Cyanine based ratio fluorescent probe and its application in hypochlorite detection.

Hypochlorite (ClO-), a weakly acidic reactive oxygen species, plays a crucial role in antibacterial and anti-inflammatory defense mechanisms. However, elevated levels of ClO- or disruptions in endogenous sites can lead to tissue damage and various diseases including cardiovascular disease, neuronal degeneration, and arthritis. To address this, the development of a specific fluorescent probe with a built-in self-calibration ratio mode for the analysis and biological imaging of ClO- is essential. In this study, a cyanine-based fluorescent probe (Cy-H) was designed for ratiometric fluorescent detection of ClO-, utilizing its aggregation behavior as a novel approach in this field. Upon exposure to ClO-, the phenolic hydroxyl group in probe Cy-H was oxidized into benzoquinone, leading to the formation of cyanine products that displayed a strong tendency to aggregate. As a result, the maximum emission peak of the probe shifted from 700 nm to 485 nm. Notably, a linear relationship was observed between the peak intensity ratio (I485/I700) and the concentration of hypochlorite, with a limit of detection (LOD) of 0.49 µM. Furthermore, this probe was successfully employed for imaging analysis of hypochlorite in living cells and zebrafish.

Fluorescent probe for highly selective detection of cysteine in living cells.

Cys play an important physiological role in the human body. Abnormal Cys concentration can cause many diseases. Therefore, it is of great significance to detect Cys with high selectivity and sensitivity in vivo. Because homocysteine (Hcy) and glutathione (GSH) have similar reactivity and structure to cysteine, few fluorescent probes have been reported to be specific and efficient for cysteine. In this study, we designed and synthesized an organic small molecule fluorescent probe ZHJ-X based on cyanobiphenyl, which can be used to specifically recognize cysteine. The probe ZHJ-X exhibits specific selectivity for cysteine, high sensitivity, short reaction response time, good anti-interference ability, and has a low detection limit of 3.8 × 10-6 M. The probe ZHJ-X was successfully applied to the visualization of Cys in living cells and had great application prospects in cell imaging and detection.

Design and Synthesis of Novel Fluorescent Probe Based on Cyanobiphenyl and its Application in Detection of Hypochlorite.

Hypochlorite is an important biological reactive oxygen species, which plays a pivotal role in various life activities. Excessive presence in the human body or excessive intake in life causes a series of diseases. To monitor the hypochlorite level in living cells, organisms and environment water samples, we herein designed and synthesized three organic small molecule fluorescent probes with different recognition sites based on nitrile biphenyl. Through performance comparison, it was found that probe A-HM exhibited the best detection performance for hypochlorite with a low detection limit of 2.47 × 10-6 M. The introduction of hypochlorite will induce probe fluorescence A-HM to turn on, and the fluorescence colour will change from colourless to green. The application of A-HM in biological systems has been demonstrated by the imaging monitoring of hypochlorite in MCF-7, L929 cells and zebrafish. Furthermore, A-HM was also used for the accurate determination of the hypochlorite level in real water samples with high sensitivity and good recoveries.

Isoquercitrin activates the AMP-activated protein kinase (AMPK) signal pathway in rat H4IIE cells.

BACKGROUND: Isoquercitrin, a flavonoid compound that is widely distributed in medicinal and dietary plants, possesses many biological activities, including inhibition of adipocyte differentiation. In this study, we investigated the effect of isoquercitrin on lipid accumulation and its molecular mechanisms in rat hepatoma H4IIE cells. METHODS: To investigate the effect of isoquercitrin on lipid accumulation, H4IIE cells were induced by FFA and the total lipid levels were detected by Oil Red O staining. Furthermore, The protein levels of AMPK and acetyl-CoA carboxylase (ACC), the gene expressions of transcriptional factor, lipogenic genes, and adiponectin receptor 1 (AdipoR1) were analyzed by Western blotting and quantitative real-time PCR. To further confirm the pathway of isoquercitrin-mediated hepatic lipid metabolism, H4IIE cells were treated with an AMPK inhibitor and AdipoR1 siRNA. RESULTS: Isoquercitrin significantly enhances AMPK phosphorylation, downregulates sterol regulatory element binding protein transcription factor 1 (SREBP-1) and fatty acid synthase (FAS) gene expressions. Pretreatment with AMPK inhibitor, significantly decreased the AMPK phosphorylation and increased FAS expression stimulated by isoquercitrin. Isoquercitrin might also upregulate the expression of AdipoR1 dose-dependently via AMPK in the presence of an AMPK inhibitor and AdipoR1 siRNA. CONCLUSIONS: Isoquercitrin appears to regulate AMPK activation, thereby enhancing AdipoR1 expression, suppressing SREBP-1 and FAS expressions, and resulting in the regulation of lipid accumulation. These results suggest that isoquercitrin is a novel dietary compound that can be potentially be used to prevent lipid metabolic disorder and nonalcoholic fatty liver disease.