Anti-leishmanial, immunomodulatory and additive potential effect of Piperine on Leishmania major: The in silico and in vitro study of Piperine and its combination

Piperine (Pn), an indole alkaloid compound found in pepper, is an effective compound with anti-leishmanial medications that administered alone or in combination. This study aimed to use Pn for possible biochemical targets and to assess mechanisms of anti-leishmanial action and immunomodulatory roles. The ability of Pn to bind to interleukin-12P40 (IL-12P40) and interferon-γ (IFN-γ) was investigated using molecular docking. The leishmanicidal effect of Pn, meglumine antimoniate (Glucantime®; MA), and Pn plus MA was assessed on Leishmania major promastigotes and amastigotes. A real-time PCR was applied to quantify cytokines gene expression in drug-treated murine macrophages. The molecular docking findings indicated that Pn could bind to IL-12P40/IFN-γ. In silico analyses showed an affinity of Pn to IL-12P40/IFN-γ, with the MolDock score of −236.91 and −64.87 kcal/mol, respectively. Pn plus MA reduced the proliferation rate of promastigote and amastigote forms of L. major compared to each drug alone (IC50 = 43.22 and 19.41 μg/mL, respectively). Moreover, the combination drug demonstrated no cytotoxicity as the selectivity index (SI) was 14.81. Also, Th1-related cytokines were upregulated, while Th2-related cytokines were downregulated in Pn combination-treated murine macrophages. The superior effectiveness of combination therapy on L. major warrants further investigations on the clinical potential of this combination in the treatment of leishmaniasis. [Display omitted] •The molecular docking findings indicated that Pn binds to interleukin-12P40/interferon-γ.•The proliferation rate of L. major promastigote and amastigote forms was reduced in Pn plus MA-treated parasites.•Pn compound as well as Pn plus MA showed lower cytotoxicity compared to MA standard dug.•The up/down-regulation of Th1/Th2-related cytokines was observed in the combination group, respectively.