A ratiometric fluorescence probe based on a novel recognition mechanism for monitoring endogenous hypochlorite in living cells.

A ratiometric fluorescence probe (named ZOC) for the fast detection of HClO/ClO- was constructed by coumarin (donor) and pyridinium (acceptor) based on Forster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) platform. ZOC possessed red emission signal (610 nm), large Stocks shift (190 nm), high energy transfer efficiency (95.3%), high selectivity and sensitivity, low detection limit (25 nM), wider detection range (from 25 nM to 30 µM), rapid response (within 13 S), and good biocompatibility. It was very interesting that the recognition mechanism involved a new organic reaction in which olefin double bond reacted first with HClO/ClO- regioselectively, followed by cyclization. ZOC was successfully used to the real time detection of endogenous HClO/ClO- in RAW 264.7 cells.

A novel lipid droplets-targeting ratiometric fluorescence probe for hypochlorous acid in living cells.

Lipid droplets were found to be involved in many organism activities. Here, a lipid droplets-targeted near-infrared fluorescence probe (named XHZ) for ratiometric detection of endogenous hypochlorous acid/hypochlorite (HClO/ClO-) in living cells was developed, which was constructed by a coumarin moiety and a malononitrile derivative. XHZ could detect HClO/ClO- with high selectivity and sensitivity in a ratiometric manner based on FRET (Förster Resonance Energy Transfer) mechanism. The two well-resolved emission (470/672 nm) bands could ensure accurate detection of HClO/ClO- in vitro as well as in vivo. XHZ was successfully used for ratiometric fluorescence imaging of exogenous and endogenous HClO/ClO- in RAW264.7 cells. A good linear relationship between the fluorescence intensity ratios of the two emissions and HClO/ClO- concentrations from 0 to 40 µM was obtained. Importantly, XHZ could localize mainly in lipid droplets of RAW264.7 cells. To the best of our knowledge, XHZ is the first lipid droplets-targeted ratiometric fluorescence probe for HClO/ClO-.

Synthesis of 6-cinnamoyl-2H-benzo[b][1,4]oxazin-3(4H)-ones and their effects on A549 lung cancer cell growth.

A series of novel 6-cinnamoyl-2H-benzo[b][1,4]oxazin-3(4H)-one derivatives was synthesized. The structures of compounds were characterized by (1)H NMR, IR, and MS. Moreover, representative crystal structure was determined by X-ray diffraction analysis. The preliminary biological evaluation of all these compounds showed that compounds 3a-3d would suppress the growth of A549 lung cells effectively by inducing autophagy and cell cycle arrest.

Novel ferrocenyl derivatives exert anti-cancer effect in human lung cancer cells in vitro via inducing G1-phase arrest and senescence.

AIM: To investigate the effects of 7 novel 1-ferrocenyl-2-(5-phenyl-1H-1,2,4-triazol-3-ylthio) ethanone derivatives on human lung cancer cells in vitro and to determine the mechanisms of action. METHODS: A549 human lung cancer cells were examined. Cell viability was analyzed with MTT assay. Cell apoptosis and senescence were examined using Hoechst 33258 and senescence-associated-ß-galactosidase (SA-ß-gal) staining, respectively. LDH release was measured using a detection kit. Cell cycle was analyzed using a flow cytometer. Intracellular ROS level was measured with the 2',7'-dichlorodihydrofluorescein probe. Phosphorylation of p38 was determined using Western blot. RESULTS: Compounds 5b, 5d, and 5e (40 and 80 µmol/L) caused significant decrease of A549 cell viability, while other 4 compounds had no effect on the cells. Compounds 5b, 5d, and 5e (80 µmol/L) induced G1-phase arrest (increased the G1 population by 22.6%, 24.23%, and 26.53%, respectively), and markedly increased SA-ß-gal-positive cells. However, the compounds did not cause nuclear DNA fragmentation and chromatin condensation in A549 cells. Nor did they affect the release of LDH from the cells. The compounds significantly elevated the intracellular ROS level, decreased the mitochondrial membrane potential, and increased p38 phosphorylation in the cells. In the presence of the antioxidant and free radical scavenger N-acetyl-L-cysteine (10 mmol/L), above effects of compounds 5b, 5d, and 5e were abolished. CONCLUSION: The compounds 5b, 5d, and 5e cause neither apoptosis nor necrosis of A549 cells, but exert anti-cancer effect via inducing G1-phase arrest and senescence through ROS/p38 MAP-kinase pathway.