Yujie Dai

Synthesis of novel flavonoid alkaloids as α-glucosidase inhibitors

A series of novel flavonoid alkaloids were synthesized with different flavonoids and attached nitrogen-containing moieties. These new compounds were screened for inhibitory activity of α-glucosidase, among which compound 23 was found to show the lowest IC50 of 4.13μM. Kinetic analysis indicates that the synthesized compounds 15 and 23 inhibit the enzyme in a non-competitive model with Ki value of 37.8±0.8μM and 13.2±0.6μM. Further docking studies suggest that the preferred binding pocket is close to the catalytic center, correlating to the experimental results. Structure activity relationship studies (SAR) indicate that 4-hyroxyl group and the 4-position carbonyl group in the flavonoid structure are important for this biological activity. Addition of extra hydrogen bonding and hydrophobic groups on ring A would increase the inhibitory activity.

Synthesis and aromatase inhibitory evaluation of 4-N-nitrophenyl substituted amino-4H-1,2,4-triazole derivatives.

In this paper, 13 4-N-nitrophenyl substituted amino-4H-1,2,4-triazole derivatives were synthesized and their aromatase inhibitory activities were measured. The results show that the substitution of the groups on benzyl group can further improve their bioactivity and the compound with Cl on the para position of benzyl has the highest bioactivity (IC50=9.02nM). A QSAR model was constructed from the 13 compounds with genetic function approximation using DS 2.1 package. This model can explain 90.09% of the variance (R(2)Adj), while it can predict 84.95% of the variance (R(2)cv) with the confidence interval of 95%.

DFT and GA Studies on the QSAR of 2-aryl-5-nitro-1H-indole derivatives as NorA Efflux Pump Inhibitors

AbstractThe structures of 2-aryl-5-nitro-1H-indole derivatives were optimized with PM3 and DFT at b3lyp/6–31xa0g* level successively. Some structural and electric descriptors were obtained from the single point energy calculation and natural bond orbital analysis at the level of b3lyp/6–31xa0g*. As efflux pump inhibitors, a QSAR model was built with genetic algrithum (GA) and partial least square (PLS) analyses. The high R2 and

The catalytic activity for ginkgolic acid biodegradation, homology modeling and molecular dynamic simulation of salicylic acid decarboxylase

R_{{text{CV}}}^{text{2}}

Mechanism for the depolymerization of cellulose under alkaline conditions

indicates the derived model has a good predictive power which can be used in prediction of activity for new 2-aryl-5-nitro-1H-indole derivatives. This model gives us a revelation that the activity of 2-aryl-5-nitro-1H-indole derivatives as efflux pump inhibitor can be improved by properly increasing the molecular volume and Mulliken atomic charge of C3 (QC3) or lowering the dipole and Mulliken atomic charge of C4 (QC4) in 2-aryl and it was found from this article that a QSAR relationship can be built for small samples with large descriptors by compressing the descriptors with GA and analyzing with PLS. With this model, a new compound, 2-(2-Azidomethyl-5-phenoxy-phenyl)-5-nitro-1H-indole was predicted to lower the MIC of berberine to 0.091xa0μg/mL for inhibiting K2361 of S. aureus with NorA efflux pump protein over expression. Figure: Basic structure of 2-aryl-5-nitro-1H-indolesn FigureBasic structure of 2-aryl-5-nitro-1H-indoles

Quantum chemical calculation of free radical substitution reaction mechanism of camptothecin

A novel mechanism for cleavage of three typical α(1→2), α(1→4) and β(1→4) glucosidic bonds induced by hydroxyl free radical was examined with DFT theory at B3LYP/6-31+G(d,p) level using PCM water solvent model. It was found that the hydrogen abstraction from the CH bonds outside the saccharide rings could induce the hydrogen transfer from the hydroxyl at the radical carbon to the oxygen atom of saccharide ring with the mediation of water, which led to the opening of saccharide ring and the breakage of glucosidic bonds. Alternatively, the hydrogen in COH outside the saccharide ring of maltose and sucrose could also transfer to the adjacent glucosidic oxygen atom with a water molecule mediation to make glucosidic bond break directly. Based on this study, it can be well explained the experimental results that the oxidation of some oligosaccharides with hydroxyl free radicals can produce molecules of glucose, fructose and other monosaccharides.

Modeling of the bacterial inactivation kinetics of dialdehyde cellulose in aqueous suspension

The toxic ginkgolic acids are the main safety concern for the application of Ginkgo biloba. In this study, the degradation ability of salicylic acid decarboxylase (SDC) for ginkgolic acids was examined using ginkgolic acid C15:1 as a substrate. The results indicated that the content of ginkgolic acid C15:1 in Ginkgo biloba seeds was significantly decreased after 5u202fh treatment with SDC at 40u202f°Cand pH 5.5. In order to explore the structure of SDC and the interaction between SDC and substrates, homology modeling, molecular docking and molecular dynamics were performed. The results showed that SDC might also have a catalytic active center containing a Zn2+. Compared with the template structure of 2,6-dihydroxybenzoate decarboxylase, the residues surrounding the binding pocket, His10, Phe23 and Phe290, were replaced by Ala10, Tyr27 and Tyr301 in the homology constructed structure of SDC, respectively. These differences may significantly affect the substrates adaptability of SDC for salicylic acid derivatives.

Physicochemical characteristics of complexes between amylose and garlic bioactive components generated by milling activating method

The discriminant analysis model of different medicinal liquor was established based on Fourier transformed infrared spectroscopy (FT-IR) combined with support vector machine (SVM) and principal component analyses (PCA) with the validation accuracy of 99% and training accuracy of 100%. The model was also tested by the external samples with the prediction accuracy of 97%. The accuracy data of the experimental showed that Fourier transform infrared spectroscopy (FT-IR) can be applied well for the classification of medicinal liquor.