Abstract: A compound of formula I wherein R1 is hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkoxy, aryloxy or alkylalkoxy, and R2 is aryloxy, or a pharmaceutically acceptable salt of an acidic compound of formula I, or a prodrug thereof. The compounds of formula I and their aforementioned salts and prodrugs can be used in the treatment or control of cancer associated with overexpresison of gelatinase-A and/or gelatinase-B, particularly skin cancer, breast cancer, prostate cancer, colon cancer, lung cancer, and gastric cancer. The compounds of the invention are also useful for other diseases associated with unregulated degradation of extracellular matrix, including rheumatoid arthritis, osteoarthritis, multiple sclerosis, corneal ulceration, periodontal disease and the like.