Design, synthesis of novel triptolide-glucose conjugates targeting glucose Transporter-1 and their selective antitumor effect.

Six positional isomers of triptolide-glucose conjugates (TG1α, TG1ß, TG2, TG3, TG4 and TG6) were designed and synthesized. These conjugates exhibited better water solubility, and had selective cytotoxicity between tumor cells with high expression of glucose transport-1 (Glut-1) and non-tumor cells with low expression of Glut-1, in which TG2 formed by triptolide (TPL) and d-glucose C2-OH had the strongest cytotoxicity to tumor cells and lowest toxicity in non-tumor cells, therefore the highest relative therapeutic index, which was 5.7 times that of triptolide and consequent the most powerful selective antitumor activity in vitro. The cytotoxicity of TG2 was highly correlated with Glut-1 function. As a prodrug of triptolide, TG2 could promote RNA Pol II degradation and induce apoptosis as TPL does. TG2 had a stronger dose-dependent antitumor effect in vivo than TPL and no adverse reaction occurred when its tumor inhibition was higher than 90%, which was associated with its selective distribution in tumor tissues. TG2 could be used as a promising drug candidate for the treatment of solid tumors with high expression of Glut-1, which is worthy of further study.

[Temperature study on lightning return stroke in the coastal area of Guangdong].

In the coastal area of Guangdong, slit-less spectra for first return strokes of lightning between the cloud and ground were obtained. After spectrum analysis and line identification were done by using multi-configuration Dirac-Fock (MCDF) method, parameters like wavelengths, oscillator strengths, transition probabilities, and excitation energies were calculated. According to the relative intensities of lines and transition parameters, temperatures for individual lightning strokes and at different heights of the discharge channel were calculated by using multiple-line method. The result shows that the temperatures in return stroke channel varied from stroke to stroke. In general, the more intensive the lightning discharge, the higher the value of channel temperature. On the other hand, for a certain return stroke channel, the temperatures at different positions show signs of falling away with increasing height along the discharge channel. Compared with that of Qinghai plateau, lightning in Guangdong coastal area is more intensive, and the lines from higher excitation potential of N II in these lightning spectra are easier observed.