Showing papers in "Journal of Chinese Pharmaceutical Sciences in 2010"

Limitations of the use of MTT assay for screening in drug discovery

Abstract: The 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyl tetrazolium bromide (MTT) assay is a routine cell viability assay for cell proliferation and cytotoxicity, which is widely used in many fields, especially in screening for drug discovery However, this assay exhibits limitations in the presence of particular compounds and under certain assay conditions, which may yield false screening results For example, polyphenols that are extracted from natural sources can react with MTT in the absence of living cells and thus interfere with the screening results We measured the absorbance of 15 polyphenols extracted from green tea and showed that the phenolic hydroxyl groups in the polyphenols are responsible for the reduction of MTT to formazan When three or more phenolic hydroxyl groups were present on a conjugated polyphenol, a significantly increased MTT reduction was observed Moreover, the type of medium also had an effect on the absorbance value, in the following order: α­MEM + 10% FBS> α­MEM>DMEM/F12>PBS The absorbance of the MTT assay recorded at 570 nm is more sensitive than that measured at 595 nm These results will improve the cell­based assay of polyphenols and clarify the limitations of the MTT assay as a method of screening in drug discovery

Photoresponsive nucleic acids for gene regulation

Abstract: For the main purpose of manipulating the functions of molecules, researchers have made great achievements on photo­ responsive molecules using light as a trigger. Light has become a promising scientific tool due to it being a clean and non­ invasive external stimulant. By attachment of photoresponsive moieties to molecules, the biological activities of molecules can be attenuated by light activation. With wide applications of laser in life sciences, it will be possible to achieve high spatiotemporal resolution. In this review, we focus on photoresponsive nucleic acids for photomodulating gene expression with light activation. With incorporation of photoswitchable or photocleavable moieties, biological behaviors of nucleic acids are photoregulated reversibly or irreversibly. Recent development and applications of photoresponsive nucleic acid in vitro and in vivo have shown a very promising future for manipulation of specific functional genes or disease genes. We expect that photoresponsive nucleic acids will be powerful scientific tools for studying biological events as well as gene therapy agents for genetic diseases. Keywords: Photoresponsive; Caging group; Photoswitchable; Gene regulation; Oligonucleotide CLC number: R9­39 Document code: A Article ID: 1003-1057(2010)1-5-10