ABSTRACT
A direct liquid chromatography method was developed for the diastereo- and enantioselective analysis of a C3,C4-substituted beta-lactamic hypolipodemic agent (SCH 48461) and its stereoisomers on two commercially available amylose-based chiral stationary phases (CSPs), namely, Chiralpak AS and Chiralpak AD. The mobile phase composition (type and content of alcoholic modifier) was considered to achieve baseline resolutions in a single chromatographic run. In order to investigate the influence of molecular flexibility on chiral recognition process, beta-lactams were ring-opened and converted into beta-amino esters derivatives. Thermodynamic parameters associated with adsorption equilibria between acyclic and cyclic stereoisomers and CSPs were calculated from chromatographic runs at various temperatures.
Subject(s)
Amylose/analogs & derivatives , Azetidines/chemistry , Chromatography, High Pressure Liquid/methods , Phenylcarbamates , beta-Lactams/chemistry , Amylose/chemistry , Anticholesteremic Agents/analysis , Anticholesteremic Agents/chemistry , Azetidines/analysis , Carbamates/chemistry , Molecular Conformation , Stereoisomerism , Temperature , ThermodynamicsABSTRACT
1H NMR studies were performed on two beta-carboline derivatives interacting with human serum albumin. The spin-lattice relaxation rates of the two derivatives, having side chains of different length and polarity, were used to demonstrate a diverse motional behavior in solution together with slightly different relaxation pathways. Single- and double-selective excitation made it possible to evaluate dynamics in the free and protein-bound states. Occurrence of a relatively long hydrophilic chain interacting with the proton-acceptor nitrogen of the beta-carboline moiety was shown to yield lower association constants, slower dissociation rates, and diverse interacting modes with the indole hydrophobic site of the protein.
Subject(s)
Carbolines/chemistry , Convulsants/chemistry , Nuclear Magnetic Resonance, Biomolecular , Serum Albumin/chemistry , Carbolines/metabolism , Convulsants/metabolism , Humans , Protein Binding , Protein Conformation , Protons , Serum Albumin/metabolismABSTRACT
Some 6- and 7-methoxy-(and hydroxy-) tacrine derivatives were synthesized and evaluated for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities. The most potent analogue in our series was the 9-heptylamino-6-methoxytacrine 3af which, in comparison with tacrine (THA), displayed an almost identical inhibitory effect, slightly lower acute toxicity and higher selectivity profile towards AchE when compared with THA.
Subject(s)
Cholinesterase Inhibitors/chemical synthesis , Tacrine/analogs & derivatives , Animals , Cholinesterase Inhibitors/pharmacology , Male , Mice , Rats , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
Under the conditions described for alkaline hydrolysis of reserpine and rescinnamine in absolute and aqueous methanol, and after esterification (with diazomethane) of the resulting acid fraction, methyl 3,4,5-trimethoxybenzoate was quantitatively recovered, whereas methyl trans-3,4,5-trimethoxycinnamate, in normal lighting conditions, was either partly isomerized to methyl cis-trimethoxycinnamate or formed an adduct with a molecule of methanol, yielding methyl 3-methoxy-3-(3,4,5-trimethoxyphenyl)propionate. The structures of the products were established by synthesis, nuclear magnetic resonance studies and mass spectrometry. This investigation of the hydrolytic conditions allowed a reliable and rapid gas chromatographic determination of reserpine and/or rescinnamine in amounts down to 500 and 2000 mug, respectively, to be devised.
