Antimicrobial resistance and the consequent inefficiency of antibiotics are the main problems faced by medicine. In view of this, numerous researches have been aimed at looking for new agents with antibacterial activity, among them natural products. Thus, this study aims to evaluate the antioxidant activity of aqueous and hydroalcoholic extracts of the leaves and roots of Spondias tuberosa by Thin Layer Chromatography (TLC), as well as to verify the antibacterial action of the extracts alone and in combination with commercial antibiotics to evaluate its potential in action of change of antibiotics. The extracts showed polar and nonpolar phenolic substances with antioxidant action. The Minimum Inhibitory Concentration (MIC) of the hydroalcoholic extracts of the leaves and roots was 1,024 μg/mL compared to the Staphylococcus aureus 25923 strain, whereas with the other strains, the products showed an MIC ≥ 2,048 µg/mL. The effect of combining extracts with amikacin, ampicillin and norfloxacin against the multidrug-resistant bacteria Escherichia coli 06, Staphylococcus aureus 10 and Pseudomonas aeruginosa 24 resulted in synergistic effects with aminoglycoside alone, achieving up to 75 % reduction in the MIC of the antibiotic. In view of the results obtained, it can be concluded that the extracts of S. tuberosa presented polar and nonpolar phenolic substances, in the antibacterial activity it can positively modify the effect of the aminoglycoside antibiotic against multi-resistant bacteria, but future studies are necessary to discover the mechanism of action of such an effect.

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Fungi of the Candida genus are responsible for invasive candidiasis, which affects people all over the world and has high mortality rates. This is due to their virulence factors, which give them great resistance and pathogenicity. In addition, the emergence of multidrug-resistant strains makes it difficult to treat these infections. In this way, natural products have emerged as an alternative to standard drugs, where plants known for their medicinal properties such as Turnera subulata become attractive to research. The present work aimed to analyze the ethanol extract of Turnera subulata leaves against standard strains of Candida albicans, Candida krusei and Candida tropicalis using broth microdilution techniques. The identification of the compounds in T. subulata leaves by LC-MS revealed the presence of a wide variety of substances such as carboxylic acids and terpenes, with flavonoids and fatty acids being more evident. The antifungal assays showed that the extract was not able to inhibit the growth of the tested strains at concentrations with a clinical relevance. However, at higher concentrations, it was able to inhibit the fungal dimorphism of C. albicans and C. tropicalis. It is possible that the T. subulata extract has potential as an inhibitor of fungal virulence factors without affecting the cell viability. Further research should be carried out in order to assess its inhibitory potential for other fungal virulence factors.

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