Isolation and structural determination of flavan-3-ol derivatives from the Polypodium vulgare L. rhizomes water extract

Abstract

Polypodium vulgare L. (Polypodiaceae) is a fern used in traditional Polish medicine as an expectorant to treat cough and pertussis. Additionally, it was used as a diuretic in renal diseases, especially in chronic nephritis and pyelonephritis. In our study, a water extract was prepared from the rhizome of common polypody and subsequently fractionated on a resin column. As a result, the mixture of flavan-3-ol derivatives was obtained after the column elution with 60% methanol. Further purification by various chromatographic techniques led us to the isolation of (+)-afzelechin (1), a new previously not reported (+)-afzelechin-7-O-α-l-arabinofuranoside (2), and three other monomer flavan-3-ol glycosides: (+)-afzelechin-7-O-β-d-apiofuranoside (3), (+)-catechin-7-O-α-l-arabinofuranoside (4) and (+)-catechin-7-O-β-d-apiofuranoside (5). Structures of the compounds were established by HR-ESI-MS, 1D and 2D NMR spectroscopy. The HSQC and HMBC NMR techniques were used in the structure elucidation of the position of sugar attachment.