Abstract: The invention relates to 3-,7-disubstituted pyrazolo[4,3-d]pyrimidines represented by the general formula I (I), and pharmaceutically acceptable salts thereof, wherein R3 is selected from the group consisting of alkyl, cycloalkyl, cycloalkyl alkyl, cycloheteroalkyl alkyl, cycloheteroalkyl, aryl, heterocycle, heteroaryl, arylalkyl, heteroarylalkyl, and heteroalkyl, wherein each of the groups may optionally be substituted, R7 is selected from the group consisting of halogen, hydroxyl, hydroxylamino, amino, carboxyl, cyano, nitro, amido, sulfo, sulfamido, carbamino, unsubstituted or substituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted arylalkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted heteroarylalkyl, substituted or unsubstituted cycloalkyl alkyl, substituted or unsubstituted cycloheteroalkyl alkyl; R7?-X— wherein X is an —NH—, —N(alkyl)-, -0- or —S— moiety and R7? is selected from the group consisting of H, alkyl, cycloalkyl, aryl, alkylcycloal

Abstract: The invention relates to 3-, 5-, 7-trisubstituted pyrazolo[4,3-d]pyrimidines represented by the general formula I and pharmaceutically acceptable salts thereof, wherein R3 is an optionally substituted alkyl, cycloalkyl, cycloheteroalkyl, cycloalkyl alkyl, aryl or alkylaryl group; R5 is halogen, —NHNH2, —NHOH, NHCONH2, guanylo (NH—C(NH)NH2) an optionally substituted C1-C6 alkyl, alkenyl, alkinyl, C3-C15 cycloalkyl, Rf (C3-C15 cycloalkyl), heterocycle, heteroalkyl, aryl, heteroaryl, arylalkyl, cycloheteroalkyl, cycloheteroalkyl alkyl, heteroarylalkyl group, the group —C(O)—Ra, —C(O)NRbRc, —SO3Rd, or —NHC(O)Re, wherein Ra and Rf are an optionally substituted C1-C6 alkyl, alkenyl, or alkinyl group, Rb, Rc and Rd are independently selected from the group consisting of H, optionally substituted C1-C6 alkyl, alkenyl, or alkinyl group, and Re is a hydroxy, amino, alkoxy, alkylamino, optionally substituted C1-C6 alkyl, alkenyl or alkinyl group; or the group —X—R5?, wherein X is —NH—, —O—, —S— or —N(alkyl)- and