Herein we reported two novel series of histone deacetylase inhibitors bearing the pyridine-2,6 dicarboxylate moiety as a zinc binding group. Tested on U937 leukemia cell line at 50 mM, compounds 4a, 4c and 4d showed cell cycle block in the S phase and apoptotic induction up to 50%, whereas compound 6h was able to give granulocytic differentiation up to 40%. From these results, the chelidamic scaffold will be further investigated to find more potent compounds.