Evaluating the Antitrypanosomatid Activity of Thiazolyl–Isatins: Synthesis, Biological Evaluation, and Electronic Structure Analysis Using the Semiempirical GFN2‐xTB Method

The Trypanosomatidae family, which includes Trypanosoma and Leishmania species, is responsible for several neglected tropical diseases. The limitations of current therapies highlight the urgent need for novel therapeutic strategies. Here, we report the design and synthesis of 43 new hybrid molecules that combine isatin and thiazole scaffolds, which were evaluated for their in vitro anti‐Trypanosomatidae activity and subjected to in silico analyses. In the anti‐ Trypanosoma cruzi assays, 12 compounds displayed EC 50 values ranging from 1.30 to 3.14 µM, comparable to that of benznidazole (EC 50 = 3.17 µM). In the leishmanicidal assays, against the promastigote form of Leishmania amazonensis , 36 compounds exhibited EC 50 values lower than miltefosine (EC 50 = 26.74 µM), with compounds 8 and 10 emerging as the most potent (EC 50 = 1.40 µM). However, none surpassed miltefosine against the amastigote form of Leishmania infantum or L. amazonensis . The compounds exhibited cytotoxicity toward RAW 264.7 macrophages and L929 fibroblasts. In silico predictions indicated that all synthesized compounds presented favorable bioavailability scores, drug‐likeness profiles, and physicochemical stability. Moreover, molecular and electronic structure analyses revealed a moderate, positive, and statistically significant correlation ( ρ = 0.50, p < 0.05) with trypanothione reductase, suggesting this enzyme as a potential biological target in T. cruzi .