Tracking of β-Lactoglobulin Binding Compounds with Biofingerprinting Chromatogram Analysis of Natural Products

Abstract

The addition of milk to tea has been shown to prevent the vascular protective effects of the tea. Thus we had an interest in evaluating the possible binding of compounds in extracts of black tea, Camellia sinensis (L.) O. Kunze, and nettle, Urtica dioica L, to β-lactoglobulin (βLG), which is the main proteinaceous component of whey. Since our previously miniaturised 96-well plate method based on fluorescence quenching is suitable only for pure compounds, we have developed a method of ultrafiltration sampling combined with HPLC to study the βLG-binding property of the extracts. The method development was made with extract of Piper nigrum L. (black pepper), because its major component is piperine, which has been earlier shown to bind to βLG. The results showed that piperine from P. nigrum was highly and rutin from U. dioica slightly bound to βLG. No components from C. sinensis were bound to βLG. We showed for the first time, that the ultrafiltration/HPLC system can be used in βLG-binding studies with plant extracts. Furthermore, we demonstrated that βLG could bind compounds from extracts and in this way either enhance, or decrease, their health benefits, for example in food preparations.