Evaluation of the in vitro trypanocidal activity of plant extracts from the Brazilian Cerrado

Chagas' disease is endemic in Latin America and affects 16–18 million people, while other 100 million are exposed to the risk of infection. Trypanosoma cruzi, the etiological agent of this disease, causes a pathology which features depend on both the inherent characteristics of the host and the virulence of the parasite. In this study we report the screening of the in vitro trypanocidal activity of twenty extracts obtained from ten different plant species growing in the Brazilian Cerrado: Aspidosperma macrocarpum Mart. (Apocynaceae), Aegiphila sellowiana Cham. (Verbenaceae), Byrsonima intermedia Juss. (Malpighiaceae), Cyperus rotundus L. (Cyperaceae), Leandra lacunosa Cogn. (Melastomataceae), Miconia ligustroides (DC.) Naudin. (Melastomataceae), Miconia sellowiana Naudin. (Melastomataceae), Myrcia variabilis Mart. ex DC. (Myrtaceae), Solanum lycocarpum St. Hil. (Solanaceae) and Tibouchina stenocarpa Cogn. (Melastomataceae). The most active extracts were submitted to phytochemical analyses. The high-resolution gas chromatography analysis of the n-hexane extract of T. stenocarpa (IC₅₀ =23.6µg/mL), the most active extract amongst all tested samples, allowed the identification of β-amyrin, α-amyrin, lupeol, friedelin,β-friedelanol, campesterol, stigmasterol, andβ-sitosterol. Oleanolic and ursolic acids were isolated from the methylene chloride extract of T. stenocarpa (IC₅₀ =51.5µg/mL), while ursolic acid was isolated from the methylene chloride extract of M. variabilis (IC₅₀ =38.4µg/mL). Solasonine and solamargine were identified as major compounds by mass spectrometry analysis in the hydroalcoholic extract of the fruits of S. lycocarpum (IC₅₀ =57.1µg/mL). The results showed that the trypanocidal activity may be related to the major compounds identified in the crude active extracts.

Acknowledgements: FAPESP and CNPq for financial support