Efficacy of a kaurenic acid extracted from the Venezuelan plant Wedelia trilobata (Asteracea) against Leishmania (Viannia) braziliensis

Abstract

Introduction. Leishmaniasis is a global public health problem without adequate treatment options, hence requiring research on new drug development.

Objective. Our main objective was the evaluation of a kaurenic acid (ent-kaur-16-in-19-oico), isolated from the Venezuelan plantWedelia trilobata (Asteracea), on Leishmania (V) braziliensis both in vivo and in vitro.

Materials and methods. The in vitro assay was performed using axenic amastigotes and promastigotes as well as infected and uninfected macrophages. Parasites and macrophages were treated with concentrations of the compound varying between 10 and 250 µg/ml. The effect of the compound on cellular viability was evaluated by counting dead and living cells in a hemocytometer and by the colorimetric method using MTT (Methylthiazoletetrazolium). For the in vivo assay, Balb/c mice were infected subcutaneously with 1x106 promastigotes of L.(V.) braziliensis and afterwards treated with a daily dose of 30 mg/kg in 100 µl of kaurenic acid administered by intraperitoneal injection for one week.

Results. The compound had a lethal effect on axenic amastigotes and promastigotes with DL50 of 0.25 and 0.78 µg/ml, respectively, in 24 hours. Low toxicity was observed for J774-G8 macrophages with a DL50 of 25 µg/ml and high viability (70-92%), while a moderate viability was observed for infected macrophages (37-81%), with concentrations of 25 µg/ml or less. Additionally, a 70% reduction was observed in the size of the skin lesions in Balb/c mice with no evident toxic effect.

Conclusion. The results indicate that this compound has a potent leishmanicidal effect on L.(V.) braziliensis.