Abstract: The present invention aims to provide antidementia agents which are free from the problem of side effects and are excellent in safety. The present invention also aims to provide agents for improving learning and memory which are useful for improvement of learning and memory and can be ingested continuously. The present invention provides antidementia agents and agents for improving learning and memory, each comprising a cyclic dipeptide with the 2,5-diketopiperazine structure as an active ingredient.

Abstract: The present invention aims to provide antidepressants which are free from the problem of side effects and are excellent in safety. The present invention also aims to provide learning motivation improvers which are useful for improvement of learning motivation and can be ingested continuously. The present invention provides antidepressants and learning motivation improvers, each comprising a cyclic dipeptide with the 2,5-diketopiperazine structure as an active ingredient.

Abstract: Extracts or beverages whose ratio between the content of 2,5-piperazinedione,3,6-bis(phenylmethyl)-,(3S,6S)-(unit: ?g/100 g) and Brix (Bx) is 6 (?g/100 g)/Bx or more are good in flavor and feeling on the tongue and further have a good appearance.

Abstract: The present invention aims to provide antidepressants which are free from the problem of side effects and are excellent in safety. The present invention also aims to provide learning motivation improvers which are useful for improvement of learning motivation and can be ingested continuously. The present invention provides antidepressants and learning motivation improvers, each comprising a cyclic dipeptide with the 2,5-diketopiperazine structure as an active ingredient.

Abstract: The present invention aims to provide antidementia agents which are free from the problem of side effects and are excellent in safety. The present invention also aims to provide agents for improving learning and memory which are useful for improvement of learning and memory and can be ingested continuously. The present invention provides antidementia agents and agents for improving learning and memory, each comprising a cyclic dipeptide with the 2,5-diketopiperazine structure as an active ingredient.

Abstract: The present invention aims to provide antidepressants which are free from the problem of side effects and are excellent in safety. The present invention also aims to provide learning motivation improvers which are useful for improvement of learning motivation and can be ingested continuously. The present invention provides antidepressants and learning motivation improvers, each comprising a cyclic dipeptide with the 2,5-diketopiperazine structure as an active ingredient.

Abstract: The present invention aims to provide extracts available for use in acidic beverage production and containing 2,5-piperazinedione,3,6-bis(phenylmethyl)-,(3S,6S)-, which is a useful substance with an improving effect on learning motivation. When an acid treatment step is included in the production of extracts containing 2,5-piperazinedione,3,6-bis(phenylmethyl)-,(3S,6S)-, it is possible to obtain acidic extracts which cause no sedimentation even when added to beverages. The extracts of the present invention can be added to beverages and so on without impairing the taste inherent to foods and beverages, and can be used for production of acidic beverages preferred by most consumers.

Abstract: The present invention aims to provide antidepressants which are free from the problem of side effects and are excellent in safety. The present invention also aims to provide learning motivation improvers which are useful for improvement of learning motivation and can be ingested continuously. The present invention provides antidepressants and learning motivation improvers, each comprising a cyclic dipeptide with the 2,5-diketopiperazine structure as an active ingredient.

Abstract: The present invention aims to provide extracts or beverages containing 2,5-piperazinedione,3,6-bis(phenylmethyl)-,(3S,6S)—, which is a useful substance with an improving effect on learning motivation, in an easy-to-ingest form and at a high concentration. Extracts or beverages whose ratio between the content of 2,5-piperazinedione,3,6-bis(phenyl-methyl)-,(3S,6S)— (unit: ?g/100 g) and Brix(Bx) is 6 (?g/100 g)/Bx or more can be ingested continuously over a long period of time as foods and beverages useful for improvement of learning motivation.