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Browsing by Author "Metzner, Beatriz Thomas"

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  • Bioactive and chemical characterization of medicinal plants
    Publication . Metzner, Beatriz Thomas; Barros, Lillian; Mandim, Filipa; Montanher, Paula Fernandes
    Medicinal plants are used worldwide for the treatment of various diseases, and there is increasing interest in studying their bioactive properties and chemical composition. A deeper understanding of these properties could drive significant advancements in multiple industrial sectors. In this study, we investigated three medicinal plants traditionally used in Brazil and Portugal: Plantago major L., Bidens pilosa L., and Pistacia lentiscus L. The primary objective was to expand scientific knowledge of these species by characterizing their chemical composition and diverse bioactive properties. The plants were characterized regarding their individual profiles in fatty acids, tocopherols, free sugars, and organic acids through adequate chromatographic methodologies. The hydroethanolic extracts were characterized in terms of phenolic composition and antioxidant and antimicrobial activities. The polyphenolic profile was analyzed by HPLC-DAD-ESI/MS. The antioxidant activity was assessed through the thiobarbituric acid reactive substances (TBARS) formation inhibition. Finally, the antimicrobial activity was assessed by the microdilution method against bacteria and fungi. P. major exhibited the highest lipid content (1.7 g/100 g dw), followed by P. lentiscus and B. pilosa (1.2 and 0.6 g/100 g dw, respectively). In all species, palmitic acid (C16:0) was the fatty acid detected in higher relative abundance (between 37.8% and 44.1%). The major tocopherol in P. major and P. lentiscus was alpha-tocopherol (35.5 and 1.7 mg/100 g, respectively), and gamma-tocopherol in B. pilosa (0.09 mg/100 g). B. pilosa contained the highest concentration of free sugars (4.5 g/100 g), followed by P. lentiscus and P. major (3.3 and 0.8 g/100 g, respectively). The most abundant organic acid in B. pilosa and P. lentiscus was quinic acid (0.76 and 0.46 g per 100 g, respectively). In turn, succinic acid was the most abundant in P. major (1.62 g per 100 g), which was also the plant with higher total organic acids. A wide variety of phenolic compounds was identified in all the studied plants. The major phenolic compounds in P. major, B. pilosa, and P. lentiscus were verbascoside, quercetin-dimethyl ether rutinoside, and galloylquinic acid, respectively. Regarding antioxidant activity, the hydroethanolic extract of P. lentiscus demonstrated the highest activity, followed by B. pilosa and P. major. For the antibacterial activity, P. major extract exhibited activity against all bacterial strains tested. P. lentiscus was effective against Salmonella enterica, Yersinia enterocolitica, Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus, while B. pilosa was only effective against Escherichia coli and S. enterica. However, none of the plants showed significant antifungal activity against Aspergillus braziliensis and Aspergillus fumigatus. In conclusion, the chemical composition, antioxidant, and antimicrobial activities of P. major, B. pilosa, and P. lentiscus were studied, which contributes to the scientific understanding of their potential. The results obtained in this study enable further investigation into their extracts and the validation of their traditional uses.
    2024Master thesis Open access Show more