Abstract: In order to search for new anti-inflammatory agents with strong activity and less toxicity relative to CDDO-Me, the ester prodrugs 2 - 8 of CDDO-Me were synthesized by treatment of oleanolic acid(OA)with DMF/K₂CO₃ to generate 1 , followed by esterification of 1 with various aliphatic and aromatic carboxylic acids, respectively. All the target compounds showed strong inhibitory effects on LPS-induced NO production in RAW 264. 7 cells. Among them, compounds 2 and 7 possessed the most potent inhibitory effects with IC₅₀=(2. 34±0. 67)and(3. 83±0. 97)nmol/L, respectively. Moreover, MTT assay indicated that all the target compounds( 2 - 8 )displayed much weaker anti-proliferative activity against RAW 264. 7 cell lines than CDDO-Me, suggesting that they may be less toxic than CDDO-Me.