Characterization of phenolic compounds from inner bark of Betula pendula

A method has been developed for the characterization of biologically active silver birch (Betula pendula) inner bark phenolics based on high-performance liquid chromatography/diode array detector (HPLC-DAD)/electrospray ionization-mass spectrometry (ESI-MS). It was demonstrated that the inner bark contains high amounts of flavonoids, arylbutanoids, diarylheptanoids, simple phenolic compounds, phenolic acids, lignans, and procyanidins. Altogether, 30 individual compounds were characterized based on their ultraviolet (UV) and MS data. Structures of 22 compounds were confirmed by nuclear magnetic resonance (NMR) spectroscopy. In addition to previously reported phenolic compounds, 12 compounds were identified in silver birch inner bark for the first time; two of them are novel compounds: 3-β-glucopyranosyloxy-2-hydroxy-1-(4-hydroxy-3-methoxy-phenyl)-propan-1-one and 1,7-bis-(4-hydroxyphenyl)-3-heptanol 3-O-β-ap-iofuranosyl-(1→2)-β-glucopyranoside.