Azacyanines as Novel Topoisomerase II Alpha Inhibitors

Divergent Synthesis of α-(1,3,5-Triazinylthio)-ketones and Thiazolo[3,2-a][1,3,5]triazines from 1,3-Dicarbonyl compounds or Chalcones with 1,3,5-Triazine-2-thiols

An efficient synthesis of α-(1,3,5-triazinylthio)-ketones from 1,3-dicarbonyl compounds with 1,3,5-triazine-2-thiols has been developed. The reaction proceeds through the C-C bond cleavage and C-S bond reconstruction of 1,3-dicarbonyl compounds, and β-keto esters, β-keto amides, and 1,3-diones were tolerated. In addition, the annulation of 1,3,5-triazine-2-thiols with chalcones has been achieved for the synthesis of thiazolo[3,2-a][1,3,5]triazines. The method occurred in moderate to good yields and tolerated chalcone with a broad functional group.

Coumarin 6H-fused fluorescent probe for highly sensitive detection of coralyne using oligonucleotide-modified silver nanoparticles

In this study, a novel, rapid, and sensitive fluorescence sensing platform was developed for the detection of coralyne (COR) by the conjugation of coumarin 6H (C6H) fluorescent dye with oligonucleotide-modified silver nanoparticles [(dT)₃₂-AgNPs]. In the presence of COR, a remarkable and rapid decrease in the fluorescence signal of the probe with a quenching efficiency of around 62% was observed. The quenching response of the system towards COR was possibly due to the displacement of thymidine-rich deoxyoligonucleotides by COR on the surface of AgNPs. The complementary experiments with an adenine-rich single strand as well as with two different secondary structures (i.e., duplex and triplex) revealed a favorable sequence specificity of the sensing platform. The influence of key parameters including the incubation time and temperature was evaluated and optimized to achieve the highest performance. The linear range of 10-183 nM with a correlation coefficient of R = 0.9982 and a limit of detection of 5.24 nM were obtained under the optimized conditions. The selectivity of the proposed probe towards COR was revealed by the evaluation of its response to other small molecules that have molecular structures similar to COR. Finally, the successful applicability of the system was shown with the obtained average recoveries in the range of 87.28-104.52% in human urine samples.

Novel Fluorescent Azacyanine Compounds: Improved Synthesis and Optical Properties

Benzothiazoles are known to possess a number of biological activities and therefore are considered to be an important scaffold in the design and synthesis of pharmacophores. In this study, an improved synthesis method for novel fluorescent benzothiazole-based cyclic azacyanine (CAC) dyes bearing different electron-donating/withdrawing groups on their scaffold is presented. The improved method enabled us to increase the synthesis yield for the previously reported CACs. More importantly, it allowed us to synthesize new CAC dyes that were not synthesizable with the previously reported method. The synthesized dyes were characterized by ¹H and ¹³C NMR spectroscopy, elemental analysis, and mass spectrometry and their optical (absorption and fluorescence) properties were investigated. All of the synthesized CACs were found to be displaying strong absorption within the range of 387-407 nm. The spectral shifts observed in the absorption and fluorescence measurements suggested that the spectroscopic and optical properties of CACs can be directly modulated by the nature of the electron-donating/withdrawing substituents. The fluorescence quantum yields (QYs) of the unsubstituted (parent CAC) and substituted CACs were also measured and compared. The fluorescence QY of CACs with electron-donating substituents (methoxy or ethoxy) was found to be at least four times higher than that of the parent CAC with no substitutions.