To produce and identify anti-inflammatory peptides, three commercial enzymes orientase, flavourzyme, and alcalase 2.4L were used to hydrolyze tuna cooking juice, and the protein hydrolysates were purified, before being evaluated for the ability to induce secretary and cellular responses in murine peritoneal macrophages RAW264.7. Alcalase hydrolysate (AH) exhibited the most potent inhibitory effect. AH was further purified using gel-filtration chromatography and high-performance liquid chromatography. The results showed that the peptide fractions with the molecular weight ranging from 204 to 1672.9 Da possessed the greatest anti-inflammatory activity. The amino acid sequences of the two anti-inflammatory peptides isolated from AH hydrolysates were Pro-Arg-Arg-Thr-Arg-Met-Met-Asn-Gly-Gly-Arg (1543.8 Da) and Met-Gly-Pro-Ala-Met-Met-Arg-Thr-Met-Pro-Gly (1211.5 Da). We thus conclude that anti-inflammatory hydrolysates from tuna cooking juice by-product may be useful ingredients in food and nutraceutical applications.

The aim of this study was to evaluate the absorption-enhancing effect for antihypertensive activity of an angiotensin I-converting enzyme (ACE) inhibitory oligopeptides in spontaneously hypertensive rats (SHR). The oligopeptides OA3, derived from tuna cooking juice, significantly reduced systolic blood pressure (SBP) in SHR at the doses of 0.5, 0.75, and 1.0 g/kg body weight; their efficacies were exhibited in a dose-dependent manner. Emulsification, microencapsulation, and lipophilization were applied to enhance the antihypertensive activity of OA3 at the dose of 0.5 g/kg body weight in SHR individually. Lipophilization revealed most effectively by 16 mm Hg in SBP in SHR 4 h after oral administration; the significant different effect lasted more than 6 h. Such efficacy is greater than that from no further treated OA3 with the dose of 1.0 g/kg body weight. Enhancing treatments by using 30% gum Arabic and 30% lecithin exhibited minor effects by 13 and 11 mm Hg, respectively. Results imply that these additional treatments could further enhance and extend the antihypertensive effect of OA3 oligopeptides. This suggests that absorption-enhancing treatments improve the bioavailability of oligopeptides to exhibit higher antihypertensive effect. Furthermore, these enhancing effects may be brought about by the changes in cell membrane permeation or the protection of oligopeptides.

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