Identification of C‐glycosyl flavones and quality assessment in Dendrobium nobile

RATIONALE: Flavones are significant indicators of quality in traditional Chinese medicines (TCMs) and thus play a significant role in the quality control of TCMs in the pharmaceutical industry. Most flavones in Dendrobium nobile Lindl, a TCM with a long cultivation history and rich sources, have not been identified. This study was aimed at identifying the flavones in D. nobile from various habitats. METHODS: High-performance liquid chromatography (HPLC) coupled with diode-array detection and HPLC multiple-stage tandem mass spectrometry was used to identify the chemical constituents of D. nobile from various habitats, and a method was established to determine the content of vicenin II, violanthin and isoviolanthin. Hierarchical cluster analysis, principal component analysis and orthogonal partial least-squares discriminant analysis were used to analyze the variations among 26 batches from different habitats. RESULTS: A total of 33 flavones were tentatively identified. Twenty-five flavones, previously undescribed in D. nobile, were acylated by p-coumaroyl, feruloyl, sinapoyl or 3-hydroxy-3-methylglutaryl. The D. nobile habitats were distinguished by significant differences in their flavone content. The C-glycosyl flavones were demonstrated to be characteristic compounds for evaluating D. nobile from various habitats. In particular, flavones acylated with 3-hydroxy-3-methylglutaryl were specific compounds that were only detected in samples from Yunnan. CONCLUSIONS: The results of this study could be used to improve the quality control of D. nobile and could provide references for the identification of acylated C-glycosyl flavones in other natural products.