P. niruri extracts obtained by ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and conventional extraction (CE) were compared. The extracts produced by PLE had the highest phenolic content. In the principal component analysis, CE and PLE 120 degrees C extracts formed a single group, separated from PLE 192 degrees C and UAE extracts. The orthogonal partial least square discriminant analysis revealed geraniin, phyllanthusiin C, repandusinic acid A, and phyllanthusiin U as chemical markers in CE and PLE 120 degrees C. PLE 192 degrees C extract presented a high content of gallic acid and ellagic acid hexose, and UAE extract presented virganin and furosin as characteristic compounds.