Antidiabetic and Immunomodulatory Properties of Peptide Fractions from Sacha Inchi Oil Press-Cake

Sacha inchi (SI) oil press-cake (SIPC), a by-product of the sacha inchi oil extraction process, represents a novel protein source with potential bioactive applications in food. In this study, a sacha inchi protein concentrate (SPC) derived from SIPC was subjected to simulated gastrointestinal digestion (SGID) using the INFOGEST 2.0 protocol. The resulting digests were fractionated by ultrafiltration (<3, 3-10, and >10 kDa), and the bioactive properties of the peptide fractions were evaluated. In vitro alpha-amylase inhibition was assessed, along with immunomodulatory markers (NO, IL-6, and TNF-alpha), in an ex vivo RAW 264.7 cell model. Both gastric and intestinal digests exhibited significant alpha-amylase inhibition (20-45%), with the <3 kDa intestinal fraction showing the highest inhibition (45% at 20 mg/mL). Both gastric and intestinal <3 kDa fractions reduced NO production in RAW 264.7 macrophages subjected to a lipopolysaccharide challenge. HPLC-MS/MS analysis facilitated de novo sequencing of the peptide fractions, identifying 416 peptides resistant to SGID through the find-pep-seq script, which were further assessed in silico for toxicity, allergenicity, and bioavailability, revealing no significant risks and potential drug-likeness development. Molecular docking simulations of three peptides (RHWLPR, RATVSLPR, and QLSNLEQSLSDAEQR) with alpha-amylase and four peptides (PSPSLVWR, RHWLPR, YNLPMLR, and SDTLFFAR) with the TLR4/MD-2 complex suggesting potential roles in alpha-amylase inhibition and anti-inflammatory activity, respectively. The findings suggest that SI protein concentrates could be used in functional foods to prevent starch breakdown through alpha-amylase-inhibiting peptides released during digestion, reduce blood glucose, and mitigate inflammation and oxidative tissue damage.