I. Mcmurrough et al., SEMIPREPARATIVE CHROMATOGRAPHIC PROCEDURE FOR THE ISOLATION OF DIMERIC AND TRIMERIC PROANTHOCYANIDINS FROM BARLEY, Journal of agricultural and food chemistry, 44(7), 1996, pp. 1731-1735
A semipreparative chromatographic method for the isolation of small am
ounts (10-20 mu g) of dimeric and trimeric proanthocyanidins from barl
ey is described. Concentrated extracts of barley were injected onto a
high-performance gel filtration column (Superdex 75 HR), and were elut
ed with methanol. This procedure resolved the dimeric proanthocyanidin
s (prodelphinidin B3 and procyanidin B3), as well as the trimeric proc
yanidin C2 and three other trimeric prodelphinidins. The separated fla
vanoid peaks were collected and their contents were estimated by UV sp
ectrophotometry, reaction with p-dimethylaminocinnamadehyde, and rever
sed phase HPLC with electrochemical detection. This method produced pr
oanthocyanidins in sufficient amounts to calibrate a system for direct
injection chromatographic analysis of beers and barley extracts. The
method described may be optimized for the isolation of dimeric proanth
ocyanidins only, in which case the preparation can take as little as 3
h; alternatively, by extending the chromatographic separation to 9 h,
the four major trimeric proanthocyanidins of barley can be recovered
also in a chromatographically pure state.