Cultivation of Guaco (Mikania laevigata Sch. Bip. ex Baker) in the Lower Amazon River and monitoring of coumarin, its principal active constituent

Mikania laevigata (Asteraceae) is popularly used in the treatment of respiratory diseases, including asthma, bronchitis, and cough. In Brazil, guaco extracts are used as medicinal products authorized by the National Health Surveillance Agency (ANVISA). In the study, it was evaluated the adaptation and the influence of the seasonal variation of guaco, in a cultivation held in Santarem, state of  Para, Brazil, and a monitoring of coumarin, its primary active constituent. In the growing of guaco, the climate variables, and the coumarin content were evaluated monthly. The coumarin was analyzed by TLC (Thin Layer Chromatography) and quantified by HPLC (High Performance Liquid Chromatography) from hydroalcoholic and aqueous extracts of dried leaves. In the rainy season (january-july), the guaco had a homogeneous growth. In the dry season (august to november), there was loss of plants grown in full sun. The coumarin content was detected throughout the development of the plant, with levels that varied from 0.470 ± 0.01% to 0.886 ± 0.063%. The time of collection does not influenced in the coumarin content of the plants grown with 50% shade, having the mean of 0.712% in the hydroalcoholic extract and 0.744% in the aqueous extract. Based on the results, in partial shade conditions, it was ensured that small farmers could replicate the cultivation of guaco in the Lower Amazon River, in their local productive arrangements of medicinal plants.