Abstract

Skytanthus acutus Meyen (Apocynaceae), commonly known as 'Cuerno de cabra,' is an endemic species from northern Chile that grows in dune and desert habitats of the Atacama region. This study evaluated the antiproliferative activity of an ethanolic extract from its aerial parts against six human tumour cell lines (A549, HBL-100, HeLa, SW1573, T-47D, and WiDr), yielding GI50 values of 16-28 & micro;g/mL. Bioassay-guided fractionation resulted in the isolation of three compounds: the pentacyclic triterpenoids betulinic acid (BA) and oleanolic acid (OA), reported for the first time in this species, and the monoterpene alkaloid beta-skytanthine N-oxide (SN), whose biological activity is described here for the first time. OA showed greater potency (GI50: 3.6-7.2 & micro;M) than BA (GI50: 14-84 & micro;M) and induced cytostatic and apoptotic effects in HeLa cells, highlighting S. acutus as a promising source of anticancer triterpenoids.