This study was aimed at the evaluation of the anti-inflammatory activity of twelve compounds isolated from the methanolic extract of fruits of Terminalia chebula. The activity was determined in terms of their ability to inhibit inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. Two gallotannins [chebulinic acid (1) and 2,3,6-tri-O-galloyl-beta-D-glucose (2)] and two triterpenoids [arjunic acid (3) and arjunolic acid(4)] efficiently reduced nitric oxide (NO) production with IC50 values of 53.4, 55.2, 48.8, and 38.0 microM, respectively. The protein expressions of iNOS and COX-2 were decreased in macrophages by treatment with compounds 1-4 (54-69% and 33-37%, respectively) at 50 microM. This is the first report of antiinflammatory property of 1-4 mediated by inhibition of iNOS and COX-2 activities at the cellular level.