Compounds of formula their tautomeric forms, their stereoisomers, their pharmaceutically acceptable salts, wherein 'A' represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; 'Y' represents either a bond or substituted or unsubstituted linear or branched (C 1 -C 6)alkyl, (C 2 -C 6)alkenyl groups or the groups represented by '-U(CH 2) m -' wherein U represents O, S o, NR 4; 'm' represents integers from 2 to 4, 'o' represents integers from 0 to 2 and R 4 represents H, substituted or unsubstituted linear or branched (C 1 -C 6)alkyl; 'Z' represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; 'X' represents either a bond, or is selected from O, S o or NR 4; wherein R 4 is as defined earlier; 'W' represents substituted or unsubstituted linear or branched (C 1 -C 6)alkyl, (C 2 -C 6)alkenyl groups; R 1 represents hydrogen, optionally substituted, (C 1 -C 6)alkyl, (C 3 -C 6)cycloalkyl, alkoxyalkyl, hydroxyalkyl, aminoalkyl, aryl, heterocyclyl, aralkyl, heterocyclylalkyl groups; R 2 represents hydrogen, or the groups selected from (C 1 -C 6)alkyl, aryl, heterocyclyl, aralkyl, heterocyclylalkyl, (C 1 -C 6)alkoxy, hydroxyalkyl, thio(C 1 -C 6)alkyl, amino, aminoalkyl, alkylamino, each of which may be optionally substituted; or R 1 and R 2 wherever possible, together may form 4 to 7 membered saturated or partially saturated ring containing from 0-2 additional heteroatoms selected from the group comprises of N, O, and S o; R 3 at each occurrence independently represents hydrogen, halogen, (C 1 -C 3)alkyl, halo(C 1 -C 3)alkyl, (C 1 -C 3)alkoxy, thio(C 1 -C 3)alkyl, sulfenyl derivatives, sulfonyl derivatives; 'n' represents integers from 0-3. 'A' represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; 'Y' represents either a bond or substituted or unsubstituted linear or branched (C 1 -C 6)alkyl, (C 2 -C 6)alkenyl groups or the groups represented by '-U(CH 2) m -' wherein U represents O, S o, NR 4; 'm' represents integers from 2 to 4, 'o' represents integers from 0 to 2 and R 4 represents H, substituted or unsubstituted linear or branched (C 1 -C 6)alkyl; 'Z' represents an optionally substituted single or fused group selected from aryl, heterocyclyl or cycloalkyl groups; 'X' represents either a bond, or is selected from O, S o or NR 4; wherein R 4 is as defined earlier; 'W' represents substituted or unsubstituted linear or branched (C 1 -C 6)alkyl, (C 2 -C 6)alkenyl groups; R 1 represents hydrogen, optionally substituted, (C 1 -C 6)alkyl, (C 3 -C 6)cycloalkyl, alkoxyalkyl, hydroxyalkyl, aminoalkyl, aryl, heterocyclyl, aralkyl, heterocyclylalkyl groups; R 2 represents hydrogen, or the groups selected from (C 1 -C 6)alkyl, aryl, heterocyclyl, aralkyl, heterocyclylalkyl, (C 1 -C 6)alkoxy, hydroxyalkyl, thio(C 1 -C 6)alkyl, amino, aminoalkyl, alkylamino, each of which may be optionally substituted; or R 1 and R 2 wherever possible, together may form 4 to 7 membered saturated or partially saturated ring containing from 0-2 additional heteroatoms selected from the group comprises of N, O, and S o; R 3 at each occurrence independently represents hydrogen, halogen, (C 1 -C 3)alkyl, halo(C 1 -C 3)alkyl, (C 1 -C 3)alkoxy, thio(C 1 -C 3)alkyl, sulfenyl derivatives, sulfonyl derivatives; 'n' represents integers from 0-3.