FACILE SYNTHESIS OF 5'-DEOXY-6-THIOPURINE AND 2',5'-DIDEOXY-6-THIOPURINE NUCLEOSIDES BY NUCLEOSIDE PHOSPHORYLASES

5'-Deoxy-6-thioguanosine, 2',5'-dideoxy-6-thioguanosine, 5'-deoxy-6-me rcaptopurine riboside and 2',5'-dideoxy-6-mercaptopurine riboside were synthesized enzymatically from thiopurine bases and corresponding rib osyl donors using nucleoside phosphorylase. This is the first report o f trans-5'-deoxyribosylation to thiopurine bases by nucleoside phospho rylase. 5'-Deoxy-6-thioguanosine selectively blocked the growth of v-r as-transformed human bronchial epithelial cells. In addition, the in v itro antitumor cytotoxicity data for 5'-deoxy- and 2',5'-dideoxy-6-thi opurine nucleosides were comparable to those for the corresponding thi opurine bases. (C) 1998 Elsevier Science Ltd. All rights reserved.