Prolyl endopeptidase inhibitory peptides in wine.

Two peptides that inhibit prolyl endopeptidase were isolated from a red wine made from Cabernet Sauvignon grapes. Their amino acid sequences and IC50 values were Val-Glu-Ile-Pro-Glu (17.0 microM) and Tyr-Pro-Ile-Pro-Phe (87.8 microM). The peptides also suppressed the degradation levels of the bioactive peptides vasopressin, substance P, and neurotensin fragments 8-13, which are involved in memory and neural communication.