Comprehensive separation and structural analyses of polyphenols and related compounds from bracts of hops (Humulus lupulus L.).

A novel sequential chromatographic technique was applied to the comprehensive separation of polyphenols and related compounds from a hop bract extract. Over 100 types of constituents were effectively isolated from only 25 g of extract in high yields by high-speed countercurrent chromatography followed by hydrophilic interaction chromatography and reversed-phase high performance liquid chromatography. Among the materials isolated, the structures of 39 compounds were elucidated on the basis of their spectroscopic data including electrospray ionization time-of-flight mass spectrometry and one-dimensional/two-dimensional nuclear magnetic resonance.