Quantification of tannins and related polyphenols in commercial products of tormentil (Potentilla tormentilla).

ABSTRACT

INTRODUCTION: Potentilla tormentilla has many biological and pharmacological properties and can be used as an ingredient of some herbal medicines or beverages. OBJECTIVE: The aim of this study was to evaluate the content of individual polyphenols, especially condensed and hydrolysable tannins in commercially available tormentil rhizomes and tinctures using chromatographic methods. METHODS: A quantitative analysis (HPLC-PDA) was preceded by qualitative studies (UPLC-qTOF-MS/MS) and the isolation (CC) of the major tannin compounds. RESULTS: The tested plant material is characterised by a high content of tannins and related polyphenols, i.e. in rhizomes even at the level above 20% and in tinctures above 2%. The main components of tormentil rhizomes are procyanidin B3 (mean ~ 3.6%), procyanidin C2 (mean ~ 2.8%), agrimoniin (mean ~ 2.5%), 3-O-galloylquinic acid (mean ~ 1.7%), catechin (mean ~ 1.6%), other flavan-3-ol oligomers (mean ~ 0.5-1.1) and laevigatins (mean ~ 0.2-0.6%). Free ellagic acid and glycosides of ellagic and methylellagic acids are secondary components. CONCLUSIONS: Underground parts of tormentil are a source of oligomeric proanthocyanidins and ellagitannins, but in smaller quantity of gallotannins. Monogalloylquinic acids are new identified compounds, which had not been described in Potentilla tormentilla before we started our research. In the analysed tormentil tinctures agrimoniin concentration is lower in relation to other tannins.