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Article

Neuropeltis acuminata (P. Beauv.): Investigation of the Chemical Variability and In Vitro Anti-inflammatory Activity of the Leaf Essential Oil from the Ivorian Species

by
Didjour Albert Kambiré
1,2,
Ahmont Claude Landry Kablan
1,
Thierry Acafou Yapi
3,
Sophie Vincenti
2,
Jacques Maury
2,
Nicolas Baldovini
4,
Pierre Tomi
2,
Mathieu Paoli
2,
Jean Brice Boti
3 and
Félix Tomi
2,*
1
UPR de Chimie Organique, Département de Mathématiques, Physique et Chimie, UFR des Sciences Biologiques, Université Péléforo Gon Coulibaly, Korhogo BP 1328, Côte d’Ivoire
2
Laboratoire Sciences Pour l’Environnement, Université de Corse—CNRS, UMR 6134 SPE, Route des Sanguinaires, 20000 Ajaccio, France
3
Laboratoire de Constitution et Réaction de la Matière, UFR-SSMT, Université Félix Houphouët-Boigny, Abidjan BP V34, Côte d’Ivoire
4
Institut de Chimie de Nice, CNRS UMR 7272, Université Côte d’Azur, Parc Valrose, CEDEX 2, 06108 Nice, France
*
Author to whom correspondence should be addressed.
Molecules 2022, 27(12), 3759; https://doi.org/10.3390/molecules27123759
Submission received: 9 May 2022 / Revised: 7 June 2022 / Accepted: 7 June 2022 / Published: 10 June 2022
(This article belongs to the Collection Essential Oils)
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Abstract

:
The variability of chemical composition of the leaf essential oil (EO) from Neuropeltis acuminata, a climbing liana growing wild in Ivory Coast, was investigated for the first time. The in vitro anti-inflammatory activity was also evaluated. Thirty oil samples were isolated from leaves collected in three forests of the country and analyzed using a combination of Column Chromatography (CC), Gas Chromatography with Retention Indices (GC(FID)), Gas Chromatography-Mass Spectrometry (GC-MS), and 13Carbon-Nuclear Magnetic Resonance (13C-NMR). Fractionation by CC led to the first-time isolation from natural source of δ-cadinen-11-ol, whose structural elucidation by one dimension (1D) and 2D-NMR spectroscopy is reported here. Finally, 103 constituents accounting for 95.7 to 99.6% of the samples’ compositions were identified. As significant variations of the major constituents were observed, the 30 oil compositions were submitted to hierarchical cluster and principal components analyses. Five distinct groups were evidenced: Group I, dominated by (E)-β-caryophyllene, kessane, and δ-cadinene, while the main constituents of Group II were germacrene B, ledol, α-humulene, (E)-γ-bisabolen-12-ol, and γ-elemene. Group III exhibited guaiol, germacrene D, atractylone, (E)-γ-bisabolen-12-ol, δ-cadinene and bulnesol as main compounds. Group IV was dominated by (E)-nerolidol, guaiol, selina-4(15),7(11)-diene and bulnesol, whereas (E)-β-caryophyllene, α-humulene and α-muurolene were the prevalent compounds of Group V. As the harvest took place in the same dry season in the three forests, the observed chemical variability could be related to harvest sites, which includes climatic and pedologic factors, although genetic factors could not be excluded. The leaf oil sample S24 behaved as a high inhibitor of LipOXygenase (LOX) activity (half maximum Inhibitory Concentration, IC50: 0.059 ± 0.001 mg mL−1), suggesting an anti-inflammatory potential.

Graphical Abstract

1. Introduction

The genus Neuropeltis of the Convolvulaceae family, comprises about thirteen species, of which nine are restricted to the Guineo-Congolian region of Africa. The remaining four species occur in tropical Asia [1,2]. Neuropeltis acuminata (P. Beauv.) is a woody liana with contorted stems up to 40 m long and 25 cm in diameter. Its leaves are alternate, simple with acuminated apex and entire margin. The inflorescences are axillary, and the flowers are bisexual, regular, and fragrant. The fruits of N. acuminata are rounded capsules of 7 mm in diameter, surrounded at the base by persistent calyx and enlarged bract. This species is widely distributed from Senegal to the Central African Republic, Democratic Republic of Congo, and Angola and located mainly in evergreen primary forests. In older forests, it becomes one of the dominant climbing species. The stems of N. acuminata are used as ropes and for tying in the construction of houses in Ghana and Ivory Coast, while the leaves are eaten as a vegetable in Gabon [1,2,3,4,5]. In South Cameroon, the fibers of the plant were used for a long time as dish sponges and toilet gloves [6].
The micromechanical, physicochemical, and thermal properties of N. acuminata fibers were evaluated through some studies reported in the literature. A few functional groups attributable to cellulose, hemicellulose, polysaccharides, lignins, and aromatic compounds were evidenced by infrared spectroscopy applied to fibers extracts [6,7]. However, no in-depth investigation on the identification of individual chemical constituents from solvent extracts and essential oils of N. acuminata has so far been reported in the literature.
The present study is part of the continuation of the chemical characterization of aromatic and medicinal plants from Ivory Coast [8,9,10,11,12,13,14,15,16]. It aims to determine for the first time the variability of the chemical composition of the leaf EO of N. acuminata. Fractionation by CC led to the first-time isolation from natural source of δ-cadinen-11-ol, whose structural elucidation by 1D and 2D-NMR spectroscopy is reported here. An EO sample was also tested for its in vitro anti-inflammatory activity.

2. Results and Discussion

Thirty samples of fresh leaves of N. acuminata were harvested in the Bossématié forest (Eastern Ivory Coast), the Haut-Sassandra forest (Western Ivory Coast) and the Yapo-Abbé forest (Southern Ivory Coast) (Table S1). The EO samples were isolated by hydrodistillation, and the extraction yields calculated on weight basis (w/w) varied poorly (Yield: 0.58–1.03%). The higher value of yield (Mean: 0.92%) was observed in the Bossématié forest and the lower (Mean: 0.73%) was observed in the Haut-Sassandra forest (Station 4) and the Yapo-Abbé forest (Station 5). Combination of chromatographic and spectroscopic techniques (GC(RI), GC-MS, and 13C-NMR) was used to perform the analyses. A computerized 13C-NMR method developed at the University of Corsica was applied to the oil samples. This method allows identification of components present at a content as low as 0.4–0.5% and compiled in our laboratory-made 13C-NMR spectral data library [17,18]. Various constituents were identified by the three above techniques.
Compounds bearing the germacrane and elemane skeletons needed special attention. Indeed, under thermal GC and GC-MS conditions, germacrene compounds bearing the cyclodeca-1,5-diene sub-structure were partially or totally rearranged to the corresponding elemenes (sigmatropic [3,3] rearrangement) [19]. As germacrene B and γ-elemene on the one hand, then furanodiene and curzerene on the other hand, were detected by GC-MS and 13C-NMR, their correct contents were obtained by combination of GC(FID) and 13C-NMR [15]. However, δ-elemene, β-elemene, and curzerenone were actual secondary metabolites produced by the plant and not rearranged products since germacrene C, germacrene A, and furanodienone were not detected by 13C-NMR. Heat-sensitive compounds are one of the main causes of artifact formation during GC and GC-MS analyses. Hence, the combination of different analytical techniques is highly recommended for a better qualitative and quantitative analysis of essential oils.

2.1. Detailed Analysis of Essential Oil Samples S3, S6, S13, S20, and S24

Despite the use of complementary techniques, several compounds remained unidentified. Therefore, samples S3 (2.605 g), S6 (3.280 g), S13 (2.318 g), S20 (2.148 g), and S24 (4.110 g), which displayed different chemical profiles and contained minor unidentified constituents, were separately submitted to repetitive fractionation by silica gel CC. These samples also represented the different stations of the three sampling forests. Analysis of CC fractions by GC(RI), GC-MS, and 13C-NMR led to the identification of several minor components. In parallel, five compounds whose NMR data were not compiled in our laboratory spectral database were isolated, and their structures were elucidated by 1D- and 2D-NMR analyses. After structural elucidations, 13C-NMR data of four compounds among the five, were found in the literature. These data were very close to our experimental 13C-NMR data, confirming the proposed structures: 1,11-oxidocalamenene (49) isolated from fraction F4.1.1 (19 mg, 94.5%) of sample S20; atractylone (93) from sample S24, fraction F3.1.2.1 (38 mg, 98.7%); (E)-γ-bisabolen-12-al (101) from sample S24, fraction F3.1.2.2 (27 mg, 96.3%) and (E)-γ-bisabolen-12-ol (102), fraction F6.3.4.1 (41 mg, 97.4%) of sample S24 (Figure 1, Table 1) [20,21,22,23]. As the 13C-NMR and 2D-NMR data of the fifth compound (δ-cadinen-11-ol (96)) were not found in the literature, we reported its structural elucidation.

2.1.1. Isolation and Structural Elucidation of δ-Cadinen-11-ol

Repetitive silica gel column chromatography, performed on sample S6, led to the isolation of compound 96 (GC: 96.7%; RIs apol/pol: 1651/2271) in the sub-fraction F.5.4.2 (12 mg). The electron impact (EI) mass spectrum of compound 96 showed a molecular ion peak (M•+) at m/z = 220 and an M•+ − 18 peak (m/z = 202), characteristic of a sesquiterpene alcohol. The measured exact mass was 220.1829 g/mol, corresponding to C15H24O formula (calculated mass = 220.1827 g/mol). The 1H-NMR, 13C-NMR, and DEPT spectra agreed with this formula, which involved four unsaturation degrees (Table 2) (Supplementary Materials, Figures S1–S8). The alcohol function was confirmed by the quaternary oxide carbon (C11, 74.57 ppm). The presence of four sp2 carbon signals, involved in two C=C double bonds, demonstrated that compound 96 obviously bears a bicyclic structure. The 1H-NMR spectrum evidenced two methyl groups linked to sp2 quaternary carbons (H14, 1.64 ppm, broad s; H15, 1.67 ppm, broad s) and an ethylenic proton (H5, 5.71 ppm, hept: 1.5 Hz) belonging to tri- and tetrasubstituted double bonds. Correlations observed in the COSY spectrum evidenced two proton groups formed by the sequences H2-H3 and H5-H6-H7-H8-H9. The HMBC correlations plots were used to build the bicyclic skeleton by linking together the observed proton groups. Indeed, H15 was correlated to C3, C4, and C5, while proton H7 (1.41 ppm, ddd: 11.0, 8.1, 3.1 Hz) correlated to C11, C12 and C13, appeared very informative about the location of the hydroxyl group (2-hydroxy-isopropyl). Correlations of methyl protons H14 with C1, C9, and C10 on the one hand, added to plots between H2α, H2β, and C1, C3, C4, C6, and C10 on the other hand, evidenced a cadinadiene alcohol structure. The relative stereochemistry of carbons C6 and C7 was established through NOESY spatial correlations. Protons H6, H12, and H13 correlated together indicating a cis stereochemistry of H6 and the 2-hydroxy-isopropyl group. Finally, the absence of correlations plots between H6 and H7 made it possible to determine the structure of compound 96 as δ-cadinen-11-ol (Figure 1). This compound is isolated from natural source for the first time. It was previously mentioned in the literature as a synthetic derivative and only its 1H-NMR data were described. The 1D- and 2D-NMR data of this compound are reported in Table 2.

2.1.2. Chemical Composition of Leaf Essential Oil Samples S3, S6, S13, S20 and S24

The chemical composition of samples S3, S6, S13, S20, and S24, which displayed different chemical profiles, were determined by combination of chromatographic and spectroscopic techniques. A total of 103 compounds, representing respectively 95.7, 97.9, 96.8, 99.6, and 98.1% of the samples’ whole compositions, were identified (Table 3). The five oil samples were very rich in sesquiterpenes (90.2–97.5%). Obviously, the major compounds displayed significant variations. Indeed, sample S3 was dominated by germacrene B (15.5%) and ledol (12.5%), followed by (E)-γ-bisabolen-12-ol (6.1%), α-humulene (5.8%), γ-elemene (5.5%) and kessane (5.2%). The main components of sample S6 were (E)-nerolidol (23.3%) and guaiol (12.2%), followed by selina-4(15),7(11)-diene (8.3%), β-eudesmol (6.3%) and bulnesol (5.2%). (E)-β-caryophyllene (20.0%), kessane (11.5%), δ-cadinene (8.4%), cadina-1(10),4-dien-8α-ol (8.1%), and germacrene D (5.2%), were the predominant constituents of sample S13. Sample S20 was largely dominated by (E)-β-caryophyllene (34.4%) and α-humulene (27.1%), followed by α-muurolene (6.6%) and β-elemene (4.6%), whereas guaiol (11.6%), germacrene D (10.2%), atractylone (10.0%), (E)-γ-bisabolen-12-ol (7.1%), δ-cadinene (7.0%), and bulnesol (6.2%), were the main compounds of sample S24. The five determined chemical compositions exhibited qualitative and quantitative variations.

2.2. Chemical Variability of Leaf Essential Oil from N. acuminata

The evaluation of the chemical variability of leaf EO from N. acuminata was conducted on 30 samples collected in three forests during the dry season: Bossématié forest (Eastern Ivory Coast, four samples from one station), Haut-Sassandra forest (Western Ivory Coast, seventeen samples from three stations), and Yapo-Abbé forest (Southern Ivory Coast, nine samples from two stations). Whatever the sample, N. acuminata can be considered as sesquiterpene-rich EO plant (87.1–98.1%). However, the main compounds varied drastically from sample to sample: (E)-β-caryophyllene (0.9–45.4%), kessane (0.1–32.5%), α-humulene (0.5–31.2%), (E)-nerolidol (0.2–30.8%), germacrene B (0.7–16.6%), germacrene D (0.5–14.4%), guaiol (0.3–13.8%), ledol (0.1–13.2%), atractylone (0.4–12.1%), cadina-1(10),4-dien-8α-ol (0.1–12.1%), δ-cadinene (0.4–12.0%), selina-4(15),7(11)-diene (0.1–11.2%), and α-muurolene (0.1–10.9%). Thus, statistical analyses were performed on the 30 EO compositions to emphasize chemical variability.
Five distinct groups were observable on the dendrogram from the hierarchical cluster analysis (HCA): Group I (8 samples), Group II (4 samples), Group III (9 samples), Group IV (5 samples), and Group V (4 samples) (Figure 2). The five groups from HCA were also evidenced by the principal component analysis (PCA) map of samples distribution (Figure 3). Its principal factors F1 and F2 accounted for 68.84% of the total variance of the chemical composition. Table 4 contains the mean contents (M) and the standard deviations (SD) of the main compounds that discriminated the groups on PCA.
Group I was dominated by (E)-β-caryophyllene (M = 17.6%, SD = 4.2%) and kessane (M = 10.3%, SD = 9.9%), followed by δ-cadinene (M = 6.2%, SD = 3.4%), germacrene D (M = 4.3%, SD = 1.1%), guaiol (M = 4.2%, SD = 2.5%), cadina-1(10),4-dien-8α-ol (M = 3.6%, SD = 4.8%), ledol (M = 3.4%, SD = 3.1%), and germacrene B (M = 3.4%, SD = 0.8%). Kessane and cadina-1(10),4-dien-8α-ol were, respectively, absent from the samples of Groups III and II. The main constituents of Group II were germacrene B (M = 13.4%, SD = 3.1%), ledol (M = 10.6%, SD = 2.7%), α-humulene (M = 6.6%, SD = 2.1%), (E)-γ-bisabolen-12-ol (M = 5.8%, SD = 0.4%), γ-elemene (M = 5.0%, SD = 0.8%), kessane (M = 4.8%, SD = 0.6%), and β-elemene (M = 4.6%, SD = 0.5%). Groups I and II were characterized by high contents of sesquiterpene hydrocarbons (respectively M = 58.6 and 55.8%, vs. 34.5 and 30.7% of oxygenated sesquiterpenes). In contrast, Groups III and IV were composed by oxygenated sesquiterpenes-rich oils (respectively M = 49.1 and 67.7%, vs. 42.1 and 27.0% of sesquiterpene hydrocarbons). Indeed, Group III exhibited guaiol (M = 11.4%, SD = 2.0%), germacrene D (M = 10.6%, SD = 1.6%), atractylone (M = 9.6%, SD = 2.3%), (E)-γ-bisabolen-12-ol (M = 7.3%, SD = 1.3%), δ-cadinene (M = 7.3%, SD = 0.4%), bulnesol (M = 5.9%, SD = 1.2%), and furanodiene (M = 4.0%, SD = 1.2%), as major compounds, while Group IV was dominated by (E)-nerolidol (M = 23.8%, SD = 5.4%), guaiol (M = 12.4%, SD = 1.3%) and selina-4(15),7(11)-diene (M = 9.5%, SD = 1.7%), followed by bulnesol (M = 6.5%, SD = 1.1%), β-elemol (M = 4.5%, SD = 0.5%), and (E)-γ-bisabolen-12-ol (M = 4.4%, SD = 2.6%). The last group (Group V) was widely dominated by sesquiterpene hydrocarbons (M = 75.3%, vs. 20.6% of oxygenated sesquiterpenes). (E)-β-caryophyllene (M = 36.6%, SD = 5.9%), α-humulene (M = 18.9%, SD = 12.1%), and α-muurolene (M = 6.2%, SD = 3.5%) were its prevalent compounds. Therefore, it could be stated that the chemical composition of the leaf EO displayed qualitative and quantitative variability.
The 8 samples of Group I were harvested from station 2 of the Haut-Sassandra forest, while the 4 samples of Group II were collected in the Bossematié forest. Group III is constituted by the 9 samples from the Yapo-Abbé forest. Samples from Groups IV and V were respectively harvested at stations 3 and 4 of the Haut-Sassandra forest. As the harvest took place in the same dry season in the three forests, the observed chemical variability could be related to harvest sites, which include climatic and pedologic factors, then vegetative stage (young or old lianas), although genetics factors could not be excluded.

2.3. Evaluation of In Vitro Anti-Inflammatory Activity

The in vitro anti-inflammatory activity of N. acuminata leaf EO (S24) was evaluated by the LOX inhibition method. Indeed, LOXs are a nonheme iron-containing dioxygenases, which were responsible for the formation of biologically active metabolites. They were key enzymes in the biosynthesis of leukotrienes that were mediators of many disorders related with inflammatory processes such as arthritis, bronchial asthma, and cancer [33,34,35,36]. The discovery of novel LOX inhibitors appeared as crucial point because they would prevent overproduction of leukotrienes and thus could constituted new therapeutic tools for treating of human inflammation-related diseases.
The inhibition ability of soybean LOX by S24 was measured and considered as an indicator of its potential anti-inflammatory activity. Results of LOX inhibition tests were presented in Table 5. The N. acuminata leaf essential oil inhibited LOX activity and this inhibition increased with the concentration of the oil (15.20% at 0.0125 mg mL−1 up to 81.87% at 0.100 mg mL−1). The IC50 values were calculated for S24 and for inhibitor NorDihydroGuaiaretic Acid (NDGA), a non-competitive inhibitor of lipoxygenase usually used as reference in anti-inflammatory assays (Table 5) [34,35,36]. The IC50 value of S24 (0.059 ± 0.001 mg mL−1) was only 4.5-higher than IC50 value of NDGA (0.013 ± 0.003 mg mL−1). This low ratio between the two IC50 values (S24 vs. NDGA) allowed to consider the N. acuminata leaf essential oil as a high inhibitor of the LOX activity, suggesting an anti-inflammatory potential [37].

3. Materials and Methods

3.1. Plant Material

Fresh leaves samples from N. acuminata were collected at six stations of three forests: Bossématié forest, Region of Abengourou, Eastern Ivory Coast (Station 1); Haut-Sassandra forest, Western Ivory Coast (Stations 2–4); Yapo-Abbé forest, Southern Ivory Coast (Stations 5 and 6). Geographical coordinates: Station 1 (6°29′26.0″ N and 3°29′11.7″ W), Station 2 (6°53′40.2″ N and 6°55′36.3″ W), Station 3 (6°57′08.5″ N and 6°59′00.5″ W), Station 4 (6°54′52.7″ N and 6°57′21.1″ W), Station 5 (5°41′08.0″ N and 4°06′31.7″ W) and Station 6 (5°41′48.7″ N and 4°05′31.0″ W). The harvest took place during the dry season (January and February 2021). Plant material was authenticated by botanists from Centre Suisse de Recherches Scientifiques (CSRS) and Centre National de Floristique (CNF) Abidjan, Ivory Coast. A voucher specimen was deposited at the herbarium of CNF, Abidjan, with the reference LAA 11029.

3.2. Essential Oil Isolation and Fractionation

The EO samples were extracted by hydrodistillation of fresh leaves for 3 h each, using a Clevenger-type apparatus. The extraction yields were calculated using the weight of essential oil/weight of fresh leaves ratio (w/w) and reported in Table S2. Five oil samples S3 (2.605 g), S6 (3.280 g), S13 (2.318 g), S20 (2.148 g), and S24 (4.110 g) were chromatographed on column with respectively 95 g, 100 g, 90 g, 80 g, and 130 g of silica gel (Acros Organics, Geel, Belgium, 60–200 μm). For each sample, seven fractions were eluted with a mixture of solvents, n-pentane (P) (VWR Chemicals, 99%)/diethyl ether (DE) (VWR Chemicals, 99%) on increasing polarity (P/DE 100/0 to 0/100). F1 and F2 (100% P) contained olefins; F3–F6 contained medium polar compounds while F7 (100% DE) contained polar compounds. The mass of fractions were reported in the Table 6. Repetitive column chromatography (SiO2, 35–70 μm, Acros Organics, Geel, Belgium) were performed on fractions from samples S6 (F4 and F5), S20 (F4 and F5), and S24 (F3 and F6), in order to isolate several unidentified compounds.

3.3. Gas Chromatography

Analyses were performed on a Clarus 500 PerkinElmer Chromatograph (PerkinElmer, Courtaboeuf, France), equipped with flame ionization detector (FID) and two fused-silica capillary columns (50 m × 0.22 mm, film thickness 0.25 µm), BP-1 (polydimethylsiloxane), and BP-20 (polyethylene glycol). The oven temperature was programmed from 60 °C to 220 °C at 2 °C/min and then held isothermal at 220 °C for 20 min; injector temperature: 250 °C; detector temperature: 250 °C; carrier gas: hydrogen (0.8 mL/min); split: 1/60; injected volume: 0.5 µL. Retention indices (RI) were calculated relative to the retention times of a series of n-alkanes (C8–C29) with linear interpolation (“Target Compounds” software from PerkinElmer, Courtaboeuf, France). The quantification of volatile compounds was obtained using Relative Response Factor (RFF), calculated according to the International Organization of the Flavor Industry (IOFI) [32]. The relative proportion of each compound (expressed in g/100 g) was calculated using the amount of EO and reference (Methyl octanoate), peak area and relative response factors.

3.4. Gas Chromatography-Mass Spectrometry in Electron Impact Mode

Analyses were performed on Clarus SQ8S PerkinElmer TurboMass detector (quadrupole), directly coupled with a Clarus 580 PerkinElmer Autosystem XL (PerkinElmer, Courtaboeuf, France), equipped with a BP-1 (polydimethylsiloxane) fused-silica capillary column (50 m × 0.22 mm i.d., film thickness 0.25 µm). The oven temperature was programmed from 60 to 220 °C at 2°/min and then held isothermal for 20 min; injector temperature, 250 °C; ion-source temperature, 250 °C; carrier gas, Helium (1 mL/min); split ratio, 1:80; injection volume, 0.5 µL; ionization energy, 70 eV. The electron ionization (EI) mass spectra were acquired over the mass range 35–350 Da.

3.5. Gas Chromatography-High Resolution Mass Spectrometry

High-resolution EI-mass spectra were performed on Agilent 7200 GC-QTOF system (Agilent, Santa Clara, CA, USA) equipped with an Agilent J&W, VF-waxMS capillary column (30 m × 0.25 mm; 0.25 µm film thickness). The mass spectrometer was operating at 70 eV with an acquisition rate of 2 GHz over a 35−450 m/z range, affording a resolution of ∼8000. Injection volume 1 µL; split ratio 1:20; inlet temperature 250 °C, detector temperature 230 °C; column flow (Helium) 1.2 mL/min; temperature program for oven 60 °C (5 min isotherm) to 240 °C at 5 °C/min, then 10 min isotherm at 240 °C.

3.6. Nuclear Magnetic Resonance

All spectra were recorded on a Bruker AVANCE 400 Fourier transform spectrometer (Bruker, Wissembourg, France) operating at 400.132 MHz for 1H and 100.623 MHz for 13C, equipped with a 5 mm probe. Solvents used were CDCl3 and C6D6, with all shifts referred to internal TMS. The 1H-NMR spectra were recorded with the following parameters: pulse width (PW), 4.3 µs; relaxation delay 1 s and acquisition time 2.6 s for 32 K data table with a spectral width (SW) of 6000 Hz. 13C-NMR spectra of the oil samples and fractions of CC were recorded with the following parameters: pulse width = 4 µs (flip angle 45°); relaxation delay D1 = 0.1 s, acquisition time = 2.7 s for 128 K data table with a spectral width of 25,000 Hz (250 ppm); CPD mode decoupling; digital resolution = 0.183 Hz/pt. The number of accumulated scans was 3000 for each sample or fraction (40 mg, when available, in 0.5 mL of CDCl3 or C6D6). For the 2D spectra, sequences from Bruker TopspinTM (Bruker, Wissembourg, France) library (DEPT, COSY, HMBC and NOESY) and Gradient-enhanced sequences were used. 1D and 2D Spectra were processed via MestreNOVA software (version 12.0.0-20080, Mestrelab, Santiago de Compostela, Spain).

3.7. Identification of Individual Components

Identification of the individual components was based on (i) comparison of their GC retention indices on apolar and polar columns, with those of reference compounds [24,38]; (ii) computer search using digital libraries of mass spectral data [38,39,40]; (iii) 13C-NMR spectroscopy following a computerized method developed in our laboratory using a home-made software by comparison of the chemical shift values in EO or fraction spectrum with those of reference spectra compiled in the laboratory-built library [15,17]. In the investigated samples, individual components were identified by 13C-NMR at contents as low as 0.4–0.5%. A few compounds were identified by comparison with literature data.

3.8. Statistical Analysis

Data of the 30 investigated samples of N. acuminata were submitted to hierarchical cluster analysis (HCA) and principal component analysis (PCA) using XLSTAT software (Addinsoft, Paris, France) [41]. Only constituents in a concentration higher than 1.0% were used as variables for the PCA analysis.

3.9. In Vitro Anti-Inflammatory Capacity of Neuropeltis acuminata Leaf Essential Oil

The in vitro anti-inflammatory capacity of N. acuminata leaf EO (S24) was conducted by in vitro lipoxygenase inhibition assay [42,43,44]. Lipoxidase type I-B (Lipoxygenase, LOX, EC 1.13.11.12) from soybean purchased from Sigma-Aldrich (Saint-Quentin-Fallavier, France) was used for the in vitro analysis for LOX inhibitory activity. It was determined by continuously monitoring the formation of conjugated dienes of the 13-hydroperoxides of linoleic acid at 234 nm using a spectrophotometric method [42,43,44].
The LOX solution was prepared by dissolving around 5.7 units mL−1 of LOX in PBS (Phosphate Buffer Solution; 1 unit corresponding to 1 µmol of hydroperoxide formed per min). The S24 sample diluted in dimethyl-sulfoxide (DMSO) was used as inhibitor solution for LOX inhibition activity assay. Five concentrations were tested: 0.0125, 0.0250, 0.0500, 0.0800 and 0.1000 mg/mL.
The LOX inhibition assays were performed as previously described [44]. Briefly, 10 µL of LOX solution and 10 µL of inhibitor solution were mixed in 970 µL of boric acid buffer (50 mM; pH 9.0) and incubating them briefly at room temperature. The enzymatic reaction started by addition of 10 µL of substrate solution (Linoleic acid, 25 mM) and the reaction rate was recorded for 30 s at 234 nm. One measurement was carried out in the absence of inhibitor solution and another with DMSO mixed with distilled water (99.85% DMSO in distilled water) in order to evaluate a possible inhibitory effect of DMSO. LOX activity was not affected by DMSO and the measurement of the LOX activity without inhibitor solution was considered as control (100% enzymatic reaction). All measurements were performed in triplicate. The percentage of LOX inhibition was calculated according to the equation:
Inhibition % = (Vcontrol − VS24) × 100/Vcontrol
Vcontrol is the activity of LOX in absence of inhibitor solution and VS24 is the activity of LOX in presence of inhibitor solution [45]. The IC50 was calculated by the concentration of S24 in DMSO inhibiting 50% of LOX activity.

3.10. Spectral Data

Compound 49: 1,11-oxidocalamenene: C15H20O; 13C-NMR (CDCl3, 100 MHz) data: see Table 1. EI-MS 70 eV, m/z (rel. int.): 216(2, M•+), 174(12), 173(100), 159(8), 158(62), 157(13), 156(9), 144(7), 143(39), 142(16), 141(17), 129(8), 128(26), 115(10), 43(13).
Compound 93: atractylone: C15H20O; 13C-NMR (CDCl3, 100 MHz) data: see Table 1. EI-MS 70 eV, m/z (rel. int.): 217(7, M+1), 216(47, M•+), 201(10), 159(7), 145(13), 131(6), 121(10), 115(6), 109(14), 108(100), 105(7), 95(7), 93(13), 91(16), 79(21), 77(15), 65(6).
Compound 96: δ-cadinen-11-ol: C15H24O; 1H-NMR (CDCl3, 400 MHz) and 13C-NMR (CDCl3, 100 MHz) data: see Table 2. HREIMS: m/z 220.1829 (calculated for C15H24O, 220.1827); EI-MS 70 eV, m/z (rel. int.): 220(1, M•+), 202(41, M-H2O), 188(10), 187(73), 174(37), 162(44), 160(17), 159(100), 147(73), 145(27), 143(12), 134(67), 133(16), 131(26), 129(16), 128(14), 120(17), 119(80), 117(20), 115(17), 107(10), 106(18), 105(69), 93(17), 92(18), 91(67), 81(16), 79(24), 77(30), 67(10), 65(13), 59(57), 55(13), 53(10), 43(20), 41(28).
Compound 101: (E)-γ-bisabolen-12-al: C15H22O; 13C-NMR (CDCl3, 100 MHz) data: see Table 1. EI-MS 70 eV, m/z (rel. int.): 219(1, M + 1), 218(2, M•+), 135(41), 134(96), 121(22), 120(10), 119(54), 107(64), 105(29), 94(10), 93(100), 92(10), 91(55), 84(10), 79(49), 77(40), 67(10), 65(10), 55(33), 53(10), 43(22), 41(25).
Compound 102: (E)-γ-bisabolen-12-ol: C15H24O; 13C-NMR (CDCl3, C6D6, 100 MHz) data: see Table 1. EI-MS 70 eV, m/z (rel. int.): EI-MS 70 eV, m/z (rel. int.): 221(1, M + 1), 220(2, M•+), 202(5, M−H2O), 135(33), 134(70), 132(11), 121(21), 119(33), 107(77), 94(11), 93(100), 91(46), 81(10), 79(42), 77(32), 67(10), 55(28), 53(10), 43(32).

4. Conclusions

Thirty oil samples were extracted and investigated using combination of chromatographic [CC, GC(RI)] and spectroscopic [GC/MS, 13C-NMR] techniques. In total, 103 constituents accounting for 95.7 to 99.6% of the sample compositions were identified. Fractionation by CC led to the first-time isolation from natural source and structural elucidation by 1D and 2D-NMR spectroscopy of δ-cadinen-11-ol.
N. acuminata leaf EO is a complex mixture characterized by a preeminence of sesquiterpenes (87.1–98.1%) exhibiting various skeletons and a tremendous chemical variability. Contents of heat-sensitive compounds such as germacrene B, furanodiene and their corresponding rearranged products, γ-elemene and curzerene were determined by combination of GC(FID) and 13C-NMR data. This combination of techniques ensured a correct qualitative and quantitative analysis of the thermolabile compounds.
Statistical analysis exhibited five distinct chemical groups. Groups I, II, and V were characterized by high contents of sesquiterpene hydrocarbons (respectively, M = 58.6, 55.8, and 75.3%, vs. 34.5, 30.7, and 20.6% of oxygenated sesquiterpenes) whereas groups III and IV were dominated by oxygenated sesquiterpenes-rich oils (respectively, M = 49.1 and 67.7%, vs. 42.1 and 27.0% of sesquiterpene hydrocarbons). The observed chemical variability could be related to climatic and pedologic factors.
Concerning the anti-inflammatory activity, the low ratio between the two values of IC50 (EO vs. NDGA) makes it possible to consider the essential oil as a high inhibitor of the LOX activity.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/molecules27123759/s1, Figures S1–S8 (NMR spectra of compound 96: δ-cadinen-11-ol), Table S1 (Chemical composition of the 30 leaf essential oil samples from Neuropeltis acuminata) and Table S2 (Yields).

Author Contributions

Conceptualization, D.A.K., F.T. and J.B.B.; methodology, D.A.K. and F.T.; software, D.A.K., P.T. and M.P.; validation, P.T., J.B.B. and F.T.; formal analysis, D.A.K., A.C.L.K. and T.A.Y.; essential oil investigation, D.A.K., A.C.L.K. and T.A.Y.; Compounds isolation, D.A.K. and N.B.; in vitro anti-inflammatory activity investigation, S.V. and J.M.; writing—original draft preparation, D.A.K., N.B. and F.T.; writing—review and editing, D.A.K., N.B. and F.T.; visualization, D.A.K., P.T. and M.P.; supervision, F.T. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available in Supplementary Materials.

Acknowledgments

The authors gratefully acknowledge the University of Corsica for providing a post-doctoral grant to D.A. Kambiré. We acknowledge H. Téré for his valuable help in the plant identification.

Conflicts of Interest

The authors declare no conflict of interest.

Sample Availability

Samples of the essential oils are available from the authors.

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Molecules 27 03759 g001 550
Figure 1. Structures of isolated compounds 49, 93, 96, 101 and 102.
Figure 1. Structures of isolated compounds 49, 93, 96, 101 and 102.
Molecules 27 03759 g001
Molecules 27 03759 g002 550
Figure 2. Dendrogram of hierarchical cluster analysis (HCA) of the 30 leaf EO samples from N. acuminata.
Figure 2. Dendrogram of hierarchical cluster analysis (HCA) of the 30 leaf EO samples from N. acuminata.
Molecules 27 03759 g002
Molecules 27 03759 g003 550
Figure 3. Principal component analysis (PCA) of the 30 leaf EO samples from N. acuminata.
Figure 3. Principal component analysis (PCA) of the 30 leaf EO samples from N. acuminata.
Molecules 27 03759 g003
Table
Table 1. 13C-NMR data of compounds 49, 93, 101, and 102.
Table 1. 13C-NMR data of compounds 49, 93, 101, and 102.
N °C4993101102
Exp[20]Exp[21]Exp[22]ExpExp *[23] *
171.9071.937.3537.526.6426.526.8727.2427.2
221.0921.139.3139.431.7231.631.7932.0531.9
332.0332.023.5923.5134.09134.1134.82135.39135.2
443.5243.536.6536.8120.53120.4120.73121.18121.0
5120.25120.2149.41149.529.7429.629.7127.2429.9
6136.50136.545.7545.9129.94129.8128.67128.93128.7
7125.29125.320.9021.0124.29124.3125.56125.63125.4
8126.48126.5116.15116.332.4432.333.7734.2334.1
9138.90138.9149.83150.028.1228.126.5526.9526.8
10142.15142.141.9642.1154.39154.9126.11125.45125.4
1173.7273.7119.55119.7139.40139.2134.16133.91133.8
1229.3629.4136.96137.1195.24195.668.9668.6368.3
1327.7827.88.158.39.149.213.6013.6213.6
1422.1222.117.5617.718.2418.218.3618.4918.4
1521.3721.4107.28107.423.3423.423.4023.5623.5
Exp: Experimental NMR data recorded in CDCl3; *: NMR data recorded in C6D6.
Table
Table 2. 1D and 2D-NMR data of δ-cadinen-11-ol (compounds 96).
Table 2. 1D and 2D-NMR data of δ-cadinen-11-ol (compounds 96).
N°Cδ 13C (ppm)DEPTδ 1H (ppm)Multiplicity
(J, Hz)		COSYHMBCNOESY
1130.26C–––––
227.45CH2α2.70ddd (12.0, 4.5, 2.6)2β,35,7,10,3,6,4,12β,3,9,14
β1.98m2α,31,3,4,6,102α,3,6
332.32CH22.04m3,2α2,1,42α,2β,15
4134.13C–––––
5128.74CH5.71sept (1.5)615,3,6,7,16,15
638.58CH2.79br s5,7–2β,5,9,8β,12,13
749.85CH1.41ddd (11.0, 8.1, 3.1)6,81,5,6,8,9,11,12,139
824.53CH2α1.69m7,9,8β9,6,7,11,108β,9
β1.35m7,9,8α6,7,10,11,12,136,8α,9
931.40CH21.95m9, 8b, 8a1,10,7,8,142α,6,7,8α,8β,14
10124.12C–––––
1174.57C–––––
1226.58CH31.23s–8,13,7,116
1329.97CH31.29s–8,12,6,7,116
1418.55CH31.67br s–1,10,92α,9
1523.41CH31.64br s–3,5,43,5
Table
Table 3. Chemical composition of five leaf EO samples from N. acuminata.
Table 3. Chemical composition of five leaf EO samples from N. acuminata.
N°Compounds aRIl bRIaRIpRRFS3 (%)S6 (%)S13 (%)S20 (%)S24 (%)Identification
1(Z)-Hex-3-en-1-ol83784013880.8260.10.10.1tr–RI, MS
2Hexanol85185413550.8260.1–0.10.1trRI, MS
3α-Thujene93292310200.7650.20.20.1–0.1RI, MS, 13C-NMR
4α-Pinene93693110160.7650.1trtrtr0.2RI, MS, 13C-NMR
5Sabinene97396611270.7650.60.30.50.10.6RI, MS, 13C-NMR
6β-Pinene97897111160.7650.4trtrtr0.2RI, MS, 13C-NMR
7Myrcene98798111660.7650.10.1–trtrRI, MS
8α-Terpinene1013101011860.7650.1–0.1–0.1RI, MS
9β-Phellandrene *1023102212150.698–tr0.1–0.1RI, MS
10Limonene *1025102212050.7650.10.1–tr0.1RI, MS
11(Z)-β-Ocimene1029102612370.765tr0.10.1–0.3RI, MS, 13C-NMR
12(E)-β-Ocimene1041103712550.7651.20.81.51.71.2RI, MS, 13C-NMR
13γ-Terpinene1051104912500.765tr0.20.1–0.2RI, MS, 13C-NMR
14Terpinolene1082107912880.7650.20.10.1–0.2RI, MS, 13C-NMR
15Linalool1086108515500.869tr0.1tr0.1trRI, MS
16Terpinen-4-ol1164116316040.8690.10.1tr–trRI, MS
17Neral1215121716800.8870.20.10.1–0.2RI, MS, 13C-NMR
18Geraniol1235123618370.8690.10.20.2–0.1RI, MS, 13C-NMR
19Geranial1244124417320.8870.10.10.1–0.1RI, MS
20Thymol1267126821900.8081.3trtrtrtrRI, MS, 13C-NMR
21Carvacrol1278127722280.8080.10.1tr––RI, MS
22Cogeijerene1285 c128215400.8080.10.10.2trtrRI, MS, 13C-NMR
23Bicycloelemene1338133214830.7510.1tr0.1–0.1RI, MS
24δ-Elemene1340133514720.7510.40.22.20.22.6RI, MS, 13C-NMR
25α-Cubebene1355134814590.7510.10.2tr–0.1RI, MS, 13C-NMR
26Cyclosativene1378136914830.7510.10.10.1–0.1RI, MS
27α-Ylangene1376137114680.7510.10.10.1tr–RI, MS
28α-Copaene1379137514930.7510.10.10.1trtrRI, MS
29β-Bourbonene1378138315200.7510.10.1tr–0.1RI, MS
30β-Cubebene *1390138715390.7510.20.30.40.11.0RI, MS, 13C-NMR
31β-Elemene *1389138715910.7514.40.61.64.61.2RI, MS, 13C-NMR
32Cyperene1402139915280.7510.20.10.2–trRI, MS, 13C-NMR
33α-Gurjunene1413140915310.7510.7tr0.20.1trRI, MS, 13C-NMR
34(E)-β-Caryophyllene1421141715970.7511.83.420.034.41.0RI, MS, 13C-NMR
35β-Copaene1430142615910.7510.50.10.70.13.1RI, MS, 13C-NMR
36γ-Elemene #1429142716400.7515.50.31.30.31.1RI, MS, 13C-NMR
37trans-α-Bergamotene1434143215860.7510.1trtrtr0.4RI, MS, 13C-NMR
38α-Guaiene1440143515910.751tr0.1–tr0.2RI, MS, 13C-NMR
39Sesquisabinene A1435143616470.751trtrtrtr0.6RI, MS, 13C-NMR
40Guaia-6,9-diene1443143716060.751trtr0.10.10.3RI, MS, 13C-NMR
41β-Gurjunene (Calarene)1437144415910.7510.10.10.10.10.2RI, MS, 13C-NMR
42(E)-β-Farnesene1446144616610.7510.10.40.1tr0.6RI, MS, 13C-NMR
43α-Humulene1455145016700.7515.81.62.727.11.7RI, MS, 13C-NMR
44cis-β-Bergamotene1435 d145216710.7510.30.20.21.1trRI, MS, 13C-NMR
45allo-Aromadendrene1462145616400.7510.2tr0.10.20.1RI, MS, 13C-NMR
46Ishwarane1468146116450.7510.1tr0.3––RI, MS, 13C-NMR
47γ-Muurolene1474146916880.7510.1tr0.20.10.1RI, MS, 13C-NMR
484,5-diepi-Aristolochene1470147117050.7510.3–tr––RI, MS, 13C-NMR
491,11-Oxidocalamenene1474147218830.8301.00.40.52.70.1RI, MS, 13C-NMR
50Germacrene D1479147517090.7513.01.15.21.010.2RI, MS, 13C-NMR
51trans-β-Bergamotene1480147816840.7510.1trtr–0.1RI, MS
52β-Selinene1486148117180.7510.50.30.20.40.3RI, MS, 13C-NMR
53Furanodiene #1485148218730.8530.40.10.40.33.9RI, MS, 13C-NMR
54Furano-elemene (Curzerene) #1485148418730.8530.1tr0.1tr0.1RI, MS
554-epi-Cubebol1490148718710.8190.20.4–––RI, MS, 13C-NMR
56Bicyclogermacrene1494149017320.7510.90.70.70.30.1RI, MS, 13C-NMR
57α-Selinene1494149117230.7510.70.20.40.22.2RI, MS, 13C-NMR
58α-Muurolene1496149417050.7512.82.21.06.60.3RI, MS, 13C-NMR
59β-Bisabolene1503150017270.7510.80.90.40.21.5RI, MS, 13C-NMR
60Cubebol1514150518850.819trtr0.7tr0.2RI, MS, 13C-NMR
61γ-Cadinene1507150717580.7510.1–0.1–0.1RI, MS
62(Z)-γ-Bisabolene1505151017320.7510.1trtr0.10.1RI, MS
63δ-Cadinene1520151417580.7512.40.88.40.97.0RI, MS, 13C-NMR
64Kessane1533152117610.7515.22.311.52.7–RI, MS, 13C-NMR
65(E)-γ-Bisabolene1521152217580.7511.10.4trtr3.4RI, MS, 13C-NMR
66Selina-4(15),7(11)-diene1534152817780.7510.58.30.10.10.2RI, MS, 13C-NMR
67β-Elemol1541153420790.8190.64.41.20.91.8RI, MS, 13C-NMR
68Selina-3,7(11)-diene1542153717780.7510.2trtrtr0.2RI, MS, 13C-NMR
69cis-Cadinene ether1551154518600.830––0.4–trRI, MS, 13C-NMR
70(E)-Nerolidol1553154820420.8190.523.31.60.70.2RI, MS, 13C-NMR
71Germacrene B #1552155118290.75115.50.93.20.73.5RI, MS, 13C-NMR
72Palustrol1569156119240.8191.51.20.20.1trRI, MS, 13C-NMR
73cis-Sesquisabinene hydrate1565e156420810.8190.1tr0.60.1trRI, MS, 13C-NMR
74Caryophyllene oxide1578157019780.8300.1tr0.32.5trRI, MS, 13C-NMR
75Curzerenone1588157520250.841–––0.10.3RI, MS, 13C-NMR
767-epi-cis-Sesquisabinene hydrate1579 e157620990.8190.3tr0.7tr0.1RI, MS, 13C-NMR
77Viridiflorol1592158120810.8190.9tr0.10.20.2RI, MS, 13C-NMR
78Guaiol1593158420880.8190.612.22.31.811.6RI, MS, 13C-NMR
79Ledol *1600159320250.81912.50.31.31.00.2RI, MS, 13C-NMR
80Copaborneol *1595159321830.8191.4tr0.1–0.2RI, MS, 13C-NMR
81Eudesm-5-en-11-ol1600 f159521320.819tr0.20.3tr0.8RI, MS, 13C-NMR
82neo-Intermedeol1601 g159921460.8190.1trtrtr0.2RI, MS, 13C-NMR
83epi-Cubenol1602160620480.819tr0.20.20.40.3RI, MS, 13C-NMR
84Alismol1619161022480.830tr–tr0.50.1RI, MS, 13C-NMR
85Eremoligenol1614161421960.8190.1––tr0.2RI, MS, 13C-NMR
8610-epi-γ-Eudesmol1609161720960.8191.40.31.3tr0.3RI, MS, 13C-NMR
87τ-Cadinol1633162521750.8190.3–0.2tr0.4RI, MS, 13C-NMR
88τ-Muurolol1633162821840.8190.70.20.8tr0.7RI, MS, 13C-NMR
89α-Muurolol1618 h163022120.8190.2tr0.60.10.2RI, MS, 13C-NMR
90β-Eudesmol1641163422250.8190.26.31.90.70.5RI, MS, 13C-NMR
91α-Cadinol1643163722280.8191.20.70.5trtrRI, MS, 13C-NMR
92α-Eudesmol1653163822160.819tr2.10.6trtrRI, MS, 13C-NMR
93Atractylone1652 i163921210.8411.03.32.71.510.0RI, MS, 13C-NMR
94Intermedeol1626 h164122490.8190.10.80.20.2trRI, MS, 13C-NMR
95Bulnesol * 1665165122070.8190.45.21.51.06.2RI, MS, 13C-NMR
96δ-Cadinen-11-ol *j165122710.8190.82.90.20.11.8RI, MS, 13C-NMR
97α-Bisabolol1673166622080.8190.3tr0.50.10.6RI, MS, 13C-NMR
98epi-α-Bisabolol1667 k166822140.8190.2–0.2–0.1RI, MS, 13C-NMR
99Cadina-1(10),4-dien-8α-ol1682167123060.819–0.48.10.40.3RI, MS, 13C-NMR
100Germacrone1684167322210.8410.80.2tr0.10.1RI, MS, 13C-NMR
101(E)-γ-Bisabolen-12-al1790 l176123480.8410.71.1trtr1.9RI, MS, 13C-NMR
102(E)-γ-Bisabolen-12-olj177625490.8196.12.51.00.37.1RI, MS, 13C-NMR
103(E)-Phytol2114209826090.9740.40.30.10.10.1RI, MS, 13C-NMR
Monoterpene hydrocarbons 3.01.92.61.83.3
Oxygenated monoterpenes 1.90.70.40.10.4
Sesquiterpene hydrocarbons 55.426.262.281.743.8
Oxygenated sesquiterpenes 34.868.731.315.850.7
Other compounds 0.60.40.30.20.1
Total 95.797.996.899.698.3
a Order of elution and percentages are given on an apolar column (BP-1), except components with an asterisk (*), where percentages are taken on a polar column (BP-20). (#) Thermolabile compound (Cope rearrangement under our GC conditions), percentage evaluated by a combination of GC-FID and 13C-NMR data [15,19]. b RIl: Retention indices reported in the Terpenoids Library Website [24] or in reference c [25]; d [25]; e [26]; f [27]; g [28]; h [29]; i [30]; k [31]; l [22]; j RI not found in literature, compounds isolated for the first time from EO. RIa, RIp: retention indices measured on apolar and polar capillary column, respectively. RRF: relative response factors calculated using methyl octanoate as internal standard (see experimental [32]). The relative proportions of constituent are expressed in g/100 g. (–): not detected; tr: traces level (<0.05%). 13C-NMR: compounds identified by NMR in the EO samples and obvious in at least one fraction of chromatography; 13C-NMR (italic): compounds identified by NMR in fractions of CC.
Table
Table 4. Chemical variability of the main constituents of leaf essential oil from Neuropeltis acuminata.
Table 4. Chemical variability of the main constituents of leaf essential oil from Neuropeltis acuminata.
Component [a]RIa [b]RIp [b]Group IGroup IIGroup IIIGroup IVGroup V
M% ± SDMinMaxM% ± SDMinMaxM% ± SDMinMaxM% ± SDMinMaxM% ± SDMinMax
β-Elemene138715912.2 ± 0.91.13.74.6 ± 0.54.15.21.4 ± 0.21.11.70.8 ± 0.30.51.13.1 ± 1.12.14.6
(E)-β-Caryophyllene1417159717.6 ± 4.212.525.02.6 ± 1.41.64.71.1 ± 0.11.01.23.3 ± 3.60.99.436.6 ± 5.932.545.4
γ-Elemene #142716401.5 ± 0.70.93.25.0 ± 0.84.15.81.2 ± 0.40.82.00.4 ± 0.20.20.70.5 ± 0.30.30.9
α-Humulene145016702.5 ± 1.31.15.26.6 ± 2.15.09.71.3 ± 0.30.51.71.0 ± 0.60.51.818.9 ± 12.16.331.2
Germacrene D147517094.3 ± 1.13.05.83.5 ± 1.42.45.610.6 ± 1.69.014.41.2 ± 0.50.52.01.7 ± 0.81.02.4
Furanodiene #148218730.2 ± 0.2tr0.40.6 ± 0.70.11.64.0 ± 1.22.25.90.3 ± 0.20.10.60.4 ± 0.20.20.6
α-Muurolene149417051.2 ± 0.80.22.52.0 ± 1.30.12.90.1 ± 0.1tr0.32.7 ± 0.52.23.46.2 ± 3.52.810.9
δ-Cadinene151417586.2 ± 3.41.812.02.2 ± 0.61.32.87.3 ± 0.46.57.80.8 ± 0.30.51.20.9 ± 0.40.41.4
Kessane1521176110.3 ± 9.91.432.54.8 ± 0.64.25.5–––1.6 ± 1.30.12.71.2 ± 1.10.42.7
Selina-4(15),7(11)-diene152817781.0 ± 1.5tr4.30.5 ± 0.10.30.50.2 ± 0.1tr0.39.5 ± 1.77.411.21.1 ± 1.10.12.2
β-Elemol153420792.2 ± 1.11.04.00.5 ± 0.3tr0.81.8 ± 0.31.52.54.5 ± 0.53.95.01.6 ± 0.90.92.9
(E)-Nerolidol154820421.9 ± 2.1tr6.60.6 ± 0.10.40.70.2 ± 0.00.20.223.8 ± 5.415.830.83.0 ± 3.40.37.8
Germacrene B #155118293.4 ± 0.82.24.813.4 ± 3.110.216.63.4 ± 1.02.35.10.4 ± 0.5tr0.91.3 ± 0.70.72.2
Guaiol158420884.2 ± 2.52.07.80.4 ± 0.3tr0.711.4 ± 2.06.913.212.4 ± 1.310.913.82.5 ± 0.81.83.5
Ledol159320253.4 ± 3.10.48.210.6 ± 2.77.313.20.2 ± 0.2tr0.60.6 ± 0.8tr1.91.8 ± 1.10.72.9
Atractylone163921211.9 ± 1.2tr3.31.2 ± 1.4tr3.29.6 ± 2.34.812.13.0 ± 0.32.63.31.5 ± 0.50.82.1
Bulnesol165122072.5 ± 1.21.44.20.4 ± 0.10.20.55.9 ± 1.23.27.26.5 ± 1.15.27.61.7 ± 0.91.03.0
Cadina-1(10),4-dien-8α-ol167123063.6 ± 4.8tr12.1–––0.3 ± 0.10.10.60.1 ± 0.2tr0.40.6 ± 0.7tr1.6
(E)-γ-Bisabolen-12-ol177625491.0 ± 0.40.41.65.8 ± 0.45.26.17.3 ± 1.35.39.44.4 ± 2.62.58.80.8 ± 0.50.31.4
[a] Order of elution and percentages on apolar column (BP-1), except components with a hash (#), percentages calculated by combination of GC(FID) and 13C-NMR; [b] RIa, RIp: Retention indices measured on apolar and polar capillary column respectively; M% ± SD: mean percentage and standard deviation; (–): not detected; tr: traces level (<0.05%).
Table
Table 5. In vitro anti-inflammatory activity of Neuropeltis acuminata leaf essential oil.
Table 5. In vitro anti-inflammatory activity of Neuropeltis acuminata leaf essential oil.
Anti-Inflammatory Activity (Percentage Inhibition of LOX)IC50 (mg mL−1)
Oil concentration (mg mL−1)Inhibition (%)Essential oil0.059 ± 0.001
0.012515.20 ± 0.30*NDGA0.013 ± 0.003
0.025024.59 ± 1.42
0.050047.35 ± 2.09
0.080064.92 ± 2.87
0.100081.87 ± 0.33
Values are means of triplicates ± standard deviation; *NDGA: NorDihydroGuaiaretic Acid.
Table
Table 6. Fractions obtained from column chromatography.
Table 6. Fractions obtained from column chromatography.
Fraction
Sample		F1
P
100%		F2
P
100%		F3
P/DE 98/2		F4
P/DE 95/5		F5
P/DE 90/10		F6
P/DE 80/20		F7
DE
100%
S3 (2.605 g)0.9280.6120.1150.1590.4560.2190.024
S6 (3.280 g)0.6980.2240.1740.0491.5420.5150.011
S13 (2.318 g)1.1090.3490.1070.0950.2320.2900.019
S20 (2.148 g)1.3110.4230.1550.0190.1310.0370.014
S24 (4.110 g)1.4110.5360.6860.0580.9290.3990.033
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Kambiré, D.A.; Kablan, A.C.L.; Yapi, T.A.; Vincenti, S.; Maury, J.; Baldovini, N.; Tomi, P.; Paoli, M.; Boti, J.B.; Tomi, F. Neuropeltis acuminata (P. Beauv.): Investigation of the Chemical Variability and In Vitro Anti-inflammatory Activity of the Leaf Essential Oil from the Ivorian Species. Molecules 2022, 27, 3759. https://doi.org/10.3390/molecules27123759

AMA Style

Kambiré DA, Kablan ACL, Yapi TA, Vincenti S, Maury J, Baldovini N, Tomi P, Paoli M, Boti JB, Tomi F. Neuropeltis acuminata (P. Beauv.): Investigation of the Chemical Variability and In Vitro Anti-inflammatory Activity of the Leaf Essential Oil from the Ivorian Species. Molecules. 2022; 27(12):3759. https://doi.org/10.3390/molecules27123759

Chicago/Turabian Style

Kambiré, Didjour Albert, Ahmont Claude Landry Kablan, Thierry Acafou Yapi, Sophie Vincenti, Jacques Maury, Nicolas Baldovini, Pierre Tomi, Mathieu Paoli, Jean Brice Boti, and Félix Tomi. 2022. "Neuropeltis acuminata (P. Beauv.): Investigation of the Chemical Variability and In Vitro Anti-inflammatory Activity of the Leaf Essential Oil from the Ivorian Species" Molecules 27, no. 12: 3759. https://doi.org/10.3390/molecules27123759

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