İlkay ORHAN*,?, Gürdal ORHAN**, Bilge ŞENER*

*Gazi University, Department of Pharmacognosy, Faculty of Pharmacy, 06330 Etiler, Ankara, TURKEY.
** Numune Education and Research Hospital, 2nd Clinic of Neurology, Ankara, TURKEY.
°Corresponding author

Summary:
Prolyl endopeptidase (PEP) is a serine protease which is known to play a role in degradation of proline-containing neuropeptides involved in the processes of learning and memory. PEP inhibitors are expected to exert their beneficial effects by increasing the brain levels of those neuropeptides which may improve and restore cognitive functions and protect vulnerable nerves against damage and cell death. Therefore, they are considered to have therapeutic potential against Alzheimer’s Disease. To date many compounds have been isolated from natural sources including plants, fungi and bacteria. Their synthetic counterparts have been also studied. This review covers PEP inhibitors isolated from plants.