Isolation and identification of beta-citryl-L-glutamic acid from newborn rat brain

An unknown compound containing glutamic acid residue was found in newborn rat brain. The compound occurred predominantly in brain. Its concentration was approx. 1 mumol/g tissue at birth and decreased to one-tenth 24 days after birth. The compound was isolated from newborn rat brains, and subjected to elementary analysis and to infrared and mass spectrometric analysis. Glutamic acid and citric acid were formed from the compound on acid hydrolysis. The compound was presumed to be a citrylglutamic acid. Two isomers, alpha- and beta-citrylglutamic acid, were synthesized. The unknown compound was identified as beta-citryl-L-glutamic acid. The occurence of this compound has not been reported in nature.