Predicting the Binding Affinity of ERß Ligands Based on a Novel Variable Selection Method.

A number of descriptors were employed to characterize the molecular structures of the 128 estrogen receptor ß ligands. A quantitative structure-activity relationship (QSAR) model of these compounds was developed by the variable selection method based on variable interaction. The QSAR model with five descriptors was internally and externally validated. The determination coefficient (R 2) and the leave-one-out cross-validated correlation coefficient (Q 2) are 0.8272 and 0.8041, respectively. The estimated correlation coefficient of the external validation is 0.8255. The mechanistic interpretation of the final model was carried out according to the definition of descriptors. As the model meets the five principles proposed by Organization for Economic Co-operation and Development, it can be used to predict the binding affinity of other derivatives.

[Study of the Detection of Histidine Based on "On-Off" Fluorescence Probe of Carbon Dots].

An new type of switch "On-Off" fluorescence probe was constructed based on fluorescence carbon dots as a novel strategy to analyze trace histidine(His) which was proposed for the first time. In water solution with pH 7.6, the fluorescence of CDs was quenched with Ru3+ due to the formation of ground state compound through electrostatic attraction, and the system was thus "turned-off". The fluorescence intensity of CDs was "turned-on" due to the competition between His and Ru towards the surface of CDs. The effect of critical parameters including pH, buffer solutions, reaction temperature and time needed to grow the fluorescence intensity of CDs was studied. Results show thatin water solution with pH 7.6, and when the temperature was between 20~25 ℃, the fluorescence intensity of the released CDs displayed a linear relationship in the range of (6.5~219.3)×10-6 mol·L-1 of captopril. Lower limit of detection for His, at the signal-to-noise ratio of 3/(3δ), was 2.15×10-6 mol·L-1. The methodology was successfully applied for the determination of His in Compound Amino Acid Injections, with the RSD≤2.07%, and the recovery rate was between 95.7%～102.4%. The result of the experiment was satisfactory. On the one hand, the excellent optical character CDs was acted as "On-Off" fluorescence probe, which could be extent the application of CDs, on the other hand, the excellent performance of the proposed fluorescence probe shows that this method possesses the potential for practical application.

Combined toxicity of the mixtures of phenol and aniline derivatives to Vibrio qinghaiensis sp.-Q67.

To test whether the dose addition and independent action models can predict the combined toxicity of the mixtures of phenol and aniline derivatives, six phenolic and two aniline derivatives were selected as the test components. The inhibition toxicity of the derivatives and their mixtures to Vibrio qinghaiensis sp.-Q67 indicated that all dose-response relationships could be effectively described by the Weibull function with correlation coefficients greater than 0.99. The combined toxicity of two equivalent-effect concentration ratio mixtures and eight uniform design concentration ratio mixtures could be predicted successfully by the dose addition model within 95% confidence intervals. However, it was also well predicted by the independent action model, especially at lower concentrations.