Chemical Composition, Antioxidant and Anti-Inflammatory Activities of Clary Sage and Coriander Essential Oils Produced on Polluted and Amended Soils-Phytomanagement Approach

Abstract

The potential of essential oils (EO), distilled from two aromatic plants-clary sage (Salvia sclarea L.) and coriander (Coriandrum sativum L.)-in view of applications as natural therapeutic agents was evaluated in vitro. These two were cultivated on a trace element (TE)-polluted soil, as part of a phytomanagement approach, with the addition of a mycorrhizal inoculant, evaluated for its contribution regarding plant establishment, growth, and biomass production. The evaluation of EO as an antioxidant and anti-inflammatory, with considerations regarding the potential influence of the TE-pollution and of the mycorrhizal inoculation on the EO chemical compositions, were the key focuses. Besides, to overcome EO bioavailability and target accession issues, the encapsulation of EO in β-cyclodextrin (β-CD) was also assessed. Firstly, clary sage EO was characterized by high proportions of linalyl acetate (51-63%) and linalool (10-17%), coriander seeds EO by a high proportion of linalool (75-83%) and lesser relative amounts of γ-terpinene (6-9%) and α-pinene (3-5%) and coriander aerial parts EO by 2-decenal (38-51%) and linalool (22-39%). EO chemical compositions were unaffected by both soil pollution and mycorrhizal inoculation. Of the three tested EO, the one from aerial parts of coriander displayed the most significant biological effects, especially regarding anti-inflammatory potential. Furthermore, all tested EO exerted promising antioxidant effects (IC₅₀ values ranging from 9 to 38 g L^-1). However, EO encapsulation in β-CD did not show a significant improvement of EO biological properties in these experimental conditions. These findings suggest that marginal lands polluted by TE could be used for the production of EO displaying faithful chemical compositions and valuable biological activities, with a non-food perspective.

Keywords: anti-inflammatory; antioxidant; aromatic plants; essential oils; phytomanagement; polluted soils.

Figure 1

Correlation circles from the PCA analyses based on chemical composition of EO from aerial parts or seeds of coriander and from clary sage, with projection on F1 and F2 axes (A) and on F1 and F3 axes (B).

Figure 2

EO’s EC₅₀ values (g L⁻¹) resulting from the DPPH^• scavenging assay. The EC₅₀ value obtained for Trolox^® (dotted line), was used as a positive control. Values are means ± SD (n = 3). Means followed by the same lowercase letter do not differ significantly by Two-way ANOVA test (α = 0.05).

Figure 3

Lactate dehydrogenase (LDH—A) and mitochondrial dehydrogenase (MDH—B) activities in cell-free culture supernatants of BEAS-2B cells, after 48 h of exposure to coriander aerial parts EO at different concentrations. Cells exposed to the culture medium only were used as a negative control (dotted line). Results are depicted as mean ± SD of 3 replicates for each exposure condition.

Figure 4

Cytokine levels in BEAS-2B cells exposed for 48 h to PM_2.5 in the presence of free or β-CD encapsulated EO: (A) IL-6 concentrations in BEAS-2B cells, (B) IL-8 concentrations in BEAS-2B cells. The negative and positive control values are represented by the black and red dotted lines, respectively. Data are presented as mean ± standard deviation (n = 3). Significant differences using a two-way ANOVA comparison (α = 0.05), between results obtained in free β-CD condition and in the presence of β-CD, are indicated by different lowercase letters, differences between experimental conditions and the negative control are displayed with an apostrophe (’), while significant difference with the positive control are displayed with an asterisk (*-p < 0.05). CD: Cyclodextrins; BEAS-2B: human bronchial epithelial cells; IL-6: interleukin 6; IL-8: interleukin 8; PM_2.5: particulate matter with an aerodynamic diameter inferior to 2.5 µm.