2.1. Polyphenolic Profile of Peppermint Leaf Dry Extract
In the present study, a dry extract was obtained from a water infusion of peppermint leaf using the solid-phase extraction (SPE) method. SPE is one of the simplest yet most efficient and versatile techniques for concentrating samples and extracts. With properly selected parameters, it also allows partial purification of the concentrated material from substances of high polarity such as salts and sugars. The peppermint leaf dry extract, containing partially purified polyphenols, was subjected to compositional analysis by UHPLC-ESI-MS against authentic flavonoid and phenolic acid standards. The qualitative composition of polyphenols is shown in The content of the major components of the extract was determined using the HPLC-DAD method previously developed and validated for plant materials in the Lamiaceae family. This method has been used successfully in several studies [