Quantitative 1 H NMR for the direct quantification of saikosaponins in Bupleurum chinense DC.

Saikosaponin a and saikosaponin d are used as chemical standards for the quality evaluation of Bupleurum chinense DC. by the high-performance liquid chromatography method in current Chinese Pharmacopoeia. However, other saikosaponins, such as saikosaponin c and saikosaponin b2, also possess pharmaceutical activity, but are not used as chemical standards. In this study, a quantitative proton nuclear magnetic resonance (1H NMR) method was developed to determine the total mass percentage (mg/g) of SSa, SSb1, SSb2 and SSd in B. chinense DC., using the H-24 (δH 0.71) signal. Furthermore, the molality (mol/kg) of type I saikosaponins (epoxy-ether structure) was also determined by quantitative 1H NMR in the area of H-11 (δH 5.95) for a more accurate quality evaluation. Validation of the method confirmed that it has acceptable selectivity, precision, stability, and repeatability. The results indicated that this method has the potential to be a reliable method for the quantification of saikosaponins in Bupleurum scorzonerifolium Willd., vinegar baked B. chinense DC. and B. scorzonerifolium Willd., Chaihu Koufuye (oral liquid of Chaihu).