Photoinduced antibacterial activity of the essential oils from Eugenia brasiliensis lam and Piper mosenii C. DC. by blue led light

The objective of this work was to evaluate the phytochemical composition and the antibacterial and antibiotic-modulating activities of the essential oils of Eugenia brasiliensis Lam (OEEb) and Piper mosenii C. DC (OEPm) singly or in association with blue LED (Light-emitting diode) light. The antibacterial and antibiotic-modulatory activities of the essential oils on the activity of aminoglycosides were evaluated to determine the minimum inhibitory concentration (MIC, \u3bcg/mL) in the presence or absence of exposure to blue LED light. The chemical analysis showed \u3b1-pinene and bicyclogermacrene as major constituents of OEPm, whereas \u3b1-muurolol was the main compound of OEEb. Both OEEb and OEPm showed MIC 65 512 \u3bcg/mL against the strains under study. However, the association of these oils with the blue LED light enhanced the action of the aminoglycosides amikacin and gentamicin. In conclusion, the association of aminoglycosides with the blue LED light and essential oils was effective against resistant bacteria

Gas chromatography coupled to mass spectrometry (GC-MS) characterization and evaluation of antibacterial bioactivities of the essential oils from Piper arboreum Aubl., Piper aduncum L. e Piper gaudichaudianum Kunth

The objective of this study was to determine the chemical profile and to evaluate the antibacterial activity of the essential oils of Piper species and modulation of the antibiotic activity, using the microdilution method to determine the minimum inhibitory concentration. The chemical components were characterized by gas chromatography coupled to mass spectrometry, which revealed \u3b2-copaen-4-\u3b1-ol (31.38%), spathulenol (25.92%), and germacrene B (21.53%) as major constituents of the essential oils of Piper arboreum, Piper aduncum, and Piper gaudichaudianum, respectively. The essential oils analyzed in this study did not present a clinically relevant activity against standard and multiresistant Escherichia coli. However, in the case of multiresistant Staphylococcus aureus, there was a significant activity, corroborating with reports in the literature, where Gram-positive bacteria are more susceptible to antimicrobial activity. The essential oils modulated the effect of the antibiotics norfloxacin and gentamicin, having on the latter greater modulating effect; however, for erythromycin, no statistically significant effect was observed. In conclusion, the results obtained in this study demonstrated that the essential oils of the analyzed Piper species present an inhibitory effect against S. aureus and modulate antibiotic activity, most of which presents synergistic activity

Modulation of antibiotic resistance by the essential oil of Ocimum gratissimum L. In association with light-emitting diodes (LED) lights

This study aimed to evaluate the antibacterial and antibiotic-enhancing effects of the essential oil obtained from Ocimum gratissimum L. (OEOg) alone or in association with light-emitting diodes (LED) lights. The essential oil was obtained by hydrodistillation and its chemical composition analysed by gas chromatography coupled to mass spectrometry. The antibacterial and antibiotic-enhancing activities against multiresistant strains of Staphylococcus aureus and Escherichia coli were evaluated by the gaseous contact method. The analysis of the photoinductive effect on the antibacterial activity of the OEOg and antibiotics was assessed through exposure to different LED lights (red, blue and yellow). The phytochemical analysis identified five compounds, including eugenol, as the major constituent. The OEOg caused a significant inhibition of the halo, indicating a direct antibacterial effect. Exposure to the LED lights significantly enhanced the activity of the OEOg against E. coli. On the other hand, the action of the essential oil against S. aureus was enhanced by exposure to both blue and yellow lights. The effects of LED light exposure on the activity of conventional antibiotics varied significantly according to the drug and the bacterial strain. However, most combinations of LED lights and the OEOg presented synergistic effects against resistant bacterial strains, indicating enhanced antibacterial activity. Thus, these in vitro findings suggest that both OEOg and LED lights have promising antibacterial effects. Nevertheless, further research is required to evaluate in vivo the potential of these therapies for the treatment of infectious skin diseases