Abstract
Pyrroglutamic acid is easily produced from glutamic acid by heating in vitro, and also it seems quite probable that in vivo glutamic acid is transformed into proline, oxyproline, ornithine, or other amino acid via pyrroglutamic acid. This acid is therefore worthy of consideration from the nutritional point of view. It is also known that pyrroglutamic acid is contained in some of our foods and seasonings.
Meanwhile Austerweil and Delort-Stachenko reported that pyrroglutamic acid showed some toxity. But our experiment on rats proved that D- and L-pyrroglutamic acids were harmless even when 1-2mg. were injected to the animal subcutaneously daily for about a month.
