Mariana Pereira da Silva’s research while affiliated with Universidade Regional do Cariri and other places

Background: Croton grewioides Baill., a species native to the Caatinga, popularly known as canela de cunhã, is used in traditional medicine to treat gastrointestinal diseases such as diarrhea, gastritis and stomach ulcers. The combination of essential oils with antibiotics reveals several beneficial effects associated with the increased efficacy of these drugs against pathogenic agents. Through this perspective, this study aimed to identify the chemical composition of the essential oil of C. grewioides (OECG) and evaluate its antibacterial and antibiotic-modifying activities against standard and multiresistant bacteria. Methods: To analyze the compounds present in the oil, the techniques of gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with a flame ionization detector (GC/FID) were used. In the bacteriological tests, the Minimum Inhibitory Concentration (MIC) was obtained by the broth microdilution technique. The modulating effect of the essential oil was determined by calculating the subinhibitory concentration, followed by a serial microdilution of the antibiotics. The MIC reduction factor (CRF) was calculated, and its data were expressed as a percentage. Results: The analysis of the chemical composition identified the presence of the major compound estragole with a relative abundance of 50.34%. The MIC values obtained demonstrated efficacy in K. pneumoniae isolated from urine with MIC values of 512 µg/mL. OECG potentiated the effects of all antibiotics tested on the strains S. aureus ATCC 29213, K. pneumoniae Carbapnemase, E. coli ATCC 25922 and S. aureus ATCC 29213 with their CRF of 97.65%, 99.80%, 99.85% and 99.88%, respectively. Conclusions: Thus, the essential oil of C. grewioides presents synergistic effects when combined with the antibiotics tested, in addition to acting in the fight against bacterial resistance to antibiotics.

Marine sponges belonging to the class Demospongiae have been shown to be promising sources of bioactive compounds, investigated from the perspective of potential medical applications. This review aimed to collect studies on biological activities of clinical importance and the chemical composition of sponge species from that class, highlighting the structure/activity relationship. To carry out this work, collections were carried out in the Science Direct, Pubmed, Scielo and Google Scholar databases, using the following descriptors: antimicrobial marine sponges, antioxidant marine sponges and marine sponges biological activity. The inclusion criteria were considered: (1) publications from the year 2022 onwards; (2) written in English or Portuguesen and (3) with information on biological assays of extracts, fractions or isolated compounds. The following were excluded: (1) duplicate works; (2) works whose content was not within the scope of the study and (3) studies that did not evaluate biological activities. Results demonstrate that 274 compounds were isolated from different metabolic classes, being evaluated in several biological assays. From the analysis of the data, it is concluded that the compounds studied demonstrate promise for the development of medicines for the control of microorganisms and the treatment of tumors, acting through different mechanisms of action.

Croton grewioides Baill., a species native to the Caatinga, popularly known as canela de cunhã, is used in traditional medicine to treat gastrointestinal diseases such as diarrhea, gastritis and stomach ulcers. This study aimed to identify the chemical composition of the essential oil of C. grewioides (OECG) and evaluate its antibacterial and antibiotic-modulating activities against both standard and multidrug-resistant bacteria. To analyze the compounds, present in the oil, gas chromatography coupled with mass spectrometry (GC/MS) and gas chromatography with flame ionization detector (GC/FID) techniques were used. In the bacteriological tests, the Minimum Inhibitory Concentration (MIC) was obtained using the broth microdilution technique. The modulating effect of the essential oil was determined by calculating the subinhibitory concentration followed by serial microdilution of the antibiotics. The MIC reduction factor (FRC) was calculated and its data expressed as a percentage. Analysis of the chemical composition identified the presence of the major compound estragole with a relative abundance of 50.34%. The MIC values obtained demonstrated efficacy in K. pneumoniae isolated from urine with MIC values of 512 µg/mL. OECG potentiated the effects of all antibiotics tested on S. aureus ATCC 29213, K. pneumoniae Carbapnemase, E. coli ATCC 25922 and S. aureus ATCC 29213 strains with their FRC of 97.65 %, 99.80 %, 99.85 % and 99.88 %, respectively. Thus, the essential oil of C. growioides presents synergistic effects when combined with the tested antibiotics, in addition to acting in the fight against bacterial resistance to antibiotics.

Objective The present study aimed to investigate the chemical profile and evaluate the antibacterial and antibiotic-modulating activity of the methanolic extract and ethyl acetate of the stem bark of C. quercifolius against standard and multiresistant strains. Methods The Minimum Inhibitory Concentration was determined by the microdilution method, and the modulating potential of the extracts on aminoglycoside and β-lactam antibiotics was evaluated. Results The classes of secondary metabolites identified from qualitative chemical prospecting were flavones, flavonols, xanthones, flavonones, flavonols, catechins and leucoanthocyanidins. The assays showed inhibition only for Klebsiella pneumoniae-producing extended-spectrum β- lactamase, Klebsiella pneumoniae carbapenemase and Escherichia coli ATCC 25922 with MICs of 256, 512 and 512 μg/mL, respectively. The extracts, when associated with gentamicin and amoxicillin, showed synergism against all standard and multiresistant strains, with the exception of Klebsiella pneumoniae carbapenemase and Klebsiella pneumoniae producing extendedspectrum β-lactamase, respectively. When combined with amikacin, they also demonstrated synergism against multidrug-resistant strains; however, only the ethyl acetate extract had a synergistic effect against E. coli ATCC 25922. The association of penicillin with methanolic extract showed synergism only for Klebsiella pneumoniae producing extended-spectrum β-lactamase and S. aureus ATCC 29213, while the ethyl acetate extracts demonstrated synergism against S. aureus and Klebsiella pneumoniae producing extended-spectrum β-lactamase. Conclusion It was found that C. quercifolius extracts have antibacterial potential against gramnegative bacteria. However, the need for additional research using specific methods against bacteria carrying different resistance mechanisms, especially gram-positive ones, is highlighted, with the aim of elucidating their mechanism of action.