Takaharu Tanaka, Naoki Higuchi, Masayuki Saitoh, Masaki Hashimoto: Novel biologically active compound having anti-prolyl endopeptidase activity. Suntory, Cushman Darby & Cushman, May 10, 1988: US04743616 (12 worldwide citation)

A novel compound that exhibits inhibitory activity against prolyl endopeptidase and a method for chemical synthesis of said compound, as well as its use as a prolyl endopeptidase inhibitor and an anti-amnesic agent that contains said compound as the active ingredient are provided.