ANTIMICROBIAL AND PHYSICOCHEMICAL ANALYSES OF COATED MICROCAPSULES CONTAINING THE Ctx(Ile21)-Ha PEPTIDE AS A POTENTIAL ZOOTECHNICAL ADDITIVE

The increasing microbial resistance to conventional antibiotics makes antimicrobial peptides (AMPs) a promising alternative, with the ability to interact with bacterial membranes and induce cell lysis. Specifically, the AMP Ctx(Ile²¹)-Ha, isolated from Boana albopunctatus frog’s skin, stands out for its action against bacteria and fungi, presenting moderate toxicity in human cells. In poultry farming, especially in Brazil, the world's largest exporter of chicken meat, diseases caused by Clostridium perfringens represent a significant challenge in intensive production systems. In this way, this study aims to evaluate the in vitro peptide Ctx(Ile²¹)-Ha antimicrobial and hemolytic activity and evaluate the physicochemical feasibility of its microencapsulation and coating for further in vivo application against the Gram-positive bacterium C. perfringens in broilers. Hemolytic activity, microencapsulation efficiency, peptide release in simulated gastric and intestinal solutions, determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), and physicochemical analyses of microcapsules containing the AMP were performed. The results showed that hemolytic activity was observed at 64 μg/mL. Quantities of 100 mg and 200 mg of microcapsules presented a peptide incorporation of 73% and 70%, respectively. The peptide release in gastric solution (simulating proventriculus and gizzard compartments of broilers) was less than 2% in one hour, while the release in intestinal solution (simulating duodenum and jejunum) was gradual, being more pronounced in the 100 mg mass. MIC and MBC against C. perfringens were 4 μg/mL and 32 μg/mL, respectively. Finally, physicochemical analyses indicated the presence of the Ctx(Ile²¹)-Ha in the microparticles, as well it remained stable and suitable for in vivo application assays, after microencapsulation and coating processes developed.