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Specialty Silicone Conditioning Agents
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Compounds of this type are prepared in a two-step reaction sequence. First the dimethicone copolyol is esterified with chloroacetic acid. The resulting dimethicone copolyol chloro-ester is then used to quaternize a tertiary amine in aqueous solution. Typically, the tertiary amine is an alkylamidopropyl dimethyl amine.
Asymmetric Reduction of C=N Bonds by Imine Reductases and Reductive Aminases
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Matthias Höhne, Philipp Matzel, Martin Gand
Imine reductases (IRED) are fascinating enzymes, because the asymmetric reduction of C=N-double bonds represents a very atom-efficient approach to prepare chiral amines and amino acid derivatives. Especially optically active secondary and tertiary amines are often found as structural units in a large variety of pharmaceuticals (Fig. 14.1). Selection of molecular structures of pharmaceutical ingredients and bioactive molecules with a secondary or tertiary amine function.
Physiology, Biochemistry, and Pathology of Neuromuscular Transmission
Published in Marc H. De Baets, Hans J.G.H. Oosterhuis, Myasthenia Gravis, 2019
AChE can be measured with a simple radiochemical method in homogenates of segments of muscle.130 ACh measurements are difficult because skeletal muscle contains little ACh, 0.2 to 1.0 pmol per mg of wet tissue weight, and gas chromatography/mass spectrometry is one of the few methods that can adequately cope with these small amounts of ACh.231 In this method the ACh extracted from the tissue or incubation medium is first purified with a precipitation method (together with tetramethylammonium ions and iodine/iodide complex) and the mixture is pyrolyzed on glass, which causes a reaction of ACh to its (volatile) tertiary amine analogue. After gas chromatography, the tertiary amine is detected with high sensitivity by mass spectrometry (GC/MS method). The main disadvantage of the GC/MS system is that it is very expensive. Recently, high performance liquid chromatography, combined with an electrochemical detector, has been used with success at much less cost for the determination of ACh in skeletal muscle, based on a method of conversion of ACh to H2O2.232-234
Novel amides of mycophenolic acid and some heterocyclic derivatives as immunosuppressive agents
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Juliusz Maksymilian Walczak, Dorota Iwaszkiewicz-Grześ, Michalina Ziomkowska, Magdalena Śliwka-Kaszyńska, Mateusz Daśko, Piotr Trzonkowski, Grzegorz Cholewiński
For A1, A8, A11, and A14 cases, 2.0 equivalents of tertiary amine (DIPEA) were applied due to standard procedure present in the literature35. However, in most cases only 1.0 equivalent was utilised on account of reaction mechanism. Initially, each reaction was carried out in a manner consistent with the reaction mechanism, but the one proposed in the literature was also studied. Differences in the base amounts may happen due to the high stability of salt formed upon MPA and amine dissolution. Increasing the amount of DIPEA alters pH balance which affects the tendency of amine to react with activated MPA as it may less readily occur in protonated form. Base excess is believed to increase coupling rates and to disrupt hydrogen bonds responsible for conformation stabilisation which affects the availability of amino groups36. A3 was synthesised with individual quantities of base and activating agent used which were developed through the optimisation process. Due to the potential N-acyl 2-aminobenzo[d]-1H-imidazole isomerisation processes observed between annular and exocyclic nitrogen atoms, two products would occur. However, 1H NMR spectrum proved N-acylation at the exocyclic nitrogen as an additional peak close to 12 ppm was observed (one annular, one amide, and one phenolic protons all deshielded in the magnetic field). Isomerisation and tautomerisation phenomena may affect reaction outcomes, e.g. decreasing yields as for A3.
Analogues of 2′-hydroxychalcone with modified C4-substituents as the inhibitors against human acetylcholinesterase
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2021
Sri Devi Sukumaran, Shah Bakhtiar Nasir, Jia Ti Tee, Michael J. C. Buckle, Rozana Othman, Noorsaadah Abd. Rahman, Vannajan Sanghiran Lee, Syed Nasir Abbas Bukhari, Chin Fei Chee
The designed 2′-hydroxychalcone derivatives were evaluated for their in vitro inhibitory activities against human recombinant AChE according to Ellman’s colorimetric assay method16. The results are summarised in Table 2. Most of the tested compounds showed promising AChE inhibitory activity when screened at 10 µM. Based on the structure–activity relationship analysis, it is clear that AChE inhibitory activity was closely related to the C4-substituent. Generally, the tertiary amine substituted compounds possessed better AChE inhibitory activity than that of tertiary amide substituted compounds. The results of 8a, 8 b, and 8d–f demonstrated that compounds with piperidine or pyrrolidine substituted at C4 position were comparably potent as that of donepezil and tacrine against AChE. When examining the efficacy of compounds 4a–e, the presence of 6′-methoxy substituent in the A ring favour the AChE activity. Compounds 4f–h which lack of a tertiary nitrogen substituent in B ring were inactive, indicating that the carboxylic group is not favoured for interaction. Besides, the length of the C4 side chain also played a significant role in the AChE inhibitory activity. Tertiary amine-bearing derivatives 8a–f which contain a side chain of 2 carbon atoms, displayed a better inhibition than those derivatives without side chain described in our previous work14.
Use of polymers for taste-masking pediatric drug products
Published in Drug Development and Industrial Pharmacy, 2018
Polymers that have ionizable functional groups exhibit pH-dependent solubility. That is, when the polymer is in its unionized state, it is insoluble in that fluid. When a sufficient number of functional groups are ionized, the polymer dissolves. This scientific principle has been exploited for taste-masking purposes due to the significant pH change between saliva (reported from 6.97 to 7.40 [50]) and gastric fluid. One of the most common polymers with pH-dependent solubility used for taste masking is Eudragit® E, a cationic copolymer based on dimethyl aminoethyl methacrylate, butyl methacrylate, and methyl methacrylate [51]. Kollicoat Smartseal® 30 D, a copolymer of methyl methacrylate and diethylaminoethyl methacrylate, also has taste-masking properties [52]. Both polymers have tertiary amine functional groups that become ionized in acidic media. Chitosan, a polysaccharide derived from shell fish, is another cationic polyamine that exhibits similar pH-dependent solubility [25].