A quest for novel antimicrobial targets: Inhibition of Asp-tRNAAsn/Glu-tRNAGln amidotransferase (GatCAB) by synthetic analogs of aminoacyl-adenosine in vitro and live bacteria.

The Asp-tRNAAsn/Glu-tRNAGln amidotransferase (GatCAB) has been proposed as a novel antibacterial drug target due to its indispensability in prominent human pathogens. While several inhibitors with in vitro activity have been identified, none have been demonstrated to have potent activity against live bacteria. In this work, seven non-hydrolyzable transition state mimics of GatCAB were synthesized and tested as the transamidase inhibitors against GatCAB from the human pathogen Helicobacter pylori. Notably, the methyl sulfone analog of glutamyl-adenosine significantly reduced GatCAB's transamination rate. Additionally, four lipid-conjugates of these mimics displayed antibacterial activity against Bacillus subtilis, likely due to enhanced cell permeability. Inhibitory activity against GatCAB in live bacteria was confirmed using a sensitive gain-of-function dual luciferase reporter in Mycobacterium bovis-BCG. Only the lipid-conjugated methyl sulfone analog exhibited a significant increase in mistranslation rate, highlighting its cell permeability and inhibitory potential. This study provides insights for developing urgently needed novel antibacterial agents amidst emerging antimicrobial drug resistance.

Design, Synthesis, and Characterization of Novel Styryl Dyes as Fluorescent Probes for Tau Aggregate Detection in Vitro and in Cells.

A series of novel styryl dye derivatives incorporating indolium and quinolinium core structures were successfully synthesized to explore their interacting and binding capabilities with tau aggregates in vitro and in cells. The synthesized dyes exhibited enhanced fluorescence emission in viscous environments due to the rotatable bond confinement in the core structure. Dye 4, containing a quinolinium moeity and featuring two cationic sites, demonstrated a 28-fold increase in fluorescence emission upon binding to tau aggregates. This dye could also stain tau aggregates in living cells, confirmed by cell imaging using confocal fluorescence microscopy. A molecular docking study was conducted to provide additional visualization and support for binding interactions. This work offers novel and non-cytotoxic fluorescent probes with desirable photophysical properties, which could potentially be used for studying tau aggregates in living cells, prompting further development of new fluorescent probes for early Alzheimer's disease detection.

Anthraquinones from the roots of Morinda scabrida Craib exhibit antiproliferative activity against A549 lung cancer cells and antitubulin polymerization.

Six anthraquinones were isolated from Morinda scabrida Craib, an unexplored species of Morinda found in the tropical forest of Thailand. All six anthraquinones showed cytotoxicity against A549 lung cancer cells, with the most active compound, nordamnacanthal (MS01), exhibiting the IC50 value of 16.3 ± 2.5 µM. The cytotoxic effect was dose-dependent and led to cell morphological changes characteristic of apoptosis. In addition, flow cytometric analysis showed dose-dependent apoptosis induction and the G2/M phase cell cycle arrest, which was in agreement with the tubulin polymerization inhibitory activity of MS01. Molecular docking analysis illustrated the binding between MS01 and the α/ß-tubulin heterodimer at the colchicine binding site, and UV-visible absorption spectroscopy revealed the DNA binding capacity of MS01.

Synthesis and evaluation of simple naked-eye colorimetric chemosensors for anions based on azo dye-thiosemicarbazones.

A series of novel, highly selective azo dye-thiosemicarbazones based anion sensors (3e-f) have been synthesized from the condensation reaction between thiosemicarbazide and six different azo salicylaldehydes. The structure of the sensors was confirmed by spectroscopic methods. The selectivity and sensitivity in the recognition for acetate anion over other anions such as fluoride, chloride, iodide and dihydrogenphosphate anions were determined by naked-eyes and UV-vis spectra. The color of the solution containing sensor had an obvious change from light yellow to orange only after the addition of acetate anion in aqueous solution (water/dimethylsulfoxide, 7:3, v/v) while other anions did not cause obvious color change. The anion recognition property of the receptor via proton-transfer is monitored by UV-vis titration and (1)H NMR spectroscopy. Under condition in aqueous solution of sensor 3e (water/dimethylsulfoxide, 7:3, v/v), linearity range for the quantification of acetate anion was 1-22 µM and limit of detection (LOD) of acetate anion was 0.71 µM.