Bioactive antinutritional peptides derived from cereal prolamins: a review

Alcohol-soluble endosperm proteins (prolamins) from some cereals (e.g. wheat, barley, and rye) give origin upon proteolytic digestion to biologically-active antinutritional peptides able to adversely affect in vivo the intestinal mucosa of coeliac patients, whereas prolamins from other cereals (e.g. maize and rice) do not. These antinutritional peptides are also able to: (a) prevent in vitro recovery of atrophic coeliac mucosa; (b) to inhibit differentiation of isolated rat fetal and chick fetal intestines; and (c) to interact with undifferentiated cells either agglutinating them or affecting their proliferation and metabolism. Studies performed with A-gliadin, a highly purified bread wheat prolamin fraction, and its fragments obtained either by chemical cleavage of A-gliadin or by synthesis from aminoacids, clearly pointed out to a few small sequences very rich in glutamine and proline residues as the biologically-active agents. Several protective substances, including mannan and N,N',N"-triacetylchitotriose, have been identified as being able to prevent the effects of these peptides in vitro, but the evidence of their in vivo activity is still missing. The present paper provides a synthetic overview of the available data concerning this highly complex matter and offers a critical appraisal of present hypotheses on the action mechanism of biologically-active peptides derived from cereal prolamins.