alterado para: Antimicrobial resistance, clonal diversity and biofilm formation of Staphylococcus aureus and other staphylococci: A One Health approach to a global threat Integrating multiple ‘omics’ analysis of methicillin-resistant Staphylococcus aureus MRSA biofilms: a One Health approach to a global threat

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Platanus hybrida’s phenolic profile, antioxidant power, and antibacterial activity against methicillin-resistant staphylococcus aureus (MRSA)

Publication . Ribeiro, Jessica; Silva, Vanessa; Aires, Alfredo; Carvalho, Rosa Paula; Barros, Lillian; Gaivão, Isabel; Igrejas, Gilberto; Poeta, Patrícia

Methicillin-resistant S. aureus (MRSA) are a threat to public health as they frequently reveal a multidrug-resistant pattern. Researchers all over the world are on an urgent hunt for new treatments to help fight infections before antibiotics become obsolete, and some natural alternatives, such as polyphenols, have already exhibited therapeutic properties. Therefore, this study aimed to determine the phenolic profile, antioxidant capacity, and antimicrobial activity against MRSA of the leaf, fruit, and stem bark extracts of Platanus hybrida. The polyphenols were extracted with a water/ethanol (20:80) mixture and the methodology included HPLC-DAD, DPPH, FRAP, and CuPRAC. To address this issue from a One Health perspective, the Kirby–Bauer disc diffusion method was performed against nine MRSA strains from three different sources (livestock, wild animals, and humans). Fourteen phenolics were identified and the leaf extract showed the highest phenolic content, followed by the fruit extract. The leaf extract also showed the highest antioxidant capacity while the fruit extract had the lowest antioxidant capacity. Both leaf and fruit extracts inhibited the growth of strains from all sources, while the stem bark extract did not inhibit the growth of human strains. This work highlights the complex chemical composition and the antioxidative and antimicrobial potential of extracts derived from P. hydrida.

2022Journal article

Open access

Evaluation of the phenolic profile of Castanea sativa mill. By-products and their antioxidant and antimicrobial activity against multiresistant bacteria

Publication . Silva, Vanessa; Falco, Virgílio; Dias, Maria Inês; Barros, Lillian; Silva, Adriana; Capita, Rosa; Alonso-Calleja, Carlos; Amaral, Joana S.; Igrejas, Gilberto; Ferreira, Isabel C.F.R.; Poeta, Patrícia

The chestnut industry generates a large amount of by-products. These agro-industrial wastes have been described as potential sources of phenolic compounds with high bioactive potential. Therefore, we aimed to extract the phenolic compounds from chestnut by-products and assess their antioxidant potential and evaluate their antimicrobial activity against multidrug resistant bacteria. The individual phenolic compounds in the ethanolic extracts of chestnut shell, inner shell, bur, and leaves were characterized by HPLC-DAD/electrospray ionization (ESI)-MS. The antioxidant properties were determined by DPPH and ABTS assays. The minimum inhibitory concentration (MIC) and the antimicrobial susceptibility was performed using the Kirby–Bauer disc di usion method against 10 bacterial strains. The major phenolic compounds identified in the extracts were trigalloyl-HHDP-glucose, gallic acid, quercetin, and myricetin glycoside derivatives. All chestnut by-products presented promising antioxidant activity in both assays, with leaf samples the ones presenting the highest antioxidant capacity. The inner shell’s extract was e ective against all Gram-positive and two Gram-negative bacteria; nevertheless, all extracts showed antibacterial activity. Staphylococcus epidermidis showed susceptibility to all extracts while none of the extracts was able to suppress the growth of Escherichia coli and Salmonella enteritidis. Chestnut by-products are a source of phenolic compounds with prominent antioxidant and antimicrobial activities. Nevertheless, further studies should be conducted to assess the correlation between phenolic compounds and the bioactivities obtained.

2020Journal article

Open access