| abstract |
Compounds of the structure: <IMAGE> wherein R1 and R2 individually are H or C1-C18 acyl and R3 is H, C1-C18 acyl or <IMAGE> or R1 is H and together R2 and R3 are <IMAGE> and X is =O or =S, Y is -OH, -SH, -NH2 or halogen, and Z is H, -NH2, -OH or halogen, wherein halogen is Cl or Br, or a pharmaceutically acceptable salt thereof are useful as antivirals, antitumors and as immune system enhancers. |