Gluten exorphin C is an opioid peptide derived from wheat gluten. Its IC 50 values are 40 μM and 13.5 μM for μ opioid and δ opioid activities in the GPI and MVD assays, respectively. In Vitro Gluten exorphin C, a novel opioid peptide, is isolated from the pepsin-trypsin-chymotrypsin digest of wheat gluten. Gluten exorphin C is evaluated its opioid activities by the GPI and MVD assays and its receptor affinities by radioreceptor assays. Its IC 50 s are 40 μM and 13.5 μM in the GPI and the MVD assays, respectively. Gluten exorphin C has a structure quite different from any of the endogenous and exogenous opioid peptides ever reported in that the N terminal Tyr is the only aromatic amino acid. The analogs containing Tyr-Pro-X-Ser-Leu are synthesized to study its structure-activity relationship. Peptides in which X is an aromatic amino acid or an aliphatic hydrophobic amino acid has opioid activity. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:IC50: 40 μM (μ opioid), 13.5 μM (δ opioid)