Exploring the phytomedicine properties of azadiradione against leishmaniasis: in silico and in vitro insights.

BACKGROUND

Leishmaniasis continues to pose a significant global health challenge, exacerbated by the increasing resistance to current therapeutic agents such as miltefosine and amphotericin B. This growing resistance highlights the urgent need for alternative treatment strategies. In this context, phytomedicine has emerged as a promising avenue for novel antileishmanial therapies. In our previous study, the crude extract derived from neem (Azadirachta indica) leaves exhibited notable antileishmanial activity. Subsequent analysis using LC-MS/MS enabled the identification of bioactive constituents within the active fraction, including azadiradione (AZD), a drug with potential therapeutic effects unexplored against leishmaniasis.

RESULTS

AZD exhibited dose-dependent growth inhibition along with structural disruption and DNA fragmentation in promastigotes with an IC of 17.09 μM. In silico docking and simulation with AZD identified Leishmania peroxidases (e.g., ascorbate peroxidase and tryparedoxin peroxidase) as probable molecular targets, with subsequent downregulation of their expression confirmed in vitro. The CC on human macrophages (MФs) and EC on intracellular amastigotes were determined as 56.32 μM and 11.67 μM for AZD, respectively. The dose-dependent reduction in MФs' infectivity demonstrates the drug potential of AZD against the pathogenic stage of Leishmania. However, the selectivity index (SI) of AZD was calculated as 4.83, indicating a moderate Leishmania-specific drug potential of AZD. The decrease in IL-10, IL-1β, and arginase expression and the increase in IL-12 and iNOS expression reinforce the immunoregulatory potential of AZD in favour of the host. Further investigations are required to optimize the dosage and improve the selectivity of AZD before proposing it for the treatment of Leishmania infection.

CONCLUSION

This study demonstrated the novel findings related to the drug potential of AZD with defined Leishmania targets and host protective cytokine response. Studies on animal models may deliver further insights into its therapeutic potential.