Brazilian green propolis is a bee product which displays many biological activities, such as antiparasitic, antimicrobial, and cytotoxic. Artepillin C andp-coumaric acid are two of its major compounds that contribute to these activities. Both compounds were submitted to degradation under light, oxygen, and heating, furnishing four and one degradation products, respectively. Artepillin C,p-coumaric acid, and their degradation products were evaluated against seven strains of oral bacteria, cancer cell lines (AGP-01 and He-La), andLeishmania amazonensis(promastigotes and amastigotes). TheZ-isomer artifact of artepillin C displayed significant activity against both gastric cancer cell line AGP-01 (IC(50)9.09 mu M) andL. amazonensis, especially against the amastigote forms of the parasite (IC(50)3.49 mu M).p-Coumaric acid also displayed a promising activity againstL. amazonensisamastigotes (IC(50)3.12 mu M), while itsZ-isomer artifact was more effective against the promastigotes (IC(50)9.35 mu M). The obtained compounds were not cytotoxic against the normal cell line CHO-k1. The present study shows that Brazilian green propolis is an important source of bioactive compounds and thatZ-artepillin C andZ-p-coumaric acid display antiparasitic and cytotoxic activities.