Six　pigments　were　separated　from　Monascus　product,　and　some　derivatives　were　chemically　synthesized.　The　cytotoxicity　of　different　Monascus　pigments　to　various　human　cancer　cells　(SH-SY5Y,　HepG2,　HT-29,　BGC-823,　AGS,　and　MKN45)　was　evaluated.　Rubropunctatin　showed　the　greatest　anticancer　effect　within　the　tested　compounds.　The　inhibition　effect　of　rubropunctatin　was　higher　than　that　of　taxol　on　the　growth　of　the　human　gastric　cancer　cell　SH-SY5Y　(P　＜　0.05),　BGC-823　(P　＜　0.01),　AGS　(P　＜　0.01),　and　MKN45　(P　＜　0.05).　On　the　other　hand,　its　cytotoxicity　to　the　normal　human　gastric　epithelial　cell　GES-1　was　less　than　that　of　taxol　(P　＜　0.01).　The　experimental　data　demonstrated　that　rubropunctatin　was　a　valuable　compound　with　high　anticancer　activity,　which　could　offer　better　therapeutic　benefits　than　taxol.　Cell　apoptosis　stages　were　assayed　by　annexin　V-EGFP/PI　staining　experiments　using　flow　cytometry.　The　data　showed　that　87.63%　of　tested　BGC-823　cells　entered　the　early　phase　of　apoptosis　when　treated　with　5　mu　M　rubropunctatin　for　24　h.　A　drug　concentration-dependent　cell　apoptosis　was　observed.　The　analysis　of　the　relationship　between　pharmaceutical　activity　and　the　chemical　structure　of　the　tested　compounds　led　to　the　conclusion　that　6-internal　ether,　4-carbonyl,　and　conjugated　double　bonds　in　the　tricyclic　structure　of　rubropunctatin　were　necessary　to　the　anticancer　effect,　whereas　the　difference　of　C2H4　in　the　side　chain　showed　little　influence.　Rubropunctatin　could　be　supplied　as　a　precursor　compound　in　the　development　of　a　new　natural　anticancer　reagent.