The discovery of new active substances is a costly, time-consuming, and demanding process. It starts with target identification and validation, followed by the selection of an appropriate screening method to reveal the hit and lead compounds. High-throughput screening (HTS) is a method that allows the detection of a vast number of hit compounds in a relatively short time from a set of a large chemical library of compounds. HTS methods include pulsed ultrafiltration affinity selection-mass spectrometry (PUF AS-MS), which, after incubation of a chemical library with a target, identifies the compounds that bind to it. A simple and rapid method for obtaining a chemical library of compounds is click chemistry or copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition.
Within the framework of the master's degree, we created a chemical library of monoalkynes, diakynes and monoazides based on click chemistry. The aim was to obtain as many compounds as possible in the shortest possible time, to confirm their presence by liquid chromatography coupled with mass spectrometry (LC-MS) and to further evaluate their activity on different targets by biochemical assays or PUF AS-MS.
Around 800 different 1,2,3-triazole products were prepared in 74 reaction mixtures by click reactions. All the products of the reactions between monoazides and monoalkynes were identified by LC-MS analysis. More difficult was the identification of a larger number of compounds formed after the reaction between monoazides and dialkynes. In this case, not all compounds could be identified, and the signals were generally weaker, so it would be necessary to automate the process of generating products and finding hits and to limit to a smaller number of compounds in one reaction mixture.
Biochemical tests were performed on the bacterial enzymes MurA and DdlB, the viral enzyme 3CLpro, the enzymes hMAO-A and hMAO-B, and the antibacterial activity against E. coli and S. aureus was evaluated. The results were mainly reported as residual activities. Among the compounds tested, MurA, DdlB and 3CLpro enzyme inhibitors were absent. Mixture 55 inhibited the growth of S. aureus. 39 reaction mixtures showed moderate inhibitory activity of hMAO-A and/or hMAO-B enzymes. In these reaction mixtures, active compounds suitable for optimisation could be further identified by PUF AS-MS.
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