Abstract: | In the current study, median lethal concentrations (LC50) were obtained in the brine shrimp assay (BSA) for 31 methanol and water plant extracts representing 21 Amazonian plant species, most of which are used in traditional medicine. The following species presented extracts with LC 50 values less than 50 μg/ml: Croton cajucara Benth., Micrandropsis scleroxylon W.A. Rodrigues, Piper aduncum L., P. hostmannianum (Miq.) C. DC., P. tuberculatum Jacq., Protium aracouchini (Aubl.) Marchand, and Tapura amazonica Poepp. The methanol extract of T. amazonica Poepp., a species known to be toxic according to ethnobotanic reports, was the most active (LC50 1.2 μg/ml). The data presented are considered useful as general toxicity parameters, and their relevance in the context of discovery of new antitumor agents and potential sources of (new) bioactive compounds in the Amazonian flora is discussed. |