Characterization and identification of the chemical constituents of Polygonum multiflorum Thunb. by high-performance liquid chromatography coupled with ultraviolet detection and linear ion trap FT-ICR hybrid mass spectrometry

Dianthrone derivatives are minor constituents of Polygonum multiflorum Thunb. (PM). These derivatives are potential hepatotoxic components in PM. Fraction D6 contains many dianthrone derivatives and was successfully enriched using an efficient three-step approach. An effective and reliable high-performance liquid chromatography (HPLC) technique coupled with ultraviolet detection (UV) and a linear ion trap FT-ICR hybrid mass spectrometry (HPLC-UV/LTQ-FT-ICR-MS) method were successfully developed to separate and identify the dianthrones of the fraction D6. The characteristic diagnostic fragment ions and characteristic fragmentation pathway of the seven dianthrone standards, namely, Polygonumnolide B1 (S1), Polygonumnolide C3 (S2), Polygonumnolide C2 (S3), Polygonumnolide E (S4), Polygonumnolide A1 (S5), Polygonumnolide A2 (S6) and cis-emodin dianthrones (S7), were compared with unknown compounds in fraction D6, and 45 dianthrone derivatives were characterized or tentatively identified. Of these derivatives, 32 new dianthrone derivatives were tentatively characterized in PM. Therefore, LTQ-FT-ICR-MS combined with a selective enrichment method provided a powerful means for analyzing dianthrone derivatives. This study provides a meaningful basis for correcting some mistakes in previous studies, as well as further quality control and pharmacological and toxicological research.