Capsaicin and dihydrocapsaicin induce apoptosis in human glioma cells via ROS and Ca2+­mediated mitochondrial pathway.

Human glioma is the most common type of primary brain tumor and one of the most invasive and aggressive tumors, which, even with treatments including surgery, radiotherapy and chemotherapy, often relapses and exhibits resistance to conventional treatment methods. Developing novel strategies to control human glioma is, therefore, an important research focus. The present study investigated the mechanism of apoptosis induction in U251 human glioma cells by capsaicin (Cap) and dihydrocapsaicin (DHC), the major pungent ingredients of red chili pepper, using the Cell Counting Kit­8 assay, transmission electron microscopy analysis, flow cytometry analysis, laser scanning confocal microscope analysis and immunohistochemical staining. Treatment of U251 glioma cells with Cap and DHC resulted in a dose­ and time­dependent inhibition of cell viability and induction of apoptosis, whereas few effects were observed on the viability of L929 normal murine fibroblast cells. The apoptosis­inducing effects of Cap and DHC in U251 cells were associated with the generation of reactive oxygen species, increased Ca2+ concentrations, mitochondrial depolarization, release of cytochrome c into the cytosol and activation of caspase­9 and ­3. These effects were further confirmed by observations of the anti­tumor effects of Cap and DHC in vivo in a U251 cell murine tumor xenograft model. These results demonstrate that Cap and DHC are effective inhibitors of in vitro and in vivo survival of human glioma cells, and provide the rationale for further clinical investigation of Cap and DHC as treatments for human glioma.

[Determination of ascorbic acid by indirect fluorimetry].

Experiments indicated that cerium(IV) ion which could not emit fluorescence was deoxidized by ascorbic acid to cerium(III) ion which could emit its characteristic fluorescence in water solution, while sodium hexametaphosphate added could greatly enhance the fluorescence intensity of the system. From this, an indirect sensitive method for determining ascorbic acid was developed. The fluorescence intensity of the system was measured in a 1 cm quartz cell with the excitation and emission wavelengths of 303 and 340 nm, respectively. The results showed that the fluorescence intensity of the system presented a linear relationship with the concentration of ascorbic acid in the range of 1.0 x 10(-7)-8.0 x 10(-6) mol x L(-1), the correlation coefficient r was 0.9997, and the detection limit (S/N = 3) was 1.6 x 10(-8) mol x L(-1). The presented method was used to determine ascorbic acid sample and vitamin C tablet, and the results were satisfactory.

[Study on the determination of ciprofloxacin by the terbium (Ill) ion fluorescence probe sensitized by the surfactant].

The experiments indicated that terbium(III) ion could complex ciprofloxacin, then emitted the characteristic fluorescence of terbium(III) ion. When the surfactant of SDBS was added, the fluorescence intensity of the system was greatly increased. From this, a sensitive method of determining the ciprofloxacin was developted. The fluorescence intensity was determined by a 1 cm quartz cell with the excitation wavelength of 300 nm and the emission wavelength of 545 nm. The optimal conditions are as follows: pH 8.0-8.5, the concentration of terbium(III) is 5.0 x 10(-5) mol x L(-1), the surfactant concentration of SDBS is 8.0 x 10(-4) mol x L(-1). The linear range is 2.5 x 10(-6) mol x L(-1) -2.0 x 10(-8) mol x L(-1), and the detection limit (S/N = 3) is 4.0 x 10(-9) mol x L(-1). The presented method was applied to determine the real pharmaceuticals of ciprofloxacin.

[Fluorescence reaction of terbium(III) ion and norepinephrine and its analytical application].

Experiments indicated that terbium(III) ion could form complex with norepinephrine, then emitted its characteristic fluorescence. In the present paper, the fluorescence reaction of terbium(III) ion with norepinephrine was studied in detail. Thus a new method for the determination of norepinephrine was propsed. The fluorescence intensity was measured in a 1 cm quartz cell with the excitation and emission wavelengths of 300 and 545 nm, respectively. The result showed that the fluorescence intensity of the system presented a linear relationship with the concentration of norepinephrine in the range of 0.01-50 microg x mL(-1), and the detection limit (S/N=3) was 1.0 ng x mL(-1). The method was used to determine pharmaceutical sample which contained norepinephrine, and the result was satisfactory.