Chiral separation of Huperzine A using CE - method validation and application in pharmaceutical formulations

The aim of this work is the development, validation and application of an MEKC method for the chiral separation of Huperzine A. Huperzine A is an important compound that is used to treat Alzheimer's disease. However, only the (-)-form of this compound is biologically active and behaves as a potential acetylcholinesterase inhibitor. Therefore, the separation of the (-)-form from the (+)-form is of greatest importance. Optimal conditions, regarding resolution and analysis time, were established by altering several experimental parameters, such as temperature, field strength, pH, type and concentration of BGE and chiral selector. A major problem that had to be solved in this study was the low intensity and efficiency of the peaks. More parameters were examined, such as the addition of modifiers, to optimize further the separation, and particularly the efficiency. Baseline enantioseparation was achieved by using a BGE of 50 mM acetate (pH 5.0), supplemented with 0.2% w/v poly(sodium N-undecanoyl-ll-alanyl-valinate) and 10% v/v tert-butanol. Finally, the optimum conditions were applied to a pharmaceutical formulation, to demonstrate the ability of the method to control the purity of the (-)-Huperzine A in pharmaceutical formulations.