Synthesis of Dipicolinic Acid Derivatives of Potential Anti-leishmanial Activity

Abstract

Abstract : Leishmaniasis is a parasitic disease caused by Leishmania species, transmitted through the bites of infected sandflies. It poses a significant public health challenge in many tropical and subtropical regions, leading to severe morbidity and mortality. Current treatments, such as miltefosine, are limited by toxicity, resistance, and accessibility issues. Therefore, developing new compounds with improved efficacy and safety profiles is essential to combat this disease effectively and provide better treatment options for affected populations. This research focuses on synthesizing and characterizing dipicolinic acid derivatives, evaluating their anti-leishmanial activities, and elucidating their mechanisms of action. Molecular docking studies were conducted to predict the binding interactions of these compounds with key targets in the Leishmania metabolic pathways. Additionally, cytotoxicity assessments and predictions regarding the absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles of the most active compounds were performed. The findings aim to provide better treatment options for affected populations and contribute to the ongoing efforts to combat leishmaniasis. The current study successfully synthesized dipicolinic acid derivatives, achieving percentage yields between 33.1% and 85.46%, with relatively easy synthetic method making these compounds attractive candidates for further study. The structures of the synthesized compounds were confirmed through spectroscopic and elemental analyses. In vitro screening against two forms of L.major demonstrated that all compounds exhibited activity, with compound IV showing the highest efficacy with IC50 of 2.86±0.14 µM against promastigotes and 3.84±0.16 µM against amastigotes, outperforming the reference drug miltefosine by nearly three times. Mechanistic studies indicated that compound 4 inhibits the folic acid pathway, as evidenced by anti-folate tests and molecular docking, which revealed a docking score of -13.73 kcal/mol for Lm-PTR1, surpassing that of trimethoprim (-11.91 kcal/mol). Additionally, in vitro cytotoxicity assays indicated a superior safety profile for compound IV, with an IS value of 108.2, significantly better than miltefosine. In silico analyses further suggested favourable bioavailability and the potential for enhanced toxicity profiles, reinforcing the viability of these compounds as promising candidates for anti-leishmanial therapies.