Aiming at isolating and investigating the active ingredients of the aqueous extract from Panax ginseng which showed enhancing memory activity, the authors characterized one ingredient. To separate the oligosaecharides and polypeptides, a DEAE-Sephadex A-50 colum was used. The enhanced memory activity in mice was studied by Mirros water maze tesk in mice. The dose of oligosacchrides, polypeptides or Piracetam was 30 mg/kg per day with intraperitoneal administration. The oligosaccharides did not show enhancing memory effect, but polypeptides did show. This result demonstrates that the active ingredients of the aqueous extract from Panax ginseng which showed enhancing memory effect was polypeptides. The purification of the polypeptides was performed on a Sephadex G-25 column. A novel tetradeeapeptide was purified from the polypeptides and its structure was determined by liquid chromatography-eleetrospray ionization-quadrupole-time of flight-mass spectrometry（LC-ESI-Q-TOF-MS） with the amino acid sequence of Lys-Ser-Leu-Thr-Leu-Thr-Ser-Ser-Leu-Ser-Tyr-Thr-Asp-Ser.
LUO Hao-mingJIANG Rui-zhiYANG Xiao-hongCHEN Ying-hongHONG TieWANG Ying
