Optimisation de l’extraction des polyphénols à partir des feuilles d’Agrimonia eupatoria L.

Abstract

Agrimonia eupatoria L. is a plant renowned for its traditional medicinal uses. Indeed, thanks to its rich secondary metabolites, it possesses diverse pharmacological properties. On this basis, the aim of our study is to optimize the extraction of polyphenols from dried Agrimonia eupatoria L. leaves. Various aqueous and ethanolic extracts of our study plant were obtained by maceration and the soxhlet technique (Aq-Mac, Eth-Mac, Hex-Sox, Eth-Sox and Aq- Sox). Qualitative phytochemical analyses based on colorimetric methods were carried out, as well as the determination of phenolic compounds such as total phenols, total flavonoids, flavonols, condensed and hydrolyzable tannins. FTIR-ATR spectroscopic analysis was also carried out to identify the functional groups present in the extracts obtained. The results of the quantitative phytochemical investigation revealed a diverse richness of phenolic compounds in the different extracts studied. Indeed, the ethanolic extracts revealed high levels of phenolic substances, in particular the ethanolic macerate (Eth-Mac), which recorded maximum values for the compounds analyzed, in the order 96.3779 mg GAE/gDM for polyphenols,2.3042 mgQE/gDM for flavonoids ,0.0150 mg QE/ gDM for flavonoles,8.3337 mg CE/gDM for condensed tannins, and 20.2271 mg TAE/gDM for hydrolysable tannins. Analysis by FTIR-ATR spectroscopy revealed the presence of functional groups characteristic of active substances, such as phenolic compounds, alkaloids, aromatic compounds derived from phenolics, monoterpenes (pinene) and sesquiterpenes. The data obtained underline the importance of Agrimonia eupatoria L. as a source of bioactive molecules such as polyphenols, flavonoids, and pave the way for the pharmacological valorization of this plant.