Novel Hit Compounds Against a Neglected Sexually Transmitted Infection: Synthesis and Trichomonacidal Activity of 1,3-Thiazolidin-4-One Derivatives

<b>Background</b>: Infections caused by the protozoan <i>Trichomonas vaginalis</i> affect millions of people worldwide and are responsible for one of the most common sexually transmitted diseases. Despite the efficacy of 5-nitroimidazoles like metronidazole, concerns regarding widespread resistance and the absence of viable alternatives for specific patient populations necessitate the development of structurally diverse pharmacological agents. In this study, we investigated the antiparasitic activity of 1,3-thiazolidin-4-one derivatives against <i>T. vaginalis</i>. <b>Methods</b>: Thiazolidines were synthesized via multicomponent reaction (MCR) using one-pot methodology and tested in vitro against the parasite and mammalian cell lines. <b>Results</b>: Seventy percent of the compounds showed more than 80% antiparasitic activity at 100 μM, with compounds <b>4a</b>, <b>4b</b>, and <b>4f</b> exhibiting IC₅₀ ≤ 20 µM. None of the molecules exhibited cytotoxic against Vero CCL-81 and HeLa cells. Evaluation of the structure-activity relationship (SAR) indicates that the substituent at the nitrogen position of the heterocycle may be involved in the antiparasitic effect of these compounds. In silico studies also revealed that the three compounds possess adequate oral bioavailability and do not present mutagenic, tumorigenic or irritating risks. Finally, molecular docking predicted strong interactions of compounds <b>4a</b>, <b>4b</b>, and <b>4f</b> with <i>T. vaginalis</i> enzymes lactate dehydrogenase and purine nucleoside phosphorylase; compound <b>4f</b> also interacted with methionine Ƴ-lyase. <b>Conclusions</b>: These preliminary results suggest that 1,3-thiazolidin-4-ones are promising scaffolds for developing new trichomonacidal agents.