OBJECTIVE:　To　design　and　synthesize　a　series　of　novel　amino　acid-modified　ursolic　acid　derivatives　containing　primary　amino-group　and　to　investigate　their　antitumor　activities　against　gastric　carcinama　in　vitro.　METHODS:　1,　2-Ethylenediamine　was　added　to　the　C28　site　of　ursolic　acid(UA)　and　the　resulting　intermediates　were　conjugated　to　amino　acid　to　get　the　amino　acid-modified　ursolic　acid　derivatives.　The　effects　of　these　UA　derivatives　on　the　growth　of　BGC823　cells　and　AGS　cells　were　assessed　by　MTT　assay.　Meanwhile,　Annexin　V/PI　dual　staining　and　cell　cycle　analysis　were　performed　to　investigate　the　anti-tumor　mechanism.　RESULTS:　Most　of　the　derivatives　exhibited　more　powerful　cytotoxicity　than　UA　against　these　two　gastric　cancer　cell　lines.　The　apoptosis　of　BGC823　cells　incubated　with　compound　3　or　compound　4　were　observed.　Cell　cycle　analysis　showed　that　compound　3-6　triggered　44.69%　-92.64%　of　the　treated　AGS　cells　into　apoptotic　status.　CONCLUSION:　Potent　anticancer　abilities　of　these　UA　derivatives　bearing　primary　amido　are　achieved　by　inducing　apoptosis.　Introducing　primary　amino　group　to　UA　is　an　effective　way　to　develop　new　UA　derivatives　with　enhanced　anti-proliferative　activities.　Copyright　2012　by　the　Chinese　Pharmaceutical　Association.