In vitro screening of 5000 plant extracts and identification of eichlerianic acid from Cabralea canjerana (Vell.) Mart as one of its trypanocidal compound

Chagas' disease, caused by Trypanosoma cruzi, affects poor and neglected populations and remains a relevant public health concern in Latin America. The drug currently used in Brazil, Benznidazole, was introduced in the market 25 years ago, and is effective only in the acute phase of the disease [1]. A total of 5228 crude extracts from 1243 plant specimens from Brazil were evaluated against amastigote and tripomastigote forms of T. cruzi (Tulahuen strain expressing b-galactosidase) in L929 cell line at a single concentration of 20 mg/mL. Cell infection was done with 10 trypomastigote/cell/2 hours. Two days after the infection, samples were added and incubated for 96h. The controls used were DMSO 1% and benzonidazole at 1 µg/mL [2]. One of the active samples was the ethanol extract of Cabralea canjerana (Vell.) Mart. (Meliaceae) which presented an IC50 value of 30 mg/mL and was selected for bioassay-guided fractionation. This plant is used by indigenous people to treat inflammation of the testicles, fungal infections, meningitis and diarrhea [3, 4]. The ethanol extract of the branches was obtained by maceration and it was suspended in a mixture of ethanol:water (8:2).

Then, the aqueous EtOH solution was partitioned with hexane, dichloromethane, ethyl acetate, respectively. The DCM fraction, which presented an IC50 value of 15 mg/mL, was then subjected to semi-preparative RP-HPLC to yield 59 subfractions. Nineteen of these subfractions were able to reduce the replication of T. cruzi in vitro and had IC50 values ranging from 7.5 to 40 mg/mL. The most promising subfraction was chromatographed to yield eichlerianic acid [5] with an IC50 value of 10 mg/mL. In conclusion, eichlerianic acid was identified as a trypanocidal compound present in the extract of C. canjerana, selected in an in vitro screen using T. cruzi.

Acknowledgements: PDTIS/FIOCRUZ, CNPq, FAPEMIG, Markus Kohlhoff.

Keywords: T. cruzi assay, screening, tropical plants, trypanocidal compounds, Cabralea canjerana, Meliaceae, aglaiaglabretol A.

References:

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