Extraction of cereal prolamins and their toxicity in coeliac disease.

Simple extraction of prolamins from cereal flour using 70% aqueous ethanol leads to co-extraction of lipids and other secondary products. Treatment of the crude extract with an excess of pure ethanol resulted in the removal of the majority of these compounds. Prolamin extracts obtained following ethanol precipitation showed little difference to products of more complex, multi stage, selective extractions, when compared using MALDI-TOF mass spectrometry. Toxicity tests on enzymic digests of ethanol-precipitated prolamins from coeliac-toxic cereals, coeliac-non-toxic cereals and oats were carried out using a rat liver lysosome assay. The prolamins from the ethanol-precipitated extracts showed greater activity than those extracted using only 70% ethanol for extraction. As the ethanol precipitation method is simple and provides a prolamin extract of sufficient purity for further evaluation, this procedure has been adopted as an alternative to more tedious procedures for preparation of cereal prolamins.