Chemical composition, antifungal activity and potential anti-virulence evaluation of the Eugenia uniflora essential oil against Candida spp.

Abstract

The development of fungal resistance to antifungal drugs has been worsening over the years and as a result research on new antifungal agents derived from plants has intensified. Eugenia uniflora L. (pitanga) has been studied for its various biological actions. In this study the chemical composition and antifungal effects of the E. uniflora essential oil (EULEO) were investigated against Candida albicans (CA), Candida krusei (CK) and Candida tropicalis (CT) standard strains. The essential oil obtained through hydro-distillation was analyzed by gas chromatography coupled to mass spectrometry (GC-MS). To determine the IC of the oil, the cellular viability curve and the inhibitory effects were measured by means of the oil's association with Fluconazole in a broth microdilution assay with spectrophotometric readings. The Minimum Fungicidal Concentration (MFC) was determined by solid medium subculture with the aid of a guide plate while the assays used to verify morphological changes emerging from the action of the fractions were performed in microculture chambers at concentrations based on the microdilution. Two major oil constituents stand out from the chemical analysis: selina-1,3,7(11)-trien-8-one (36.37%) and selina-1,3,7(11)-trien-8-one epoxide (27.32%). The concentration that reduced microorganismal growth was ≥8,192 μg/mL while the IC varied, this being between 1892.47 and 12491.80 μg/mL (oil), 10.07 - 80.78 μg/mL (fluconazole) and 18.53 - 295.60 μg/mL (fluconazole + oil). The combined activity (fluconazole + oil) resulted in indifference and antagonism. A MFC of the oil in association with fluconazole was recorded at the concentration of 8,192 μg/mL against CA and CK. The oil caused the inhibition of CA and CT morphological transition. In view of the results obtained, additional research is needed to elucidate the activity of the E. uniflora oil over genetic and biochemical processes regarding its effect on Candida spp. virulence.

Antibiotic Potential and Chemical Composition of the Essential Oil of Piper caldense C. DC. (Piperaceae)

“…Inhibition of virulence of C. albicans strains by natural products was also shown by other scientists, among them Santos et al [26], who evaluated the essential oil of Eugenia uniflora L. (Myrtaceae) and demonstrated that at concentrations of 8192 µg/mL there is inhibition of hyphal projection. Two other species also from the same family that have the ability to inhibit the virulence of C. albicans are Psidium brownianum Mart.…”

Essential Oils and Microbial Communication

“…Citronellol can exert a broad inhibitory activity against the formation of biofilm. In fact, it acts against the planktonic forms of different Gram-positive (Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis) and Gramnegative species (E.coli, Pseudomonas aeruginosa), inhibiting their capability to form biofilm when used at percentage ranging between 3.5% and 7% wt [58,59]. However, the antibacterial effectiveness can vary depending not only on the EO but also on the bacteria.…”

In vitro evaluation of the activity of an essential oil from Pistacia vera L. variety Bronte hull against Candida sp.

“…Gucwa et al [5] have recently reported the activity of EOs from Thymus vulgaris , Citrus limonum , Pelargonium graveolens , Cinnamomum cassia , Ocimum basilicum and Eugenia caryophyllus against 183 clinical isolates of C. albicans and 76 isolates of C. glabrata . The chemical composition and antifungal effects of the Eugenia uniflora EO were recently investigated against C. albicans , C. krusei and C. tropicalis standard strains [6].…”