- A simple HPLC-UV method for the determination of dimenhydrinate and related substances - Identification of an unknown impurity
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During the revision of the dimenhydrinate monograph of the European Pharmacopoeia a HPLC-UV method was developed. The procedure described allows a qualitative and quantitative determination of both dimenhydrinate compounds and of thirteen related substances. Furthermore a hitherto unknown impurity was identified and integrated into the purity check. Also 18 samples of dimenhydrinate have been tested. Thereby the relevant impurities of dimenhydrinate could be nominated and quantified.
- Doege, Ulrica,Eger
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- Riboflavin Is Directly Involved in N-Dealkylation Catalyzed by Bacterial Cytochrome P450 Monooxygenases
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Like a vast number of enzymes in nature, bacterial cytochrome P450 monooxygenases require an activated form of flavin as a cofactor for catalytic activity. Riboflavin is the precursor of FAD and FMN that serves as indispensable cofactor for flavoenzymes. In contrast to previous notions, herein we describe the identification of an electron-transfer process that is directly mediated by riboflavin for N-dealkylation by bacterial P450 monooxygenases. The electron relay from NADPH to riboflavin and then via activated oxygen to heme was proposed based on a combination of X-ray crystallography, molecular modeling and molecular dynamics simulation, site-directed mutagenesis and biochemical analysis of representative bacterial P450 monooxygenases. This study provides new insights into the electron transfer mechanism in bacterial P450 enzyme catalysis and likely in yeasts, fungi, plants and mammals.
- Zhang, Chengchang,Lu, Meiling,Lin, Lin,Huang, Zhangjian,Zhang, Rongguang,Wu, Xuri,Chen, Yijun
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- Bacterial Biosynthetic P450 Enzyme PikCD50N: A Potential Biocatalyst for the Preparation of Human Drug Metabolites
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Human drug metabolites (HDMs) are important chemicals widely used in drug-related studies. However, acquiring these enzyme-derived and regio-/stereo-selectively modified compounds through chemical approaches is complicated. PikC is a biosynthetic P450 enz
- Cheng, Fangyuan,Du, Lei,Durairaj, Pradeepraj,Guo, Jiawei,Li, Fengwei,Li, Shengying,Liu, Xiaohui,Long, Xiangtian,Ma, Li,Tang, Dandan,Zhang, Gang,Zhang, Wei,Zhang, Xingwang
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p. 14563 - 14571
(2021/11/12)
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- OLIGOMER-ANTIHISTAMINE CONJUGATES
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The invention provides antihistamine drugs that are chemically modified by covalent attachment of a water-soluble oligomer. A conjugate of the invention, when administered by any of a number of administration routes, exhibits characteristics that are different from the characteristics of the antihistamine drug not attached to the water-soluble oligomer.
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Page/Page column 38
(2008/12/07)
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- Synthesis and pharmacology of combined histamine H1-/H2-receptor antagonists containing diphenhydramine and cyproheptadine derivatives
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The classical histamine H1-receptor antagonists diphenhydramine (3a) and cyproheptadine (9) and their derivatives (3b-d, 10) were connected with a 2-guanidinothiazole containing structure (28) derived from the H2-receptor antagonist tiotidine in order to obtain combined H1/H2-receptor antagonists. The two moieties were not directly linked together, but were separated by a polymethylene spacer and a polar group (nitroethenediamine or urea). Thus 12 compounds were obtained that proved in vitro to possess high H1- and H2-receptor antagonist activity at the isolated guinea-pig ileum (H1) and the isolated guinea-pig right atrium (H2), respectively. The incorporation of the diphenhydramine as well as the cyproheptadine component provides high affinity to H1-receptors. The tricyclic cyproheptadine and its 10,11-dihydro derivative (30-32, 34), however, cause a decrease of H2-receptor antagonist potency compared to the diphenhydramines (29a-d, 33a-d). Using nitroethenediamine as the polar group is apparently more favourable to H1- and H2-receptor affinity as the urea function. All compounds elicit a dual mode of competitive and noncompetitive antagonism. Among the novel compounds the nitroethenediamines with 4-fluoro- or 4-methyl-substituted diphenhydramine as H1-receptor antagonist moiety (29c, d) display the most potent H1- and H2-receptor antagonist effects. The presented concept is a very promising way to combine H1- and H2-receptor antagonist properties in one molecule.
- Wolf, Cornelia,Schunack, Walter
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- GABA uptake inhibitors. Syntheses and structure-activity studies on GABA analogues containing diarylbutenyl and diarylmethoxyalkyl N-substituents
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A number of analogues of GABA or β-alanine containing 4,4-diphenyl-3-butenyl (DPB), benzhydryl ethyl ether (BEE), or benzhydryl propyl ether N-substituents have been synthesized and tested as inhibitors of synaptosomal GABA uptake. Whereas the N-DPB and N
- Falch,Krogsgaard-Larsen
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