Identification of phenolic compounds from Scutellaria lateriflora by liquid chromatography with ultraviolet photodiode array and electrospray ionization tandem mass spectrometry.

Scutellaria lateriflora has been used more than 200 years as a mild relaxant and as a therapy for anxiety, nervous tension, and convulsions. Currently, it is one of the most popular botanicals with many products on the USA market. Flavonoids with anxiolytic property have been reported from the aerial parts of this plant. From the HPLC chromatogram of the methanolic extract of this plant, it can be concluded that some flavonoids have not been identified yet. In the present study a simple high-performance liquid chromatography with UV and electrospray ionization mass spectrometric detection (HPLC-DAD/ESI-MS(n)) method has been developed for the identification of major phenolic compounds from it. The ESI-MS(n) fragmentation pathways of four types of flavonoid references have been interpreted which provide very useful guidance for the characterization of different types of flavonoids from this plant. Further analysis of the methanolic extract of S. latellaria based on the combination of their fragmentation patterns with the UV spectra led to characterize thirteen flavonoids and one stilbene derivative, seven of which are described for the first time from this species.