Novel xanthine oxidase inhibitor studies. Part 2. Synthesis and xanthine oxidase inhibitory activities of 2-substituted 6-alkylidenehydrazino- or 6-arylmethylidenehydrazino-7H-purines and 3-and/or 5-substituted 9H-1,2,4-triazolo[3,4-i]purines

The facile and general synthesis of 2-substituted 6-alkylidenehydrazino- or 6-arylmethylidenehydrazino-7H-purines and 3- and/or 5-substituted 9H-1,2,4 -triazolo[3,4-i]purines, which were obtained by oxidative cyclisation of th e corresponding 6-aldehyde hydrazones of 7H-purine, as a new class of poten tial xanthine oxidase inhibitors are reported. Their inhibitory activities against bovine milk xanthine oxidase in vitro were also investigated, and s ome purines 2 and 6 and triazolopurines 7 exhibited from several times to s everal hundred times more potent activities than allopurinol.