The “febrifuge principle” of cinchona barks

The antipyretic properties of cinchona barks were known since ancient times in South America, particularly in Peru. The use of these barks in medicines against “fevers” in Europe in the 17th century made the exploitation of cinchonas of Peru a highly productive process, and those cinchona trees became menaced. The Portuguese government aware of the problem searched an alternative in cinchona varieties existing in Brazil. By the beginning of 19th century, samples of different Brazilian barks were shipped to Portugal in order to evaluate their therapeutic properties, in particular their antipyretic properties. Clinical and chemical studies were carried out in Coimbra and Lisbon, by the most eminent scientists of that time, in order to find out the best way to use the barks and identify the “febrifuge principle”. During this research, Bernardino António Gomes isolated in 1810 the first known alkaloid – the cinchonine. This discovery raised international interest and led in 1820 to the isolation of quinine, by Caventou and Pelletier in France. This reinforced the interest in cinchona barks and the producing countries tried to establish a monopoly, forbidding the export of seeds and plants. Some European governments studied then possible solutions for the problem, namely acclimatizing cinchonas in their African and Asian colonies. Getting the plants was difficult, but finally, in Dutch and British colonies, large plantations of cinchonas were made, and so the import from South America was no longer needed. The Portuguese also tried to develop plantations in different regions in Africa. In São Tomé the culture of the cinchonas was economically sustainable and a small pharmaceutical industry was developed during some decades. In this communication we present a brief account of the isolation of cinchonine and of the development of the culture of cinchona trees in Portuguese colonies