The ability of eleven known flavonoids isolated from Nectandra amazonum (Lauraceae) was tested for in vitro PGHS (COX) inhibition. All test compounds exhibited a dose dependent activity at different levels, exhibiting selectivity towards COX-1 inhibition. Autodock Vina was used to dock the compound structures within the active site of the PGHS-1 (PDB: 3N8V). In vitro results showed that chalcone and dihydrochalcone-related compounds exhibited reasonable inhibitory properties (IC 50 : 1.56-36.5 μM), with good correlation with docking results. Arg120 (or Tyr355) and Ser530 were found to be the key residues to dock the most active flavonoids, indicating such interaction might interfere with the formation of prostaglandin H 2 in the active site of COX-1.