Theoretical and Experimental Investigations of Large Stokes Shift Fluorophores Based on a Quinoline Scaffold.

A series of novel styrylquinolines with the benzylidene imine moiety were synthesized and spectroscopically characterized for their applicability in cellular staining. The spectroscopic study revealed absorption in the ultraviolet-visible region (360-380 nm) and emission that covered the blue-green range of the light (above 500 nm). The fluorescence quantum yields were also determined, which amounted to 0.079 in the best-case scenario. The structural features that are behind these values are also discussed. An analysis of the spectroscopic properties and the theoretical calculations indicated the charge-transfer character of an emission, which was additionally evaluated using the Lippert-Mataga equation. Changes in geometry in the ground and excited states, which had a significant influence on the emission process, are also discussed. Additionally, the capability of the newly synthesized compounds for cellular staining was also investigated. These small molecules could effectively penetrate through the cellular membrane. Analyses of the images that were obtained with several of the tested styrylquinolines indicated their accumulation in organelles such as the mitochondria and the endoplasmic reticulum.

Acid selective pro-dye for cellular compartments.

A novel pro-dye approach for the acid-selective staining of the subcellular compartments for better permeability and selectivity was applied. The designed sensor has suitable physicochemical properties such as a large Stokes shift and a long-lived intracellular fluorescence. The Schiff base fragment was used for the acid-sensitive release of a fluorophore without affecting the overall stability of the biological systems. Due to the presence of an imine bond in its structure and its unique fluorescent properties, it can be presented as a "pro-dye" for acidic structures such as lysosomes. As a result of an imine bond cleavage, a new fluorescent compound is released, whose substantially shifted excitation and emission wavelengths enable a more selective and effective imaging of lysosomes and endosomes. The presented report provides the chemical, physicochemical and optical profiles as well as biological assays and theoretical calculations.

Electrolytic copper as cheap and effective catalyst for one-pot triazole synthesis.

Electrolytic copper is a well-known form of pure, oxygen free copper that is used for industrial applications. In this work, the catalytic potential of this relatively cheap material was studied. The addition of less than 0.015 mol equivalent of copper powder effectively catalysed the one-pot synthesis of triazoles from a diverse range of organic halides and alkynes. Quantitative conversions in aqueous solvents can be achieved within minutes. The heterogenous nature of the catalyst afforded a low level of copper contamination in the products, thus meeting the rigorous criteria of the pharmaceutical industry.

Quinoline Fluorescent Probes for Zinc - from Diagnostic to Therapeutic Molecules in Treating Neurodegenerative Diseases.

BACKGROUND: Fluorescent compounds had gained strong attention due to their wide and appealing applications. Microscopic techniques and visualization are good examples among others. Introduction of fluorescent dyes into microbiology opens the possibility to observe tissues, organisms or organelle with exceptional sensitivity and resolution. Probes for detection of biologically relevant metals as zinc, iron or copper seems to be particularly important for drug design and pharmaceutical sciences. OBJECTIVE: Quinoline derivatives are well known for their good metal affinity and wide spectrum of biological activity. In this regard, molecular sensors built on this scaffold may be useful not only as analytical but also as therapeutic agents. METHODS: In the present review, application of quinoline moiety in designing of novel fluorescent probes for zinc is presented and discussed. RESULTS: Zinc cations are relevant for vast majority of processes and recently attract a great deal of attention for their role in neurodegenerative diseases. Compounds interacting with Zn2+ may be used for early diagnosis of such disorders, for example the Alzheimer disease. CONCLUSION: Quinoline-based zinc probes may exert some beneficial role in organism acting as theranostic agents. First preliminary drugs for Alzheimer therapy that are based on quinoline moiety are good example of this trend.

Small molecule glycoconjugates with anticancer activity.

Glycoconjugates are combinations of sugar moieties with organic compounds. Due to their biological resemblance, such structures often have properties that are desirable for drugs. In this study we designed and synthesised several glycoconjugates from small molecular quinolines and substituted gluco- and galactopyranosyl amines. Although the parent quinoline compounds were inactive in affordable concentrations, the glycoconjugates that were obtained appeared to be cytotoxic against cancer cells at the micromolar level. When combined with copper ions, their activity increased even further. Their mechanism of action is connected to the formation of reactive oxygen species and the intercalation of DNA.