Enhancement of the antioxidant and antimicrobial activities of porphyran through chemical modification with tyrosine derivatives

The chemical modification of porphyran hydrocolloid is attempted, with the objective of enhancing its antioxidant and antimicrobial activities. Sulfated galactan porphyran is obtained from commercial samples of the red algae Porphyra dioica using Soxhlet extraction with water at 100ºC and precipitation with isopropyl alcohol. The extracted porphyran is then treated with modified L-tyrosines in aqueous medium in the presence of NaOH, at ca. 70ºC. The modified tyrosines L1 and L2 are prepared through a Mannich reaction with either thymol or 2,4-di-tert-butylphenol, respectively. While the reaction with 2,4-di-tert-butylphenol yields the expected tyrosine derivative, a mixture of products is obtained with thymol. The resulting polysaccharides are structurally characterized and the respective antioxidant and antimicrobial activities are determined. Porphyran treated with the N-(2-hydroxy-3,5-di-tert-butyl-benzyl)-L-tyrosine derivative, POR-L2, presents a noticeable superior radical scavenging and antioxidant activity compared to native porphyran, POR. Furthermore, it exhibited some antimicrobial activity against S. aureus. The surface morphology of films prepared by casting with native and modified porphyrans is studied by SEM/EDS. Both POR and POR-L2 present potential applicability in the production of films and washable coatings for food packaging with improved protecting characteristics.

Description

The authors of MARE-Politécnico de Leiria acknowledge the MARE-Marine and Environmental Sciences Centre, Instituto Politécnico de Leiria, which is financed by national funds from FCT/MCTES (UID/MAR/04292/2019, UIDB/04292/2020) and the project “SmartBioR-Smart Valorization of Endogenous Marine Biological Resources Under a Changing Climate” (Centro01-0145-FEDER-000018) co-funded by Centro 2020, Portugal 2020 and European Regional Development Fund (FEDER). The authors of Centro de Química Estrutural acknowledge the financial support of Fundação para a Ciência e a Tecnologia (UIDB/0100/2020), the IST-UL Centers of the Portuguese NMR and Mass Spectrometry Networks (REM2013, RNNMR), RECI/QEQ-QIN/0189/2012, RECI/QEQ-MED/0330/2012, grants SFRH/BD/135797/2018 and PD/BD/106078/2015. FCT is also acknowledged through CeFEMA, under the strategic project UID/CTM/04540/2019.

Keywords

Modified porphyran Antioxidant activity Antimicrobial activity

URI

http://hdl.handle.net/10400.8/5944

Citation

Adão, P.; Reboleira, J.; Teles, M.; Santos, B.; Ribeiro, N.; Teixeira, C.M.; Guedes, M.; Pessoa, J.C.; Bernardino, S. Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives. Molecules 2021, 26, 2916. https://doi.org/10.3390/molecules 26102916