Emergence of hydrogen bonds from molecular dynamics simulation of substituted N-phenylthiourea-catechol oxidase complex.

A series of N-phenylthiourea derivatives was built starting from the X-ray structure in the molecular mechanics framework and the interaction profile in the complex with the catechol oxidase was traced using molecular dynamics simulation. The results showed that the geometry and interactions between ligand and receptor were highly related to the position of the substituted side chains of phenyl moiety. At the end of molecular dynamics run, a concentrated multicenter hydrogen bond was created between the substituted ligand and receptor.

Discrimination of cinnamon bark and cinnamon twig samples sourced from various countries using HPLC-based fingerprint analysis.

A simple and efficient HPLC method was developed to evaluate the quality of traditional herbal medicines made from cinnamon bark (CB) and cinnamon twig (CT). Seven major bioactive ingredients in 56 samples (24 CB and 32 CT) collected from China, Vietnam, and Indonesia were separated and quantified. The method was validated following the International Conference on Harmonisation (ICH) guidelines.

Racemization of 6-methoxydihydrosanguinarine in methanol investigated by enantioselective dynamic HPLC.

A biologically active benzophenanthridine alkaloid, 6-methoxydihydrosanguinarine (MS), was isolated from Hylomecon plants. Although enantiomers of MS can be separated by chiral HPLC, its isomers rapidly form a racemic mixture in methanol. The rate constants for the racemization of MS enantiomers were 9.

Computational studies of COX-2 inhibitors: 3D-QSAR and docking.

The 3D-QSAR (three-dimensional quantitative structure-activity relationships) studies for 88 selective COX-2 (cyclooxygenase-2) inhibitors belonging to three chemical classes (triaryl rings, diaryl cycloalkanopyrazoles, and diphenyl hydrazides) were conducted using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Partial least squares analysis produced statistically significant models with q(2) values of 0.84 and 0.

Enantioselective stabilization of inclusion complexes of metoprolol in carboxymethylated beta-cyclodextrin.

The inclusion complexes of metoprolol (MT) and carboxymethyl-beta-cyclodextrin (CMCD) were prepared and the stability constants of the complexes were determined. Binding studies performed using high performance liquid chromatography (HPLC), UV spectrometry and capillary electrophoresis (CE) indicated that a complex with 1:1 stoichiometry is predominant in the solution. The enantiomers of MT possess relatively high affinity towards CMCD with stability constants of 288 and 262 per M for (R)- and (S)-MT, respectively.