A new fluorescent pH probe for imaging lysosomes in living cells.

A new rhodamine B-based pH fluorescent probe has been synthesized and characterized. The probe responds to acidic pH with short response time, high selectivity and sensitivity, and exhibits a more than 20-fold increase in fluorescence intensity within the pH range of 7.5-4.1 with the pKa value of 5.72, which is valuable to study acidic organelles in living cells. Also, it has been successfully applied to HeLa cells, for its low cytotoxicity, brilliant photostability, good membrane permeability and no 'alkalizing effect' on lysosomes. The results demonstrate that this probe is a lysosome-specific probe, which can selectively stain lysosomes and monitor lysosomal pH changes in living cells.

A new rhodamine B-based lysosomal pH fluorescent indicator.

We designed and synthesized a new pH fluorescent probe, RCE, based on structural changes of rhodamine dye at different pH values. The probe exhibits high selectivity, high sensitivity and quick response to acidic pH, as well as low cytotoxicity, excellent photostability, reversibility and cell membrane permeability. Fluorescence intensity at 584 nm was increased more than 150-fold within pH range 7.51-3.53. This probe has pKa value 4.71, which is valuable for studying acidic organelles. Because of its long absorption and emission wavelengths, RCE can avoid associated cell damage. The probe can selectively stain lysosomes and monitor lysosomal pH changes in living cells.

Synthesis and discovery of novel pyrazole carboxamide derivatives as potential osteogenesis inducers.

A series of novel N-aryl-3-aryl-1-arylmethyl-1H-pyrazole-5-carboxamide derivatives 4a-l was synthesized by the reaction of 3-aryl-1-arylmethyl-1H-pyrazole-5-carbonyl chloride with substituted aniline in good to excellent yields. Structures of the compounds were determined by IR, (1) H NMR, and HR-MS spectroscopy. The molecular structure was confirmed by the X-ray crystal analysis of one compound (4j) that was prone to crystallization. These compounds were used to induce mouse osteoblast precursors MC3T3-E1 into osteoblasts and the induction was assessed by alkaline phosphatase (ALP) activity and the gene expression of bone sialoprotein (BSP). The results showed that the compounds 4a-d, 4g, 4h, and 4k could increase the ALP activity in comparison with the negative control group and compound 4h was the most effective one which could induce osteogenesis. Furthermore, mRNA expression of BSP which is a marker of osteogenesis was up-regulated by the compound 4h.

A rhodamine chromene-based turn-on fluorescence probe for selectively imaging Cu²+ in living cell.

We describe the development of a rhodamine chromene-based turn-on fluorescence probe to monitor the intracellular Cu(2+) level in living cells. The new fluorescent probe with a chlorine group in chromene moiety exhibits good membrane-permeable property than previous reported because the predicted lipophilicity of present probe 4 is stronger than that of methoxyl substituted probe in our previous work (CLogP of 4: 8.313, CLogP of methoxyl substituted probe: 7.706), and a fluorescence response toward Cu(2+) under physiological conditions with high sensitivity and selectivity, and facilitates naked-eye detection of Cu(2+). The fluorescence intensity was remarkably increased upon the addition of Cu(2+) within 1 or 2 min, while the other sixteen metal ions caused no significant effect.

Synthesis of 5-benzyl-2-phenylpyrazolo[1,5-a]pyrazin-4,6(5H,7H)-dione derivatives and discovery of an apoptosis inducer for H322 lung cancer cells.

A series of substituted 5-benzyl-2-phenylpyrazolo[1,5-a]pyrazin-4,6(5H,7H)-dione derivatives was synthesized by one-step reaction of ethyl 3-phenyl-1H-pyrazole-5-carboxylate derivatives and N-arylalkyl-2-chloroacetamide. Structures of the compounds were determined by IR, (1)H NMR and mass spectroscopy. In addition, a representative single-crystal structure was characterized by using X-ray diffraction analysis. The compound 5j could selectively inhibit the growth of H322 lung cancer cells which contain a mutated p53 gene in a dose-dependent manner through inducing apoptosis of cells.

Synthesis, X-ray crystal structure and optical properties of novel 5-(3-aryl-1H-pyrazol-5-yl)-2-(6-methoxy-3-methylbenzofuran-2-yl)-1,3,4-oxadiazole.

A series of novel 5-(3-aryl-1H-pyrazol-5-yl)-2-(6-methoxy-3-methylbenzofuran-2-yl)-1,3,4-oxadiazole derivatives has been synthesized from 6-methoxy-3-methylbenzofuran-2-carboxylic acid and ethyl 3-aryl-1H-pyrazole-5-carboxylate. The structures of compounds obtained were determined by IR, (1)H NMR and HRMS spectra. Typically, the spatial structure of compound 7e was determined by using X-ray diffraction analysis. UV-vis absorption and fluorescence spectral characteristics of the compounds in dichloromethane and acetonitrile were investigated. The results showed that the absorption maxima of the compounds vary from 321 to 339 nm depending on the substituents in N-1 position of pyrazole moiety and para position of benzene moiety. The maximum emission spectra of compounds in two different solvents were mainly dependent on groups in N-1 position of pyrazole moiety. The intensity of absorption and fluorescence was also correlated with substituents on the aryl ring bonded to pyrazole moiety. In addition, the absorption and emission spectra of these compounds change with increasing solvent polarity.

Synthesis, X-ray crystal structures and optical properties of novel substituted pyrazoly 1,3,4-oxadiazole derivatives.

Novel pyrazoly 1,3,4-oxadiazole derivatives were synthesized and characterized by (1)H NMR, IR, HRMS and X-ray diffraction analysis. UV-vis absorption and fluorescence properties of these compounds in different solutions showed that the maximum absorption wavelength was not significantly changed in different solvents; however, maximal emission wavelength was red-shifted with the increase of solvent polarity. Absorption λ(max) and emission λ(max) was less correlated with substituent groups on aryl rings.

The synthesis, X-ray crystal structure and optical properties of novel 5-aryl-3-ferrocenyl-1-pyridazinyl-pyrazoline derivatives.

A series of novel 5-aryl-3-ferrocenyl-1-pyridazinyl pyrazoline derivatives was synthesized by the reaction of ferrocenyl chalcone and 3-chloro-6-hydrazinylpyridazine in 10-65% yields. The compounds were characterized using IR, (1)H NMR, HRMS spectroscopic techniques and representative compounds 3c and 4c were assigned based on the X-ray crystallographic structure. The absorption and fluorescence characteristics of the compounds were investigated in chloroform, tetrahydrofuran and acetonitrile, respectively. The results showed that the absorption maxima of the compounds varied from 323 to 327 nm depending on the groups bonded to benzene and pyridazine ring. The maximum emission spectra of compounds in CHCl(3) were dependent on groups in pyridazine ring in which a strong donating-electron group such as propoxyl group on pyridazine ring in N-1 position of pyrazoline made the emission wavelength of 4a-4e small red shifte than that of compounds 3a-3e with chlorine group. The intensity of absorption and fluorescence was also correlated with substituent on aryl ring in C-5 position of pyrazoline. In addition, the absorption spectra of these compounds changed very little, but the fluorescence spectra had much change with increasing solvent polarity.

Synthesis of novel oxime-containing pyrazole derivatives and discovery of regulators for apoptosis and autophagy in A549 lung cancer cells.

A series of novel oxime-containing pyrazole derivatives were synthesized by the reaction of ethyl 3-phenyl-1H-pyrazole-5-carboxylate derivatives and 2-bromo-1-phenylethanone followed by the reaction with hydroxylamine hydrochloride. The structures were determined by IR, (1)H NMR, HRMS, and X-ray analysis. A dose- and time-dependent inhibition of proliferation was observed in A549 lung cancer cell after compound treatment. Inhibition of growth was mainly attributed to the autophagy induction.

The synthesis, X-ray crystal structure and optical properties of novel 1-ferrocenyl-2-(3-phenyl-1H-1,2,4-triazol-5-ylthio)ethanone derivatives.

A series of novel 1-ferrocenyl-2-(3-phenyl-1H-1,2,4-triazol-5-ylthio)ethanone derivatives was synthesized by the reaction of 3-substituted-1H-1,2,4-triazole-5-thiol and chloroacetyl ferrocene in the presence of sodium hydride and potassium iodide at reflux. The structures of the new compounds were determined by IR and (1)H NMR spectroscopy and HRMS. The structure of compound 5c was established by X-ray crystallography. UV-vis absorption and fluorescence spectra were recorded in ethanol and dichloromethane. The results showed that compounds 5a-g display similar absorptions ranging from 300 to 500nm and maximal emission bands are about 566nm. The intensity of fluorescence and maximal emission bands are dependent on the groups bonded to triazole rings.

Synthesis, single-crystal characterization and preliminary biological evaluation of novel ferrocenyl pyrazolo[1,5-a]pyrazin-4(5H)-one derivatives.

A series of novel ferrocenyl pyrazolo[1,5-a]pyrazin-4(5H)-one derivatives was synthesized and characterized by 1H NMR, 13C NMR, IR, HRMS and X-ray diffraction analysis. Preliminary evaluation of biological applications showed that the compounds 6c and 6f inhibit the growth of A549 cells in dosage-dependent manners through cell cycle arrest.

Synthesis of novel pyrazole carboxamide derivatives and discovery of modulators for apoptosis or autophagy in A549 lung cancer cells.

A series of novel 3-aryl-1-arylmethyl-1H-pyrazole-5-carboxamide derivatives 3a-l, were synthesized by the reaction of 3-aryl-1-arylmethyl-1H-pyrazole-5-carbonyl chloride with substituted amine in excellent yields. The compounds 3e-h could suppress A549 lung cancer cell growth. More interestingly, compounds 3e and 3f might inhibit the A549 cell growth by inducing apoptosis; whereas compounds 3g and 3h with fluorine group might inhibit the A549 cell growth by inducing autophagy.