Berry polyphenols inhibit pancreatic lipase activity in vitro

Polyphenol-rich extracts from a range of berries were tested for their ability to inhibit pancreatic lipase activity in vitro. Blackcurrant and rowan extracts had no effect, blueberry caused slight inhibition, whilst lingonberry, Arctic bramble, cloudberry, strawberry and raspberry were considerably more effective. Inhibition by the cloudberry extract showed a saturation effect with an apparent EC50 of around 5 μg phenols/ml.The inhibitory components from cloudberry were retained in a tannin-rich fraction prepared by sorption to Sephadex LH-20. Comparison of the polyphenol composition of the active and inactive fractions using liquid chromatography–mass spectrometry (LC–MS) strongly suggested that the active components were ellagitannins. Similarly prepared fractions from raspberry and strawberry were also effective inhibitors. Direct infusion mass spectra (DIMS) of the raspberry tannin and cloudberry tannin fractions were very similar, with minor differences in the abundance of certain ellagitannin components, whereas the strawberry tannin fraction was enriched in a mixture of ellagitannin and proanthocyanidin components. The effective inhibition of lipase by the lingonberry extract may have been due to proanthocyandin components. The nature, mechanism and possible physiological relevance of lipase inhibition by berry components are discussed.