The present invention relates to compounds of formula (I), or pharmaceutically acceptable salts thereof, wherein Z is NR11, NHCO, NHSO2, NHCH2, CH2, CH2CH2, or CH═CH; X is a hydrocarbyl group optionally substituted by one or more R12 groups; R10 and R11 are each independently II or alkyl; R1-R4 are each independently II or (CII2)mR12, where m is O, 1, 2, or 3; each R12 is independently (CH2)aR16, where each R16 is independently selected from O(CH2)bR13, R13, COR13, COOR13, CN, CONR13R14, NR13R14, NR13COR14, SR13, SOR13, SO2R13, NR13SO2R14, SO2OR13, SO2NR13R14, halogen, CF3, and NO2, and wherein each a is 0, 1, 2, or 3 and b is 0, 1, 2, or 3; R13 and R14 are each independently H or (CH2)aR15, where n is 0, 1, 2, or 3; and each R15 is independently selected from alkyl, cycloalkyl, heteroaryl, aralkyl, aryl and heterocycloalkyl, each of which may be optionally substituted by one or more substituents selected from halogen, OH, CN, COO-alkyl, aralkyl, SO2-alkyl, SO2-aryl, COOH, CO-alkyl, CO-aryl, NH2, NH-alkyl, N(alkyl)2, CF3, alkyl and alkoxy, wherein said alkyl and alkoxy groups may be further substituted by one or more OH groups. Further aspects of the invention relate to pharmaceutical compositions comprising compounds of formula I, and the use of compounds of formula (I) in the preparation of a medicament for treating a variety of disorders, including proliferative disorders, viral disorders, stroke, etc.