The present invention relates to novel heterocyclic compounds, their analogs, their tautomers, their regioisomers, their stereoisomers, their enantiomers, their diastereomers, their polymorphs, their pharmaceutically acceptable salts, their appropriate N-oxides, their pharmaceutically acceptable solvates and their pharmaceutical compositions containing them. The present invention more particularly relates to novel Phosphodiesterase type 4 (PDE4) inhibitors of the Formula (1), their analogs, tautomers, enantiomers, diasteromers, regioisomers, stereoisomers, polymorphs, pharmaceutically acceptable salts, appropriate N-oxide, pharmaceutically acceptable solvates and the pharmaceutical compositions containing them.