Chemical constituents and quality control of two Dracocephalum species based on high-performance liquid chromatographic fingerprints coupled with tandem mass spectrometry and chemometrics

Two similar Dracocephalum species, namely, Dracocephalum tanguticum Maxim and Dracocephalum moldavica L, are commonly used as ethnic medicines in China. Here we describe a strategy of combining high-performance liquid chromatography with quadrupole timeof- flight mass spectrometry, as well as fingerprints and chemometrics for characterization and discrimination of chemical constituents on the two herbs. A total of 49 compounds including 33 flavonoids, 5 phenylethanol glycosides, 1 coumarin glycoside, 8 organic acids, and 2 other types of compounds were unambiguously or tentatively identified from the two Dracocephalum species. Among the compounds identified, 26 were characterized for the first time and 4 compounds, rosmarinic acid (7), salvianolic acid B (10), luteoloside (22), diosmetin-7-O-glucoside (28), were inferred as common constituents for the two herbs. Flavonoids featured in these two Dracocephalum species while their types presented significant differences. Acacetin (45) and acacetin glycosides (acatetin-7-O-glucuronide (30), acacetin-7-O-(6 ''-O-malonyl) glucoside (33), buddleoside (34), tilianin (35), and agastachoside (42)) were detected only in D. moldavica, which can be used to discriminate two herbal medicines. In addition, six characteristic constitutes in D. tanguticum were simultaneously quantified. Moreover, the induced chemometrics methods including similarity analysis and hierarchical clustering analysis were successfully applied for origin discrimination and quality evaluation of D. tanguticum and D. moldavica.