Author(s): Carlos Zani, Anthony Carroll, Tânia Alves, Mara Benetti, Gilberto Schwartsmann, Antoniana Krettli and Isabela Ceravolo

Abstract: Malaria remains a serious public health problem, being lethal to near 400,000 people every year, mostly in Africa. Due to the resistance of Plasmodium falciparum to available antimalarials, including artemisinin derivatives, and P. vivax to chloroquine, new therapies are necessary, since drug treatment remains as the main method to control the disease. The medicinal plants are an important source of malaria treatment and remains as an important strategy in the field of drug discovery. This study aimed to identification the antimalarials bioactive compounds isolated from Symphyopappus casarettoi inflorescences. The extract was investigated using a bioassay-guided fractionation protocol based on the assay with P. falciparum, and the cytotoxicity using monkey kidney cells. A fraction derived from the crude extract was active against P. falciparum and showed low cytotoxicity. From this fraction we isolated the flavonoid caryatin, a compound with activity against P. falciparum in vitro. It was, however, not active in the experiments with animals infected with P. berghei. The present work is the first to report the presence of caryatin in the family Asteraceae and its antiplasmodial activity. Another finding was the isolation of a new labdane type diterpene with a rare hydroxylation pattern.