Dioscorea bulbifera, the Air potato, is a yam species. It is also known as Varahi in Sanskrit, Kaachil in Malayalam and Dukkar Kand in Marathi. The Air potato plant is native to Africa and Asia. It is an invasive species in many tropical species, including Florida. Three norclerodane diterpenoids, diosbulbins K-M, and one analogous enolglycoside, diosbulbinoside G, together with four norclerodane diterpenoids, diosbulbins B, E, F and G, were isolated from rhizomes of Dioscorea bulbifera. Antitumor activities of water extract (fraction A), ethanol extract (fraction B), ethyl acetate extract (fraction C), non-ethyl acetate extract (fraction D) and compound diosbulbin B isolated from DioscoreabulbiferaL. (DB) were investigated in vivo in this present study. Dioscorea bulbifera L.(DB75-E) showed different inhibitory effects on tumor promotion by the assay-- inhibition on the promotion of JB-6 tumorigenic cell lines Cl22 (clone 22),Cl 41 induced by a promoter TPA (1ng/mL) in vitro.