Quantification of flavonoid glycosides in an aqueous extract from the traditional Mongolian medicinal plant Dianthus versicolor FISCH.

ABSTRACT

An HPLC-diode array detection (DAD) method was established in order to investigate dried aerial parts of Dianthus versicolor FISCH. (Caryophyllaceae), a plant used in traditional Mongolian medicine against liver impairment. Aqueous extracts were separated on an Aquasil(®) C(18) column with a linear gradient of acetonitrile (ACN) and water (adjusted to pH 2.8 with formic acid) as the mobile phase. LC-IT-MS facilitated the assignment of 26 flavonoids, among them a series of rare C-glycosylated as well as O-glycosylated derivatives, which are assumed to be the active principles. Quantification was performed and validated using isovitexin-7-O-glucoside (saponarin) as the external standard. The method showed good linear behaviour (r(2) ≥0.9999) over the investigated concentration range (0.007-3.5 mg/mL). The good precision of the method allowed the successful qualitative and quantitative analysis of flavonoid-glycosides in the aqueous extracts prepared from five different D. versicolor samples. Depending on the origin of the samples, the total flavonoid content was found to vary considerably from 0.41 to 3.30% in the aqueous extracts and from 0.07 to 0.57% in the crude drug. In addition, the relative composition of the various flavonoids was found to differ strongly. These results highlight the need for proper quality control for this herbal drug.