ADENOSINE DERIVATIVES

1. A compound of formula (I) wherein R represents C1-4 alkyl, halogen or hydrogen; R3 represents straight or branched alkyl group of 1-6 carbon atoms; R represents a group selected from: (1) -( C1-3 alk)n-( C3-7) cycloalkyl, including bridged (C4-7) cycloalkyl, said cycloalkyl group optionally substituted by one or more substituents selected from OH, halogen, -(C1-3) alkoxy, wherein n represents 0 or 1. (2) an aliphatic heterocyclic group of 4 to 6 membered rings containing at least one heteroatom selected from O, N or S optionally substituted by one or more substituents selected from the group consisting of -(C1-4) alkyl, -CO2-(C1-4) alkyl or =O (3) Straight or branched C1-6 alkyl, optionally including one or more O, S(=O)2 or N substituted within the alkyl chain, said alkyl optionally substituted by one or more of the following groups: phenyl, halogen, hydroxy or NH2; (4) a fused bicyclic aromatic ring wherein B represents a 5 or 6 membered heterocyclic aromatic group containing 1 or more O, N or S atoms, wherein the bicyclic ring is attached to the nitrogen atom of formula (I) via a ring atom of ring A and ring B is optionally substituted by -CO2(C1-4 alkyl); (5) a phenyl group optionally substituted by one or more substituents selected from: -halogen, -(C1-6 alk)n-OH, -( C2-6 alk)n-OH, -(O)m-(C1-6 alk)N-CO2R, -(O)m-(C2-6 alkn)n-CO2R, tetrazolyl, optionally substituted by C1-4 alkyl, wherein m and n are 0 or 1 and R represents hydrogen or a -(C1-4) alkyl; with the proviso that, when R represents C1-6 alkyl, R represents C1-4 alkyl, R cannot represent phenyl optionally substituted by one or more substituents selected from halogen, CO2R and -OR; and salts and solvates thereof, in particular, physiologically acceptable solvates and salts thereof. 2. A compound according to claim 1 wherein R represents C1-3 alkyl. 3. A compound according to claim 2 wherein R represents methyl or ethyl. 4. A compound according to claim 3 wherein R represents methyl. 5. A compound according to any preceding claim wherein R represents hydrogen, methyl or halogen. 6. A compound according to claim 5 wherein R represents hydrogen or methyl. 7. A compound according to any of claims 1-6 wherein R represents -(C1-3 alk)n-C5-7-cycloalkyl wherein n is 0 or 1, optionally substituted by at least one substituent selected from halogen, C1-3 alkoxy, and OH or is unsubstituted. 8. A compound according to claim 7 wherein the cycloalkyl group is unsubstituted or monosubstituted with fluorine.