In vitro and in vivo therapeutic potentials of 6-gingerol in combination with amphotericin B for treatment of Leishmania major infection: Powerful synergistic and multifunctional effects.

The ongoing conventional drugs for leishmaniasis treatment are insufficient. The present study aimed to assess 6-gingerol alone and in combination with amphotericin B on Leishmania major stages using experimental and in vivo murine models. Here, arrays of experimental approaches were designed to monitor and evaluate the 6-gingerol potential therapeutic outcomes. The binding affinity of 6-gingerol and IFN-γ was the basis for docking conformations. 6-Gingerol combined with amphotericin B represented a safe mixture, extremely leishmanicidal, a potent antioxidant, induced a remarkable apoptotic index, significantly increased the expression of the Th1-related cytokines (IL-12p40, IFN-γ, and TNF- α), iNOS, and transcription factors (STAT1, c-Fos, and Elk-1). In contrast, the expression of the Th2-related cytokines was significantly downregulated (p < 0.001). This combination was also potent when the lesion appearance was evaluated following three weeks of treatment. The histopathological and immunohistochemical patterns of the murine model represented clusters of CD4+ and CD8+ T lymphocytes which compressed and deteriorated the macrophages harboring Leishman bodies. The primary mode of action of 6-gingerol and amphotericin B involved broad mechanistic insights providing a coherent basis for further clinical study as a potential drug candidate for CL. In conclusion, 6-gingerol with amphotericin B synergistically exerted anti-leishmanial activity in vitro and in vivo and potentiated macrophages' leishmanicidal activity, modulated Th1- and Th2-related phenotypes improved the histopathological changes in the BALB/c mice infected with L. major. They elevated the leukocyte infiltration into the lesions. Therefore, this combination should be considered for treating volunteer patients with CL in clinical studies.