γ-Glutamyl dipeptides in Petiveria alliacea

Isolation and identification of three γ-glutamyl dipeptides from Petiveria alliacea L. roots is reported. These include ( S C2 R C7)-γ-glutamyl- S-benzylcysteine together with both diastereomers of the corresponding S-oxide. Three γ-glutamyl dipeptides have been isolated from Petiveria alliacea L. roots. These dipeptides include ( S C2 R C7)-γ-glutamyl- S-benzylcysteine together with two diastereomeric sulfoxides, namely ( S C2 R C7 R S)- and ( S C2 R C7 R S)-γ-glutamyl- S-benzylcysteine S-oxides (γ-glutamyl-petiveriins A and B, respectively). Their structures and absolute configurations have been determined by NMR, MALDI-HRMS, IR and CD spectroscopy, and confirmed by comparison with authentic compounds obtained by synthesis.