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N-Heterocycles
Published in Navjeet Kaur, Metals and Non-Metals, 2020
Ondansetron is a prototypic 5-HT3 receptor antagonist. The imidazole moiety present in ondansetron is incorporated into the molecule upon substitution of trimethylammonium group of an advanced intermediate by 2-methylimidazole [21]. This substitution is carried out on cyclohexenone prior to the Fischer indole synthesis [22]. The imidazole required here is synthesized by various protocols. For example, the desired compound is obtained in excellent yields (95%) by the reaction of glyoxal, acetaldehyde and ammonium carbonate (Scheme 5). The 2-methylimidazole is formed in approximately 90% yield by condensation of ethylenediamine and acetic acid at high temperatures in the presence of γ-aluminium oxide as the catalyst [23–24].
Opportunities and Challenges of Biosensors Based on Nanomaterials and Nanodevices
Published in Li Jun, Wu Nianqiang, Biosensors Based on Nanomaterials and Nanodevices, 2017
Effective strategies, including physical, covalent, and bioaffinity immobilization, have been developed, which are summarized in review articles [11,14,16] and detailed in relevant chapters. Direct adsorption of the molecular recognition probes on a large area of a flat solid surface of bulk materials not only limits the number of immobilized molecules but also does harm to the activity of biomolecules. Hence, physical immobilization is typically applied to special nanoparticles (NPs) or porous nanostructures. For example, single-stranded DNA can be simply immobilized on the surface of graphene oxide sheets via physical adsorption. Covalent linkage is a commonly used immobilization method, which enables the long-term stability of immobilized biomolecules. A flexible linker molecule is typically employed between the transducer and the molecular recognition probe in order to reduce the steric hindrance by the solid surface and to ensure that the molecular recognition probe remains the same biological activity as those in the bulk solution. The small size and large surface curvature of nanomaterials have been found to significantly reduce the steric effects compared to micro- or macro-transducers. The third immobilization method is to use biochemical affinity reactions. In particular, bioaffinity immobilization is widely used for the attachment of proteins on the transducer. The commonly used bioaffinity pairs include antibody–antigen interaction, receptor–antagonist/agonist, oligonucleotide duplex, affinity-capture ligand system, DNA-directed systems, etc. [14].
Static, Low-Frequency, and Pulsed Magnetic Fields in Biological Systems
Published in James C. Lin, Electromagnetic Fields in Biological Systems, 2016
Many studies have demonstrated that ELF-EMFs may be involved in hyperalgesia. Jeong, Choi, Moon, et al. (2005) suggested that an ELF-EMF (60 Hz, 2.5 mT) can produce hyperalgesia and such a response can be regulated by the benzodiazepine system in rats. Diazepam (a benzodiazepine receptor agonist), flumazenil (a benzodiazepine receptor antagonist), or both were used with EMF exposure. When testing the pain threshold of rats using hot plate tests, EMF or diazepam was found to induce hyperalgesic effects with a reduction in latency. These effects were blocked by pretreatment with flumazenil. When the rats were exposed simultaneously to EMF and diazepam, the latency tended to decrease without statistical significance. The induction of hyperalgesia by coexposure to EMF and diazepam was also blocked by flumazenil. However, pretreatment by γ-aminobutyric acid (GABA) receptor antagonists such as bicuculline (a GABAA antagonist) or phaclofen (a GABAB antagonist) did not antagonize the hyperalgesic effect of EMF. These results suggest that the benzodiazepine system may be involved in EMF-induced hyperalgesia. The same research group later suggested that the ELF-EMF might cause Ca2+-dependent NOS activation, which then induces hyperalgesia with an increase in NO synthesis in mice (Jeong et al. 2006). They concluded that ELF-EMF may produce hyperalgesia by modulating NO synthesis via Ca2+-dependent NOS.
Estimating the physicochemical properties of antiemetics using degree-based topological descriptors
Published in Molecular Physics, 2023
Zhi-hao Hui, Muhammad Naeem, Abdul Rauf, Adnan Aslam
Based on the predominant receptor, antiemetic medications are categorised into a few classes. In order to minimise the side effects, optimise effectiveness, selecting the most suitable antiemetics is an important task. The first type of antiemetic medication is known as a 5-HT3 receptor antagonist. This class contains granisetron, ondansetron (Zofran) and palonosetron (2nd generation). The second class, namely dopamine antagonists, contains domperidone (Motilium), metoclopramide (Reglan) and chlorpromazine [2]. These antiemetics are mostly used in cases of motion sickness and postoperative nausea. The third class, H1 antihistamines, contain promethazine, cyclizine, and diphenhydramine. These drugs are used to treat vomiting and nausea induced by vestibular disturbance like motion or vertigo [3]. Neurokinin-1 (NK-1) receptor antagonists are a relatively new class of medication used to suppress chemotherapy and radiotherapy-induced vomiting and nausea. It contains rolapitant (Varubi) and aprepitant (Emend). These antiemetics should not be used if you are breastfeeding or pregnant [4]. The molecular structures of some antiemetic drugs that we study in this work are depicted in Figures 1 and 2.
Progress in pretreatment of methadone: an update since 2015
Published in Preparative Biochemistry & Biotechnology, 2023
Methadone (C21H27NO), a µ-opioid receptor agonist and N-methyl-d-aspartate receptor antagonist, since developed between 1937 and 1939 by Gustav Ehrhart and Max Bockmühl, has been widely tested as an opiate drug[1–3]. With similar medical effects to that of morphine (analgesic, miosis, sedative, etc.) but longer action time, (4–8 h one dose) less drug tolerance production and lower drug dependence[4], methadone has become one of the commonly used medicines in WHO Model List of Essential Medicines[5]. For the characteristics of easy production and relatively low price, it has been widely used in the clinical field all over the world. Containing two characteristic benzene ring structures, methadone (6-Dimethylamino-4,4-diphenyl-3-heptanone) has a molecular weight of 345.91[6,7] (Figure 1).
Structural conversion of an oxazolidine ligand upon treatment with copper(I) and (II) halides; structural, spectral, theoretical and docking studies
Published in Journal of Coordination Chemistry, 2018
Zahra Mardani, Vali Golsanamlou, Zahra Jabbarzadeh, Keyvan Moeini, Saba Khodavandegar, Cameron Carpenter-Warren, Alexandra M. Z. Slawin, J. Derek Woollins
The oxazolidine moiety is an important building block for pharmacologically active compounds such as antidiabetic [1], antitubercular [2], anticonvulsant [3] and aldose reductase inhibitors [4]. It is called pseudo-proline to mimic the proline skeleton for the investigation of peptide biological activity [5]. The oxazolidine-based compounds are pseudo-irreversible inhibitors of serine proteases [6] and are used as elastase inhibitors [7]. Some of these derivatives exhibited very high binding affinities for both NK1 and NK2 receptors. There is speculation that a combined NK1 and NK2 receptor antagonist might be an effective drug for the treatment of asthma and chronic airway obstruction [8]. Oxazolidines have been studied extensively as crosslinking agents [9] and for their anti-proliferative activity against cancer cell lines [10].