N-Propargyltetrahydrocarbazoles and N-propargyltetrahydro-γ-carbolines in 1,3-cycloaddition with azide-containing pharmacophores

Microwave-assisted synthesis, molecular docking studies of 1,2,3-triazole-based carbazole derivatives as antimicrobial, antioxidant and anticancer agents

Herein, a new series of N-substituted 1,2,3-triazolylmethyl indole derivatives 4(a-u) was synthesized by rationally incorporating a pharmacophoric active heterocyclic ring containing indole and triazole moieties in one molecular frame via the conventional and microwave irradiation methods. Briefly, the new compounds 4(a-u) were synthesized via the N-alkylation of tetrahydro-1H-carbazoles followed by click reaction and copper-catalyzed Huisgen [3 + 2] cycloaddition in the presence of copper sulphate and sodium ascorbate with various aromatic azides 3(a-m). All the newly synthesized compounds were characterized via ¹H and ¹³C NMR, mass, and IR spectroscopy and evaluated for their antimicrobial, antioxidant and anticancer activities. Among the synthesized compounds, 4d, 4j, 4n, 4p, 4s and 4r were found to exhibit good antimicrobial, antioxidant, anticancer activities. The biological activity of the synthesized compounds was further supplemented by molecular docking studies against the target receptors caspase-3 and 17-beta-hydroxy steroid dehydrogenase type 1, revealing that the reported structures best fit into the active site pocket of the target molecules.

Exploring the chemical space of 1,2,3-triazolyl triclosan analogs for discovery of new antileishmanial chemotherapeutic agents

Triclosan and isoniazid are known antitubercular compounds that have proven to be also active against Leishmania parasites. On these grounds, a collection of 37 diverse 1,2,3-triazoles based on the antitubercular molecules triclosan and 5-octyl-2-phenoxyphenol (8PP) were designed in search of novel structures with leishmanicidal activity and prepared using different alkynes and azides. The 37 compounds were assayed against Leishmania donovani, the etiological agent of leishmaniasis, yielding some analogs with activity at micromolar concentrations and against M. tuberculosis H37Rv resulting in scarce active compounds with an MIC of 20 μM. To study the mechanism of action of these catechols, we analyzed the inhibition activity of the library on the M. tuberculosis enoyl-ACP reductase (ENR) InhA, obtaining poor inhibition of the enzyme. The cytotoxicity against Vero cells was also tested, resulting in none of the compounds being cytotoxic at concentrations of up to 20 μM. Derivative 5f could be considered a valuable starting point for future antileishmanial drug development. The validation of a putative leishmanial InhA orthologue as a therapeutic target needs to be further investigated.