Obtenção de peptídeos com atividades biológicas obtidas a partir das vísceras de tilápia (Oreochromis spp.)

Abstract

The intensive production of tilapia (Oreochromis spp.) in Brazil generates large volumes of organic waste, particularly viscera, which are rich in proteins and enzymes and hold biotechnological potential. This study aimed to obtain, fractionate, and characterize bioactive peptides from tilapia viscera, with an emphasis on antioxidant, antimicrobial, and toxicological activities, in alignment with principles of circular economy and sustainable development. Proteins were extracted using organic solvents, desalted by molecular exclusion chromatography (Sephadex G-25), and fractionated by molecular exclusion chromatography (Sephadex G-50), yielding seven peptide fractions (F1 to F7). The antioxidant activity was evaluated by the ABTS•⁺ radical scavenging assay, using Trolox as the standard. Fractions F4, F5, and F6 showed the highest antioxidant capacities (1933.4; 1520.5; and 1546.7 µmol·L⁻¹ Trolox equivalents, respectively), suggesting the presence of low molecular weight peptides enriched in amino acid residues such as tyrosine, tryptophan, and histidine. Toxicological evaluation was performed using larvae of Tenebrio molitor as an alternative in vivo model in compliance with the 3Rs principles. The fractions were injected at three different concentrations (10, 40, and 80 µg), and larval survival was monitored over 120 hours. A binomial generalized linear model (GLM) indicated dose- and time-dependent toxicity. Fractions F4, F5, and F6 were the most toxic (≥ 93.3 % mortality at 80 µg), while F2 showed the lowest toxicity, with mortality remaining below 40 % even at the highest dose. Conversely, none of the peptide fractions exhibited detectable antimicrobial activity against Staphylococcus aureus, Escherichia coli, or Pseudomonas aeruginosa under the disc diffusion assay, possibly due to the absence of bactericidal peptides or limitations in compound diffusion through the agar matrix. In conclusion, the tilapia viscera represent a promising source of antioxidant peptides, with fractions F4, F5, and F6 standing out as candidates for further development. The use of T. molitor proved to be a viable alternative model for preliminary toxicity screening. These findings support the valorization of aquaculture by-products as bioactive resources and provide a foundation for developing functional ingredients for the food, pharmaceutical, or cosmetic industries