Identification of polyphenolic compounds and determination of antioxidant activity in extracts and infusions of buckwheat leaves

The objective of this study was to determine the chemical composition in the dried leaves and the content of bioactive compounds, antioxidant activity as well as the identification of polyphenolic compounds not only in extracts but also in infusions prepared from leaves of selected strains of buckwheat. To the best of our knowledge, it is the first comprehensive and in-depth study, which focuses on identification and quantitative determination of individual polyphenolic compounds of buckwheat leaves. Furthermore, the aim of presented research is to analyse the new, unknown strains of buckwheat. A statistically significant effect of strain on the content of individual components was observed. The extracts contained more polyphenols and were characterized by higher antioxidant activity than infusions. Strains DW15 and DWO Karzel were characterized by one of the highest contents of polyphenols, dietary fibre, protein, ash and antioxidant activity. Phenolic acids (3,5-diCQA, ferulic acid, sinapinic acid, p-coumaric acid), flavanones (hesperidin), flavonoids (isorhamnetin) as well as flavanols (catechin) and flavonols (rutin, quercetin) in the extracts and infusions, were found. Both extracts and infusions were the richest in ferulic acid. These studies indicate that the buckwheat leaves can be used for preparation of various types of tea and can also be introduced for consumers as the source of bioactive compounds.