N-Acetyl-<
FONT SIZE="-1">L-glutamine decomposition products glutamine, glutamic acid, pyroglutamic acid,
N-acetylglutamic acid, and a novel compound,
N-(2,6-dioxo-3-piperidinyl) acetamide, have beenidenti
fied by NMR and MS techniques.
N-Acetylglutamine, a modi
fied amino acid, o
ffers greaterchemical stability than glutamine in conditions that are experienced during typical sterilizationand shel
f storage o
f liquid nutritionals. However, to support sa
fety and stability studies, potentialdecomposition products o
f N-acetyl-
L-glutamine needed to be identi
fied. There
fore, atypically harshconditions were used; an unbu
ffered (pH <3) 1 mg/mL water solution o
f N-acetyl-
L-glutamine washeated to 100
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f">C
for 3 h. One-dimensional proton and proton-decoupled carbon-13 NMR andelectrospray LC-MS/MS techniques were employed to identi
fy the molecular structures o
f thegenerated
N-acetyl-
L-glutamine decomposition products. Additionally, DEPT and two-dimensionalNMR techniques TOCSY, GMQCOSY, GHSQC, and GHMBC were employed to derive the
finalstructure o
f the acetamide.
Keywords: Functional
foods; NMR; LC-MS; HPLC; glutamine; N-acetylglutamine; decompositionproducts; stability