A reversed‐phase compatible thin‐layer chromatography autography for the detection of acetylcholinesterase inhibitors

A dual readout autographic assay to detect acetylcholinesterase inhibitors present in complex matrices adsorbed on reversed‐phase or normal‐phase thin‐layer chromatography plates is described. Enzyme gel entrapment with an amphiphilic copolymer was used for assay development. The effects of substrate and enzyme concentrations, pH, incubation time, and incubation temperature on the sensitivity and the detection limit of the assay were evaluated. Experimental design and response surface methodology were used to optimize conditions with a minimum number of experiments. The assay allowed the detection of 0.01% w/w of physostigmine in both a spiked Sonchus oleraceus L. extract chromatographed on normal phase and a spiked Pimenta racemosa (Mill.) J.W. Moore leaf essential oil chromatographed on reversed phase. Finally, the reversed‐phase thin‐layer chromatography assay was applied to reveal the presence of an inhibitor in the Cymbopogon citratus (DC.) Stapf essential oil. The developed assay is able to detect acetylcholinesterase inhibitors present in complex matrixes that were chromatographed in normal phase or reversed‐phase thin‐layer chromatography. The detection limit for physostigmine on both normal and reversed phase was of 1×10^?4 μg. The results can be read by a change in color and/or a change in fluorescence.     

Microwave-assisted synthesis of 2-styrylquinoline-4-carboxylic acid derivatives to improve the toxic effect against Leishmania (Leishmania) amazonensis

The identification of new compounds is urgent to develop safe and efficacious candidates for leishmaniasis treatment, especially from natural products as a potential source of active molecules against neglected tropical parasite diseases. Inspired by the efficacious quinoline alkaloid microbial effects, we have previously reported the synthesis and biological activity of 2-phenylquinoline-4-carboxylic acids and poly-substituted quinolines against parasites. In this work, a series of eighteen 2-styryl-4-quinolinecarboxylic acids were synthesized under microwave irradiation settings obtaining from good to excellent yields (60%-90%), shorter reaction times (2 minutes), and eco-friendly experimental conditions. All these products were evaluated against infective forms of Leishmania (Leishmania) amazonensis, such as promastigotes and intracellular amastigotes, based on cytotoxicity assays, including host macrophage infection assays. Compounds 4 and 5 possessing a 2-chloro or 4-chlorostyryl moiety, respectively, were considered the most promising antileishmanial agents due to the parasite killing effect in intracellular forms inside infected macrophages. Thus, our results revealed that the 2-styryl-4-quinolinecarboxylic acid backbone structure was essential for the activity against intracellular pathogens like L. (L.) amazonensis.