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- Bark residues valorization potential regarding antioxidant and antimicrobial extractsPublication . Neiva, Duarte; Luís, Ângelo; Gominho, Jorge; Domingues, Fernanda C.; Duarte, Ana Paula; Pereira, HelenaBark residual side streams from industries (Eucalyptus globulus—Eg and Picea abies—Pa) or from control of invasive species in Mediterranean countries (Acacia melanoxylon—Am and Acacia dealbata—Ad) are burned for energy production, although their high content of extractable compounds points to a possible valorization as sources of phytochemicals with antioxidant and antimicrobial activities. Non-polar and polar extracts were obtained, and their phenolic contents, antioxidant activity, antiquorum sensing and antimicrobial potential against several human pathogenic microbes (nine bacteria and two yeasts) were determined. Extraction yield ranged from 0.5 to 37% of barks dry weight varying with species and solvent used, and both water and ethanol extracts presented strong or very strong scavenging antioxidant ability. Eg and Pa non-polar extracts showed the lowest minimum inhibitory concentration for gram-positive bacteria (0.04–1.25 mg/mL), while Ad presented the best results among polar extracts regarding bacteria (0.16 mg/mL for K. pneumoniae) and yeast strains (0.02–0.04 mg/mL). Non-polar extracts showed great response against both Candida species (MIC=0.04–0.63 mg/mL). Each extract had diferent antimicrobial activity showing that species and solvents can be used to tailor compounds to target specifc pathogens. Information regarding these bioactive extracts from residual forest side streams can provide possible utilization routes for natural compounds recovery prior to combustion.
- First Chemical Profile Analysis of Acacia PodsPublication . Pedro, Soraia; Fernandes, Tiago A.; Luís, Ângelo; Antunes, A M M; Gonçalves, J. C.; Gominho, Jorge; Gallardo, Eugenia; Anjos, OféliaThis study intended to evaluate the potential industrial applications of various Acacia species (Acacia melanoxylon, Acacia longifolia, Acacia cyclops, Acacia retinodes, Acacia pycnantha, Acacia mearnsii, and Acacia dealbata) by examining their chemical composition, antioxidant, and antimicrobial properties. Using high-resolution mass spectrometry, a comprehensive analysis successfully identified targeted compounds, including flavonoids (flavonols/flavones) and phenolic acids, such as 4-hydroxybenzoic acid, p-coumaric acid, and ellagic acid. Additionally, p-coumaric acid was specifically identified and quantified within the hydroxycinnamic aldehydes. This comprehensive characterization provides valuable insights into the chemical profiles of the studied species. Among the studied species, A. pycnantha exhibited a higher concentration of total phenolic compounds, including catechin, myricetin, quercetin, and coniferaldehyde. Furthermore, A. pycnantha displayed notable antibacterial activity against K. pneumoniae, E. coli, S. Typhimurium, and B. cereus. The identified compounds in Acacia pods and their shown antibacterial activities exhibit promising potential for future applications. Moreover, vibrational spectroscopy was a reliable method for distinguishing between species. These significant findings enhance our understanding of Acacia species and their potential for various industrial applications.