•Great amount of phenolics was observed in Piper auritum and Porophyllum ruderale.•Little antioxidant activity was observed in the two types of dried plants.•The ethanol–water blend, used for extracting phenolics, was important.•Safrole was the main compound found in P. auritum.•No relationship was observed between antioxidant activity and total phenolics. Extracts from fresh and dried samples of Mexican pepperleaf (Piper auritum Kunth) and “papalo” (Porophyllum ruderale) were obtained using a stirring or an ultrasound extraction system with five types of solvents (water, 50:50% v/v ethanol:water, 70:30% v/v ethanol:water, 85:15% v/v ethanol:1.5N HCl, and ethanol). Total phenolic compounds and antioxidant activity were evaluated with the phenol Folin Ciocalteu reagent and the ABTS method, respectively. Total phenolic compounds (PC), trolox (T), and ascorbic acid (AA), in the two herbs, were in the range of 6.79–68.03mg of galic acid (GA)/g dry solids (d.s.), 4.88–64.99mg of T/gd.s., and 5.31–49.84mgAA/gd.s., respectively. Extracts from fresh “papalo”, using ultrasound as the extraction system, had the highest amount of total phenolic compounds. The fresh pepperleaf extract, obtained using ultrasound as the extraction method contained the highest amount of antioxidant activity.