Objective: To synthesize and evaluate anti-tumor activity of oleanolic acid-α-aminophosphonate derivatives. Method: Oleanolic acid-α-aminophosphonate derivatives were synthesized from oleanolic acid

which was treated by acetylation

then the acetylated product was reacted with oxalyl chloride

followed by esterification with α-aminophosphonate under triethylamine to obtain nine target compounds. The structures of these compounds were identified. MTT method was used to assay the anti-tumor activity of synthesized compounds against human lung cancer cell lines A549

human hepatic cell lines HepG-2

human cervical carcinoma cell lines Hela and human breast cancer cell lines MDA-MB-231.The density of cell culture was 2-3×104/mL

the concentration of drug was 50 μmol·L-1 for 48 hours. Result: These target compounds showed varying degrees of inhibitory activity against tumor cell lines. Compounds 2

4

7 and 10 exhibited significant inhibitory activity against human lung tumor cell A549 and human cervical carcinoma Hela (the inhibition rate against A549 was respectively 87.5%

85.3%

87.1% and 87.8%;the inhibition rate against Hela was respectively 85.7%

78.7%

83.6% and 87.9%). Compounds 2 and 10 showed high inhibitory activity against human breast tumor cell MDA-MB-231 (the inhibition rate was respectively 82.0% and 88.1%). Conclusion: These oleanolic acid-α-aminophosphonate derivatives exhibited varying degrees of inhibitory activity against tumor cell lines. The compounds with ortho-substituted by halogen in phenyl ring showed better inhibitory activity.