A compound having a structure of formula (I): Wherein each of R1A, R1B, R1C, R1D, R1E and R1F is independently selected from the group consisting of a hydrogen atom, a hydroxide group, and a substituted or unsubstituted C1-C8 alkoxy group, R2 is selected from the group consisting of a hydrogen atom and a hydroxide group, R3 is hydrogen atom, R4 is selected from the group consisting of a hydrogen atom, a C1-C3 alkyl group, and a C1-C3 fluoroalkyl group, R5 is selected from the group consisting of a hydrogen atom, a C1-C6 alkyl, and a C1-C6 fluoroalkyl, n is 1 or 2, and X is a negatively charged anion. Removal of the substituted nitroimidazole affords a phenanthroindolizidine or phenanthroquinolizidine alkaloid derivative. The compound is used in a pharmaceutical composition and a method of treating a proliferative disease.