Over a century since ephedrine discovery: an updated revisit to its pharmacological aspects, functionality and toxicity in comparison to its herbal extracts.

Ephedrine, a sympathomimetic amine that exhibits several adrenaline actions, is a plant alkaloid that is a common ingredient in several cold, asthma and narcolepsy treatment preparations, and in obesity management and sport medicine. Its principal action mechanism relies on its direct adrenergic actions as well as indirect role that involves the release of epinephrine and norepinephrine, thus increasing the activity of epinephrine and norepinephrine at the postsynaptic α and ß receptors. Nevertheless, its serious side effects, including stroke, heart attack, drug abuse and interactions, have never been comprehensively reviewed. We conducted a systematic review of data on ephedrine, including its occurrence in functional foods, pharmacological aspects, metabolism, pharmaco/toxicokinetics and clinical features. Furthermore, a review of ephedrine natural structural analogues with regards to their differential adrenergic receptor binding affinities, food interaction, and their impact on the pharmacokinetics and effects relative to ephedrine are presented for the first time, and in comparison to its action when present in herbs.

Adrenergic Modulation With Photochromic Ligands.

Adrenoceptors are ubiquitous and mediate important autonomic functions as well as modulating arousal, cognition, and pain on a central level. Understanding these physiological processes and their underlying neural circuits requires manipulating adrenergic neurotransmission with high spatio-temporal precision. Here we present a first generation of photochromic ligands (adrenoswitches) obtained via azologization of a class of cyclic amidines related to the known ligand clonidine. Their pharmacology, photochromism, bioavailability, and lack of toxicity allow for broad biological applications, as demonstrated by controlling locomotion in zebrafish and pupillary responses in mice.

Hydroxypropyl ß-cyclodextrin nanohybrid monoliths for use in capillary electrochromatography with UV detection: application to the enantiomeric separation of adrenergic drugs, anticholinergic drugs, antidepressants, azoles, and antihistamine.

Two kinds of hydroxypropyl ß-cyclodextrin nanohybrid monoliths were synthesized and applied in capillary electrochromatography with UV detection. One column was fabricated by concurrently using glycidyl methacrylate-bonded hydroxypropyl ß-cyclodextrin (GMA-HP-ß-CD), sodium 3-mercaptopropanesulphonate, and alkoxysilanes in the "one-pot" process. The other was prepared by free radical polymerization of GMA-HP-ß-CD, vinylmethylcyclosiloxane, ethylene dimethacrylate, and 2-acrylamido-2-methyl propane sulfonic acid. Compared to the former hybrid monolith, the latter one displayed improved enantiomeric separation. For ten adrenergic drugs, six anticholinergic drugs, two antidepressants, six azoles, and one antihistamine enantiomeric separation was obtained on the monolith synthesized by free radical polymerization. Twelve out of twenty-five drugs were baseline-separated. Especially, anisodamine with two chiral centers was successfully separated with resolution values of 3.06, 2.11, and 2.17. The nanohybrid monoliths were characterized by optical microscopy, scanning electron microscopy, FT-IR, nitrogen adsorption analysis, and thermogravimetric analysis. Relative standard deviation values less than 5% were obtained through run-to-run, day-to-day, and column-to-column investigations (n = 3). Graphical abstract Schematic representation of two kinds of hydroxypropyl ß-cyclodextrin nanohybrid monoliths based on "one-pot" approach (route I) and free radical polymerization approach (route II), respectively.

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH.

Coordinate and redox interactions of epinephrine (Epi) with iron at physiological pH are essential for understanding two very different phenomena - the detrimental effects of chronic stress on the cardiovascular system and the cross-linking of catecholamine-rich biopolymers and frameworks. Here we show that Epi and Fe3+ form stable high-spin complexes in the 1:1 or 3:1 stoichiometry, depending on the Epi/Fe3+ concentration ratio (low or high). Oxygen atoms on the catechol ring represent the sites of coordinate bond formation within physiologically relevant bidentate 1:1 complex. Redox properties of Epi are slightly impacted by Fe3+. On the other hand, Epi and Fe2+ form a complex that acts as a strong reducing agent, which leads to the production of hydrogen peroxide via O2 reduction, and to a facilitated formation of the Epi-Fe3+ complexes. Epi is not oxidized in this process, i.e. Fe2+ is not an electron shuttle, but the electron donor. Epi-catalyzed oxidation of Fe2+ represents a plausible chemical basis of stress-related damage to heart cells. In addition, our results support the previous findings on the interactions of catecholamine moieties in polymers with iron and provide a novel strategy for improving the efficiency of cross-linking.

Ligand-binding characterization of simulated ß-adrenergic-like octopamine receptor in Schistocerca gregaria via progressive structure simulation.

It is important to design insecticides having both low drug resistance and less undesirable toxicity for desert locust control. Specific GPCRs of Schistocerca gregaria, especially ß-adrenergic-like octopamine receptor (SgOctßR), can be considered as its potential effective insecticide targets. However, either the unavailability of SgOctßR's structure or the inadequate capability of its sequence lead the development of insecticide for Schistocerca gregaria meets its plateau. To relax this difficulty, this paper develops a promising progressive structure simulation from SgOctßR's sequence, to its predicted structure of SgOctßR in vacuum, to its conformation as well as its complex with endogenous ligand octopamine in a solvent-membrane system. The combined approach of multiple sequence alignment, static structural characterization, and dynamic process of conformational change during binding octopamine reveal three important aspects. The first one is the characterization of SgOctßR's active pocket, including the attending secondary structure elements, its hydrophobic residues and nonpolar surface. The second one is the interaction with octopamine, especially the involved hydrogen bonds and an aromatic stacking of pi-pi interactions. The third one is the potential binding sites, including six highly conserved residues and one highly variable residue for locust insecticide design. This work is definitely helpful for the further structure-based drug design for efficient and eco-friendly insecticides, as well as site-directed mutagenesis biochemical research of SgOctßR.

Fluparoxan: A Comprehensive Review of its Discovery, Adrenergic and CNS Activity and Treatment of Cognitive Dysfunction in Central Neurodegenerative Diseases.

BACKGROUND: The design, medicinal chemistry, pharmacokinetics and development of the highly selective α2-adrenoceptor antagonist fluparoxan are reviewed. METHOD: The drug's activity and selectivity in vitro, its efficacy in animals and its excellent oral pharmacokinetics and central α2-adrenoceptor antagonist activity in man, are evaluated as well as its ability to increase extracellular levels of noradrenaline, dopamine and acetylcholine in vivo. CONCLUSION: Furthermore, its potential for the treatment of central neurodegenerative diseases is highlighted, in particular its improvement of cognitive dysfunction in schizophrenia and in models of Alzheimer's disease.

Dual protection of hydroxytyrosol, an olive oil polyphenol, against oxidative damage in PC12 cells.

Hydroxytyrosol (3,4-dihydroxyphenylethanol, HT), a major polyphenol in olive oils, has received increasing attention due to its multiple pharmacological activities. However, it is not well understood how HT works on the neuronal system. We report herein that HT efficiently scavenges free radicals in vitro and displays cytoprotection against oxidative stress-induced damage in PC12 cells. HT completely protects the cells from hydrogen peroxide-induced death and rescues the cells from 6-hydroxydopamine-induced damage. Mechanistic studies reveal that Nrf2 is a prerequisite for the neuroprotection of HT as knocking down Nrf2 eliminated this action. HT, via activation of the Keap1-Nrf2 pathway, elevates a panel of cytoprotective enzymes, including glutamate-cysteine ligase, HO-1, NQO1 and thioredoxin reductase. Our study reveals that HT provides dual neuroprotection and cellular antioxidant defense as both a free radical scavenger and Nrf2 activator, suggesting the potential pharmaceutical usage of HT for the treatment of neurodegenerative disorders.

Proteomic identification of calcium-binding chaperone calreticulin as a potential mediator for the neuroprotective and neuritogenic activities of fruit-derived glycoside amygdalin.

Amygdalin is a fruit-derived glycoside with the potential for treating neurodegenerative diseases. This study was designed to identify the neuroprotective and neuritogenic activities of amygdalin. We initially demonstrated that amygdalin enhanced nerve growth factor (NGF)-induced neuritogenesis and attenuated 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in rat dopaminergic PC12 cells. To define protein targets for amygdalin, we selected a total of 11 mostly regulated protein spots from two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels for protein identification by matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry. We verified the effect of amygdalin on six representative proteins (i.e., calreticulin, Hsp90ß, Grp94, 14-3-3η, 14-3-3ζ/δ and Rab GDI-α) for biological relevance to neuronal survival and differentiation. Calcium-binding chaperone calreticulin is of special interest for its activities to promote folding, oligomeric assembly and quality control of proteins that modulate cell survival and differentiation. We transiently knocked down calreticulin expression by specific siRNA and studied its effect on the neuroprotective and neuritogenic activities of amygdalin. We found that amygdalin failed to enhance NGF-induced neuritogenesis in calreticulin-siRNA transfected cells. On the other hand, amygdalin rescued 6-OHDA-induced loss of calreticulin expression. We also found that amygdalin increased the intracellular calcium concentration possibly via inducing calreticulin. Collectively, our results demonstrated the role of calreticulin in mediating the neuroprotective and neuritogenic activities of amygdalin.

New α-adrenergic property for synthetic MTß and CM-3 three-finger fold toxins from black mamba.

Despite their isolation more than fifteen years ago from the venom of the African mamba Dendroaspis polylepis, very few data are known on the functional activity of MTß and CM-3 toxins. MTß was initially classified as a muscarinic toxin interacting non-selectively and with low affinity with the five muscarinic receptor subtypes while no biological function was determined for CM-3. Recent results highlight the multifunctional activity of three-finger fold toxins for muscarinic and adrenergic receptors and reveal some discrepancies in the pharmacological profiles of their venom-purified and synthetic forms. Here, we report the pharmacological characterization of chemically-synthesized MTß and CM-3 toxins on nine subtypes of muscarinic and adrenergic receptors and demonstrate their high potency for α-adrenoceptors and in particular a sub-nanomolar affinity for the α1A-subtype. Strikingly, no or very weak affinity were found for muscarinic receptors, highlighting that pharmacological characterizations of venom-purified peptides may be risky due to possible contaminations. The biological profile of these two homologous toxins looks like that one previously reported for the Dendroaspis angusticeps ρ-Da1a toxin. Nevertheless, MTß and CM-3 interact more potently than ρ-Da1a with α1B- and α1D-AR subtypes. A computational analysis of the stability of the MTß structure suggests that mutation S38I, could be involved in this gain in function.

Parallel synthesis of potent dopaminergic N-phenyltriazole carboxamides applying a novel click chemistry based phenol linker.

Taking advantage of our click chemistry based methodology to construct novel SPOS (solid phase organic synthesis) resins, the triazolylmethyl linked catechol 6a was discovered, which is readily available via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) of azidomethyl substituted polystyrene with O-propargylcatechol and can be applied for the parallel synthesis of N-phenyltriazole carboxamides. As a proof-of-concept, a 'catch-and-release' strategy could be successfully applied for a parallel synthesis of dopaminergic phenyltriazoles of type 2. A focused model library of 20 test compounds revealing three points of diversity was generated by a three-step SPOS approach. Product purification was performed employing a solid-supported carboxylic acid anhydride as a scavenger. GPCR-ligand binding screening revealed dopamine D3 receptor ligands with K(i) values in the single digit nanomolar range.

Evolution of neurotoxins: from research modalities to clinical realities.

In the 1950s, the discovery of anti-nerve growth factor, an immunotoxin stunting sympathetic neural development, signaled the advent of neurotoxins as research modalities. Other selective neurotoxins were discovered in rapid succession. In the 1960s, 6-hydroxydopamine and 6-hydroxydopa were shown to destroy noradrenergic and dopaminergic nerves. Excitotoxins (glutamate, aspartate, and analogs) were discovered in the 1970s. DSP-4 [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine] proved to be selective for noradrenergic destruction, while 5,6- and 5,7-dihydroxytryptamines were relatively selective for serotonin neurons. Additional neurotoxins were discovered, but it was MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) that predominated neurotoxicity research in the 1980s. Eventually, Clostridium botulinum neurotoxin (BoNT), discovered as a "poisonous" principle in the late 1800s, resurfaced in purified and standardized forms as a clinically useful drug. Neurotoxins represent chemical tools, useful not only for discerning neuronal mechanisms and animal modeling of neurological disorders, but also for their use in medicine and potential as treatments for medical disorders. This unit reviews the early discovery of neurotoxins, describes categories of neurotoxins, and finally characterizes their usefulness--first as research tools, and eventually as clinical therapeutic agents.

Evaluation of the cholinergic and adrenergic effects of two tropane alkaloids from Erythroxylum pervillei.

Pervilleine A is an aromatic ester tropane alkaloid from Erythroxylum pervillei that has shown promising activity as a multidrug resistance inhibitor. Due to its structural similarity with the well known (-)-hyoscyamine and (-)-cocaine, the cholinergic and adrenergic activities of pervilleine A were evaluated. At 30 microm (+/-)-pervilleine A hydrochloride exhibited non-competitive inhibition of the cholinergic response in the guinea-pig ileum and did not affect the carbachol-induced contraction of the rat anococcygeus smooth muscle. (+/-)-Pervilleine A hydrochloride blocked nonspecifically the vascular response of (-)-norepinephrine in the rat aorta ring, while the contractile response of rat vas deferens to (-)-norepinephrine was not affected significantly at a 100 microm concentration. An analogue of pervilleine A, (+/-)-pervilleine H, without a 6-O-trans-3,4,5-trimethoxycinnamoyl ester substituent required for anti-multidrug resistance activity, did not exhibit any effects in these experiments. The data suggest that (+/-)-pervilleine A hydrochloride has weak nonspecific anticholinergic and vascular antiadrenergic activities. The lack of significant cholinergic and adrenergic receptor-mediated activities may be considered advantageous for the further development of pervilleine A as a new adjuvant in cancer chemotherapy.

Adrenoceptor and other pharmacoactive compounds as putative antifoulants.

The search for new antifouling methods, which are non-hazardous for the marine environment, is intense. However, even if several innovations in this field of research have been made, the search for unique molecules with characteristics such as strong biological activity, low residence time in the marine environment and which target special physiological features in marine invertebrate larvae, biofilm forming bacteria or algal spores is still required. This chapter reviews the effects of biogenic amine receptor agonists and antagonists, primarily G protein-coupled receptors, on settling barnacle cypris larvae. Biotechnological research on adrenoceptor compounds as lead molecules in new antifouling technologies is also reviewed.

[TLC-FT-SERS study on a pair of optic isomers in ephedra].

A new method for analyzing the ingredients of a pair of optic isomers in ephedra, nor-ephedrine and nor-pseudo-ephedrine, using hyphenated high-efficiency thin layer chromatography (TLC) and surface-enhanced Raman spectroscopy (SERS) techniques, is reported. The results show that the characteristic spectral bands of nor-ephedrine and nor-pseudo-ephedrine can be obtained from the TLC spot with 8 microg sample of about 2.0 mm in diameter. The difference between the SERS and solid spectra was found. Spectral bands at 1004 cm(-1) and 1605 cm(-1) were found greatly enhanced. Molecule was absorbed in surface silver sol by pi electrons in ring. Under similar experimental conditions the spectral information of Levo-nor-ephedrine ramifications TLC-SERS is rich with strong credibility, whereas dextral-nor-ephedrine ramifications show a relatively strong fluorescence backdrop with less spectral information and weak credibility. The effective combination of TLC and SERS can be used to analyse the chemical ingredients with high sensitivity.

Separation of ephedrine stereoisomers by molecularly imprinted polymers--influence of synthetic conditions and mobile phase compositions on the chromatographic performance.

Separation of ephedrine stereoisomers by molecularly imprinted polymers was performed to study the factors that affect the selectivity and column efficiency. The polymer synthesized with pentaerythritol triacrylate as the cross-linker and chloroform as the porogen was found to have the best overall separation performance. Investigation of the recognition mechanism by NMR and chromatographic analysis revealed that the major binding forces between the polymer stationary phase and ephedrine are the ionic and hydrogen bonding interactions. Studies of the influence of mobile phase compositions on the HPLC analysis have shown that a methanol-aqueous buffer was the suitable mobile phase for the separation in which pH, ionic strength and water content can be adjusted to optimize the chromatographic analysis.

4-Hydroxylation of debrisoquine by human CYP1A1 and its inhibition by quinidine and quinine.

A panel of 15 recombinant cytochromes P450 expressed in human B-lymphoblastoid cells was used to study debrisoquine 4-hydroxylation. Both CYP2D6 and CYP1A1 carried out the reaction. The apparent K(m) (micromolar) and V(max) (picomoles per minute per picomole of P450) for CYP2D6 were 12.1 and 18.2 and for CYP1A1 were 23.1 and 15.2, respectively. CYP1A1 debrisoquine 4-hydroxylase was inhibited by the CYP1A1 inhibitor alpha-naphthoflavone and the CYP1A1 substrate 7-ethoxyresorufin. Additionally and surprisingly, this reaction was also inhibited by quinidine and quinine, with respective IC(50) values of 1.38 +/- 0.10 and 3.31 +/- 0.14 microM, compared with those for CYP2D6 debrisoquine 4-hydroxylase of 0.018 +/- 0.05 and 3.75 +/- 2.07 microM, respectively. Anti-CYP1A1 monoclonal antibody (mAb) 1-7-1 abolished CYP1A1 debrisoquine hydroxylase and anti-CYP2D6 mAb 50-1-3 eradicated CYP2D6 debrisoquine 4-hydroxylase. Three further CYP2D6-specific reactions were tested: dextromethorphan O-demethylation, bufuralol 1'-hydroxylation, and sparteine dehydrogenation. The CYP2D6 specificity, judged by the CYP2D6/CYP1A1 activity ratios was 18.5, 7.0, 6.0, and 1.6 for dextromethorphan, bufuralol, sparteine, and debrisoquine, respectively. Thus, debrisoquine is not a specific CYP2D6 substrate and quinidine is not a specific CYP2D6 inhibitor. These findings have significant implications for the conduct of in vitro drug metabolism inhibition studies and underscore the fallacy of "specific chemical inhibitors" of a supergene family of enzymes that have overlapping substrate specificities. The use of highly specific mAbs in such studies is mandated. It is unclear as yet whether these findings have implications for the relationship between CYP2D6 genotype and in vivo debrisoquine 4-hydroxylase activity.

6-hydroxydopamine increases the hydroxylation and nitration of phenylalanine in vivo: implication of peroxynitrite formation.

In the present study, we investigated the effect of the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA) on hydroxyl free radical and peroxynitrite formation in vivo using D-phenylalanine as a novel mechanistic probe. In vivo microdialysis was carried out in the striatum of freely moving male Wistar rats. The microdialysis probes were perfused with artificial cerebrospinal fluid containing 5 mM D-phenylalanine (flow rate 2 microL/min). After obtaining a stable baseline 6-OHDA was delivered into the striatum via reverse microdialysis for 60 min. HPLC measurements of the effluent were performed using photodiode array detection for determination of phenylalanine derived o-tyrosine and m-tyrosine (as hydroxylation markers) as well as of nitrotyrosine and nitrophenylalanine (as nitration markers). The basal levels of the hydroxylation derived products of phenylalanine were approximately 100-fold higher than those of the nitration derived products. 6-OHDA (0.1, 1, 10 mM) significantly increased o- and m-tyrosine up to nine- and 13-fold, respectively, whereas levels of 3-nitrotyrosine and 4-nitrophenylalanine were significantly increased up to 422- and 358-fold, respectively. The results demonstrate that phenylalanine is a sensitive in vivo marker for 6-OHDA-induced hydroxylation and nitration reactions which are clearly concentration dependent. We conclude that peroxynitrite formation is involved in 6-OHDA-induced neurochemical effects.

Direct enantioseparation of adrenergic drugs via thin-layer chromatography using molecularly imprinted polymers.

Molecularly imprinted polymers (MIPs) of (-)-pseudoephedrine and (-)-norephedrine were prepared to use as chiral stationary phases (CSPs) in thin layer chromatography (TLC). The resolution of the enantiomers of adrenergic drugs, including pseudoephedrine, ephedrine, norephedrine, and epinephrine were investigated on these CSPs. In preparation of MIPs, two monomers: (1) methacrylic acid and (2) itaconic acid were employed as functional monomers. Mobile phase system of either methanol or acetonitrile was used and the effects of acetic acid content of the mobile phases were also investigated. The best resolution was achieved for enantioseparation of norephedrine on plates based on MIP of (-)-norephedrine using itaconic acid as functional monomer (alpha = 5.1) in mobile phase 1% acetic acid in methanol. Moreover, these MIPs were able to resolve the racemates of compounds whose structures corresponded to print molecule. The results obtained showed that TLC based on MIPs could succeed the direct separation of enantiomers of adrenergic drugs as a method of separation. The method offers a rapid, sensitive and reliable method for quality control of optically active compounds.

Orally active benzamide antipsychotic agents with affinity for dopamine D2, serotonin 5-HT1A, and adrenergic alpha1 receptors.

New antipsychotic drugs are needed because current therapy is ineffective for many schizophrenics and because treatment is often accompanied by extrapyramidal symptoms and dyskinesias. This paper describes the design, synthesis, and evaluation of a series of related (aminomethyl)benzamides in assays predictive of antipsychotic activity in humans. These compounds had notable affinity for dopamine D2, serotonin 5-HT1A, and alpha1-adrenergic receptors. The arylpiperazine 1-[3-[[4-[2-(1-methylethoxy)phenyl]-1-piperazinyl]methyl]benzoyl]p ipe ridine (mazapertine, 6) was chosen because of its overall profile for evaluation in human clinical trials. The corresponding 4-arylpiperidine derivative 67 was also highly active indicating that the aniline nitrogen of 6 is not required for activity. Other particularly active structures include homopiperidine amide 14 and N-methylcyclohexylamide 31.