In vitro effect of Acanthospermum australe (Asteraceae) extracts on Acanthamoeba polyphaga trophozoites

Lc Castro,St Vand Der Sand,Em Ethur,Sp Cibulski,Aw Muniz,Pm Roehe,J Souza,Ip Sauter,L Weidlich,Jc Germani,Mb Rott,Pm Lohmann,R Dall'Agnol,C Kauffmann

doi:10.1590/s1516-05722013000400016

Abstract

Acanthamoeba is a free-living protozoan widely distributed in the environment, occurring in vegetative trophozoite and resistance cyst stages during its life cycle. It constitutes an etiological agent of Acanthamoeba keratitis, a disease that may cause severe ocular inflammation and blindness. New drugs can be developed from molecules found in plants and thus help in its difficult treatment. Acanthospermum australe (Asteraceae), a plant used in folk medicine, had its effect tested on Acanthamoeba polyphaga. Aqueous and ethanolic extracts of A. austral were obtained from aerial parts for infusion and static maceration, respectively. Concentrations of 10, 5, 2.5, 1.25 and 0.625 mg/ml of the extract were tested against Acanthamoeba polyphaga trophozoites. The cytotoxic effect of the extracts was tested in mammalian cells using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The 10 mg/ml concentration of ethanolic extract was lethal to 100% of the A. polyphaga trophozoites in 24 h and both extracts presented cytotoxic effect against mammalian cells. These findings suggest that the A. austral ethanolic extract may have compounds with relevance to the development of new amoebicidal drugs.

Highlights

The free-living amoebae (FLA) are a group of protozoa widely dispersed in nature, being found in soil, water and air
Kuntze extract was tested against A. polyphaga trophozoites, which were chosen as the standard of clinical origin
A. polyphaga trophozoites underwent the same test with different doses of A. australe Ethanolic Extract (EE)

Summary

Introduction

The free-living amoebae (FLA) are a group of protozoa widely dispersed in nature, being found in soil, water and air. Some species of Acanthamoeba are opportunistic pathogens that can cause Acanthamoeba Granulomatous Encephalitis (AGE) and Acanthamoeba keratitis, but may be associated with cutaneous lesions and sinusitis in immunocompromised patients (Khan, 2006). Acanthamoeba keratitis is a chronic inflammation of the cornea caused by infection with several Acanthamoeba species. The available treatments include aromatic diamidines (hexamidine, pentamidine, or propamidine isothionate), cationic antiseptics, aminoglycosides, imidazoles and polyenes (amphotericin B) (Auran et al 1987; Chomicz et al, 2005; Obeid et al, 2003). Because these drugs do not have great efficacy against the cystic form of this organism, the treatment is long and complex. The search for new drugs is crucial to develop dynamic therapies and facilitate treatment (Obeid et al, 2003)

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