Dipeptidyl peptidase IV (DPP IV) (EC 3.4.14.5) is a serine peptidase [4] that cleaves the N-terminal region of incretins such as
glucagon-dependent insulinotropic polypeptide (GIP) and
glucagon-like peptide-1 (GLP-1), and reduction of insulin secretion
is induced by inactivation of incretin by DPP IV [5e8]. DPP IV inhibitors have beneficial effects on plasma glucose level in diabetic
patients [9]. DPP IV inhibitors have also been found in several
plants [10