Anti-staphylococcal activity of Syagrus coronata essential oil: Biofilm eradication and in vivo action on Galleria mellonela infection model.

In this study, essential oil extracted from Syagrus coronata seeds (SCEO) was evaluated for antibacterial and antibiofilm activities against Staphylococcus aureus; in addition, Galleria mellonella model was used as an in vivo infection model. SCEO was mainly composed by fatty acids (89.79%) and sesquiterpenes (8.5%). The major components were octanoic acid, dodecanoic acid, decanoic acid and γ-eudesmol. SCEO showed bactericidal activity (minimal bactericidal concentration from 312 to 1250 µg/mL) against all tested S. aureus clinical isolates, which showed distinct biofilm-forming and multiple drug resistance phenotypes. SCEO weakly reduced biomass but remarkably decreased cell viability in pre-formed biofilms of S. aureus isolate UFPEDA-02 (ATCC-6538). Electron microscopy analysis showed that SCEO treatments decreased the number of bacterial cells (causing structural alterations) and lead to loss of the roughness in the multiple layers of the three-dimensional biofilm structure. In addition, overproduction of exopolymeric matrix was observed. SCEO at 31.2 mg/kg improved the survival of G. mellonela larvae inoculated with UFPEDA-02 isolate and reduced the bacterial load in hemolymph and melanization. In conclusion, SCEO is an antibacterial agent against S. aureus strains with different resistance phenotypes and able to disturb biofilm architecture. Our results show SCEO as a potential candidate to drug development.

Essential Oils from Leaves of Medicinal Plants of Brazilian Flora: Chemical Composition and Activity against Candida Species.

Background: The biotechnological potential of medicinal plants from Brazilian Caatinga and the Atlantic Forest has not been extensively studied. Thus, screening programs are important in prospecting for compounds for developing new drugs. The purpose of this study was to determine the chemical composition and to evaluate the anti-Candida activity of essential oils from leaves of Hymenaea courbaril var. courbaril, Myroxylon peruiferum, and Vismia guianensis. Methods: The oils were extracted through hydrodistillation and their chemical compositions were analyzed by gas chromatography coupled with mass spectrometry. Antifungal activity against C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, and C. krusei was evaluated by determining the minimal inhibitory (MIC) and fungicidal (MFC) concentrations. Results: The major compounds of the oils were caryophyllene oxide and trans-caryophyllene for H. courbaril; spathulenol, α-pinene, and caryophyllene oxide for M. peruiferum; and caryophyllene oxide and humulene epoxide II for V. guianensis oil. The oils showed antifungal activity against all the strains tested, and the MIC values ranged between 0.625 and 1.25 µL/mL and MFC from 0.625 to 2.5 µL/mL. Conclusion: The essential oils from the species studied have the potential to be evaluated as clinical applications in the treatment of candidiasis.