Mangiferin induces cell death against rhabdomyosarcoma through sustained oxidative stress

AbstractBackgroundEmbryonic rhabdomyosarcoma (RD) is the most prevalent type of cancer among children. The present study aimed to investigate cell death induced by mangiferin in RD cells.MethodsThe Inhibitory concentration (IC50) value of mangiferin was determined by an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. Cell death induced by mangiferin against RD cells was determined through lactate dehydrogenase and nitric oxide release, intracellular calcium levels, reactive oxygen species generation, antioxidant status, mitochondrial calcium level, and mitochondrial membrane potential. Furthermore, acridine orange/ethidium bromide staining was performed to determine early/late apoptotic event.ResultsMangiferin induced cell death in RD cells with an IC50 value of 70μM. The cytotoxic effect was reflected in a dose-dependent increase in lactate dehydrogenase leakage and nitric oxide release during mangiferin treatment. Mangiferin caused dose dependent increase in reactive oxygen species generation, intracellular calcium levels with subsequent decrease in antioxidant status (catalase, superoxide dismutase, glutathione-S-transferase, and glutathione) and loss of mitochondrial membrane potential in RD cells. Further data from fluorescence microscopy suggest that mangiferin caused cell shrinkage and nuclear condensation along with the occurrence of a late event of apoptosis.ConclusionResults of the present study shows that mangiferin can act as a promising chemopreventive agent against RD by inducing sustained oxidative stress

The isolation of chitinase from Streptomyces thermocarboxydus and its application in the preparation of chitin oligomers

[[abstract]]Microbial chitinase has received great attention due to its medical, biological, and agricultural applications. In this study, over 50 bacterial strains were isolated from Taiwanese soils using medium containing squid pen powder (SPP) as the sole source of carbon/nitrogen. Based on chitinolytic activity, Streptomyces thermocar-boxydus TKU045 was selected for further study. Optimized culture conditions revealed that S. thermocarboxydus TKU045 could produce the highest chitinase activity (52.985 U/mL) when cultured in a medium containing 1% (w/v) SPP at 45 °C for 36h. Characterized TKU045 chitinase showed novel properties with a smallest molecular weight (12.8 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis) and more acidic optimal pH (pH 4) than those of other Streptomyces chitinases. A combination of high-performanceliquid chromatography and matrix-assisted laser desorption ionization time of flight mass spectrometer data revealed that chitin oligomers (COS) obtained from the hydrolysis of colloidal chitin by TKU045 chitinase comprise oligomers with multiple degrees of polymerization (DP) varying from 1 to 7. The COS with low DP exhibited enhanced 2,2-diphenyl-1-picrylhydrazyl radical scavenging capability and promoted the growth of Lactoba-cillus lactis. Taken together, the COS obtained by hydrolyzing colloidal chitin with TKU045 chitinase could have the potential to be used in medicine or nutraceuticals due to its active anti-oxidant and prebiotic contents.[[sponsorship]]科技部[[notice]]補正完