Chemical Constituents of Fenugreek Using UPLC-Q-TOF MS

Fenugreek in invigorating kidney, falling blood sugar, etc, have very good medicinal value. Much attention has been paid to saponins, flavonoids, the separation and purification, the compatibility mechanism of these components have been studied in depth, but the preparation is complicated, time-consuming, labor-intensive and poor economic. In this research, compounds in the ethanol extract and the water extract after sugar removal of fenugreek were qualitatively analyzed by ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOFMS). And the liquiritin was selected as the internal standard for semi-quantitative analysis of all the identified components. Chromatographic separation was performed on a Unitary C18 column (4.6 mm×150 mm×5 μm). Acetonitrile and 0.1% (volume fraction) formic acid solution were used as the mobile phase for gradient elution with the flow rate of 0.5 mL/min. The MS analysis was carried out by the electrospray ionization (ESI) source in negative mode. The qualitative analysis results showed that the total ion chromatograms of the ethanol extract and the water extract after sugar removal of fenugreek were similar with each other, and 36 compounds were identified, including 12 flavonoids and 24 saponin components. Taking typical flavonoids and saponins as examples, the structures of flavonoids and saponin were described in detail, and the possible breaking rules of flavonoids and saponin were deduced. The results of semi-quantitative analysis showed that the relative content of the main components in the two extracts was different. The sum of the relative contents of the flavonoids in the ethanol extract was 1.13 times that in the aqueous extract. The sum of the relative contents of the saponin compounds was 1.32 times that in the aqueous extract. The method is very simple, rapid and sensitive, and the obtained results will provide a theory basis for further research on fenugreek, as well as development and application research of fenugreek.