Phenylahistin and the phenylahistin analogs, a new class of anti-tumor compounds

A method of treating a cancer selected from at least one of the following, lung cancer, stomach cancer, colon cancer, ovarian cancer, cancer of the central nerve system, kidney cancer, and melanoma, in a vertebrate comprising:

• administering to the vertebrate an effective tumor-growth-inhibiting amount of a compound, its pharmaceutically acceptable salt or pro-drug ester, having the following structure:
• wherein:
• R1, R2, R5, R7, and R8 are each separately selected from the group consisting of a hydrogen atom, a halogen atom, and saturated C1-C24 alkyl, unsaturated C1-C24 alkenyl, cycloalkyl, cycloalkenyl, alkoxy, cycloalkoxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, amino, substituted amino, nitro, phenyl, and substituted phenyl groups,
• R3, R4, and R6 are each separately selected from the group consisting of a hydrogen atom, a halogen atom, and saturated C1-C12 alkyl, unsaturated C1-C12 alkenyl, cycloalkyl, alkoxy, cycloalkoxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, amino, substituted amino, and nitro groups,
• X1 and X2 are separately selected from the group consisting of an oxygen atom, and a sulfur atom, and
• the dashed bond represents a bond selected from the group consisting of a carbon-carbon single bond and a carbon-carbon double bond.