Huperzia serrata (Thunb.) Trev. composition comprising compounded Huperzine A and Huperzine B and methods for preparing it

A Huperzia serrata (Thunb.) Trev. composition for treating a memory and/or cognition dysfunction, comprising a combination of isolated fractions of an extract of Huperzia serrata (Thunb.) Trev., wherein the composition contains 30-99 wt % of total alkaloids, the total alkaloids contain Huperzine A and Huperzine B, the total content of the Huperzine A and Huperzine B is 50-99 wt % of total alkaloids;

• and the weight ratio of the Huperzine A and Huperzine B is 1:0.5-5;
• wherein the composition is obtained by the following steps (a)-(c):
• a) extracting a raw material of Huperzia serrata (Thunb.) Trev with an acid aqueous solution having a pH between 1-3, thereby obtaining an extract solution of the raw material, and extracting a residue of the extraction of the raw material with an aqueous solution, thereby obtaining an extract solution of the residue;
• b) concentrating the extract solution of the raw material and the extract solution of the residue obtained in step a), thereby obtaining a concentrate of the extract solution of the raw material and a concentrate of the extract solution of the residue, and treating the concentrates as follows:
• (b1) extracting, concentrating, decolorizing and re-concentrating the concentrate of the extract solution of the raw material, thereby obtaining a reconcentrate of the concentrate of the extract solution of the raw material;
• loading the reconcentrate onto a first chromatography column and eluting the first chromatography column with water, a C1-C6 alkanol solvent, or a mixture including water and the C1-C6 alkanol solvent, and collecting a fraction b1 containing the total alkaloids;
• (b2) diluting and centrifuging the concentrate of the extract solution of the residue, loading a supernatant obtained from the centrifuging onto a second chromatography column and eluting the second chromatography column with water, a polar solvent, a non-polar solvent, or a mixture including water, the polar solvent and the non-polar solvent, and collecting a fraction b2 containing total alkaloids;
• and
• c) combining fractions b1 and b2 and concentrating and drying the combined fractions b1 and b2, thereby obtaining the Huperzia serrata (Thunb.) Trev. composition.