Purification and characterization of a novel zinc chelating peptides from Holothuria scabra and its ex vivo absorption activity in the small intestine

Zinc supplements currently marketed in Indonesia are second-generation zinc supplements, which must be improved for the effectiveness caused by their low absorption rate and side effects on the gastrointestinal tract. Third-generation zinc supplements are currently being investigated to improve the effectiveness of the previous generation of supplements. The present study aimed to discover a new alternative source of zinc-chelating peptide (ZCP) from Holothuria scabra. In addition, the research investigates the ZCP characteristics and absorption abilities in an ex vivo evaluation using the everted gut sac model method. The results obtained were six zinc peptides: Asp-Asp-Ala-Phe-Gln-Ala-Phe-Cys; Thr-Asp-Asn-Leu; Leu-Gly-Cys; Pro-Gly-Thr; Ser-Cys; and Pro-Tyr. The characterization showed that the resulting peptides comprised two to eight amino acids with molecular weights between 208 and 915 Da. The highest zinc binding capacity of the peptides was 92.11 mg/100 g at 30 kDa for molecular weight. Fourier-transform infrared spectra indicate that zinc ions (Zn²⁺) bind to carboxyl groups and interact with nitrogen atoms in amino acids and amides. The scanning electron microscope-energy dispersion spectroscopy results stated that, topographically and morphologically, ZCP has a different surface with peptides with Zn composition in the sample. Furthermore, we evaluated the peptide fractions for ex vivo absorption in the small intestine using the everted gut sac method. We found that zinc-binding peptides transported and enhanced zinc absorption in the duodenum segment at 60 minutes, resulting in a 40% increase in absorption rate. The potency of ZCPs from H. scabra as an alternative to third-generation zinc supplements with higher absorption than previous-generation supplements.