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Alexander Lipp, Dorota Ferenc, Christoph Gütz, Mario Geffe, Nina Vierengel, Dieter Schollmeyer, Hans Jürgen Schäfer, Siegfried R Waldvogel, Till Opatz
The biosynthesis of thebaine is based on the regioselective, intramolecular, oxidative coupling of (R)-reticuline. For decades, chemists have sought to mimic this coupling using stoichiometric oxidants. However, all approaches suffered from low yields or the formation of undesired regioisomers. Electrochemistry would represent a sustainable alternative in this respect but all attempts to accomplish an electrochemical synthesis of thebaine have failed so far. Herein, a regioselective and diastereoselective anodic coupling of 3',4',5'-trioxygenated laudanosine derivatives is presented, which finally enabled an electrochemical access to (-)-thebaine...
May 22, 2018: Angewandte Chemie
Ahmed Ma'mun, Mohamed K Abd El-Rahman, Mohamed Abd El-Kawy
In recent years, the whole field of ion-selective electrodes(ISEs) in pharmaceutical sciences has expanded far beyond its original roots. The diverse range of opportunities offered by ISEs was broadly used in a number of pharmaceutical applications, with topics presented ranging from bioanalysis of drugs and metabolites, to protein binding studies, green analytical chemistry, impurity profiling, and drug dissolution in biorelevant media. Inspired from these advances and with the aim of extending the functional capabilities of ISEs, the primary focus of the present paper is the utilization of ISE as a tool in personalized medicine...
May 30, 2018: Journal of Pharmaceutical and Biomedical Analysis
Tomáš Siatka, Markéta Adamcová, Lubomír Opletal, Lucie Cahlíková, Daniel Jun, Martina Hrabinová, Jiří Kuneš, Jakub Chlebek
Alzheimer's disease is an age-related, neurodegenerative disorder, characterized by cognitive impairment and restrictions in activities of daily living. This disease is the most common form of dementia with complex multifactorial pathological mechanisms. Many therapeutic approaches have been proposed. Among them, inhibition of acetylcholinesterase, butyrylcholinesterase, and prolyl oligopeptidase can be beneficial targets in the treatment of Alzheimer's disease. Roots, along with aerial parts of Argemone platyceras, were extracted with ethanol and fractionated on an alumina column using light petrol, chloroform and ethanol...
July 14, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Miguel A Torres, Elesha Hoffarth, Luiz Eugenio, Julia Savtchouk, Xue Chen, Jeremy S Morris, Peter J Facchini, Kenneth K-S Ng
Benzylisoquinoline alkaloids (BIAs) are produced in a wide variety of plants and include many common analgesic, antitussive, and anticancer compounds. Several members of a distinct family of S-adenosylmethionine (SAM)-dependent N-methyltransferases (NMTs) play critical roles in BIA biosynthesis, but the molecular basis of substrate recognition and catalysis is not known for NMTs involved in BIA metabolism. To address this issue, the crystal structure of pavine NMT from Thalictrum flavum was solved using selenomethionine-substituted protein (dmin = 2...
November 4, 2016: Journal of Biological Chemistry
Limei Chang, Jillian M Hagel, Peter J Facchini
Transcriptome resources for the medicinal plant Glaucium flavum were searched for orthologs showing identity with characterized O-methyltransferases (OMTs) involved in benzylisoquinoline alkaloid biosynthesis. Seven recombinant proteins were functionally tested using the signature alkaloid substrates for six OMTs: norlaudanosoline 6-OMT, 6-O-methyllaudanosoline 4'-OMT, reticuline 7-OMT, norreticuline 7-OMT, scoulerine 9-OMT, and tetrahydrocolumbamine OMT. A notable alkaloid in yellow horned poppy (G. flavum [GFL]) is the aporphine alkaloid glaucine, which displays C8-C6' coupling and four O-methyl groups at C6, C7, C3', and C4' as numbered on the 1-benzylisoquinoline scaffold...
October 2015: Plant Physiology
Andrea Ruiz-Olalla, Martien A Würdemann, Martin J Wanner, Steen Ingemann, Jan H van Maarseveen, Henk Hiemstra
A general procedure for the synthesis of 1-benzyl-1,2,3,4-tetrahydroisoquinolines was developed, based on organocatalytic, regio- and enantioselective Pictet-Spengler reactions (86-92% ee) of N-(o-nitrophenylsulfenyl)-2-arylethylamines with arylacetaldehydes. The presence of the o-nitrophenylsulfenyl group, together with the MOM-protection in the catechol part of the tetrahydroisoquinoline ring system, appeared to be a productive combination. To demonstrate the versatility of this approach, 10 biologically and pharmaceutically relevant alkaloids were prepared using (R)-TRIP as the chiral catalyst: (R)-norcoclaurine, (R)-coclaurine, (R)-norreticuline, (R)-reticuline, (R)-trimemetoquinol, (R)-armepavine, (R)-norprotosinomenine, (R)-protosinomenine, (R)-laudanosine, and (R)-5-methoxylaudanosine...
May 15, 2015: Journal of Organic Chemistry
Ming Zuo, Jieying Gao, Xiaoqing Zhang, Yue Cui, Zimian Fan, Min Ding
Capillary electrophoresis with electrochemiluminescence detection for the simultaneous analysis of cisatracurium besylate and its degradation products (laudanosine, quaternary monoacrylate) in pharmaceutical preparation was developed and fully validated. The significant parameters that influence capillary electrophoresis separation and electrochemiluminescence detection were optimized. The total analysis time of the analytes was 15 min. The linearities of the method were 0.1∼40.0 μg/mL for cisatracurium besylate and 0...
July 2015: Journal of Separation Science
Eduard Badarau, Sébastien Dilly, Johan Wouters, Vincent Seutin, Jean-François Liégeois
An asparagine or a histidine are present in a similar position in the outer pore region of SK2 and SK3 channels, respectively. Therefore, this structural difference was targeted in order to develop selective blockers of SK channel subtypes. Following docking investigations, based on theoretical models of truncated SK2 and SK3 channels, the benzyl side chain of N-methyl-laudanosine (NML) was functionalized in order to target this specific amino-acid residues. Chiral butanamide and benzyloxy analogues were prepared, resolved and tested for their affinity for SK2 and SK3 channels...
December 15, 2014: Bioorganic & Medicinal Chemistry Letters
Jiaquan Chen, Yingxiang Du, Fenxia Zhu, Bin Chen, Qi Zhang, Shuaijing Du, Ping Li
It has been reported that chiral dual system is able to improve the enantioseparation of enantiomers in many cases. Currently, the dual systems involved in CE chiral separation are mostly dual CDs systems, and the polysaccharides-based chiral dual system was reported in only one paper. To the best of our knowledge, the use of chondroitin sulfate C (CSC)-based dual system for enantiomeric separation has not been reported previously. Herein, four CSC-based chiral dual systems, namely CSC/glycogen, CSC/chondroitin sulfate A (CSA), CSC/hydroxypropyl-β-CD (HP-β-CD), as well as CSC/β-CD (β-CD), were evaluated for the first time for their enantioseparation capability by CE in this paper...
February 2015: Electrophoresis
T Szakmany, T Woodhouse
Cisatracurium is currently one of the most commonly used neuromuscular blocking agent (NMBA) in intensive care units. Cisatracurium was developed primarily for anaesthetic purposes in order to attempt to resolve some of the problems associated with earlier NMBAs, such as histamine release and laudanosine accumulation. Cisatracurium, the the R-cis-R-cis isomer of atracurium, is up to 5 times more potent than atracurium and so is administered in smaller quantities and produces a lesser degree of laudanosine accumulation in the plasma...
April 2015: Minerva Anestesiologica
Qi Zhang, Yingxiang Du, Jiaquan Chen, Guangfu Xu, Tao Yu, Xiaoyi Hua, Jinjing Zhang
Various chiral selectors have been utilized successfully in capillary electrophoresis (CE); however, the number of polysaccharides used as chiral selectors is still small and the mechanism of enantiorecognition has not been fully elucidated. Chondroitin sulfate D (CSD) and chondroitin sulfate E (CSE), belonging to the group of glycosaminoglycans, are linear, sulfated polysaccharides with large mass. In this paper, they were investigated for the first time for their potential as chiral selectors by CE. The effect of buffer composition and pH, chiral selector concentration, and applied voltage were systematically examined and optimized...
February 2014: Analytical and Bioanalytical Chemistry
Yingying Yang, Mei Chen, Yushan Kuang, Liming Ye, Wensheng Zhang
A high performance liquid chromatographic method coupled with fluorometric detection has been developed for the determination of atracurium and its major metabolite laudanosine in dog plasma. The separation of atracurium and laudanosine was performed on an Agilent Eclipse Plus C18 column, and the mobile phase consisted of 0.03 mol/L dipotassium hydrogen phosphate and acetonitrile (72: 28, v/v) at a flow rate of 1.0 mL/min. Verapamil was used as the internal standard. The sample was extracted by dichloromethane, concentrated and dissolved in the mobile phase...
June 2013: Se Pu, Chinese Journal of Chromatography
Xiabing Li, Daniele Leonori, Nadeem S Sheikh, Iain Coldham
The lithiation of N-tert-butoxycarbonyl (N-Boc)-1,2,3,4-tetrahydroisoquinoline was optimized by in situ IR (ReactIR) spectroscopy. Optimum conditions were found by using n-butyllithium in THF at -50 °C for less than 5 min. The intermediate organolithium was quenched with electrophiles to give 1-substituted 1,2,3,4-tetrahydroisoquinolines. Monitoring the lithiation by IR or NMR spectroscopy showed that one rotamer reacts quickly and the barrier to rotation of the Boc group was determined by variable-temperature NMR spectroscopy and found to be about 60...
June 10, 2013: Chemistry: a European Journal
Julio Cesar Orejarena Pacheco, Günther Lahm, Till Opatz
The Stevens rearrangement of nitrile-stabilized ammonium ylides in conjunction with the reductive removal of the nitrile function permits the facile construction of α-branched amines from α-aminonitriles. We employed this reaction sequence for the preparation of (±)-laudanosine, (±)-laudanidine and (±)-armepavine, (±)-7-methoxycryptopleurine, and (±)-xylopinine from two closely related and readily accessible bicyclic α-aminonitriles. The final products were obtained in high to almost quantitative yields (71-98%) from the quaternary ammonium salts obtained by N-alkylation of these starting materials...
May 17, 2013: Journal of Organic Chemistry
Thu-Thuy T Dang, Peter J Facchini
Noscapine is a benzylisoquinoline alkaloid produced in opium poppy (Papaver somniferum) and other members of the Papaveraceae. It has been used as a cough suppressant and more recently was shown to possess anticancer activity. However, the biosynthesis of noscapine in opium poppy has not been established. A proposed pathway leading from (S)-reticuline to noscapine includes (S)-scoulerine, (S)-canadine, and (S)-N-methylcanadine as intermediates. Stem cDNA libraries and latex extracts of eight opium poppy cultivars displaying different alkaloid profiles were subjected to massively parallel pyrosequencing and liquid chromatography-tandem mass spectrometry, respectively...
June 2012: Plant Physiology
Nancy Blank, Till Opatz
Under controlled conditions, 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-1-carbonitrile can be quantitatively deprotonated in the α-position. Its alkylation directly furnishes 3,4-dihydroisoquinolines which can serve as starting materials for the preparation of various alkaloids. Here, the preparation of the benzylisoquinolines (+)-laudanidine, (+)-armepavine, and (+)-laudanosine as well as the tetrahydroprotoberberines (-)-corytenchine and (-)-tetrahydropseudoepiberberine using Noyori's asymmetric transfer hydrogenation are described...
December 2, 2011: Journal of Organic Chemistry
Eduard Badarau, Sébastien Dilly, Fabien Dufour, Sylvie Poncin, Vincent Seutin, Jean-François Liégeois
A structure-activity relationship study of N-methyl-laudanosine, a SK channel blocker, has indicated that the 6,7-dimethoxy group could be successfully replaced by a hydrophobic moiety such as an isopropyl substituent in position 8 of the isoquinoline ring. In the present study, bis-(8-isopropyl-isoquinolinium) derivatives (2a-e) were synthesized and tested for their affinity for cloned SK2 and SK3 channels in comparison with their 6,7-dimethoxy analogues (4a-f). Several ligands were investigated, both in flexible (propyl, butyl and pentyl) and rigid (m- or p-xylyl) series, the m-xylyl derivative (2d) having the best profile in terms of affinity and selectivity for SK3/SK2 channels...
November 15, 2011: Bioorganic & Medicinal Chemistry Letters
Nadège Castaing, Larbi Benali, Dominique Ducint, Mathieu Molimard, Sophie Gromb, Karine Titier
The suicide of a 43-year-old male by intravenous injection of cisatracurium, a non-depolarizing neuromuscular blocking agent, and thiopental, an ultra-short-acting barbiturate, is presented. Systematic toxicological screening by gas chromatography-mass spectrometry (GC-MS), liquid chromatography (LC)-diode-array detection, and LC-MS-MS confirmed the presence of thiopental. A large peak in the GC-MS chromatogram was matched by the Pfleger-Maurer library as corlumine, but neither atracurium neither its metabolite, laudanosine, were detected...
July 2011: Journal of Analytical Toxicology
Jiaquan Chen, Yingxiang Du, Fenxia Zhu, Bin Chen
Several chiral reagents including cyclodextrins (CDs) and derivatives, crown ethers, proteins, chiral surfactants and polymers have been involved in dual selector systems for enantioseparation of a series of chiral compounds by capillary electrophoresis (CE). In comparison to the chiral reagents above-mentioned, there is no report concerning the use of polysaccharides in dual chiral CE system. In this paper we first investigate the enantioselectivity of polysaccharide-based dual selector systems towards some chiral drugs...
November 5, 2010: Journal of Chromatography. A
Xu Han, Marc Lamshöft, Nadja Grobe, Xuan Ren, Anthony J Fist, Toni M Kutchan, Michael Spiteller, Meinhart H Zenk
Papaverine is one of the earliest opium alkaloids for which a biosynthetic hypothesis was developed on theoretical grounds. Norlaudanosoline (=tetrahydropapaveroline) was claimed as the immediate precursor alkaloid for a multitude of nitrogen containing plant metabolites. This tetrahydroxylated compound was proposed to be fully O-methylated. The resulting tetrahydropapaverine should then aromatize to papaverine. In view of experimental data, this pathway has to be revised. Precursor administration to 8-day-old seedlings of Papaver followed by direct examination of the metabolic fate of the stable-isotope-labeled precursors in the total plant extract, without further purification of the metabolites, led to elucidation of the papaverine pathway in vivo...
August 2010: Phytochemistry
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