A chiral derivatization strategy with phenylglycine methyl
ester (PGME) was employed to develop a straightforward
method to determine the absolute configurations of N,N-dimethyl
amino acids. The PGME derivatives were analyzed using
liquid chromatography-mass spectrometry to identify the absolute configurations of various N,N-dimethyl
amino acids based on their elution
time and order. The established
method was applied to assign the absolute configuration of the N,N-dimethyl
phenylalanine in sanjoinine A (4), a
cyclopeptide alkaloid isolated from Zizyphi Spinosi
Semen widely used as
herbal medicine for
insomnia. Sanjoinine A displayed
production of
nitric oxide (NO) in LPS-activated
RAW 264.7 cells.