Quinine (US /ˈkwaɪnaɪn/, UK /ˈkwɪniːn/ or /kwɪˈniːn/ kwin-een) is a natural white crystalline alkaloid having antipyretic (fever-reducing), antimalarial, analgesic (painkilling), and anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine which, unlike quinine, is an antiarrhythmic. Quinine contains two major fused-ring systems: the aromatic quinoline and the bicyclic quinuclidine.
Though it has been synthesized in the laboratory, quinine occurs naturally in the bark of the cinchona tree. The medicinal properties of the cinchona tree were originally discovered by the Quechua, who are indigenous to Peru and Bolivia; later, the Jesuits were the first to bring cinchona to Europe.