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, OR?, SH, SR?, SOR?, SO2R?, NO2, NH2, NHR?, N(R?)2, NHC(O)R?, CN, halogen, C(?O