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In Vitro Evaluation of the Antibacterial and Antioxidant Activities of Extracts of Gracilaria gracilis with a View into Its Potential Use as an Additive in Fish Feed

MARE—IPLeiria—Marine and Environmental Sciences Centre, Polytechnic of Leiria, Edifício CETEMARES, Avenida Porto de Pesca, 2520-641 Peniche, Portugal
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Academic Editor: Caterina Faggio
Appl. Sci. 2021, 11(14), 6642; https://doi.org/10.3390/app11146642
Received: 23 June 2021 / Revised: 13 July 2021 / Accepted: 16 July 2021 / Published: 20 July 2021
Fish in aquaculture systems are subject to several stressors that inhibit the immune response and potentiate the development of disease and increased mortality. The inclusion of additives in the fish diet, namely seaweeds or their extracts, that are natural sources of bioactive compounds can be an important tool for promoting the health and well-being of these animals. The present study aims at the development of sustainable and effective methodologies for the extraction of bioactive compounds of the red seaweed Gracilaria gracilis, exploring its antibacterial and antioxidant potential and considering its potential use as an additive for functional fish feeds. The yield of the extraction methods was evaluated upon the use of sequential solid–liquid extraction techniques with ethanol and water as solvents, different extraction temperatures (room temperature: 40 °C and 70 °C), and extraction time. The results demonstrated that the adoption extraction times of 30 min at 40 °C provided higher yields. We also evaluated the antioxidant capacity and the antibacterial properties of the obtained extracts against different strains that cause fish diseases by disk diffusion and broth microdilution methods. The antioxidant activity was determined by the DPPH reducing capacity method and quantification of total polyphenols content (TPC). With these results, we can establish extraction procedures that allow the future use of G. gracilis extracts, with antibacterial and antioxidant effects in a safe and effective way. View Full-Text
Keywords: marine seaweed; Rhodophyta; gracilariod; antimicrobial; antioxidant; quantification of total polyphenols; DPPH marine seaweed; Rhodophyta; gracilariod; antimicrobial; antioxidant; quantification of total polyphenols; DPPH
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MDPI and ACS Style

Afonso, C.; Correia, A.P.; Freitas, M.V.; Mouga, T.; Baptista, T. In Vitro Evaluation of the Antibacterial and Antioxidant Activities of Extracts of Gracilaria gracilis with a View into Its Potential Use as an Additive in Fish Feed. Appl. Sci. 2021, 11, 6642. https://doi.org/10.3390/app11146642

AMA Style

Afonso C, Correia AP, Freitas MV, Mouga T, Baptista T. In Vitro Evaluation of the Antibacterial and Antioxidant Activities of Extracts of Gracilaria gracilis with a View into Its Potential Use as an Additive in Fish Feed. Applied Sciences. 2021; 11(14):6642. https://doi.org/10.3390/app11146642

Chicago/Turabian Style

Afonso, Clélia, Ana P. Correia, Marta V. Freitas, Teresa Mouga, and Teresa Baptista. 2021. "In Vitro Evaluation of the Antibacterial and Antioxidant Activities of Extracts of Gracilaria gracilis with a View into Its Potential Use as an Additive in Fish Feed" Applied Sciences 11, no. 14: 6642. https://doi.org/10.3390/app11146642

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