Novel compounds of the general formula (I), having histone deacetylase (HDAC) inhibiting enzymatic activity, their derivatives, analogs, tautomeric forms, stereoisomers, polymorphs, hydrates, solvates, intermediates, pharmaceutically acceptable salts, pharmaceutical compositions, metabolites and prodrugs thereof. The present invention more particularly provides novel compounds of the general formula (I). Also included is a method for treatment of cancer, psoriasis, proliferative conditions and conditions mediated by HDAC, in a mammal comprising administering an effective amount of a novel compound of formula (I).