Patent ID: 7250416

Claim:
A compound of Formula I, or its pharmaceutically acceptable salt, wherein R x is hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, halogen-substituted alkyl or aryl, phenyl, benzyl, hydroxyl, thiol, substituted or unsubstituted amino, —O-alkyl, —S-alkyl, —O-aryl or —S-aryl; R y is alkyl, or substituted or unsubstituted ribose or 2′-deoxyribose; and R z is a hydrogen, aryl, arylalkyl, amino, dialkylamino, alkylarylamino, hydrazine, hydroxylalkylamino, —O-alkyl, —S-alkyl, —O-aryl or —S-aryl, provided that when R x is phenyl or benzyl, and R y is ribose or 2′-deoxyribose, R z is not amino or dimethylamino.