSH-supplemented human and rat liver microsomes and recombinant P450 2B enzymes, two sulfhydryl conjugates with MH+ ions at 547 and 482 Da, respectively, were detected by LC/MS/MS. Shebley et al. [(2006) Drug Metab. Dispos. 34, 375-383] have also observed the GSH conjugate 1 with MH+ at 547 Da in PCP incubations with rat P450 2B1 and rabbit P450 2B4 isoforms fortified with NADPH and GSH. The molecular weight of 1 is consistent with a bioactivation pathway involving Michael addition of the sulfhydryl nucleophile to the putative 2,3-dihydropyridinium metabolite of PCP obtained via a four-electron oxidation of the piperidine ring in the parent compound. The mass spectrum of the novel GSH adduct 2 with an MH+ ion at 482 Da was suggestive of a unique PCP bioactivation pathway involving initial ortho- or para-hydroxylation of the phenyl ring in PCP followed by spontaneous decomposition to piperidine and an electrophilic quinone methide intermediate, which upon reaction with GSH yielded adduct 2. The LC retention times and mass spectral properties of enzymatically generated 2 were identical to those of a reference standard obtained via reaction of GSH with synthetic p-hydroxyPCP in phosphate buffer (pH 7.4, 37 degrees C). 1H NMR and 13C-distortionless enhancement by polarization transfer (DEPT) NMR spectral studies on synthetically generated 2 suggested that the structural integrity of the p-hydroxyphenyl and cyclohexyl rings likely was preserved and that the site of GSH addition was the benzylic carbon joining the two scaffolds. The formation of 2 in human microsomes was reduced upon addition of the dual P450 2C19/P450 2B6 inhibitor (+)- N-3-benzylnirvanol. Consistent with this finding, both recombinant P450 2B6 and P450 2C19 catalyzed PCP bioactivation to 2. In the absence of GSH, synthetic p-hydroxyPCP underwent rapid decomposition (t1/2 approximately 5.2 min) to afford p-hydroxyphenylcyclohexanol and p-hydroxyphenylcyclohexene, presumably via the quinone methide intermediate. Overall, our findings on the facile degradation of synthetic p-hydroxyPCP to yield an electrophilic quinone methide intermediate capable of reacting with nucleophiles, including GSH and water, suggest an inherent instability of the putative phenolic PCP metabolite. Thus, if formed enzymatically in vivo, p-hydroxyPCP may not require further metabolism to liberate the quinone methide, which can then react with macromolecules. To our knowledge, this is the first report of a quinone methide reactive intermediate obtained in human-liver microsomal metabolism of PCP.

Formation of scopolamine from N-butyl-scopolammonium bromide in cigarettes.

Scopolamine (hyoscine) is a naturally occurring alkaloid found in solonacea, the so-called "night shade" plants. Therapeutic applications of scopolamine are in ophthalmology to cause mydriasis and for the prevention of motion sickness, among others. It is known to induce hallucinogenic effects at a high dose. The N-butyl bromide derivative of scopolamine, available commercially as Buscopan, is commonly used as an antispasmotic. The possibility of forming scopolamine from N-butyl-scopolammonium bromide when burning cigarettes fortified with Buscopan was investigated based on a record of a prison inmate who claimed to experience hallucinations after smoking Buscopan. Liquid chromatography-tandem mass spectrometry in electrospray ionization mode was used to monitor the formation of scopolamine. Various series of eight cigarettes spiked with 10 mg of N-butyl-scopolammonium bromide with and without filters and in different smoking modes were investigated. The smoke of the burning cigarettes, the ashes, and the filter were analyzed for the presence of scopolamine. Scopolamine was detected in all cases.

Neurotoxicity mechanisms of thioether ecstasy metabolites.

3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy"), is a widely abused, psychoactive recreational drug that is known to induce neurotoxic effects. Human and rat hepatic metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, which are both catechols that can undergo oxidation to the corresponding ortho-quinones. Ortho-quinones may be conjugated with glutathione (GSH) to form glutathionyl adducts, which can be transported into the brain and metabolized to the correspondent N-acetylcysteine (NAC) adducts. In this study we evaluated the neurotoxicity of nine MDMA metabolites, obtained by synthesis: N-Me-alpha-MeDA, alpha-MeDA and their correspondent GSH and NAC adducts. The studies were conducted in rat cortical neuronal cultures, for a 6 h of exposure period, under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Our findings show that thioether MDMA metabolites are strong neurotoxins, significantly more than their correspondent parent catechols. On the other hand, N-Me-alpha-MeDA and alpha-MeDA are more neurotoxic than MDMA. GSH and NAC conjugates of N-Me-alpha-MeDA and alpha-MeDA induced a concentration dependent delayed neuronal death, accompanied by activation of caspase 3, which occurred earlier in hyperthermic conditions. Furthermore, thioether MDMA metabolites time-dependently increased the production of reactive species, concentration-dependently depleted intracellular GSH and increased protein bound quinones. Finally, thioether MDMA metabolites induced neuronal death and oxidative stress was prevented by NAC, an antioxidant and GSH precursor. This study provides new insights into the neurotoxicity mechanisms of thioether MDMA metabolites and highlights their importance in "ecstasy" neurotoxicity.

Differential helical orientations among related G protein-coupled receptors provide a novel mechanism for selectivity. Studies with salvinorin A and the kappa-opioid receptor.

Salvinorin A, the active component of the hallucinogenic sage Salvia divinorum, is an apparently selective and highly potent kappa-opioid receptor (KOR) agonist. Salvinorin A is unique among ligands for peptidergic G protein-coupled receptors in being nonnitrogenous and lipid-like in character. To examine the molecular basis for the subtype-selective binding of salvinorin A, we utilized an integrated approach using chimeric opioid receptors, site-directed mutagenesis, the substituted cysteine accessibility method, and molecular modeling and dynamics studies. We discovered that helix 2 is required for salvinorin A binding to KOR and that two residues (Val-108(2.53) and Val-118(2.63)) confer subtype selectivity. Intriguingly, molecular modeling studies predicted that these loci exhibit an indirect effect on salvinorin A binding, presumably through rotation of helix 2. Significantly, and in agreement with our in silico predictions, substituted cysteine accessibility method analysis of helix 2 comparing KOR and the delta-opioid receptor, which has negligible affinity for salvinorin A, revealed that residues known to be important for salvinorin A binding exhibit a differential pattern of water accessibility. These findings imply that differences in the helical orientation of helix 2 are critical for the selectivity of salvinorin A binding to KOR and provide a structurally novel basis for ligand selectivity.

Neurotoxicity of Ecstasy metabolites in rat cortical neurons, and influence of hyperthermia.

3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") is a widely abused, psychoactive recreational drug. There is growing evidence that the MDMA neurotoxic profile may be highly dependent on both its hepatic metabolism and body temperature. Metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, both of which are catechols that can undergo oxidation to the corresponding ortho-quinones. In the presence of glutathione (GSH), ortho-quinones may be conjugated with GSH to form glutathionyl adducts. In this study, we evaluated the neurotoxicity of MDMA and three of its metabolites obtained by synthesis, N-Me-alpha-MeDA, alpha-MeDA, and 5-(GSH)-alpha-MeDA [5-(glutathion-S-yl)-alpha-methyldopamine] in rat cortical neuronal serum-free cultures under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Cell viability was assessed, and the mechanism of cell death was also evaluated. Our study shows that these metabolites are more neurotoxic [5-(GSH)-alpha-MeDA being the most toxic] than the parent compound MDMA. The neurotoxicity of MDMA metabolites was partially prevented by the antioxidants N-acetylcystein and also, in a minor extent, by alpha-phenyl-N-tert-butyl nitrone. All the tested compounds induced apoptotic cell death in cortical neurons, and their neurotoxic effect was potentiated under hyperthermic conditions. These data suggest that MDMA metabolites, especially under hyperthermic conditions, contribute to MDMA-induced neurotoxicity.

Tetrahydrocannabinols in clinical and forensic toxicology.

Cannabinoids are the natural constituents of marihuana (cannabis). The main of them are delta9-tetrahydrocannabinol (9THC)--psychoactive agent, cannabinol (CBN) and cannabidiol (CBD). Cannabis is administered either by smoking or orally. 9THC potency and duration of action as well as its and two of its major metabolites concentrations in organism highly depend on the route of administration. A single active dose of 9THC is estimated on 520 mg. 9THC is rapidly metabolised. It is hydroxylated to an active metabolite, I1 -hydroxy-delta9-tetrahydro-cannabinol (11-OH-THC), then oxidised to an inactive 11-nor-9-carboxy-delta9-tetrahydrocannabinol (THCCOOH), which is conjugated with glucuronic acid and predominantly excreted in the urine. The maximum psychological effect persists for 4-6 h after administration despite of very low 9THC blood concentrations. 9THC plasma concentration declined to values of 2-3 ng/ml during 3-4 h after smoking. Such a low concentration of the active compound in human organism create a demand for use of sensitive analytical methods for detection and determination of 9THC and its metabolites. The most effective techniques for 9THC and related compounds determination in biological material are chromatographic ones (gas and liquid) with mass spectrometric detection and different ionization modes. 9THC and its two metabolites (11-OH-THC and THCCOOH) are present in blood and hair, 9THC in saliva, and THCCOOH in urine. 9THC and related compounds are determined in autopsy material, although deaths by overdose of cannabis are exceptionally rare. Fatalities happen most often after intravenous injection of hashish oil. 9THC and its metabolites determination in different biological materials gives the basis for a wide interpretation of analytical results for clinical and forensic toxicology purposes.

Quantification of the plant-derived hallucinogen Salvinorin A in conventional and non-conventional biological fluids by gas chromatography/mass spectrometry after Salvia divinorum smoking.

A gas chromatography method with mass spectrometric detection is described for the determination of Salvinorin A, the main active ingredient of the hallucinogenic mint Salvia divinorum. The method was validated in plasma, urine, saliva and sweat using 17-alpha-methyltestosterone as internal standard. The analytes were extracted from biological matrices with chloroform/isopropanol (9:1, v/v). Chromatography was performed on a 5% phenyl methyl silicone capillary column and analytes were determined in the selected ion monitoring mode. The method was validated over the concentration range 0.015-5 microg/mL plasma, urine and saliva and 0.01-5 microg/patch in the case of sweat. Mean recoveries ranged between 77.1 and 92.7% for Salvinorin A in different biological matrices, with precision and accuracy always better than 15%. The method was applied to the analysis of urine, saliva and sweat from two consumers after smoking 75 mg plant leaves to verify the presence of the active ingredient of S. divinorum in human biological fluids as a biomarker of plant consumption. Salvinorin A was detected in urine (2.4 and 10.9 ng/mL) and saliva (11.1 and 25.0 ng/mL), but not in sweat patches from consumers.

Hepatotoxicity of 3,4-methylenedioxyamphetamine and alpha-methyldopamine in isolated rat hepatocytes: formation of glutathione conjugates.

The amphetamine designer drugs 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") and its N-demethylated analogue 3,4-methylenedioxyamphetamine (MDA or "love") have been extensively used as recreational drugs of abuse. MDA itself is a main MDMA metabolite. MDMA abuse in humans has been associated with numerous reports of hepatocellular damage. Although MDMA undergoes extensive hepatic metabolism, the role of metabolites in MDMA-induced hepatotoxicity remains unclear. Thus, the aim of the present study was to evaluate the effects of MDA and alpha-methyldopamine (alpha-MeDA), a major metabolite of MDA, in freshly isolated rat hepatocyte suspensions. The cells were incubated with MDA or alpha-MeDA at final concentrations of 0.1, 0.2, 0.4, 0.8, or 1.6 mM for 3 h. The toxic effects induced following incubation of hepatocyte suspensions with these metabolites were evaluated by measuring cell viability, the extent of lipid peroxidation, levels of glutathione (GSH) and glutathione disulfide (GSSG), the formation of GSH conjugates, and the activities of GSSG reductase (GR), GSH peroxidase (GPX), and GSH S-transferase (GST). MDA induced a concentration- and time-dependent GSH depletion, but had a negligible effect on lipid peroxidation, cell viability, or on the activities of GR, GPX, and GST. In contrast, alpha-MeDA (1.6 mM, 3 h) induced a marked depletion of GSH accompanied by a loss on cell viability, and decreases in GR, GPX and GST activities, although no significant effect on lipid peroxidation was found. For both metabolites, GSH depletion was not accompanied by increases in GSSG levels; rather, 2-(glutathion- S-yl)-alpha-MeDA and 5-(glutathion- S-yl)-alpha-MeDA were identified by HPLC-DAD/EC within cells incubated with MDA or alpha-MeDA. The results provide evidence that one of the early consequences of MDMA metabolism is a disruption of thiol homeostasis, which may result in loss of protein function and the initiation of a cascade of events leading to cellular damage.

Stereochemical analysis of 3,4-methylenedioxymethamphetamine and its main metabolites by gas chromatography/mass spectrometry.

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is consumed as the racemate but some metabolic steps are enantioselective. In addition, chiral properties are preserved during MDMA biotransformation. A quantitative analytical methodology using gas chromatography/mass spectrometry (GC/MS) to determine enantioselective disposition in the body of MDMA and its main metabolites including 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) was developed. Plasma and urine samples were collected from a male volunteer. The analysis of MDMA, MDA, and 4-hydroxy-3-methoxy metabolites by GC/MS required a two-step derivatization procedure. The first step consisted of derivatization of the amine with enantiomerically pure Mosher's reagent ((R)-MTPCl). Triethylamine was used as a base to neutralize hydrochloric acid formed during the reaction allowing quantitative derivatization, which resulted in a substantial improvement in the sensitivity of the method compared with other previously described techniques. Further treatment with ammonium hydroxide was required since both amine and hydroxyl groups underwent derivatization in the reaction. Ammonium hydroxide breaks bonds formed with hydroxyl groups without affecting amine derivatives. The second derivatization step using hexamethyldisilazane was needed for metabolites containing phenol residues. This derivatization method permitted the stereochemically specific study of MDMA and its main monohydroxylated metabolites by GC/MS. A detailed study of the chemical reactions involved in the derivatization steps was indispensable to develop a straightforward, sensitive, and reproducible method for the analysis of the parent drug compound and its metabolites.