TABLE 2.

GC analysis of amino acids constituting compounds B, cyclo(Phe-Pro), and C, cyclo(Phe-4-OH-Pro), isolated from L. plantarum MiLAB 393a

CompoundRetention time (min)
ReferenceCompound BCompound C
d-Pro10.12
l-Pro10.3110.31
trans-4-OH-d-Prob11.91
trans-4-OH-l-Pro12.1112.15
cis-4-OH-d-Pro14.46
cis-4-OH-l-Pro14.70
d-Phe20.33
l-Phe20.5720.5620.60
  • a The cyclic dipeptides were hydrolyzed with 6M HCl and subsequently derivatized with 2-(S)-butanol and perfluoropropionic anhydride. The GC analysis was performed using a nonchiral GC column (see the text for details).

  • b The amino acid trans-4-OH-d-Pro was not commercially available. To obtain a reference compound behaving identically on a nonchiral GC column, the enantiomeric compound trans-4-OH-l-Pro was derivatized with 2-(R)-butanol and perfluoropropionic anhydride.