The present invention relates to novel compounds of Formula I, their pharmaceutically acceptable derivatives, tautomeric forms, stereoisomers including R and S isomers, polymorphs, prodrugs, metabolites, salts or solvates thereof. The invention also relates to the processes for the synthesis of novel compounds of Formula I, their pharmaceutically acceptable derivatives, tautomeric forms, stereoisomers, polymorphs, prodrugs, metabolites, salts or solvates thereof. The present invention also provides pharmaceutical compositions comprising compounds of Formula I and methods of treating or preventing one or more conditions that may be regulated or normalized via inhibition of dipeptidyl peptidase IV (DPP-IV).