RESUMO
Abstract Choisya ternata Kunth, C. ternata var. sundance Kunth and the hybrid Choisya 'Aztec-Pearl' are three related species belonging to the Rutaceae family. Ethanol extracts were prepared from the leaves of these three species and evaluated in relation to their antioxidant activity using in vitro and ex vivo models. The ethanol extracts belonging to the three species produced a very high antioxidant profile as evidenced by the DPPH radical scavenging activity, the determination of total phenolics and flavonoid equivalent. The generation of reactive species of oxygen in leukocytes stimulated with LPS was dramatically reduced when the three ethanol extracts were used. The alkaloids anhydroevoxine and choisyine were isolated from the ethanol extract of C. ternata using HEMWat (4:6:5:5) as the solvent system by means of high-speed countercurrent chromatography. This was the first time quinoline alkaloids were isolated from this species using HSCCC. These compounds were also assayed for their capacity to inhibit the generation of ROS in leukocytes stimulated by LPS and the results also suggested that they are reactive oxygenase inhibitors.