Wheat and spinach contain opioid peptides with pain-reducing properties. - GreenMedInfo Summary
Delta opioid peptides derived from plant proteins.
Curr Pharm Des. 2003;9(16):1325-30. PMID: 12769740
Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan. email@example.com
Opioid peptides showing selectivity for delta receptor have been isolated from enzymatic digests of plant proteins. Five peptides were derived from wheat gluten, and named gluten exorphins A5, A4, B5, B4 and C. Two opioid peptides were also released from spinach ribulose-bisphosphate-carboxylase/oxygenase (Rubisco), and named rubiscolins-5 and -6. Among them, gluten exorphin 5A (Gly-Tyr-Tyr-Pro-Thr) and rubiscolin 6 (Tyr-Pro-Leu-Asp-Leu-Phe) improved learning performance in step-through type passive avoidance test after post-training oral administration in mice at doses of 300 mg/kg and 100 mg/kg, respectively, which are smaller than those required for antinociceptive activity.