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Open Access Highly Accessed Research article

Evaluation of the anti-mycobacterium tuberculosis activity and in vivo acute toxicity of Annona sylvatic

Rafaele CP Araujo1, Francisco AR Neves2, Anelise SN Formagio3, Candida AL Kassuya1, Maria EA Stefanello4, Vanessa V Souza1, Fernando R Pavan5 and Julio Croda1*

Author Affiliations

1 Faculty of Health Sciences, Federal University of Grande Dourados, Rodovia Dourados – Itaúm. Km 12, Dourados, Mato Grosso do Sul 79804-970, Brazil

2 Faculty of Health Sciences, University of Brasília (UNB), Brasília, Brazil

3 Faculty of Agrarian Sciences, Federal University of Grande Dourados, Dourados, Brazil

4 Department of Chemistry, Federal University of Paraná, Curitiba, Paraná, Brazil

5 Biological Science Department – College of Pharmaceutical Sciences, Estadual University of São Paulo, Araraquara, Brazil

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BMC Complementary and Alternative Medicine 2014, 14:209  doi:10.1186/1472-6882-14-209

Published: 28 June 2014

Abstract

Background

The recent emergence of extensively multidrug-resistant Mycobacterium tuberculosis strains has further complicated the control of tuberculosis. There is an urgent need for the development of new molecular candidates antitubercular drugs. Medicinal plants have been an excellent source of leads for the development of drugs. The aim of this study was to evaluate the in vitro activity of 28 alcoholic extracts and essential oils of native and exotic Brazilian plants against Mycobacterium tuberculosis and to further study these extracts through chemical fractionation, the isolation of their constituents, and an evaluation of the in vivo acute toxicity of the active extracts. To the best of our knowledge this is the first chemical characterization, antituberculosis activity and acute toxicity evaluation of Annona sylvatica.

Methods

The anti-mycobacterial activity of these extracts and their constituent compounds was evaluated using the resazurin reduction microtiter assay (REMA). To investigate the acute toxicity of these extracts in vivo, female Swiss mice were treated with the extracts at doses of 500, 1000 and 2000 mg · kg-1 of body weight. The extracts were characterized by LC-MS, and the constituents were isolated and identified by chromatographic analysis of spectroscopic data.

Results

Of the 28 extracts, the methanol extract obtained from the leaves of Annona sylvatica showed anti-mycobacterial activity with an minimal inhibitory concentration (MIC) of 184.33 μg/mL, and the ethyl acetate fraction (EAF) resulting from liquid-liquid partitioning of the A. sylvatica extract showed an MIC of 115.2 μg/mL. The characterization of this extract by LC-MS identified flavonoids and acetogenins as its main constituents. The phytochemical study of the A. sylvatica EAF resulted in the isolation of quercetin, luteolin, and almunequin.

Conclusions

Among the compounds isolated from the EAF, luteolin and almunequin were the most promising, with MICs of 236.8 μg/mL (827.28 μM) and 209.9 μg/mL (328.48 μM), respectively. The acute administration of the EAF fraction in doses of 500, 1000, and 2000 mg · kg-1 of body weight did not cause signs of toxicity in the treated animals.

Keywords:
Mycobacterium tuberculosis; Annona sylvatica; Resazurin reduction toxicity; Luteolin; Almunequin