Abstract:In the course of our ongoing work on the chemical characterization of Corsican olive oil, we have developed and validated a method for direct quantification of squalene using 13 C Nuclear Magnetic Resonance (NMR) spectroscopy without saponification, extraction, or fractionation of the investigated samples. Good accuracy, linearity, and precision of the measurements have been observed. The experimental procedure was applied to the quantification of squalene in 24 olive oil samples from Corsica. Squalene accounted for 0.35-0.83% of the whole composition.

The composition of 48 samples of essential oil isolated from the wood of Cedrus atlantica growing in Corsica was investigated by GC (in combination with retention indices), GC/MS, and (13) C-NMR. Twenty-three compounds accounting for 73.9-96.0% of the oil composition were identified. The oils consisted mainly of monoterpene hydrocarbons and sesquiterpenes, in particular α-pinene (5; up to 79.4%), himachalol (4; up to 66.2%), β-pinene (up to 21.4%), β-himachalene (2; up to 19.3%), γ-himachalene (3; up to 11.0%), and α-himachalene (1; up to 10.9%). The 48 oil compositions were submitted to k-means partitioning and principal-component analysis, which allowed the distinction of two groups within the oil samples. The composition of Group I (44% of the samples) was dominated by 5, while the samples of Group II (56% of the samples) contained mainly 4.

The composition of oil samples isolated from needles of Pinus halepensis growing in three locations in Corsica (Saleccia, Capo di Feno, and Tre Padule) has been investigated by combination of chromatographic (GC with retention indices) and spectroscopic (MS and (13)C-NMR) techniques. In total, 35 compounds that accounted for 77 - 100% of the whole composition have been identified. α-Pinene, myrcene, and (E)-β-caryophyllene were the major component followed by α-humulene and 2-phenylethyl isovalerate. Various diterpenes have been identified as minor components. 47 Oil samples isolated from pine needles have been analyzed and were differentiated in two groups. Oil samples of the first group (15 samples) contained myrcene (M = 28.1 g/100 g; SD = 10.6) and (E)-β-caryophyllene (M = 19.0 g/100 g; SD = 2.2) as major components and diterpenes were absent. All these oil samples were isolated from pine needles harvested in Saleccia. Oil samples of the second group (32 samples) contained mostly (E)-β-caryophyllene (M = 28.7 g/100 g; SD = 7.9), α-pinene (M = 12.3 g/100 g; SD = 3.6), and myrcene (M = 11.7 g/100 g; SD = 7.3). All these oil samples were isolated from pine needles harvested in Capo di Feno and Tre Padule.

Identification and quantitative determination of individual components of resin collected on the trunk of 28 Cedrus atlantica trees, grown in Corsica, has been carried out using 13C NMR spectroscopy. Eight resin acids bearing either the pimarane or abietane skeleton, two monoterpene hydrocarbons and four oxygenated neutral diterpenes have been identified, as well as three lignans, scarcely found in resins. Three groups could be distinguished within the 28 resin samples. The nine samples of Group I had their composition dominated by diterpene acids (33.7-45.8%), with abietic acid (6.2-18.7%) and isopimaric acid (5.1-12.6%) being the major components. The four samples of Group II contained resin acids (main components) and lignans in moderate amounts (up to 10.3%). Conversely, lignans (38.8-63.8%) were by far the major components of the 15 samples of Group III. Depending on the sample, the major component was pinoresinol (18.1-38.9%), lariciresinol (17.2-33.7%) or lariciresinol 9′-acetate (16.9-29.1%). Finally, due to the high biological interest in lignans, a rapid procedure, based on 1H NMR spectroscopy, was developed for quantification of lignans in resins of C. atlantica.

The composition of the essential oil isolated from cones of Pinus halepensis grown in Corsica has been investigated by a combination of chromatographic (CC, GC) and spectroscopic (MS, 13 C NMR) techniques. In total, 48 compounds that accounted for 95.5% of the whole composition have been identified. -Pinene (47.5%) was the major component followed by myrcene (11.0%), (E)--caryophyllene (8.3%) and caryophyllene oxide (5.9%). Various diterpenes have been identified by 13 C NMR in the fractions of CC. Fifteen oil samples isolated from cones harvested in three forests have been analyzed and two groups of similar importance have been differentiated within the 15 compositions. Oil samples of the first group contained -pinene (mean 45.0 g/100 g, SD = 5.5) as the major component. The composition of samples of the second group was dominated by myrcene (mean 30.3 g/100g, SD = 9.0) and -pinene (mean 24.6 g/100 g, SD = 3.1).

The composition of oil samples isolated from needles of Pinus halepensis growing in three locations in Corsica (Saleccia, Capo di Feno and Tre Padule) has been investigated by combination of chromatographic (GC with retention indices) and spectroscopic (MS, C-NMR) techniques. In total, 35 compounds that accounted for 77-100% of the whole composition have been identified. α-Pinene, myrcene and (E)-β-caryophyllene were the major component followed by α-humulene and 2-phenylethyl isovalerate. Various diterpenes have been identified as minor components. Forty seven oil samples isolated from pine needles have been analyzed and were differentiated in two groups. Oil samples of the first group (15 samples) contained myrcene (M= 28.1g/100g; SD = 10.6) and (E)-β-caryophyllene (M = 19.0g/100g; SD = 2.2) as major components and diterpenes were absent. All these oil samples were isolated from pine needles harvested in Saleccia. Oil samples of the second group (32 samples) contained mostly (E)-β-caryophyllene (M = 28.7g/100g; SD = 7.9), α-pinene (M = 12.3g/100g; SD = 3.6) and myrcene (M = 11.7g/100g; SD = 7.3). All these oil samples were isolated from pine needles harvested in Capo di Feno and Tre Padule. This article is protected by copyright. All rights reserved.