Discovery of cinchona. Illustration of native Peruvians offering the cinchona plant (Cinchona officinalis) to Europeans with malaria. The plant, which contains the active ingredients quinine and cinchonine, was used by indigenous people to treat malaria. Quinine was the most effective antimalarial drug until the 1930s and Cinchona trees became rare as they were over-exploited. Illustration from 1888.