Effect of various extraction methods on the structure of polyphenolic-polysaccharide conjugates from Fragaria vesca L. leaf

The purpose of this study was to compare the application of several extraction methods, including cold extraction (CAE), hot extraction (HAE), ultrasonic-assisted extraction (UAE), and microwave-assisted extraction (MAE), all carried out in 0.1 M NaOH, under their respective best parameters, for obtaining products from leaf of Fragaria vesca L. The extracts with the highest anticoagulant activity were purified by multi-step extraction procedure and separated by gel permeation chromatography, giving rise to the macromolecular complexes. They were subsequently structurally characterized using colorimetric methods, FT-IR, GC–MS, and NMR (1H and 1H/13C HSQC), as polyphenolic-polysaccharide conjugates with the anticoagulant activity. The polysaccharide parts of the conjugates obtained by different extraction procedures were found to vary significantly. The most selective in their activity were the glycoconjugates extracted in UAE and MAE processes, i.e. arabinogalactan and pectin-like conjugates, respectively. In terms of their anticoagulant activity all of them were non-direct factor Xa inhibitors mediated by antithrombin. •Cold, hot, ultrasonic- and microwave-assisted alkaline extractions of Fragaria vesca leaves were carried out.•All these extractions yielded polyphenol-polysaccharide complexes.•The isolates varied in polyphenolic and polysaccharide compositions.•The polysaccharide parts differed in relative amounts of glucan, HG and RG I with associated AG.•All F. vesca glycoconjugates are anticoagulants, non-direct factor Xa inhibitors.