Effects of 7-hydroxycalamenene-rich essential oil extracted from C. cajucara on nitric oxide production by infected mouse peritoneal macrophages. Parasites and/or macrophages were treated with MIC (250 μg/mL) or subMIC (125 μg/mL) of red sacaca essential oil 20 min prior to macrophage–parasite interaction. In addition, macrophages previously infected with L. chagasi were treated with the essential oil for 20 min and then incubated for 120 min at 37°C in a 5% CO2 atmosphere. The supernatants from controls (untreated cultures) and L. chagasi- infected macrophages were collected, and the nitrite concentration was determined by the Griess reaction. Each bar represents the mean ± standard error from at least three independent experiments, each performed in triplicate. (MØ) macrophages; (P) parasites; (PtMØ) pre-treated macrophages; (PtP) pre-treated parasites; (IMØ) infected macrophages; (Post-IMØ) post-treated infected macrophages.