Analysis of the traditional medicine YiGan San by the fragmentation patterns of cadambine indole alkaloids using HPLC coupled with high-resolution MS

YiGan San (YGS) has long been used in traditional Japanese and Chinese folk medicine and serves as a potent and novel therapeutic agent to treat Alzheimer's disease. In the present study, a rapid and sensitive method based on HPLC coupled with diode-array detection and quadrupole TOF MS (Q-TOF-MS) was designed to reveal the chemical constituents of YGS. Thirty-six compounds were identified and assigned in YGS, including 14 alkaloids, nine γ-lactones, six flavonoids, three triterpenoid saponinares, two small molecular organic acids, and two other types of compounds. In addition, the accurate fragment weight and MS/MS fragmentation reactions of a subtype indole alkaloid in Uncariae ramulus cum uncis were summarized for the first time to realize rapid identification without reference substances. For the first time, 11 major constituents were comprehensively quantified with a HPLC coupled with triple-quadrupole MS method. A three-section switch was used to realize such multicomponent identification. The contents of saikosaponin B2 and isoliquiritin, which produce anti-inflammatory and antidepressant-like effects, were extremely different, up to 700 times, in two sources of YGS. The developed qualitative and quantitative method was proved to be precise, accurate, and reproducible.