Comparison of the phenolic component profiles of skullcap (Scutellaria lateriflora) and germander (Teucrium canadense and T. chamaedrys), a potentially hepatotoxic adulterant.

Introduction: Scutellaria lateriflora, commonly known as skullcap, is used as an ingredient in numerous herbal products. Unfortunately, it has occasionally been adulterated with Teucrium canadense or T. chamaedrys, commonly known as germander, which contains potentially hepatotoxic diterpenes. Chromatographic profiles of the phenolic components provide a means of distinguishing between these plants and enhancing public safety.

Objective: To develop a chromatographic method for the identification of Scutellaria lateriflora and two Teucrium species and to quantify the latter as adulterants.

Methodology: Samples were extracted with aqueous methanol and the extracts were analysed using a standardised LC-DAD-ESI/MS profiling method to obtain their phenolic profiles.

Results: Skullcap contained primarily flavonoids, while the major phenolic components of the two Teucrium species were the phenylethanoids, verbascoside and teucrioside. Using the phenylethanoids as markers, it was possible to clearly distinguish between the two genus and to determine 5% Teucrium mixed with Scutellaria using either ultraviolet absorption spectrometry or mass spectrometry in the total ion count mode. Using MS in the selective ion monitoring (SIM) mode, 1% Teucrium could be measured.

Conclusions: This study showed that chromatographic profiling was able to identify Scutellaria and Teucrium, separately and when mixed together.