Computational studies of the binding mode and 3D-QSAR analyses of symmetric formimidoester disulfides: a new class of non-nucleoside HIV-1 reverse transcriptase inhibitor.

Symmetric formimidoester disulfides (DSs) have recently been identified as a new class of potent non-nucleoside HIV-1 reverse transcriptase (RT) inhibitors. Given that three geometric isomers for DSs are possible, a computational strategy based on molecular docking studies, followed by comparative molecular fields analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) was used in order to identify the most probable DS isomer interacting with RT, to elucidate the atomic details of the RT/DS interaction, and to identify key features impacting DS antiretroviral activity. The CoMFA model was found to be the more predictive, with values of r(2)ncv, r(2)cv, SEE = 0.264, F = 80, and r(2)pred=0.73.

Analysis of dencichine in Panax notoginseng by gas chromatography-mass spectrometry with ethyl chloroformate derivatization.

Dencichine (beta-N-oxalyl-l-alpha,beta-diaminopropionic acid) is a haemostatic agent present in well-known traditional Chinese medicinal herbs such as Panax notoginseng, as well as other Panax species. It is also a reported neurotoxic agent found in Lathyrus sativus (grass pea seed) and cycad seeds. A method was developed for quantitative determination of the non-protein amino acid, dencichine, in plant samples of P. notoginseng and the adventitious roots directly from the explants of P. notoginseng after derivatization with ethyl chloroformate (ECF) by gas chromatography-mass spectrometry (GC-MS). l-2-chlorophenylalanine was used as an internal standard. Calibration curves were linear (r(2)=0.9988, n=6) in the range of 10-800 microg/ml for dencichine. Limit of detection and quantification for dencichine were 0.5 microg/ml and 2 microg/ml, respectively. This rapid and specific method may be applied to the quantification of dencichine in complex medicinal plants and their products.