Highly selective alkylcoumarates and diterpenoids isolated from leaves of Baccharis quitensis: a search for new hit compounds against Trypanosoma cruzi

In the present work, the hexane extract of aerial parts of Baccharis quitensis Kunth. was subjected to chromatographic fractionation to afford two alkyl phenylpropanoids: n-docosyl (E)-p-coumarate (1) and n-tetracosyl (E)-p-coumarate (2) as well as five diterpenes: ent-kaurenoic acid (3), grandifloric acid (4), 15 beta-senecioyl-oxy-ent-kaur-16-en-19-oic acid (5), and 15-oxo-ent-kaurenoic acid (6). Using an ex-vivo assay with macrophages infected with Trypanosoma cruzi, compounds 1 and 2 demonstrated high potency against intracellular amastigotes, with EC50 values of 7.5 and 6.9 mu M, respectively. Compound 6 revealed a moderate potency against T. cruzi, with an EC50 of 25.6 mu M, and compounds 3-5 showed no effectiveness. Additionally, compounds 1-6 compounds presented no toxicity for mammalian cells to the highest tested concentration of 200 mu M. Based on potency and the selectivity indexes of 1, 2 and 6, these compounds could be future candidates for optimisation studies for the design of prototypes against Chagas disease.