Synthesis of ginseng oligopeptides

In the course of our investigation of the water - soluble constituents of g inseng, some oligopeptides, oxidized glutathione, N, N' - bis - (gamma - gl utamylglycyl) cystine 1, N, N' - his - gamma - glutamylcystinylglycine 2, N - gamma - glutamylcystinyl - bis - glycine 3 and gamma - glutamylcysteinyl glycinamide disulfide were isolated for the first time from aqueous extract s of Panax ginseng root. Here the chemical synthesis of peptide 1, 2, 3, an d gamma - glutamylglycylcysteine 4 was described. All peptides were prepare d by solution method and using an organophosphorus compound 3 - O - (dietho xyphosphoryloxy) - 1, 2, 3 - benzotriazin - 4 - (3H) - one (DEPBT) as a cou pling reagent. The synthesis of asymmetrical disulfides, peptide 2 and 3, b ased on glutathione ( GSH) thiolysis of the thiolsulfonate derivatives of c orresponding peptides N, N' - gamma - glutamylcystine and cystinyl - bis - glycine. The final products were separated from contaminating compounds by ion - exchange chromatography or HPLC and confirmed by MS, NMR and amino ac id analysis.