In vitro/in vivo Assessment and Cellular Mechanisms of Astragalus spinosus Extract Against Leishmania Major

Background: In recent years, increasing resistance to synthetic agents, their long‑term treatment, and lasting side effects, has faced many problems in treatment of leishmaniasis; so that finding a new high‑efficacy antileishmanial drug with minimal side effects seems very necessary. This experimental study was aimed to evaluate the in vitro and in vivo leishmanicidal activity and cellular mechanisms of Astraglus spinosus methanolic extract (ASME) against Leishmania major infection. Materials and Methods: In vitro antileishmanial effect of ASME was evaluated on intracellular amastigotes of L. major in macrophage model. The effect of ASME on the NO production of macrophage cells was determined based on the Griess reaction for nitrites. Effect of ASME on the caspase‑3‑like activity of L. major promastigotes was performed according to the measuring the rate of color spectrophotometry. The 50% cytotoxic concentrations (CC50) of the ASME on macrophages were measured to assess the cytotoxicity of ASME. In addition, in vivo effects of ASME were evaluated in infected BALB/c mice by measuring of the diameter of CL lesions and parasite load in the tested mice before and after 28 days of therapy. Results: The mean number of intracellular amastigotes of L. major significantly (P < 0.001) decreased with the IC50 value of 36.9 ± 3.012 µg/mL and 44.3 ± 3.012 µg/mL for ASME and MA, respectively. Although more NO was produced by increasing the concentrations of the ASME, but, a notable rise was detected at the IC50 (P < 0.001). ASME especially at the concentrations of ½ IC50 and IC50 significantly provoked the caspase‑3 activation, by 10.3%, 25.6%, and 29.8%, respectively. The measured CC50 value of ASME and MA was 463.3 µg/mL and 835 µg/mL, respectively. Treatment of the infected mice with various doses of ASME (50 and 100 mg/kg for 28 days), markedly declined the mean diameter of the CL lesions and parasite load in tested mice. Conclusion: Based on the obtained results, ASME can be considered as a promising herbal drug candidate for the isolation and production of a new alternative agent for CL treatment. As a result, this survey presented adequate results in the parasite eliminating in both in vitro and in vivo assay. Nevertheless, additional studies are needed to elucidate the accurate mechanisms of action of ASME and its effectiveness in clinical subjects.