Structure-dependent of 3-fluorooxindole derivatives interacting with ctDNA: Binding effects and molecular docking approaches.

3-Fluorooxindole has been shown to be a biologically active structural unit, novel derivative containing 3-fluorooxindole unit has been successfully constructed using 3-fluorooxindole as a substrate in previous work. Here, the interactions between novel 3-fluorooxindole derivatives and ctDNA were explored through molecular docking, multi-spectral and NMR methods, and the dependence of the binding mechanism on the structure was revealed by combined physical chemistry and organic chemistry. Firstly, molecular docking indicated that the planarity of the molecule enhances the binding strength to ctDNA. UV absorption result showed a weak binding effect. Fluorescence spectroscopy suggested the binding mechanism of 3-fluorooxindoles and ctDNA via groove binding. Moreover, the binding mechanism of 3-fluorooxindoles to ctDNA was further confirmed by 1H NMR spectroscopy, viscometry, and CD spectroscopy as groove binding. FT-IR spectroscopy reflected a more obvious disturbance of the phosphate group in the groove region of ctDNA. Electrochemistry was also used to probe the binding strength of 3-fluorooxindoles to ctDNA, and it showed a weak binding strength. From the above study, we concluded that 3-fluorooxindoles bind mainly in the groove region of ctDNA with weak binding strength. This study provides an idea for the activity screening aspect of 3-fluorooxindole derivatives from molecular planarity consideration and relevant information on biophysical and bioorganic aspects for drug development.

[Physiochemical properties and microbial community characteristics of rhizosphere soil in Parashorea chinensis plantation]. / æœ›å¤©æ ‘äººå·¥æž—æ ¹é™ åœŸå£¤ç†åŒ–æ€§è´¨åŠå¾®ç”Ÿç‰©ç¾¤è½ç‰¹å¾.

We explored the impacts of different mixed trees on the improvement of soil microecological environment in rhizosphere of Parashorea chinensis, including pure P. chinensis plantation (WC), mixed P. chinensis and Dalbergia odorifera plantation (WJ), mixed P. chinensis and Eucalyptus urophylla × E. grandis plantation (WA). Soil physical and chemical properties were analyzed. The characteristics and distribution of soil microbes in the rhizosphere were measured by the methods of Biolog-Eco micro plate and phospholipid fatty acid methyl ester (PLFA). Soil water content, soil pH, organic matter, total nitrogen, total potassium content and the activities of sucrase, urease and acid phosphatase in rhizosphere soil of WA were significantly higher than those of WC and WJ, without difference between WC and WJ. There were no significant differences in the contents of nitrate nitrogen, ammonium nitrogen, and available potassium between WA and WJ, which were obviously higher than those in WC. There were significant differences in total phosphorus and available phosphorus contents among the three stands, with an order of WJ>WA>WC. The average color change rate (AWCD), Shannon index, Simpson index, McIntosh index and the utilization of six types of carbon source substrates in microorganisms were the highest in the rhizosphere soil of WA, followed by WJ and WC. Results of principal component analysis showed that carbohydrates, amino acids and phenolic acids were the main carbon sources for microbial utilization. In WA, the PLFA content of rhizosphere soil microorganism, bacteria, fungi and actinomycetes was the highest, followed by WJ and WC. There were significant positive correlation between soil physical and che-mical properties and the microbial characteristics. Combining the physical and chemical properties of soil and the functional and structural characteristics of microbial communities, the mixed P. chinensis and E. urophylla × E.grandis plantation may be most conductive to the improvement of the rhizosphere microecological environment and increase soil available nutrients at the young tree phase of P. chinensis.