Quantitative structure activity relationship models based on heuristic method and gene expression programming for the prediction of the pK(a) values of sulfa drugs / 药学学报

Quantitative structure-property relationships (QSPR) were developed to predict the pK(a) values of sulfa drugs via heuristic method (HM) and gene expression programming (GEP). The descriptors of 31 sulfa drugs were calculated by the software CODESSA, which can calculate constitutional, topological, geometrical, electrostatic, and quantum chemical descriptors. HM was also used for the preselection of 4 appropriate molecular descriptors. Linear and nonlinear QSPR models were developed based on the HM and GEP separately and two prediction models lead to a good correlation coefficient (R) of 0.90 and 0.95. The two QSPR models are tseful in predicting pK(a) during the discovery of new drugs and providing theory information for studying the new drugs.

Determination of tetrandrine and fangchinoline in Radix Stephaniae tetrandrae and its preparation by nonaqueous capillary chromatography / 中国中药杂志

<p><b>OBJECTIVE</b>To establish a new method for the determination of fangchinoline and tetrandrine in Stephania tetrandra and Fengtongan capsule by noanqueous capillary electrophoresis.</p><p><b>METHOD</b>Separation was carried out in an uncoated fused capillary (50 cm x 75 microm i.d.) with a running buffer containing 50 mmol x L(-1) ammonium acetate, 1.0% acetic acid and 20% acetonitrile in methanol. A separation voltage of 20 kV and a UV detector wavelength at 214 nm were adopted. Sample was introduced from the anode.</p><p><b>RESULT</b>The calibration ranges were 1.00, 500 mg x L(-1) for both analytes. Under the optimum conditions, the relative standard deviation (RSD, n = 6) for the migration time of each analyte were 0.09%, 1.9% (intra-day) and 0.63%, 1.9% (inter-day); The RSD for the peak area of each analyte were 0.45%, 5.9% (intra-day) and 2.3%, 5.6% (inter-day), respectively. The contents of the analytes were determined easily with average recoveries 102% for fangchinoline and 105% for tetrandrine in S. tetrandra and 94.6% for fangchinoline and 98.7% for tetrandrine in Fengtongan capsules, respectively.</p><p><b>CONCLUSION</b>The proposed method is simple, rapid, accurate and higher repeatable, and can be used to control of the quality of S. tetrandra and Fengtongan capsules.</p>