Kabushiki Kaisha Yakult Honsha

Kunio Kado

Shusuke Hashimoto

Teruo Yokokura

Tadashi Yoshimoto

Yoshiyuki Shishido

Hisao Hagiwara

Takayuki Shioiri

Daisuke Tsuru

Naoko Irako

Yasumasa Hamada

Shuichi Tanabe

Toshizo Shiga

Masayoshi Furushiro

Tetsuya Terasaki

Peptides and nootropic agent

New thiazolidine derivatives of the general formula: ##STR1## wherein X stands for a proline or thioproline residue and R for --CH.sub.2 OH or --CHO, a process for preparing the same which comprises reacting N-benzyloxycarbonyl-L-proline or --L-thioproline with L-thioprolinol and, if necessary, oxidizing the resultant N-benzyloxycarbonyl-L-prolyl-L-thioprolinol or --L-thioprolyl-L-thioprolinol to the corresponding thioprolinal compound, and an anti-amnestic composition containing at least one of the thiazolidine derivatives together with a conventional excipient. The new thiazolidine derivatives are extremely strong in anti-amnestic activity when compared with known similar anti-amnestic agents.

New thiazolidine derivatives, process for preparing same and

New proline derivatives of the general formula: ##STR1## wherein R stands for a lower alkyl group and X for a N-terminal protective group conventional in amino acid chemistry or an acyl group derived from an amino acid with a protective group at the N-terminal. They have inhibitory activity against prolylendopeptidase and are relatively chemically stable as compared with known compounds of this type.

Proline derivatives

An anti-amnestic agent which comprises as an active ingredient thereof at least one prolinal derivative of the general formula: ##STR1## wherein A is a protective groups for amino group in the field of amino acid chemistry and X is a residue of an amino acid, in a pharmacologically active amount together with an exipient. This agent is less toxic and can be safely administered to patients orally or intravenously for the remedy of memory disorder.

Anti-amnestic agent

Growing community of inventors

Tokyo, Japan

Kunio Kado