Aerial parts of Pterocaulon polystachyum from Chaco province, Argentina, afforded the known coumarins ayapin, isoscopoletin, prenyletin, prenyletin methyl ether, virgatenol, obtusinin, 5-methoxy-6,7-methylenedioxycoumarin, 5-(3,3-dimethylallyloxy)-6,7-methylenedioxycoumarin,
Fractionation of antifungal hexane extracts of the aerial parts of three Pterocaulon spp., Pterocaulon alopecuroides, Pterocaulon balansae and Pterocaulon polystachyum (Asteraceae) from South Brazil traditionally used to treat animal mycoses, afforded the coumarins