This invention providesthe compound having the structurewherein n is 1- 10; X is C-R11 or N,wherein R11 is H, OH, SH, F, Cl, SO2R7,NO2, trifluoromethyl, methoxy, orCO-R7, wherein R7 is alkyl, alkenyl,alkynyl, C3-C8 cycloalkyl, or aryl; R2 isH or NR3R4, wherein R3 and R4 are eachindependently H, C1-C6 alkyl, or C3-C8cycloalkyl; R5 is OH or SH; and R6,R12A R13, and R14are each independentlyH, OH, SH, F, Cl, SO2R15, NO2,trifluoromethyl, methoxy, or CO-R15,wherein R15 is alkyl, alkenyl, alkynyl,C3-C8 cycloalkyl, or aryl, or a salt ofthe compound, which is useful in thetreatment of tumors.