Abstract: New spisulosine derivatives of use in treating tumors are of the formula (I) wherein: each X is the same or different, and represents H, OH, OR′, SH, SR′, SOR′, SO2R′, NO2, NH2, NHR′, N(R′)2, CN, halogen, C(═O)H, C(═O)CH3, CO2H, CO2CH3, substituted or unsubstituted C1-C18 alkyl, substituted or unsubstituted C2-C18 alkenyl, substituted or unsubstituted C2-C18 alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaromatic, or two groups X may together form ═O; Y is NR1, OR1, PR1, SR1, or halogen, wherein the number of substituents R1 is selected to suit the valency and each R1 is independently selected of H, OH, C(═O)R′, P(═O)R′R″, substituted or unsubstituted C1-C18 alkyl, substituted or unsubstituted C2-C18 alkenyl, substituted or unsubstituted C2-C18 alkynyl, substituted or unsubstituted aryl, and wherein the dotted line indicates an optional double bond; each Z is the same different, and represents H, OH,