Nifuroxazide and 4-Hydroxybenzhydrazone Derivatives as New Antiparasitic (Trypanosoma cruzi and Leishmania mexicana) and Anti- Mycobacterium tuberculosis Agents

Abstract

Background/Objectives: Nifuroxazide (Nfz) is a drug that has been used as a scaffold for designing antimicrobial and antiparasitic agents. This study aimed to synthesize and evaluate in vitro of Nfz and twenty-five 4-hydroxybenzhydrazone derivatives as potential anti-Trypanosoma cruzi, anti-Leishmania mexicana, and anti-Mycobacterium tuberculosis agents. Methods: The compounds were synthesized by condensing 4-hydroxybenzhydrazide with appropriate aldehydes in acidic conditions and structurally confirmed by spectroscopic techniques. All compounds were evaluated in vitro against T. cruzi strains (NINOA and A1), L. mexicana (M379 and FCQEPS strains), and M. tuberculosis (H37Rv strain), followed by enzymatic assays against T. cruzi cysteine proteases. Results: Compound Nfz-24 (IC₅₀ = 6.8 μM) had better trypanocidal activity than the reference drugs benznidazole (IC₅₀ > 30 μM) and nifurtimox (IC₅₀ > 7 μM) against the NINOA strain, and Nfz-8 (IC₅₀ = 7.2 μM) was the compound most active against the A1 strain with a high inhibition of T. cruzi cysteine proteases (IC₅₀ = 4.6 μM) and low cytotoxic effects (CC₅₀ >100 μM). On the other hand, compound Nfz-5 (IC₅₀ = 5.2 μM) had a 25-fold better leishmanicidal effect than glucantime (IC₅₀ > 125 μM) against the L. mexicana M379 strain, and compound Nfz-13 had the best leishmanicidal effects (IC₅₀ = 10.2 μM) against the FCQEPS strain. Finally, Nfz, Nfz-1, and Nfz-2 had minimum inhibitory concentration (MIC) values of 12.3, 5.1, and 18.8 μg/mL against M. tuberculosis, respectively. Conclusions: In summary, these results suggest that the compounds Nfz-1, Nfz-2, Nfz-5, Nfz-8, Nfz-10, Nfz-15, Nfz-24, and Nfz-25 are candidates for further studies to develop new and more potent anti-T. cruzi, anti-leishmaniasis, and anti-M. tuberculosis agents.

Keywords: Leishmania mexicana; Trypanosoma cruzi; anti-Mycobacterium tuberculosis; cysteine protease inhibitors; hydrazone moiety; nifuroxazide.

Figure 1

Chemical structures of some approved 5-nitrofuran (blue circle) drugs containing the N-acylhydrazone framework (red).

Figure 2

Structural modification of nifuroxazide to obtain new derivatives with anti-T. cruzi, anti-L. mexicana, and anti-Mycobacterium tuberculosis activity. The pink arrows indicate the final compounds reported by Kannigadu et al. [19], Badenhorst et al. [20], and those obtained in this investigation. The blue square highlights the chemical modification to Nfz performed by Kannigadu et al., and the yellow square indicates the substituents incorporated into Nfz reported by Badenhorst et al. The green box shows the substituents incorporated into the 4-hydroxybenzhydrazide fragment in this work.

Scheme 1

Synthetic route and percentage of yield of nifuroxazide and 4-hydroxybenzhydrazone derivatives obtained.

Figure 3

SAR analysis of Nfz and 4-hydroxybenzhydrazone derivatives against T. cruzi. The blue square highlights the retained 4-Hydroxybenzhydrazone pharmacophore, and the green arrow indicates the substituents most active.

Figure 4

SAR analysis of Nfz and the 4-hydroxybenzhydrazone derivatives against L. mexicana. The yellow square highlights the retained 4-Hydroxybenzhydrazone pharmacophore, and the pink arrow indicates the substituents most active.

Figure 5

SAR analysis of Nfz and its analogs against the M. tuberculosis H37Rv strain. The blue square highlights the retained 4-Hydroxybenzhydrazone pharmacophore, and the pink square indicates the heterocycle substituents more active.