Structure elucidation of some proanthocyanidins in barley by1H 270 MHz NMR spectroscopy

Abstract

In the present paper the composition of proanthocyanidins isolated from barley is investigated. Separation by affinity chromatography and HPLC yields a large number of substances. Six of these have been isolated in this work. Based on the chromatographic preparation they are expected to be two dimers D1 and D2 and four trimeric substances T1-T4. Studies by means of1H NMR spectroscopy at 270 MHz confirmed D1 and D2 as being dimeric compounds, a prodelphinidin and procyanidin B3 respectively. The spatial structure of the prodelphinidin corresponds to procyanidin B3. The peracetates of all six compounds have also been studied by means of1H NMR spectrocopy. By comparison with data for the analogous peracetates of (+)-catechin and (-)-epicatechin and with literature data, T1-T4 have been identified as trimeric proanthocyanidins and their structures have been elucidated. © 1981 Carlsberg Laboratory.