Antileishmanial Activity of Manganese (III) Oxide Nanoparticles (Mn2O3 NPs) Alone and in Combination with Shark Cartilage Extract against Leishmania infantum: in Vitro and in Vivo Approaches

Abstract

Background: The recent increase in unresponsive cases to current treatments poses a significant challenge in the effort to discover new antileishmanial drugs. We aimed to investigate the effects of Mn₂O₃ NPs alone or in combination with shark cartilage extract (ShCE) on L. infantum (MCAN/ES198/LIM-877) both in vitro and in vivo.

Methods: The susceptibility of promastigotes and amastigotes was evaluated using MTT and microscopy assays with different concentrations of Mn₂O₃ NPs alone or in combination with ShCE (Mn₂O₃-ShCE). The combination index (CI) was used to assess potential synergy. Cytotoxicity against J774.A1 macrophages was measured, and the selectivity index (SI) was calculated. Also, apoptosis was analyzed in promastigotes. The therapeutic and prophylactic effects were tested in BALB/c mice, and survival rates were monitored.

Results: Mn₂O₃ NPs caused a dose-dependent decrease in proliferation of promastigotes (IC₅₀=19.8±1.1 μg/mL) and amastigotes (IC₅₀=29.9±0.05 μg/mL). Co‑treatment with ShCE significantly enhanced the antileishmanial activity, reducing the IC₅₀ values of promastigotes and amastigotes. The CC₅₀ values were 159.9±4.2 μg/mL for Mn₂O₃ NPs and 276.5±7.9 μg/mL for Mn₂O₃-ShCE. Apoptosis rates in promastigotes treated with Mn₂O₃ and Mn₂O₃-ShCE were 80.7% and 86.3%, respectively. Parasite loads in the tissues significantly decreased (P<0.001) in BALB/c mice treated with Mn₂O₃ NPs, and survival rates increased significantly (P<0.05). The combination with ShCE further improved outcomes, with 100% survival observed in the Mn₂O₃-ShCE group (P<0.01).

Conclusion: These findings demonstrated a synergistic effect between Mn₂O₃ NPs and ShCE against L. infantum. Therefore, it may serve as a promising candidate for future development of leishmanicidal drugs.