ISOLATION AND CHARACTERIZATION OF A GROUP OF OLIGOPEPTIDES RELATED TOOXIDIZED GLUTATHIONE FROM THE ROOT OF PANAX-GINSENG

Six gamma-glutamyl oligopeptides were isolated for the first time from aqueous methanol extracts of Panax ginseng root by using column chrom atography on ion-exchange resin, gel filtration and reverse-phase high -performance liquid chromatography. Their structures had been establis hed with the methods of amino acid analysis, N-terminal, C-terminal de termination and double-coupling sequence analysis. They were: P-I (N-g amma-glutamylcystinyl-bis-glycine), P-II (gamma-glutamylcysteinylglyci ne disulfide, oxidized glutathione), P-III (N,N '-bis-gamma-glutamylcy stinylylycine), P-IV (gamma-glutamylcysteinylglycinamide disulfide), P -V (N-gamma-glutamylglycylcysteine disulfide), P-VI (gamma-glutamylarg inine); five of them are related to oxidized glutathione. The structur es were further confirmed by the chemical synthesis. As far as we know , P-V (N-gamma-glutamylglycylcysteine disulfide) is a new biologically active peptide which exhibits somnogenic effect and is more potent th an that of P-II.