Patients suffering from cancer are treated by being administered a compound represented by the following formula: wherein each R individually is H or an aliphatic or aromatic acyl group; A is selected from the group consisting of wherein X is selected from the group consisting of hydrogen, fluorine, alkoxy, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, amino, monoalkylamino, dialkylamino, cyano and nitro. The above compounds also inhibit DNA replication in mammalian cells.