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A novel membrane chromatographic method with a membrane adsorber (Sartobind S) has been developed on the laboratory scale that allows a fractionation of bilberry (Vaccinium myrtillus) constituents into the following three groups of polyphenols: anthocyanins, copigments, and polymers. By using this methodology, a pure anthocyanin fraction free of other copigments and polymeric phenols can be obtained. Using this approach, it provides fractions allowing a more thorough testing of the biological effects of the individual groups of bilberry polyphenols as well as the study of possible synergistic effects between these different groups of bioactive constituents from bilberry.

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Dimeric procyanidins B1-B8 were produced via semisynthesis from a polymeric proanthocyanidin fraction of hazelnut skins (Corylus avellana L.). This polymeric fraction was found to consist mostly of (+)-catechin and (-)-epicatechin as upper units. Therefore, according to the choice of nucleophile agent, it is possible to semisynthesize dimeric procyanidins B1, B3, B6, and B7 with (+)-catechin and B2, B4, B5, and B8 with (-)-epicatechin. The semisynthetic mixtures were separated on a preparative scale using high-speed countercurrent chromatography (HSCCC) and low-speed rotary countercurrent chromatography (LSRCCC). C4 → C8 linked dimeric procyanidins B1-B4 were isolated in amounts of 350-740 mg. To the best of the authors' knowledge this is the first study isolating dimeric procyanidins B1-B8 in large amounts with countercurrent chromatography. Moreover, the dimeric prodelphinidins B1, B2, and B3 and their structural elucidation by (1)H NMR spectroscopy without derivatization are described for hazelnuts as natural compounds for the first time.

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