Leishmanicidal Activity of Moringa oleifera (L.) Leaf Protein Extract on the Indian Strain of Leishmania donovani: An In Vitro Study

Abstract

Introduction

Recurring incidents of drug resistance and the health hazards associated with the chemotherapeutic treatment of visceral leishmaniasis necessitate the search for safer yet equally effective biologically available alternate therapeutics. Plant products are being emphasised in this regard. Thus, Moringa oleifera leaf was chosen here, and an in vitro study was undertaken to determine its antileishmanial activity against visceral leishmaniasis.

Methods

The protein in M. oleifera leaf extract (Mo-EX) was identified by denaturing polyacrylamide gel electrophoresis. The antipromastigote activity and cytotoxicity of the proteinaceous Mo-EX were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Phase contrast microscopy and scanning electron microscopy analyses confirmed the morphological alterations of the promastigotes. The anti-amastigote activity of Mo-EX was determined by microscopic intracellular counting. Apoptosis, reactive oxygen species (ROS) generation, and thiol depletion were assessed by flow cytometric analysis, and nitric oxide production was determined by colorimetric assays.

Results

M. oleifera leaf extract displayed 50% inhibitory concentration valuesagainst Leishmania donovani promastigotes and intracellular amastigotes of 11.85 ± 0.08 and 8.86 ± 0.03 μg/ml, respectively, with a 50% lethal concentration in RAW 264.7 macrophages of 2 036.25 ± 0.04 μg/ml. Mo-EX reduced thiol production, significantly increased ROS generation, and induced apoptosis in L. donovani promastigotes while altering their morphology. Mo-EX evoked ROS and nitric oxide generation in parasite-infected host cells ex vivo.

Conclusions

The findings of the present study elucidate the leishmanicidal activity of protein-rich Mo-EX in L. donovani (MHOM/IN/1983/AG83) promastigotes and amastigotes, and Mo-EX was found to be moderately safe in RAW 264.7 host macrophages in vitro.