Greek Fir Seeds and Cones as Underestimated Source of Essential Oil: Composition and Biological Properties

Abstract

Greek fir (Abies cephalonica) seeds and cone scales were used, for the first time, for an analysis of their biologically active volatile compounds. It was observed that the yield of seed essential oil was 18%, which, among plants, is impressive. The seed essential oil was characterized by a distinctive forest scent with a subtle lemon undertone. The determination of the chemical compositions of the hydrodistilled oils isolated from the seeds and cone scales, achieved via chromatographic and spectroscopic methods (MS, NMR), revealed more than 100 compounds, mostly monoterpene hydrocarbons. The above methods allowed for the identification of 99.4% and 98.3% of the total seed and cone scale oil compositions, respectively. Limonene in its enantiomeric levorotatory form (S) constituted over 80% of the essential oil isolated from the Abies cephalonica seeds. This abundance of limonene makes them a potential natural source for obtaining this compound, which has demonstrated various biological properties. The main cone essential oil compounds were α- and β-pinenes as well as limonene. The cytotoxic effects of both essential oils were analyzed using the MTT assay in skin fibroblasts, keratinocytes, and melanoma cell lines, in the range of 0.012–0.2 μL/mL of essential oil. The cone scale essential oil was slightly more cytotoxic and induced a decrease in the cell viability in concentrations of 0.05–0.1 μL/mL, with small differences between the cell lines. The tested essential oils did not have selective effects on the melanoma cells (A375 and C32) when compared with normal cells. Both the seed and cone scale essential oils revealed good antimicrobial effects on Staphylococcus aureus and Escherichia coli.