Comparison of raw and processed Radix Polygoni Multiflori (Heshouwu) by high performance liquid chromatography and mass spectrometry

BACKGROUND: Radix Polygoni Multiflori is the dried root tuber of Polygonum multiflorum Thunb. (Fam. Polygonaceae). According to Chinese medicine theory, raw (R-RPM) and processed (P-RPM) Radix Polygoni Multiflori possess different properties. The present study investigates the differences in chemistry between raw and processed Radix Polygoni Multiflori. METHODS: Five pairs of R-RPM and P-RPM as well as 15 commercial decoction pieces were analyzed with high performance liquid chromatography (HPLC) and mass spectrometry (MS). RESULTS: Two anthraquinones, namely emodin-8-O-(6'-O-malonyl)-glucoside and physcion-8-O-(6'-O-malonyl)-glucoside disappeared or decreased significantly and 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucopyranoside, emodin-8-O-beta-D-glucopyranoside and physcion-8-O-beta-D-glucopyranoside decreased after the R-RPM samples being processed. On the other hand, the contents of emodin and physcion generally increased after processing. CONCLUSION: The present study indicates that processing Radix Polygoni Multiflori may change the contents and types of chemicals in it. These changes are probably responsible for the various pharmacological effects of R-RPM and P-RPM as well as hepatotoxicity.