Abstract: Hyperacidified tumors having high .beta.-glucuronidase activity can be treated with glucuronides with aglycones toxic to the tumor cells with great safety toward the rest of the body by first administering an alkalinizing agent in an amount sufficient to maintain the pH level of non-tumor tissues at approximately 7.4 during the glucuronide treatment. This will cause inactivation of .beta.-glucuronidase activity in the rest of the body. Novel glucuronides are disclosed the aglycones of which exert a higher toxic effect in an acid environment or is water-soluble only in an alkaline environment. Such compounds have particular utility with the above process. By substituting radioisotopes into the aglycone, diagnosis and in situ radiation therapy may be accomplished. Bacterial cells having .beta.-glucuronidase activity may also be diagnosed and treated in accordance with the present invention.