Bin Liu,Xiaofang Li,Jie Zhang,Liyun Du,Rongjin Zeng
The reaction of 6,7-dihydroindolizin-8(5H)-one and an aromatic aldehyde yielded (E)-7-(arylmethylene)-6,7-dihydroindolizin-8(5H)-ones which underwent addition of bromoform in the presence of magnesium under N2 to give a novel series of 3-aryl-2,2-dibromo-5′H-spiro[cyclopropane-1,7′-indolizin]-8′(6′H)-one derivatives. The structures of the products were established by 1H NMR, 13C NMR, IR spectroscopy and mass spectra.
Jing-Bo Wang,Xue-Ru Zhao,Xi-Le Hu,Yi Zang,Jia Li,Xiao-Peng He
The sensitive detection of glycosidases in live cells is crucial to understanding their functional roles in disease progression. Here, we develop a fluorogenic labeling probe for β-galactosidase (β-Gal) based on a bright green-emitting fluorescent dye, fluorescein. Galactose was introduced to a fluoromethyl-substituted fluorescein derivative through a benzyl spacer, resulting in a quenched fluorescence due to spirocyclization of the dye. After removal of the galactosyl residue by β-Gal, an ∼210-fold enhanced green fluorescence (emission maximum at 524 nm) was detected, and the presence of other glycosidases and hydrolases did not produce false-positive signals. The probe was successfully used for imaging of the endogenous β-Gal activity in cancer and senescent cells, and the imaging results agree with the β-Gal expression level of the cells, as determined by Western blotting and polymerase chain reaction. Importantly, we demonstrated that upon hydrolysis of galactose, the fluoromethyl-substituted fluorescein derivative is covalently attached to adjacent proteins, both in solution and in live cells. This study offers a small-molecule probe for the sensitive monitoring of endogenous glycosidase activity.
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