Abstract
The objective was to determine the lethal concentration 50% of extracts of Erythroxylum caatingae and Erythroxylum revolutum, as a toxicity/bioactivity parameter. The methanolic extract and basic aqueous phase of Erythroxylum caatingae and the methanolic extract of Erythroxylum revolutum were tested. The bioassay with Artemia salina was adopted, with each concentration of extracts tested in triplicate and repeated in at least three experiments. lethal concentrations 50% were analyzed by non-linear regression. The lethal concentrations 50% values for the methanolic and aqueous phase extracts of Erythroxylum caatingae and for the crude extract of Erythroxylum revolutum were 203.7 (190.1-218.2) µg/mL, 1,074.0 (949, 6-1,214.0) µg/mL and 308.1 (241.1-393.6) µg/mL, respectively. Therefore, it is concluded that there is a toxic concentration of the tested extracts, as well as a directly proportional relationship between the concentration of the extract and mortality for A. salina. The methanolic extract of Erythroxylum caatingae was more toxic, while the aqueous phase had the lowest lethality.