Compounds of formula their tautomeric forms, their stereoisomers, their pharmaceutically acceptable salts, and pharmaceutical compositions containing them wherein 'Z A ' represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; Each of 'X' and 'Z' independently represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; Alternatively, Z-X- Z A may together form tricyclic 8-15 membered fused ring system containing 1-4 hetero atoms selected from N, O or S; R 1, R 2 and R 3 independently at each occurrence represents H, (C 1 -C 6) linear or branched alkyl, (C 1 -C 6) linear or branched alkenyl, (C 1 -C 6)linear or branched alkynyl, hydroxy, (C 1 -C 6) alkoxy, (C 1 -C 6) alkenoxy, hydroxy(C 1 -C 6)alkyl, alkoxyalkyl, haloalkyl, (C 1 -C 6)cycloalkyl, thio(C 1 -C 6)alkyl, (C 1 -C 6)alkylthio, halo, oxo, imino, nitro, aryl, heterocyclyl, optionally substituted amino, amino(C 1 -C 6)alkyl, alkylamino, cyano, formyl, haloalkoxy, aryl, aryloxy, aralkyl, aralkoxy, heterocylyl, heterocyclylalkyl, heterocycloxy, heterocyclylalkoxy groups or the groups selected from carboxylic acid and its derivatives such as esters and amides, alkylsulfonyl, alkylsulfonylamino, alkylsulfonyloxy, each of which may be optionally substituted; 'm' 'n' and 'o' independently represents integers from 0 to 5; 'Y' represents either a bond, or O, S p or NR 4 wherein R 4 represents H, (C 1 -C 6)linear or branched alkyl, (C 1 -C 6)cycloalkyl, aryl, heterocyclyl, heterocyclylalkyl, cycloalkylalkyl and 'p' represents integers from 0 to 2; `W' represents (C 1 -C 6)linear or branched alkyl or (C 1 -C 6)linear or branched cycloalkyl; 'V' represents O or S; 'Z A ' represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; Each of 'X' and 'Z' independently represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; Alternatively, Z-X- Z A may together form tricyclic 8-15 membered fused ring system containing 1-4 hetero atoms selected from N, O or S; R 1, R 2 and R 3 independently at each occurrence represents H, (C 1 -C 6) linear or branched alkyl, (C 1 -C 6) linear or branched alkenyl, (C 1 -C 6)linear or branched alkynyl, hydroxy, (C 1 -C 6) alkoxy, (C 1 -C 6) alkenoxy, hydroxy(C 1 -C 6)alkyl, alkoxyalkyl, haloalkyl, (C 1 -C 6)cycloalkyl, thio(C 1 -C 6)alkyl, (C 1 -C 6)alkylthio, halo, oxo, imino, nitro, aryl, heterocyclyl, optionally substituted amino, amino(C 1 -C 6)alkyl, alkylamino, cyano, formyl, haloalkoxy, aryl, aryloxy, aralkyl, aralkoxy, heterocylyl, heterocyclylalkyl, heterocycloxy, heterocyclylalkoxy groups or the groups selected from carboxylic acid and its derivatives such as esters and amides, alkylsulfonyl, alkylsulfonylamino, alkylsulfonyloxy, each of which may be optionally substituted; 'm' 'n' and 'o' independently represents integers from 0 to 5; 'Y' represents either a bond, or O, S p or NR 4 wherein R 4 represents H, (C 1 -C 6)linear or branched alkyl, (C 1 -C 6)cycloalkyl, aryl, heterocyclyl, heterocyclylalkyl, cycloalkylalkyl and 'p' represents integers from 0 to 2; `W' represents (C 1 -C 6)linear or branched alkyl or (C 1 -C 6)linear or branched cycloalkyl; 'V' represents O or S;