Development of an oral feed additive against intestinal infections based on microparticles’ systems loaded with Ctx(Ile²¹)-Ha peptide coated with HPMCAS/Chitosan

In recent decades, resistant bacteria have generated a worldwide concern, since prolonged exposure to different compounds produces or acquires these mutations. The Ctx(Ile²¹)-Ha antimicrobial peptide is widely studied by our research group, proved to be effective against multidrug-resistant bacteria and Salmonella enteritidis, both in in vitro and in vivo studies. However, its oral administration is affected by external factors that induce degradation. In this study, Ctx(Ile²¹)-Ha peptide was synthesized in solid-phase peptide synthesis and characterized by LC/MS. Alginate microparticles loaded with the peptide were produced by ionic gelation and coated with hypromellose acetate/succinate and chitosan by immersion. Microparticles developed were characterized by SEM, DSC/TGA, XDR. Antimicrobial evaluation against intestinal bacteria and gastrointestinal release profile was performed. The results showed an encapsulation efficiency of 84.52%. In addition, they corroborated the presence and stability of the peptide throughout its release and enzymatic hydrolysis. Also, the antibacterial activity, depending on the strain tested, was around 16-128 μg of Ctx(Ile²¹)-Ha. The crystallinity of the compounds was slightly modified to a semi-amorphous state, although thermal stability was maintained up to 80°C. The results showed high physicochemical stability since this peptide has strong characteristics of the frog skin from which it was initially isolated. The peptide-controlled release was achieved, and the hydrolysis and degradation produced by gastric pH could be prevented. In conclusion, the administration of encapsulated/coated antimicrobial peptides would be a new option for the treatment of intestinal diseases, including resistant pathogens.