This work presented a new PEG modified calix[4]arene stationary phase (C4A-PEG-2PTSC) for gas chromatographic (GC) separations. The statically coated C4A-PEG-2PTSC column exhibited moderate polarity and column efficiency of 2224 plates m-1 determined by 1-octanol at 120 oC. The results showed that the C4A-PEG-2PTSC column exhibited the good separation performance for various types of analytes containing halogenated benzenes, benzaldehydes, phenols, alcohols, anilines isomers and showed the different retention behavior with the comparative columns. Importantly, it showed the better separation capacity of toluidine and xylidine isomers than commercial HP-35 column. Moreover, it was applied in practical sample analysis to detect the content of isomer impurities. This work exhibited the good application potential of C4A-PEG-2PTSC stationary phase in GC analyses.

Rhein is a primary anthraquinone found in the roots of a traditional Chinese herb, rhubarb, and has been shown to have some anticancer effects. The aim of the present study was to investigate the effect of rhein on the apoptosis of the human gastric cancer line SGC-7901 and to identify the mechanism involved. SGC-7901 cells were cultured and treated with rhein (0, 50, 100, 150, and 200 µM) for 24, 48, or 72 h. Relative cell viability assessed by the MTT assay after treatment was 100, 99, 85, 79, 63% for 24 h; 100, 98, 80, 51, 37% for 48 h, and 100, 97, 60, 36, 15% for 72 h, respectively. Cell apoptosis was detected with TUNEL staining and quantified with flow cytometry using annexin FITC-PI staining at 48 h after 100, 200 and 300 µm rhein. The percentage of apoptotic cells was 7.3, 21.9, 43.5%, respectively. We also measured the mRNA levels of caspase-3 and -9 using real-time PCR. Treatment with 100 µM rhein for 48 h significantly increased mRNA expression of caspase-3 and -9. The levels of apoptosis-related proteins including Bcl-2, Bax, Bcl-xL, and pro-caspase-3 were evaluated in rhein-treated cells. Rhein increased the Bax:Bcl-2 ratio but decreased the protein levels of Bcl-xL and pro-caspase-3. Moreover, rhein significantly increased the expression of cytochrome c and apoptotic protease activating factor 1, two critical components involved in mitochondrial pathway-mediated apoptosis. We conclude that rhein inhibits SGC-7901 proliferation by inducing apoptosis and this antitumor effect of rhein is mediated in part by an intrinsic mitochondrial pathway.