New Claims for Wild Carrot (Daucus carota subsp. carota) Essential Oil

Abstract

The essential oil of Daucus carota subsp. carota from Portugal, with high amounts of geranyl acetate (29.0%), α-pinene (27.2%), and 11αH-himachal-4-en-1β-ol (9.2%), was assessed for its biological potential. The antimicrobial activity was evaluated against several Gram-positive and Gram-negative bacteria, yeasts, dermatophytes, and Aspergillus strains. The minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) were evaluated showing a significant activity towards Gram-positive bacteria (MIC = 0.32-0.64 μL/mL), Cryptococcus neoformans (0.16 μL/mL), and dermatophytes (0.32-0.64 μL/mL). The inhibition of the germ tube formation and the effect of the oil on Candida albicans biofilms were also unveiled. The oil inhibited more than 50% of filamentation at concentrations as low as 0.04 μL/mL (MIC/128) and decreased both biofilm mass and cell viability. The antioxidant capacity of the oil, as assessed by two in chemico methods, was not relevant. Still, it seems to exhibit some anti-inflammatory potential by decreasing nitric oxide production around 20% in LPS-stimulated macrophages, without decreasing macrophages viability. Moreover, the oils safety profile was assessed on keratinocytes, alveolar epithelial cells, macrophages, and hepatocytes. Overall, the oil demonstrated a safety profile at concentrations below 0.64 μL/mL. The present work highlights the bioactive potential of D. carota subsp. carota suggesting its industrial exploitation.

Figures

Figure 1

Biofilm biomass after treatment with D. carota subsp. carota essential oil, using the crystal violet assay. Biofilm biomass was determined using the formula (Abs620 sample/Abs620 control) ∗ 100. Results are shown as mean ± standard deviation of at least three independent determinations carried out in duplicate. ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001, compared to control using one-way ANOVA followed by Dunnett's multiple comparison test. Control (100%) corresponds to an absorbance mean value of 1.587.

Figure 2

Biofilm viability after treatment with D. carota subsp. carota essential oil using the XTT viability assay. Results are shown as mean ± standard deviation of at least three independent determinations carried out in duplicate. ∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001, compared to control using one-way ANOVA followed by Dunnett's multiple comparison test. Control (100%) corresponds to an absorbance mean value of 0.621.

Figure 3

NO scavenging activity of Daucus carota subsp. carota essential oil. Different concentrations of essential oil (1.25–0.08 μL/mL) were incubated with the NO donor, SNAP (100 mM), in culture medium for 3 h. Results are shown as mean ± SEM of three independent assays, done in duplicate.

Figure 4

Anti-inflammatory effect of Daucus carota subsp. carota in LPS-stimulated Raw 264.7 macrophages: (a) NO production and (b) cell viability. Macrophages were treated with essential oil (1.25–0.08 μL/mL) for 1 h prior to LPS (1 μg/mL) activation and further incubated for 24 h. NO release was determined in the supernatants of the cultures using the Griess reagent (a) and cell viability was assessed on adherent cells using the resazurin reagent and expressed as percentage of cell viability by control cells (b). Results are shown as mean ± SEM of at least three independent assays. (∗p < 0.05; ∗∗p < 0.01; ∗∗∗∗p < 0.0001, compared to LPS). Cell viability control (100%) corresponds to an absorbance mean value of 0.435.