Identification of novel β‐lactoglobulin‐derived peptides, wheylin‐1 and ‐2, having anxiolytic‐like activity in mice

Scope We found that thermolysin digest of β‐lactoglobulin, a major protein of bovine milk whey, exhibited anxiolytic‐like activity in a behavioral experiment in mice, and then identified active components from the digest. Methods and results In the elevated plus‐maze test, thermolysin digest of β‐lactoglobulin had anxiolytic‐like activity after intraperitoneal administration in mice. We identified several low‐molecular‐weight peptides in a fraction separated by reverse‐phase HPLC having the most potent anxiolytic‐like activities. Among them, Met‐His and Met‐Lys‐Gly, corresponding to β‐lactoglobulin (145–146) and (7–9), had anxiolytic‐like activity at a dose of 0.3–1 and 3 mg/kg, respectively, after intraperitoneal administration. We named Met‐His and Met‐Lys‐Gly wheylin‐1 and ‐2, respectively. Next, we focused on wheylin‐1, a more potent peptide with anxiolytic‐like activity than wheylin‐2. Wheylin‐1 (1 mg/kg) had anxiolytic‐like activity after oral administration. In the open‐field test, wheylin‐1 was also active. The anxiolytic‐like activity of wheylin‐1 was blocked by bicuculline, an antagonist of γ‐amino butyric acid type A (GABA A ) receptor, suggesting that wheylin‐1 exhibited anxiolytic‐like activity via the GABA A system. Conclusion Novel β‐lactoglobulin‐derived peptides, wheylin‐1 and ‐2, may exhibit anxiolytic‐like activities.