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International audience; Objective: To evaluate the antimicrobial potency of Rosmarinus eriocalyx (R. eriocalyx) essential oil and total polyphenols against pathogenic microorganisms.Methods: Antimicrobial activity of R. eriocalyx extracts was assessed by disc diffusion method and minimum inhibitory concentrations determination. Essential oil obtained from endemic rosemary by hydrodistillation was analysed by gas chromatograph/retention index and gas chromatograph-mass spectrometer.Results: An interesting antimicrobial activity was shown by R. eriocalyx extracts. Polyphenols, constituted mainly by flavonoids, were the most effective extract with very low minimum inhibitory concentrations values, ranged between 0.06 and 8.00 mg/mL, while essential oil was less efficient. It should be noted that antimicrobial activities of both R. eriocalyx extracts were more directed against fungi and Gram-positive bacteria than Gram-negative ones, in whichStaphylococcus aureus, Enterococcus faecalis, and Candida albicans were the most sensitive strains. Concerning chemical composition of R. eriocalyx essential oil, camphor (37.8%), 1,8-cineole (17.4%), camphene (13.3%), and α-pinene (10.9%) were the major compounds.Conclusions: The findings of the present study indicate that R. eriocalyx extracts possess significant bactericidal and fungicidal activities. Because of its richness in essential oil, and especially flavonoids, R. eriocalyx may be a source for effective and safe antimicrobial agents.

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International audience; Chemical and genetic diversity of Teucrium polium L. subsp. polium from western Algeria and T. polium L. subsp. capitatum from Corsica were investigated. Diversity within and among the two populations of subspecies was assessed according to the chemical composition of their essential oils and the genetic diversity. Chemical analysis was performed using a combination of capillary GC-RI and GC/MS after fractionation using column chromatography. Genetic structures were mapped using three polymorphic genetic markers: two chloroplast markers (RPL32-TRNL and TRNL-F) and ribosomal nuclear markers (ITS region). The statistical analysis showed that both subspecies were clearly distinguished by these chemical and genetic markers. The oil chemical compositions differed qualitatively and quantitatively between the subspecies. Both collective oils were dominated by hydrocarbon compounds however the Algerian sample oils exhibited higher amounts of hydrocarbon sesquiterpenes than those of Corsica (31.2 g/100 g vs. 4.4 g/100 g) while the latter displayed higher amounts of hydrocarbon monoterpenes than the first (59.3 g/100 g vs. 34.3 g/100 g). Neighbor-joining, Maximum likelihood and Bayesian trees constructed from chloroplast markers and nuclear ITS region sequences showed the existence of two groups associated with taxonomic and chemical characteristics. The study indicated that variation in the essential oil composition within subspecies depends on genetic background. The samples of subsp. capitatum from Corsica are a homogeneous group, in contrast to samples of subsp. polium from Algeria which were clustered in two groups. Chemical and genetic diversity of Algerian populations could be explained by geographical isolation of the populations. In addition, the morphological polymorphism observed throughout the colour of flowers could be explained by environmental parameters as well as the soil pH.

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International audience; The chemical composition of Phagnalon sordidum (L.) essential oil was investigated for the first time using gas chromatography and chromatography/mass spectrometry. Seventy-six compounds, which accounted for 87.9% of the total amount, were identified in a collective essential oil of P. sordidum from Corsica. The main essential oil components were (E)--caryophyllene (14.4%), -pinene (11.0%), thymol (9.0%), and hexadecanoic acid (5.3%). The chemical compositions of essential oils from 19 Corsican locations were investigated. The study of the chemical variability using statistical analysis allowed identifying direct correlation between the three populations of P. sordidum widespread in Corsica and the essential oil compositions they produce. The in vitro antimicrobial activity of P. sordidum essential oil was evaluated and it exhibited a notable activity on a large panel of clinically significant microorganisms.

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International audience; The chemical composition of the essential oils isolated from the aerial parts of Micromeria inodora (Desf.) Benth. collected in 24 Algerian localities was investigated from the first time using GC-FID, GC/MS and 13C-NMR. Altogether, 83 components which accounted for 94.7 % of the total oil composition were identified. The main compounds were trans-sesquisabinene hydrate (1; 20.9 %), α-terpinyl acetate (2; 19.8 %), globulol (3; 4.9 %), caryophyllene oxide (4; 4.3 %), β-bisabolol (5; 2.9%) and trans-7-epi-sesquisabinene hydrate (6; 2.6%). Comparison with the literature highlighted the originality of the Algerian M. inodora oil and indicated that 1 might be used as taxonomical marker. The study of the chemical variability allowed the discrimination of two main clusters confirming that there is a relation between the essential-oil compositions and the soil nature of the harvest locations. Biological activity of M. inodora essential oil was assessed against fourteen species of microorganisms involved in nosocomial infections using paper disc diffusion and dilution agar assays. The in vitro study demonstrated a good activity against Gram-positive strains such as S. aureus, B. cereus, B. subtilis and E. faecalis, and moderate activity against Candida albicans. These results might be useful for the future commercial valorization of M. inodora essential oil as a promising source of natural products with potential against various nosocomial community and toxinic infections.

International audience; The extract (E) and oil of Melissa Officinalis leaves (EO) have been evaluated as a corrosion inhibitors for carbon steel in 1.0 M HCl solution by means of weight loss measurements, potentio dynamic polarization, and electro chemical impedance spectroscopy (EIS). Tafel polarization study revealed that extract (E) and oil of Melissa Officinalis (EO) act as a mixed type inhibitors. The Nyquist plots showed that with increasing the inhibitors concentrations, the charge-transfer resistance increased and the double-layer capacitance decreased, involving increased inhibition efficiency. The inhibition was found to increase with increasing the concentration of the extract (E) and oil of Melissa Officinalis (EO). The values of inhibition efficiency calculated from weight loss, Tafel polarization curves, and EIS were in good agreement. The effect of temperature on the corrosion behaviour of mild steel in 1.0 M HCl with addition of both extract (E) and oil of Melissa Officinalis (EO) was also studied and thermodynamic parameters were determined and discussed.

International audience; The effect of four cultivation parameters (postmaturity harvest date, storage period at 0 °C, and input of nitrogen and potassium fertilizers) on the mineral composition of kiwi fruit (Actinidia deliciosa var. Hayward) from Corsica were evaluated. The kiwi fruit were harvested on three dates at two-week intervals and some fruit were stored for three and four months. The kiwi fruit orchard was fertilized with controlled levels of nitrogen (five levels) and potassium (three levels) during one growing season. The concentrations of 67 elements in kiwi fruit were measured using various analytical methods, such as flow injection spectrophotometry, flame atomic absorption spectrometry, flame atomic emission spectrometry, electrothermal atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry, and filtration. The main elements in kiwi fruit are K, N, Cl, P, and Si and, to a lesser amount, Ca, Mg, Na, and Fe. This study demonstrates a high degree of difference in the amount of 23 mineral elements depending on the harvest date, the time of storage, and the input of fertilizers.

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International audience; This work reports for the first time the anti-MRSA activity of the essential oil and ethanol extract of Lavandula multifida L. on clinical and reference strains of methicillin-resistant Staphylococcus aureus (MRSA). Hospitalized patients with infected wounds at the University Hospital of Tlemcen constitute the source of collection for different clinical isolates used in this study. The oils of fresh samples were obtained by hydrodistillation at three developmental stages (before inflorescence, full-inflorescence and afterinflorescence). The oils from the aerial parts of L. multifida were analyzed at three developmental stages. Oil yield was found to vary depending on the stage of development and the highest content of oil (0.2% w/w) was obtained at full-inflorescence. The chemical composition of essential oils studied by GC and GC-MS showed that the main components were carvacrol (from 27.5 to 57%), β-bisabolene (from 25.2 to 38.4%) and caryophyllene oxide (from 3.5 to 7.5%). The Anti-MRSA activity of L. multifida essential oil and ethanol extract was tested by using disc diffusion method and microtiter plates perform for determining their minimum inhibitory concentration (MIC) values. We found a good anti-MRSA activity of L. multifida essential oil since the inhibition diameters reached 27 mm and MICs were lower than 0.1 μl/ml, whereas the ethanol extract was less active. These results seem to be interesting for applications of L. multifida essential oil to fight against MRSA.

International audience; Known therapeutic applications of medicinal plants were made of them an alternative to synthetic compounds. In this situation, the present study was designed to give more knowledge and helping to exploit the leaves of Thymus algeriensis by determining the chemical composition of its essential oil, the phenolic content of the aqueous extract and evaluate the antioxidant and anticorrosive activity. The essential oil was characterized by Geranyl acetate (80.8%) as mainly compound. The aqueous extract has exhibited a moderate antioxidant activity against free radical DPPH. On the other hand, this work describes the successful performance of T. algeriensis as an eco-friendly corrosion inhibitor for acidic media. The corrosion inhibiting effect of the extract and the essential oil of T. algeriensis (TAE & TAO) on mild steel in 0.5 M H 2 SO 4 solution was investigated by electrochemical studies in the presence of different concentrations of TAE & TAO ranging from 0.25 g/L to 2 g/L. Potentiodynamic polarization showed that TAE and TAO behaves as mixed type inhibitors. Nyquist plots show that the efficiency of inhibition increases with increasing concentration of T. algeriensis and the increased charge transfer resistance.

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International audience; Thymus Capitatus is a shrub, which is native of the Mediterranean basin. The purpose of this study was to determine the chemical composition and inhibitory effect of essential oil of Thymus Capitatus on the corrosion of mild steel in hydrochloric acid (1M).The essential oil of Thymus Capitatus has been studied using gas chromatography (GC) and GC-mass spectrometry (GC-MS). 91.2% of the components are detected (32 components) and the major components were, p-Cymene(18.9%), carvacrol (13.4%), acetate of geranyl (12.2%), borneol (10.2%), Camphene (3.9%), α-pinene (2.9%) and trans caryophyllene (2.9%).The inhibitory effect of essential oil of Thymus Capitatus was estimated on the corrosion of mild steel in 1M in Hydrochloric acid (HCl) using weight loss, Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization curves. The results of the polarization curves show that the corrosion current density decreases 698μA/cm2 to 290μA/cm2 after addition of the inhibitor (essential oil of Thymus Capitatus), the charge transfer resistance increases 49 ohm.cm2 to 101 ohm.cm2 in the electrochemical impedance spectrum after addition of the inhibitor. The inhibition of the compound effect is attributed to the formation of afilm on the surface of the steel.

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International audience; The analysis of Mentha rotundifolia L. essential oil by Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC/MS) allowed the identification of 25 components, which accounted for 94.3% of the total oil. Pulegone (69.1%) and menthone (18.5%) were identified as main compounds. The inhibitive effect of this essential oil on the corrosion of mild steel in 1M HCl solution has been investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The gravimetric results indicate that MR oil exhibits good inhibition efficiency in 1M HCl solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 303–333K. Polarization measurements showed that the studied inhibitor is mixed type with significant reduction of cathodic and anodic current densities. Electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance increases with increase in the concentration of essential oil. Various activation parameters such as activation energy, activation enthalpy and activation entropy are evaluated and discussed. Adsorption thermodynamic parameters are also computed. Linearity of Langmuir isotherm adsorptions indicated the monolayer formation of inhibitor on mild steel surface.

International audience; Essential oil from Tropaeolum majus L. aerial parts, a plant native to North Western Algeria, was obtained by hydrodistillation. The oil volatile components were identified by a combination of gas chromatography/flame ionization detection (GC/FID), GC-mass spectrometry (GC-MS) techniques, and NMR spectroscopy. Nine components representing 92.0 % of the essential oil total (GC/FID chromatogram) were identified. The most abundant compounds were benzyl isothiocyanate (82.5 %), benzene acetonitrile (3.9 %) and 2-phenylethyl isovalerate (2.9 %). Higher content in nitrogen- and sulfur-containing compounds accounting to 86.4 % of the volatile fraction composition of T. majus were quantified.

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Chikungunya fever is caused by an arthropod-borne virus that is associated with massive epidemics and severe morbidity (virus-induced arthralgia, fever, myalgia and rashes). Worldwide expansion of the mosquito vectors, such as Aedes albopictus ("Tiger moquito) is responsible for the spread of Chikungunya virus (CHIKV) throughout the world. A. albopictus has spread throughout Mediterranean areas, which could lead to epidemics outbreaks. Currently, no antiviral drugs or vaccines are available for the treatment or prevention of CHIKV infection. Since ten years, however, recent results showed that diterpene esters from Trignostemon (Euphorbiaceae) possess inhibiting activity of CHIKV replication.With the objective to discover new compounds with antiviral activities, 45 extracts from various plant parts of 11 Euphorbiaceae species native to Corsica were evaluated for selective inhibition of CHIKV replication. In collaboration with Dr. Leyssen (KU Leuven, Belgium), several extracts made from 10 Euphorbia species exhibited significant and selective anti-CHIKV activity in a virus-cell-based assay. The antiviral activities of 29 commercially available phorboïds were studied. Some phorboïds were potent inhibitors of CHIKV and human immunodeficiency virus (VIH) replication. Results allowed drawing new structure-activity relationships, which supported the hypothesis that PKC may be an important target in CHIKV replication. In order to confirm or infirm the presence of phorboïds with anti-CHIKV activity in Euphorbia extracts, a liquid chromatography (LC) coupled to linear ion trap mass spectrometry (MSn) method was developed using standard compounds. Application of this methodology indicated that none anti-CHIKV phorboïds was present in Euphorbia extracts. A second LC-MSn procedure was developed to profile untargeted phorboïdes. Results suggested that numerous other diterpene esters were present in the Euphorbia extracts. The species Euphorbia amygdaloides ssp. semiperfoliata was selected to perform a bioassay-guided purification procedure, which led to the isolation and identification of 14 jatrophane esters, including eight new components. Among them, antiviral evaluation indicated that one jatrophane ester was possessing anti-CHIKV and anti-HIV activities. Furthermore, the structure of an atypical jatrophane ester derivative, jatrohemiketal, was determined unambiguously through an original strategy combining NMR spectroscopy and molecular modeling. Finally, an original tandem mass spectrometry (MS/MS)-targeted supercritical fluid chromatography (SFC) method was developed and used to study bioactive fractions of E. amygdaloïdes ssp. semiperfoliata. The MS/MS data were analyzed by molecular networking. Thanks to this approach, four 4-deoxyphorbol esters and two new jatrophane esters were targeted, isolated and identified. Collaboration with the group of Pr. Alcami (CNM, Espagne) was started to explore the anti-HIV properties of the isolated diterpene esters. Thus, one compound derived from 4-deoxyphorbol esters proved to possess a potent inhibiting activity of HIV-1 replication (IC50 = 8 nM, and selectivity index > 6250). The investigation of the mechanism of this component indicated that it acted like prostratin, but with antiviral effect more than 28-fold. Furthermore, the evaluation of the anti-CHIKV activity indicated that another 4-deoxyphorbol derivative was one of the strongest inhibitor of CHIKV replication isolated up to date (EC50 = 0.34 ± 0.12 µM and selectivity index > 638)., Le chikungunya est une maladie transmise par des moustiques du genre Aedes (dont A. albopictus, dit "moustique tigre"). Cette maladie provoque d'intenses fièvres et des douleurs articulaires chroniques fortement invalidantes. Les moustiques potentiellement vecteurs du virus du chikungunya (CHIKV) sont des espèces invasives qui, à la faveur du réchauffement climatique, se sont récemment implantés dans plusieurs régions du monde, dont la région méditerranéenne. Sa présence constitue un terreau favorable à la survenue d'épidémie. A l'heure actuelle, il n'existe ni vaccin, ni traitement médicamenteux efficace. Toutefois, des articles scientifiques ont récemment rapporté que des esters de diterpène isolés du genre Trigonostemon (Euphorbiaceae), avaient une activité inhibitrice de la réplication du CHIKV.Dans le cadre de ces travaux de thèse, des extraits de plantes du genre Euphorbia de Corse ont été étudiés dans le but d'isoler de nouvelles molécules douées d'activité antivirale sur la réplication du CHIKV. En collaboration avec le Dr. P. Leyssen (KU Leuven, Belgique), l'évaluation de l'activité anti-CHIKV de 45 extraits, obtenus à partir de 11 Euphorbiaceae de Corse, a permis de mettre en évidence la forte activité inhibitrice et sélective de des extraits d'espèces du genre Euphorbia in cellulo. L'activité antivirale d'une série de 27 diterpènes de type phorboïde, disponibles commercialement, a également été étudiée. Les résultats ont montré que certains dérivés avaient une forte activité inhibitrice de la réplication du CHIKV, mais aussi sur celle du virus de l'immunodéficience humaine (VIH). Ces études ont permis d'une part, de déduire des relations structure-activité inédites et d'autre part, de soutenir l'hypothèse d'un mécanisme d'action anti-CHIKV impliquant la modulation des protéines kinases C (PKCs) par les phorboïdes. Dans le but de confirmer ou d'infirmer la présence des phorboïdes dans les extraits d'Euphorbia, une première méthode utilisant la chromatographie liquide (LC) haute performance couplée à un spectromètre de masse à trappe d'ions (MSn), a été développée à partir des composés standards. L'application de cette méthodologie a révélé qu'aucun des phorboïdes ciblés n'était présent dans les extraits d'Euphorbia. Ainsi, une seconde procédure LC-MSn a été mise en œuvre afin de détecter - de manière non ciblée - différents types d’esters diterpéniques. L'utilisation de cette approche a révélé que de nombreux diterpènes, non-apparentés aux phorboïdes, étaient présents dans les extraits. Un extrait de l'espèce Euphorbia amygdaloides subsp. semiperfoliata a été sélectionné pour réaliser un fractionnement bio-guidé, aboutissant à l'isolement et l'identification de 14 esters de jatrophane, dont neuf nouveaux composés. Parmi eux, l'un s'est avéré inhiber la réplication du CHIKV et du VIH. Par ailleurs, la structure d'un ester de jatrophane atypique, le jatrohémicétal, a été élucidée grâce à une approche originale combinant modélisation moléculaire et spectroscopie par résonance magnétique nucléaire (RMN). Enfin, une nouvelle procédure de purification ciblée par spectrométrie de masse tandem (MS/MS) en chromatographie en phase fluide supercritique (SFC) a été développée et appliquée sur des fractions bioactives d'E. amygdaloïdes subsp. semiperfoliata. L’interprétation des données MS/MS s’est appuyée sur la génération de réseaux moléculaires. Par cette méthodologie, quatre nouvelles molécules ont pu être détectées, purifiées et identifiées ; il s’agit de deux nouveaux esters de jatrophane et de quatre esters dérivés du 4-déoxyphorbol. L'activité anti-VIH des constituants isolés a également pu être explorée dans le cadre d’une collaboration avec l'équipe du Pr. Alcami (CNM, Espagne). Ainsi, l’un des esters de 4-deoxyphorbol s’est révélé être doué d'un exceptionnel pouvoir inhibiteur de la réplication du VIH-1 (IC50 = 8 nM et index de sélectivité > 6250). Son mécanisme d'action semble s'apparenter à celui de la prostratine (molécule antivirale de référence) mais avec des propriétés antivirales environ 28 fois supérieur. Un deuxième ester de 4-déoxyphorbol s’est avéré être un des plus puissants inhibiteurs du CHIKV isolé à ce jour (EC50 = 0,34 ± 0,12 µM and SI > 638). Mots clés : Euphorbia, activité antivirale, chikungunya, diterpène, spectrométrie de masse

International audience; The inhibitive effect of Thymus algeriensis plant extract (TEA) on the corrosion of mild steel in 1.0 M HCl solution has been investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of Thymus algeriensis plant extract reduces remarkably the corrosion rate of mild steel in acidic solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 313-343 K. The results from this corrosion test clearly reveal that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 1.0 g/L. The Nyquist plots showed that increasing TEA concentration, charge-transfer resistance increased and double-layer capacitance decreased, involving increased inhibition efficiency. Linearity of Temkin isotherm adsorption.

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International audience; A comparative study of volatile compounds from Daucus muricatus obtained by hydrodistillation and liquid–liquid extraction by GC and gas chromatography mass spectroscopy (GCMS) was conducted. The essential oils extracted from roots were mainly composed of aliphatic compounds while oils extracted from aerial part were characterized by monoterpene hydrocarbons. However, the GCMS analyses of composition hydrosol extracts shows only oxygenated compounds; no hydrocarbons were noted. The antioxidant activity of the hydrosol extracts exhibited the high antioxidant activity with IC50 value of 50.08 and 63.05 μg.mL−1 for roots and aerial parts, respectively, better than from synthetic antioxidant BHT (103.98 μg.mL−1).

The proliferation of invasive species is a global problem. The introduction of exogenous species is after pollution and habitat destruction a major cause of the disappearance of the worldwide plant and animal biodiversity. Corsica is not spare to the phenomenon and every year there are numerous dangerous species which are introduced to the island ecosystem.In this study, we have studied four invasive species of Asteraceae (X. italicum, X. spinosum, S. angulatus and S. inaequidens) from Corsica. The aim of this study is to initiate a possible valuation pathway of these species by production of their essential oils. For this purpose, we investigated the chemical variability of each essential oil and their antioxidant and anticorrosive activities. Then we have extended our investigations to the others species of Senecio genus and to Limbarda crithmoides, anciently parented taxa.GC and GC/MS analysis allowed the identification of 107 and 74 components which accounted for 98.7 and 93.5% of the X. italicum and X. spinosum essential oils, respectively. Essential oils of X. italicum and X. spinosum were dominated by hydrocarbon monoterpenes (66.2%) and oxygenated sesquiterpenes (41.5%), respectively. The same metabolomic pathways seem occur for both species during the vegetative cycle of the plant: oxygenated sesquiterpene-production was higher during the flowering stage. Moreover the study of 25 sample oils of X. italicum and X. spinosum showed that the chemical variability of both essential oils could be linked to morphological characters.A comprehensive work on the chemical variability of 180 sample oils of Senecio was carried out and 251 components were identified. Among them, using mono and bi-dimensional NMR the structures of 8-acetoxybisabolene-1,9-diol and 8-acetoxy-1,9-oxobisabolene, two new components of S. transiens essential oil were described for the first time. Corsican Senecio species exhibited interspecies chemical variability: the halotolerant Senecio species (S. transiens, S. cineraria and S. aquaticus erraticus) were characterized by essential oils dominated by non-terpenic compounds while the so-called “terrestrial” Senecio species (S. angulatus, S. ineaquidens, S. lividus, S. vulgaris and S. serpentinicola) exhibited terpenic component-rich oils. The study of intra-species chemical variability highlighted direct correlations between the plant-production of secondary metabolites and the nature of soils on which S. lividus, S. vulgaris and S. transiens grows. Hence essential oil compositions and morphological polymorphism are indirectly related. In the same way, the chemical variability of S. cineraria essential oils seems to be linked to the geology of the soils while the oil diversity of the invasive S. angulatus, could be linked to the both spots of introduction on Corsica Island. In addition, an original chiral-gas chromatographic method was improved and applied to the main components of the essential oils in order to complement the chemical composition of the Senecio sample oils.Furthermore the originality of Corsican Limbarda crithmoides essential was highlighted by the occurrence of two p-cymenene derivatives, never reported in the related studies from literature. The investigation of 25 Corsican L. crithmoides focuses on a direct correlation between the water salinities of the plant locations and the chemical compositions of the essential oils.Finally the antioxidant activities, anti-free radical and reducing power, were measured on some essential oils of the studied species. Essential oils of the Xanthium genus appeared to be most effectives. In addition, anticorrosion properties of the essential oils were investigated and the best corrosion inhibiting activity was exhibited by those of S. inaequidens . Anticorrosion activity could be attributed to the cacalohastine, a naphtalofuranic component, isolated form the whole essential oil after column chromatography., La prolifération d’espèces invasives est un problème d’ampleur planétaire. Après la pollution et la destruction des habitats, l’introduction d’espèces exogènes est une des principales causes de la disparition de la biodiversité animale et végétale. La Corse n’est pas épargnée par le phénomène et chaque année on dénombre de plus en plus d’espèces végétales potentiellement envahissantes et dangereuses qui introduisent l’écosystème insulaire.Dans le cadre de ces travaux de thèse, nous nous sommes intéressés à quatre plantes envahissantes de la famille des Asteracées appartenant aux genres Xanthium et Senecio (X. italicum et X. spinosum ainsi que S. angulatus et S. inaequidens). L’objectif de notre étude est d’initier une possible voie de valorisation par la production d’huile essentielle. Notre étude s’est néanmoins étendue à l’ensemble des espèces du genre Senecio et à Limbarda crithmoides, espèce anciennement apparentée au genre Senecio.Dans un premier temps, nous avons caractérisé par CPG et CPG/SM les compositions chimiques des huiles essentielles de X. italicum et X. spinosum : deux plantes reconnues comme envahissantes. Ainsi, 107 et 74 composés représentant 98,7 et 93,5 % de la composition chimiques ont été respectivement identifiés. L’huile essentielle de X. italicum est riche en monoterpènes hydrocarbonés (66,2%), tandis que celle de X. spinosum est dominée par des sesquiterpènes oxygénés (41,5%). Des similitudes dans le comportement métabolique ont pu être observées au cours du cycle végétatif des deux espèces : les sesquiterpènes oxygénés sont majoritaires au moment de la floraison. De plus, l’étude de la variabilité chimique réalisée sur 25 échantillons d’huiles essentielles de X. italicum et X. spinosum a validé une corrélation liée aux caractères morphologiques des plants.L’étude de la diversité chimique des huiles essentielles du genre Senecio a été réalisée à partir de huit espèces poussant à l’état spontané sur l’île. Sur un total de 251 composés répertoriés, l’identification de deux nouvelles molécules l’oxyde d’acétoxybisabolène et le 8-acétoxybisabolène-1,9-diol ont été identifiées dans S. transiens après purification et élucidation structurale par RMN mono et bidimensionnelle. L’analyse statistique effectuée à partir de 180 échantillons, a permis de distinguer les espèces dites halotolérantes (S. transiens, S. cineraria et S. aquaticus erraticus) riches en composés non terpéniques, des espèces plus « terrestres » (S. angulatus, S. ineaquidens, S. lividus, S. vulgaris et S. serpentinicola) dominées par des composés terpéniques. L’étude de la variabilité chimique intraspécifique de S. vulgaris, S. lividus et S. transiens a permis de mettre en évidence les corrélations entre la composition chimique des huiles essentielles et le polymorphisme des taxons et/ou le biotope. Les caractéristiques pédologiques des sols semblent être à l’origine de la diversité chimique de S. cineraria alors que celle de S. angulatus est imputable au mode d’introduction de l’espèce qui semble avoir évolué en deux populations chimiques distinctes retrouvées respectivement sur les côtes orientale et occidentale de la Corse. Par ailleurs, l’application de la CPG chirale aux huiles essentielles du genre Senecio, nous a conduits à déterminer les proportions énantiomériques de six composés majoritaires (limonène, α-pinène, β-pinène, camphène, sabinène et α-phellandrène). Ainsi, nous avons constaté la dominance d’un énantiomère vis-à-vis de son isomère optique ; ceci soutient l’hypothèse d’un métabolisme commun aux espèces de Senecio. En outre, nous avons pu établir l’originalité de l’huile essentielle de Limbarda crithmoides de Corse par rapport à celles d’autres origines géographiques. L’étude de la variabilité chimique a permis de démontrer l’influence des teneurs en NaCl (halo-dépendance de la plante) sur les caractères morphologiques de l’espèce et sur la production des métabolites secondaires (teneurs en p-cymène et en oxyde de thymyle et de méthyle). Enfin, les propriétés antioxydantes des huiles essentielles ont été établies ; il apparait que X. italicum et X. spinosum présentent les meilleures activités anti-radicalaires et du pouvoir réducteur. La recherche des principes actifs responsables de l’activité des huiles essentielles de L. crithmoides et S. inaequidens a permis de mettre en évidence l’implication des phénylpropanoïdes et des alcools terpéniques. L’étude des propriétés anticorrosives a permis de démontrer la forte activité de la cacalohastine (constituant de S. inaequidens) dont la nature benzofuranique serait à l’origine de son pouvoir anticorrosif

This thesis was focused on the Corsican honeys under the AOC and AOP appellation “Miel de Corse-Mele di Corsica”. The Corsican honey was classified in six varietal categories: “spring”, “spring maquis”, “honeydew”, “summer maquis”, “chestnut grove” and “automne maquis”. The aim of this work was to characterize the volatile composition of Corsica honey and to develop an interdisciplinary approach to complete the characterization of Corsican honey and the qualification of the botanical and/or geographical origin. In the first part, 195 nectar honeys were characterized by melissopalynological, physico-chemical and volatile analyses. Pollen analysis allowed the certification of Corsican origin and highlights the main nectariferous species and/or characteristic plant associations of each varietal range. Thus, the volatile analysis by SPME, GC and GC/MS allowed the identification of some chemical markers of honey, namely 2-aminoacetophenone (“chestnut grove”); p-anisaldehyde and 4-n-propylanisole (“spring maquis”); isophorone and 3,4,5-trimethylphenol (“automne maquis”); isomers of lilac aldehydes and p-menth-1-en-9-al (“spring clementine”).For each honey range, an interdisciplinary study was carried out by using statistical analysis of multifactorial data (melissopalynological, physico-chemical and volatile data). These results allowed us to identify the “monofloral” honey samples; to propose some hypotheses about the nectar and/or honeydew contribution in honeys with dominant over-represented (“chestnut grove”) and normal taxon (“spring maquis”); and to determine the role of different nectariferous and/or polleniferous species in honeys with underrepresented taxon (“spring” and “autumn maquis”) and those with complex botanical origin (“summer maquis”).In the second part of our work, the volatile fraction of 74 Corsican honeydews and blend honeys has also been investigated. Statistical analysis of the volatile composition has distinguished Metcalfa honeydew by a high abundance of 3-furaldehyde. Otherwise, the other honey samples were characterized by a high abundance of 2-aminoacetopheneone (marker of “chestnut grove” honey) and/or p-anisaldehyde and 4-n-propylanisol (characteristic compounds of “spring maquis" honey). These observations could be explained by the nectar contribution of Castanea sativa and/or Erica arborea in the honeydew samples. Finally, this work has allowed us to develop an innovative approach based on multifactorial approach (pollen analysis, physic-chemical parameters, volatile composition) to obtain discriminant information for the determination of the floral origin from Corsican honeys., Ce travail de thèse porte sur les miels de Corse commercialisés sous l’AOC et l’AOP « Miel de Corse-Mele di Corsica » et classés en six catégories variétales : « printemps », « maquis de printemps », « miellat du maquis », « maquis d’été », « châtaigneraie » et « maquis d’automne ». Notre objectif principal était de caractériser la composition volatile des miels de Corse et de développer une approche interdisciplinaire en vue de compléter la caractérisation de ces productions par la recherche de nouveaux critères pour la qualification de l’origine botanique et/ou géographique. Les travaux ont donc consisté à croiser les données obtenues par la méthode conventionnelle basée sur les analyses polliniques, sensorielles et physico-chimiques avec celles issues de l’analyse chimique de la fraction volatile des miels.Dans une première partie, 195 miels de nectar ont été caractérisés au niveau pollinique, physico-chimique ainsi que par leurs compositions volatiles. L’analyse pollinique a permis de certifier l’origine Corse et de mettre en évidence les principales espèces nectarifères de chaque gamme variétale et/ou les associations végétales caractéristiques des miellées. L’analyse de la fraction volatile par MEPS, CPG et CPG/SM a conduit à l’identification des marqueurs chimiques des diverses variétés de miels, à savoir la 2-aminoacétophénone (« châtaigneraie ») ; le p-anisaldéhyde et le 4-n-propylanisole (« maquis de printemps ») ; l’isophorone et le 3,4,5-triméthylphénol (« maquis d’automne ») ; les isomères de lilac aldéhyde et du p-menthèn-9-al (« printemps typé clémentinier »). De plus, une étude interdisciplinaire (analyse mélissopalynologique, physico-chimique et fraction volatile) basée sur l’utilisation de traitements statistiques des données multifactorielles a été menée sur chacune des catégories variétales. Les résultats obtenus ont permis de mieux cerner l’origine botanique des miels « quasi-monofloraux » ; de proposer des hypothèses sur les autres apports nectarifères et/ou miellatifères dans les miels à taxon dominant de type sur-représenté (« châtaigneraie ») et normal (« maquis de printemps ») ; de déterminer les différentes contributions nectarifères dans les miels dont l’espèce dominante à un taxon de type sous-représenté (« printemps » et « maquis d’automne ») et dans ceux ayant une origine botanique complexe (« maquis d’été »).Dans la seconde partie de nos travaux, nous avons caractérisé la fraction volatile de 74 miels des gammes « miellat du maquis » et « miel de Corse ». L’analyse statistique de la variabilité chimique a permis de distinguer les miellats de Metcalfa par la teneur en 3-furaldéhyde. Par ailleurs, nous avons pu qualifier l’origine botanique des miels dit « génériques » (mélange « miel de miellat »/« miel de nectar »), notamment les apports significatifs de « châtaigneraie » (molécule marqueur : 2-aminoacétophénone) et/ou de « maquis de printemps » (p-anisaldéhyde et 4-n-propylanisol).Enfin, ces travaux ont permis de développer une approche innovante basée sur une approche multifactorielle (polliniques, physico-chimiques et volatils) afin de mieux qualifier la complexité des origines botaniques des miels de Corse.

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