The invention provides novel substituted heterocyclic compounds represented by Formula I and Formula II, or a pharmaceutically acceptable salt, solvate, polymorph, ester, tautomer or prodrug thereof, and a composition comprising these compounds. The compounds provided can be used as inhibitors of MEK and are useful in the treatment of inflammatory diseases, cancer and other hyperproliferative diseases. The invention further provides a method of treatment for inflammatory diseases, cancer and other hyperproliferative diseases in mammals, especially humans.