Photoelectrochemical determination of ractopamine based on inner filter effect between gold nanoparticles and graphitic carbon nitride-copper(II) polyphthalocyanine coupled with 3D DNA stabilizer.

Copper(II) polyphthalocyanine (CuPPc) was combined with graphitic carbon nitride (g-C3N4) to form a heterojunction with enhanced photoelectrochemical (PEC) signal. A sensitive PEC method was developed for determination of ractopamine based on a PEC inner filter effect between gold nanoparticles (AuNPs) and the g-C3N4/CuPPc. A gold electrode was modified with g-C3N4/CuPPc and the DNA was linked to the AuNPs. Initially, the PEC signal is weak due to the inner filter effect between the AuNPs and g-C3N4/CuPPc. In the presence of ractopamine, it interacts with the aptamer and the complementary chain (C chain) is released. This triggers the entropy-driven cyclic amplification and results in the release of the substrate B chain (SB chain) from three-dimensional DNA stabilizer. The probe is released from the electrode due to the interaction of probe DNA and the SB chain. As a result, the PEC signal increases linearly in the 0.1 pmol·L-1 to 1000 pmol·L-1 ractopamine concentration range. The detection limit is 0.03 pM, and the relative standard deviation is 3.4% (at a 10 pmol·L-1 level; for n = 11). The method has been successfully applied to the determination of ractopamine in pork samples. Graphical abstract Schematic presentation of detection method based on PEC inner filter effect between AuNPs and the g-C3N4/CuPPc being fabricated for ractopamine. 3D DNA was used as stabilizer to decrease the PEC blank signal.

Structurally Related Kappa Opioid Receptor Agonists with Substantial Differential Signaling Bias: Neuroendocrine and Behavioral Effects in C57BL6 Mice.

Background: The kappa opioid receptor system has been revealed as a potential pharmacotherapeutic target for the treatment of addictions to substances of abuse. Kappa opioid receptor agonists have been shown to block the rewarding and dopamine-releasing effects of psychostimulants. Recent investigations have profiled the in vivo effects of compounds biased towards G-protein-mediated signaling, with less potent arrestin-mediated signaling. The compounds studied here derive from a series of trialkylamines: N-substituted-N- phenylethyl-N-3-hydroxyphenylethyl-amine, with N-substituents including n-butyl (BPHA), methylcyclobutyl (MCBPHA), and methylcyclopentyl (MCPPHA). Methods: BPHA, MCBPHA, and MCPPHA were characterized in vitro in a kappa opioid receptor-expressing cell line in binding assays and functional assays. We also tested the compounds in C57BL6 mice, assaying incoordination with rotarod, as well as circulating levels of the neuroendocrine kappa opioid receptor biomarker, prolactin. Results: BPHA, MCBPHA, and MCPPHA showed full kappa opioid receptor agonism for G-protein coupling compared with the reference compound U69,593. BPHA showed no measurable ß-arrestin-2 recruitment, indicating that it is extremely G-protein biased. MCBPHA and MCPPHA, however, showed submaximal efficacy for recruiting ß-arrestin-2. Studies in C57BL6 mice reveal that all compounds stimulate release of prolactin, consistent with dependence on G-protein signaling. MCBPHA and MCPPHA result in rotarod incoordination, whereas BPHA does not, consistent with the reported requirement of intact kappa opioid receptor/ß-arrestin-2 mediated coupling for kappa opioid receptor agonist-induced rotarod incoordination. Conclusions: BPHA, MCBPHA, and MCPPHA are thus novel differentially G-protein-biased kappa opioid receptor agonists. They can be used to investigate how signaling pathways mediate kappa opioid receptor effects in vitro and in vivo and to explore the effects of candidate kappa opioid receptor-targeted pharmacotherapeutics.

A new cinnamoylphenethylamine derivative from a Mongolian Allium species, Allium carolinianum.

A new cinnamoylphenethylamine derivative, compound 1, was isolated as the main HPLC peak after partitioning the methanol extract of bulbs of a Mongolian onion species, Allium carolinianum DC. The chemical structure of this substance was determined by spectroscopic analysis including MS, and 1D and 2D NMR. Compound 1 showed weak cytotoxic activity in the murine leukemia cell line P388.

5-HT2A/5-HT2C Receptor Pharmacology and Intrinsic Clearance of N-Benzylphenethylamines Modified at the Primary Site of Metabolism.

The toxic hallucinogen 25B-NBOMe is very rapidly degraded by human liver microsomes and has low oral bioavailability. Herein we report on the synthesis, microsomal stability, and 5-HT2A/5-HT2C receptor profile of novel analogues of 25B-NBOMe modified at the primary site of metabolism. Although microsomal stability could be increased while maintaining potent 5-HT2 receptor agonist properties, all analogues had an intrinsic clearance above 1.3 L/kg/h predictive of high first-pass metabolism.

Rubemamine and Rubescenamine, Two Naturally Occurring N-Cinnamoyl Phenethylamines with Umami-Taste-Modulating Properties.

Sensory screening of a series of naturally occurring N-cinnamoyl derivatives of substituted phenethylamines revealed that rubemamine (9, from Chenopodium album) and rubescenamine (10, from Zanthoxylum rubsecens) elicit strong intrinsic umami taste in water at 50 and 10 ppm, respectively. Sensory tests in glutamate- and nucleotide-containing bases showed that the compounds influence the whole flavor profile of savory formulations. Both rubemamine (9) and rubescenamine (10) at 10-100 ppm dose-dependently positively modulated the umami taste of MSG (0.17-0.22%) up to threefold. Among the investigated amides, only rubemamine (9) and rubescenamine (10) are able to directly activate the TAS1R1-TAS1R3 umami taste receptor. Moreover, both compounds also synergistically modulated the activation of TAS1R1-TAS1R3 by MSG. Most remarkably, rubemamine (9) was able to further positively modulate the IMP-enhanced TAS1R1-TAS1R3 response to MSG ∼ 1.8-fold. Finally, armatamide (11), zanthosinamide (13), and dioxamine (14), which lack intrinsic umami taste in vivo and direct receptor response in vitro, also positively modulated receptor activation by MSG about twofold and the IMP-enhanced MSG-induced TAS1R1-TAS1R3 responses approximately by 50%. In sensory experiments, dioxamine (14) at 25 ppm in combination with 0.17% MSG exhibited a sensory equivalent to 0.37% MSG.

Receptor interaction profiles of novel N-2-methoxybenzyl (NBOMe) derivatives of 2,5-dimethoxy-substituted phenethylamines (2C drugs).

BACKGROUND: N-2-methoxybenzyl-phenethylamines (NBOMe drugs) are newly used psychoactive substances with poorly defined pharmacological properties. The aim of the present study was to characterize the receptor binding profiles of a series of NBOMe drugs compared with their 2,5-dimethoxy-phenethylamine analogs (2C drugs) and lysergic acid diethylamide (LSD) in vitro. METHODS: We investigated the binding affinities of 2C drugs (2C-B, 2C-C, 2C-D, 2C-E, 2C-H, 2C-I, 2C-N, 2C-P, 2C-T-2, 2C-T-4, 2C-T-7, and mescaline), their NBOMe analogs, and LSD at monoamine receptors and determined functional 5-hydroxytryptamine-2A (5-HT2A) and 5-HT2B receptor activation. Binding at and the inhibition of monoamine uptake transporters were also determined. Human cells that were transfected with the respective human receptors or transporters were used (with the exception of trace amine-associated receptor-1 [TAAR1], in which rat/mouse receptors were used). RESULTS: All of the compounds potently interacted with serotonergic 5-HT2A, 5-HT2B, 5-HT2C receptors and rat TAAR1 (most Ki and EC50: <1 µM). The N-2-methoxybenzyl substitution of 2C drugs increased the binding affinity at serotonergic 5-HT2A, 5-HT2C, adrenergic α1, dopaminergic D1-3, and histaminergic H1 receptors and monoamine transporters but reduced binding to 5-HT1A receptors and TAAR1. As a result, NBOMe drugs were very potent 5-HT2A receptor agonists (EC50: 0.04-0.5 µM) with high 5-HT2A/5-HT1A selectivity and affinity for adrenergic α1 receptors (Ki: 0.3-0.9 µM) and TAAR1 (Ki: 0.06-2.2 µM), similar to LSD, but not dopaminergic D1-3 receptors (most Ki:>1 µM), unlike LSD. CONCLUSION: The binding profile of NBOMe drugs predicts strong hallucinogenic effects, similar to LSD, but possibly more stimulant properties because of α1 receptor interactions.

Further insights into the pharmacology of the human trace amine-associated receptors: discovery of novel ligands for TAAR1 by a virtual screening approach.

Trace Amine-Associated Receptor 1 (TAAR1) is a G protein-coupled receptor that is expressed in brain and periphery and responds to a class of compounds called trace amines, such as ß-phenylethylamine (ß-PEA), tyramine, tryptamine, octopamine. The receptor is known to have a very rich pharmacology and could be also activated by different classes of compounds, including dopaminergic, adrenergic and serotonergic ligands. It is expected that targeting hTAAR1 could provide a novel pharmacological approach for several human disorders, such as schizophrenia, depression, attention deficit hyperactivity disorder, Parkinson's disease and metabolic diseases. Only recently, a small number of selective hTAAR1 agonists (among which RO5166017 and T1 AM) and antagonist (EPPTB), have been reported in literature. With the aim to identify new molecular entities able to act as ligands for this target, we used an homology model for the hTAAR1 and performed a virtual screening procedure on an in-house database of compounds. A number of interesting molecules were selected and by testing them in an in vitro assay we found several agonists and one antagonist, with activities in the low micromolar range. These compounds could represent the starting point for the development of more potent and selective TAAR1 ligands.

Determination of selected biogenic amines in Acacia rigidula plant materials and dietary supplements using LC-MS/MS methods.

Extracts of Acacia rigidula leaves are used in weight-loss products sold in vitamin shops and over the internet with little or no published data about their potential biological effects. In our chemical investigations on authenticated A. rigidula plant material, we established a rapid and sensitive LC-MS/MS method for the quantitative determination of several phenethylamine, tyramine and tryptamine derivatives. Stable isotopically labeled compounds were used as internal standards for quantitative analysis. We found total calculated contents of 6 biogenic amines in A. rigidula leaf of 18.6 and 32.9µg/g. The content of selected amines in 21 dietary supplements labeled as containing A. rigidula was determined by a second LC-MS/MS method. Our study revealed significant differences in the amine profiles of authenticated plant materials and dietary supplements. ß-Methylphenethylamine, a non-natural compound, was found in 9 of the 21 dietary supplement products. ß-Methylphenethylamine was found at levels of 960-60,500µg/g while phenethylamine was found at levels of 710-171,620µg/g. ß-Methylphenethylamine is a positional isomer of amphetamine and our results showed that it can be misidentified as amphetamine during LC-MS analysis. An independent GC-MS analysis was used to confirm the presence of ß-methylphenethylamine and the absence of amphetamine in dietary supplements labeled as containing A. rigidula. This study demonstrates that confirmations by independent analytical methods are essential to verify findings of unusual or unexpected compounds in dietary supplements.

'Legal highs'--novel and emerging psychoactive drugs: a chemical overview for the toxicologist.

INTRODUCTION: 'Legal highs' are psychoactive chemicals which are sold from 'head shops', the internet and from street suppliers and may be possessed without legal restriction. An increase in the marketing of these materials has resulted in a corresponding increase in published reports of their adverse effects. However, a lack of primary literature pertaining to their chemistry, pharmacology and toxicology, makes an evaluation of their harm difficult. This review covers the basic chemistry of these novel psychoactive compounds and relates them to endogenous neurotransmitters and existing drugs of abuse. METHODS: A survey of the internet was used to identify websites that are marketing 'legal highs' in the UK. Trivial and systematic chemical compound names, for example methoxetamine, 4-methoxyphencycline, 4-fluorotropacocaine and ethyl phenidate were entered into PubMed to retrieve data on these compounds. This search elicited no citations. Other search terms which were more fruitful included desoxypipradrol, diphenylprolinol, methylenedioxy-2-amino-indane and methylenedioxy-2-amino-tetralin, alpha-methyltryptamine and 5-methoxy-N,N-diallyl-tryptamine. RESULTS: 'Legal highs' from the phenylethylamine, cocaine, tryptamine and phencyclidine classes are increasingly being marketed and, in the majority of cases, little is cited in the literature on their true chemical identity, pharmacology or toxicology. CONCLUSIONS: 'Legal highs' are gaining in popularity and present clear challenges to toxicologists and society as a whole. Whilst improved use of existing legislation and development of new legislation can be used to reduce the supply of these materials, investment in better education for young people on the harms associated with 'legal highs' is needed.

Two novel phenethylamine alkaloids from streptomyces sp. YIM10049.

Two novel phenethylamine alkaloids were isolated from Streptomyces sp. YIM 10049. On the basis of spectral data, their structures were determined as (S)-N-(cu-phenylethyl)-2 -hydroxyl-acrylimine (1) and (S)-N-nitroso-1-amino-p-hydroxy phenylethanol (2). Three known compounds, indole-3-carboxylic acid (3), cyclo(L-Ala-L-Tyr)(4), and bis(2-ethylhexyl) phthalate (5), were also isolated and characterized. Compound 1 is a rare enol tautomer, and compound 2 an unusual phenethylamine alkaloid with a N-NO group.

G protein- and agonist-bound serotonin 5-HT2A receptor model activated by steered molecular dynamics simulations.

A 5-HT(2A) receptor model was constructed by homology modeling based on the ß(2)-adrenergic receptor and the G protein-bound opsin crystal structures. The 5-HT(2A) receptor model was transferred into an active conformation by an agonist ligand and a G(αq) peptide in four subsequent steered molecular dynamics (MD) simulations. The driving force for the transformation was the addition of several known intermolecular and receptor interhelical hydrogen bonds enforcing the necessary helical and rotameric movements. Subsquent MD simulations without constraints confirmed the stability of the activated receptor model as well as revealed new information about stabilizing residues and bonds. The active 5-HT(2A) receptor model was further validated by retrospective ligand screening of more than 9400 compounds, whereof 182 were known ligands. The results show that the model can be used in drug discovery for virtual screening and structure-based ligand design as well as in GPCR activation studies.

Cinnamoylphenethylamine 1H-NMR chemical shifts: a concise reference for ubiquitous compounds.

1H-NMR data of 25 cinnamoylphenethylamine derivates were recorded and compared in order to assign signals unequivocally without additional spectroscopic data. The spectra provide a key for the rapid identification of these ubiquitous natural products. The compounds isomerize rapidly in UV light, producing a characteristic upfield shift of the olefinic protons consistent with distorted planarity of the cis cinnamate, and this requires special attention during preparative work.

Chemistry, pharmacology, and metabolism of emerging drugs of abuse.

In recent years, besides the classic designer drugs of the amphetamine type, a series of new drug classes appeared on the illicit drugs market. The chemistry, pharmacology, toxicology, metabolism, and toxicokinetics is discussed of 2,5-dimethoxy amphetamines, 2,5-dimethoxy phenethylamines, beta-keto-amphetamines, phencyclidine derivatives as well as of herbal drugs, ie, Kratom. They have gained popularity and notoriety as rave drugs. The metabolic pathways, the involvement of cytochrome P450 isoenzymes in the main pathways, and their roles in hepatic clearance are also summarized.

Effects of synephrine and beta-phenethylamine on human alpha-adrenoceptor subtypes.

Synephrine and beta-phenethylamine, two naturally occurring compounds, are structurally related to ephedrine. In this study, the effects of synephrine and beta-phenethylamine on alpha-adrenergic receptor (alpha-AR) subtypes are investigated in human embryonic kidney (HEK293) or Chinese hamster ovary (CHO) cells, and compared to that of 1R,2S-norephedrine. The rank order of binding affinities was found to be the same for the subtypes tested (alpha(1A)-, alpha(2A)-, and alpha(2C)-AR) viz, 1R,2S-norephedrine > beta-phenethylamine > synephrine. Functional studies on the alpha(1A)-AR subtype showed that synephrine was a partial agonist giving a maximal response at 100 microM that was equal to 55.3 % of the L-phenylephrine maximum. In contrast, neither 1R,2S-norephedrine nor beta-phenethylamine exhibited agonist activity at the highest concentration tested (300 microM). beta-Phenethylamine was more potent as an antagonist than 1R,2S-norephedrine and synephrine on the alpha(1A)-AR subtype. Functional studies on the alpha(2A)- and alpha(2C)-AR subtypes indicated that synephrine and beta-phenethylamine did not act as agonists. Similar to 1R,2S-norephedrine, both of these analogs reversed the effect of medetomidine against forskolin-induced cAMP elevations at 300 microM, and the rank order of antagonist potency was: 1R,2S-norephedrine = beta-phenethylamine > synephrine; and beta-phenethylamine > 1R,2S-norephedrine > synephrine, respectively. These differences suggest that the presence of a 4-hydroxy group, as in synephrine, reduced the potency in these subtypes. In conclusion, at the alpha(1A)-AR, synephrine acted as a partial agonist, while beta-phenethylamine did not exhibit any direct agonist activity. Both, synephrine and beta-phenethylamine, may act as antagonists of pre-synaptic alpha(2A/2C)-ARs present in nerve terminals.

Fast high-performance liquid chromatography analysis of phenethylamine alkaloids in Citrus natural products on a pentafluorophenylpropyl stationary phase.

In this study, the chromatographic performance of a pentafluorophenylpropyl (PFPP) stationary phase was evaluated for the rapid separation of phenethylamine alkaloids (i.e. (+/-)-octopamine, (+/-)-synephrine, tyramine, N-methyltyramine and hordenine) in Citrus aurantium plant material (fruits and peel), various Citrus species, extracts and dietary supplements claiming to contain C. aurantium. The problems of phenethylamine alkaloid separation, such as peak tailing, low retention and low resolution, were successfully solved with this stationary phase. The parameters used for the method optimization included the mobile phase counter ion concentration and column temperature. A Discovery HS F5 column (150 mm x 4.6 mm i.d., 5 microm) was used, with an isocratic mobile phase composed of 10 mM ammonium acetate in 90:10 ACN-H(2)O (v/v), at a flow rate of 1.0 mL/min. The column temperature was set at 20 degrees C. The photodiode array detector monitored the eluent at 225 nm. The total analysis time was 10 min. The validation parameters, such as linearity, sensitivity, accuracy, precision and specificity, were found to be highly satisfactory. With a simple sample preparation procedure, different matrices were successfully analyzed for their alkaloid content. The results indicated that the products on sale, labeled as dietary supplements, vary widely in the quantitative composition of the active constituents: the amount of (+/-)-synephrine, the major alkaloid, in such products ranged from 0.65 to 27.41 mg/g. The other compounds were either not detected or were present at low levels. The developed method can be considered suitable for the quality control of Citrus plant material and commercial products.

[Studies on constituents from the fermentation of Alternalia sp].

OBJECTIVE: To study the metabolites of marine fungus Alternalia sp. METHOD: Compounds were separated by column chromatography and their structures were elucidated by means of chemical and spectral analysis. RESULT: Six compounds were isolated from the ethyl acetate and n-butanol extracts of the fermentation of marine fungus Alternalia sp. Their structures were elucidated as p-benzyloxy-phenol ( I ), p-hydroxy phenyl ethylamine( II ), 3-hydroxymethyl-8-hydroxyl-pyrrolopiperazine-2, 5-dione ( III ), 3-isobutyl-6-secbutyl-piperazine-2, 5-dione (IV), 5alpha, 8alpha-epidioxy-ergosta-6, 22-diene-3beta-ol (V), 3beta-hydroxxy-cholesta-5-ene (VI). CONCLUSION: Compounds I , II, III, IV have the activity of inducing morphological deformation of mycelia germinated from conidia of Pyricularia oryzae. Compounds I , II , III were isolated from the genus Alternalia for the first time.

Discovery of nonxanthine adenosine A2A receptor antagonists for the treatment of Parkinson's disease.

During a program to investigate the biochemical basis of side effects associated with the antimalarial drug mefloquine, the authors made the unexpected discovery that the (-)-(R,S)-enantiomer of the drug is a potent adenosine A2A receptor antagonist. Although the compound was ineffective in in vivo animal models of central adenosine receptor function, it provided a unique nonxanthine adenosine A2A receptor antagonist lead structure and encouraged the initiation of a medicinal chemistry program to develop novel adenosine A2A antagonists for the management of Parkinson's disease (PD). The authors have synthesized and screened more than 2,000 chemically diverse and novel adenosine A(2A antagonists. Early examples from two distinct chemical series are the thieno[3,2-dy]pyrimidine VER-6623 and the purine compounds VER-6947 and VER-7835, which have high affinity at adenosine A2A receptors (K(i) values 1.4, 1.1, and 1.7 nmol/L, respectively) and act as competitive antagonists. In particular, VER-6947 and VER-7835 demonstrate potent in vivo activity reversing the locomotor deficit caused by the D2 receptor antagonist haloperidol, with minimum effective doses comparable with that of KW6002 (0.3 to 1 mg/kg). In conclusion, the authors have discovered potent, selective, and in vivo active nonxanthine adenosine A2A antagonists that have considerable promise as a new therapy for PD.

Synthesis and biological activity of KCB-328 and its analogues: novel class III antiarrhythmic agents with little reverse frequency dependence.

A series of 3,4-dimethoxyphenethylamine derivatives was prepared, and their prolongation effects on effective refractory period of contractile response (ERPc) and action potential duration (APD) in isolated guinea-pig papillary muscles at 1 Hz and 3 Hz were examined. SAR studies led to the identification of KCB-328 (51) which is a novel class III antiarrhythmic agent with little reverse frequency dependence.