Anti-parasitic activity of Annona muricata L. leaf ethanolic extract and its fractions against Toxoplasma gondii in vitro and in vivo

Abstract

Ethnopharmacological relevance: Sulfadiazine and pyrimethamine are the two drugs used as part of the standard therapy for toxoplasmosis, however; they may cause adverse side effects and fail to prevent relapse in many patients, rendering infected individuals at risk of reactivation upon becoming immunocompromised. Extracts from various parts of Annona muricata have been widely used medicinally for the management, control and/or treatment of several human diseases, acting against parasites that cause diseases in humans.

Aim of the study: This study was performed to investigate the action of the ethanolic extract of A. muricata (EtOHAm) and its fractions in the control of the apicomplexan parasite Toxoplasma gondii in vitro and in vivo, and the effect of EtOHAm on the inflammatory response and lipid profile alteration induced by in vivo T. gondii infection.

Materials and methods: The cytotoxicity of EtOHAm and its fractions ethyl acetate (EtOAcAm), n-butanol (BuOHAm), aqueous (H₂OAm), hexane (HexAm) and dichloromethane (CH₂Cl₂Am) was evaluated in NIH/3T3 fibroblasts using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The cells were infected with T. gondii, treated with the extracts, and parasite proliferation was analyzed. For the in vivo experiments, C57BL/6 mice were orally infected with T. gondii and, treated with different concentrations of extract fractions that were effective in vitro (EtOHAm, EtOAcAm, HexAm and CH₂Cl₂Am). Tissue parasitism, histological alterations, systemic cytokine and lipid profile were investigated.

Results: EtOHAm, EtOAcAm, BuOHAm, H₂OAm presented low cytotoxicity until doses of 200 μg/mL, while HexAm and CH₂Cl₂Am presented toxicity from doses of 100μg/mL. EtOHAm, HexAm and CH₂Cl₂Am decreased the parasitism in vitro, presenting a therapeutic index of 2.62, 2.44, and 2.96, respectively. In vivo, EtOHAm, HexAm and CH₂Cl₂Am improved the survival rate of infected animals, however, only EtOHAm was able to decrease the parasitism in the small intestine and lung. Additionally, EtOHAm decreased the systemic interferon (IFN)-γ and tumor necrosis factor (TNF) systemically in infected mice, and was able to maintain the triglycerides and very-low-density lipoprotein (VLDL) lipid fractions at similar levels to uninfected animals. Although treatment with EtOHAm could not control the inflammation induced by oral infection in the tissues analyzed, it was able to preserve the number of goblet cells in the small intestine.

Conclusions: Ethanolic A. muricata leaf extract could be considered as a good candidate for the development of a complementary/alternative therapy against toxoplasmosis, and also as an anti-inflammatory alternative for decreasing TNF and IFN-γ concentrations and lipid fractions in specific diseases.

Keywords: Annona muricata L. extracts; In vitro parasite replication; Inflammation; Lipid profile; Toxoplasma gondii; Toxoplasmosis treatment.