Evaluation of larvicidal and in vitro antiparasitic activities of plants in a biodiversity plot in the Altos de Campana National Park, Panama

This TDR/WHO project was carried out from 2003 to 2005 in an 0.1-ha biodiversity plot in the Altos de Campana National Park to discover novel active antiparasitic and larvicidal compounds in Panamanian plants. One-hundred-fifty organic plant extracts representing 43 families, 73 genera, and 93 species were tested in a panel of antimalarial (Plasmodium falciparum W2, chloroquine resistant), antileishmanial (Leishmania mexicana amastigotes), antitrypanosomal (rypanosoma cruzi trypomastigotes), and larvicidal (Aedes aegypti) screens. Of these 150 plant extracts, two (1.3%) ( Talisia nervosa and Topobea parasitica) showed significant antimalarial activity (IC50 values < 10 mu g/ml), two (1.3%) (Cestrum megalophyllum and Zanthoxylum acuminatum) weak antileishmanial activity (IC50 values ranging from 10 to 20 mu g/ml), one (0.6%) (Zanthoxylum acuminatum) weak antitrypanosomal activity (IC50 values ranging from 10 to 20 mu g/ml), and one 0.6%) (Piper fimbriula-tum) larvicidal activity (LC100 values < 30 mu g/ml). Ethyl gallate (1) and methyl gallate (2) were isolated from stems of Talisia nervosa by bioassay-guided fractionation. Both (1) and (2) showed weak in vitro antiplasmodial activity against P. falciparum (IC50 35.3 mu M and IC50 38.0 mu M, respectively), but both compounds were less active than chloroquine (IC50 0.088 mu M). Moreover, compounds (1) (IC50 33.1 mu M) and (2) (IC50 33.6 mu M) showed weakly antileishmanial activity miltefosine: IC50 0.5 mu M), but they were not cytotoxic to Vero mammalian cells.