Добірка наукової літератури з теми "Limettier"

Modifying the composition of dental restorative materials with antimicrobial agents might induce their antibacterial potential against cariogenic bacteria, e.g., S.mutans and L.acidophilus, as well as antifungal effect on C.albicans that are major oral pathogens. Essential oils (EOs) are widely known for antimicrobial activity and are successfully used in dental industry. The study aimed at evaluating antibacterial and antifungal activity of EOs and composite resin material (CR) modified with EO against oral pathogens. Ten EOs (i.e., anise, cinnamon, citronella, clove, geranium, lavender, limette, mint, rosemary thyme) were tested using agar diffusion method. Cinnamon and thyme EOs showed significantly highest antibacterial activity against S.mutans and L.acidophilus among all tested EOs. Anise and limette EOs showed no antibacterial activity against S.mutans. All tested EOs exhibited antifungal activity against C.albicans, whereas cinnamon EO showed significantly highest and limette EO significantly lowest activity. Next, 1, 2 or 5 µL of cinnamon EO was introduced into 2 g of CR and microbiologically tested. The modified CR showed higher antimicrobial activity in comparison to unmodified one. CR containing 2 µL of EO showed the best antimicrobial properties against S.mutans and C.albicans, while CR modified with 1 µL of EO showed the best antimicrobial properties against L.acidophilus.

The aroma quality of citrus fruit is determined by volatile compounds, which bring about different notes to allow discrimination among different citrus species. However, the volatiles with various aromatic traits specific to different citrus species have not been identified. In this study, volatile profiles in the fruit peels of four citrus species collected from our previous studies were subjected to various analyses to mine volatile biomarkers. Principal component analysis results indicated that different citrus species could almost completely be separated. Thirty volatiles were identified as potential biomarkers in discriminating loose-skin mandarin, sweet orange, pomelo, and lemon, while 17 were identified as effective biomarkers in discriminating clementine mandarins from the other loose-skin mandarins and sweet oranges. Finally, 30 citrus germplasms were used to verify the classification based on β-elemene, valencene, nootkatone, and limettin as biomarkers. The accuracy values were 90.0%, 96.7%, 96.7%, and 100%, respectively. This research may provide a novel and effective alternative approach to identifying citrus genetic resources.

Coumarins are the secondary metabolites of some plants, fungi, and bacteria. Coumarins and the hybrid molecules of coumarins are the compounds which have been widely studied for their potential anticancer effects. They belong to benzopyrone chemical class, more precisely benzo-α-pyrones, where benzene ring is fused to pyrone ring. In nature, coumarins are found in higher plants like Rutaceae and Umbelliferae and some essential oils like cinnamon bark oil, cassia leaf oil and lavender oil are also rich in coumarins. The six main classes of coumarins are furanocoumarins, dihydrofuranocoumarins, pyrano coumarins, pyrone substituted coumarins, phenylcoumarins and bicoumarins. As well as their wide range of biological activities, coumarins and the hybrid molecules of coumarins are proven to have an important role in anticancer drug development due to the fact that many of its derivatives have shown an anticancer activity on various cell lines. Osthol, imperatorin, esculetin, scopoletin, umbelliprenin, angelicine, bergamottin, limettin, metoxhalen, aurapten and isopimpinellin are some of these coumarins. This review summarizes the anticancer effects of coumarins and their hybrid molecules including the novel pharmaceutical formulations adding further information on the topic for the last ten years and basically focusing on the structureactivity relationship of these compounds in cancer.

Abstract In preclinical studies, simple coumarins (scoparone, limettin) and furanocoumarins (imperatorin, xanthotoxin, bergapten) have already found to demonstrate procognitive abilities. This suggests that they hold antioxidative, anti-inflammatory and inhibitory action towards acetylcholinesterase activities. However, little is known about their influence on the amyloidal structure formation, the leading cause of Alzheimer’s disease (AD). In vitro and in cellulo assays were applied to evaluate the effect of selected coumarins on the different stages of Aβ40/42 and tau protein aggregation. Kinetic analyses were performed to evaluate their inhibiting abilities in time. Limettin revealed the most potent inhibiting profile towards Aβ40 aggregation, however, all tested compounds presented low influence on Aβ42 and tau protein aggregation inhibition. Despite the preliminary stage of the project, the promising effects of coumarins on Aβ40 aggregation were shown. This suggests the coumarin scaffold can serve as a potential multitarget agent in AD treatment, but further studies are required to confirm this.

Présent dans le monde entier à l’exception du bassin méditerranéen et le Moyen-Orient, le Huanglongbing (HLB), encore appelé citrus greening ou maladie du dragon jaune, est aujourd’hui considéré comme la maladie bactérienne la plus dévastatrices au sein des agrumes cultivés. La bactérie responsable de cette maladie est une alphaprotéobactérie non-cultivable à Gram négatif en forme de bacille appelé Candidatus Liberibacter transmise par des psylles Diaphorina citri et Trioza erytreae. Il existe trois souches de cette bactérie, Candidatus Liberibacter asiaticus (CLas ; Las), Candidatus Liberibacter americanus (CLam ; Lam) et Candidatus Liberibacter africanus (CLaf ; Laf). Une fois infecté par la bactérie responsable du HLB, la réponse de l’arbre est d’induire la synthèse de callose au niveau des pores du phloème empêchant ainsi le passage de la sève élaborée vers les organes puits tels que les fruits ou encore les racines. La conséquence de ce blocage va engendrer des marbrures asymétriques au niveau des feuilles des arbres infectés à cause des produits photosynthétiques comme l’amidon qui vont s’y accumuler. De plus, le HLB va induire un stress oxydatif, caractérisé par la synthèse d’espèces réactives de l’oxygène (ROS), qui sera néfaste pour les arbres. Contrairement aux feuilles, aucun dépôt – voir très peu – de callose n’est observable au niveau des racines justifiant le fait qu’elles puissent être considérées comme un réservoir car elles seraient le lieu de multiplication et de développement de la bactérie. De ce fait, la dégradation des racines observées serait due à une action directe de la bactérie et non indirecte comme au niveau foliaire. Tout ceci va entrainer une chute des feuilles, des fruits mais aussi à une dégradation des racines aboutissant ainsi une baisse de la production fruitière. Les agrumes sont généralement diploïdes (n = 9 soit 18 chromosomes). Néanmoins il existe des agrumes polyploïdes, qui se comportent mieux notamment en conditions de stress biotiques que les variétés diploïdes. La polyploïdie est un phénomène qui a depuis longtemps montré des avantages dans le monde végétal notamment en termes d’adaptation. En effet, chez les agrumes polyploïdes, les cellules et organes sont plus gros que chez les diploïdes respectifs. Leurs systèmes de défense face aux stress oxydatifs engendrés par des stress biotiques ou abiotiques, sont également plus efficaces. Le premier chapitre de cette thèse correspond à l’étude de l’impact de la ploïdie sur la tolérance à la maladie du HLB, en évaluant deux variétés de limettiers, le limettier Mexicain diploïde (2x) et le limettier Tahiti triploïde (3x) greffés avec un porte-greffe 2x au moyen d’analyses physiologiques, microscopiques et biochimiques. La 2ème étude de cette thèse a été réalisée sur des porte-greffes citrumelo Swingle 2x et tétraploïdes (4x) greffés avec les mêmes variétés 2x et 3x évaluées dans la première étude. L’étude s’est focalisée au niveau des racines de porte-greffes. La 3ème étude a été réalisée sur les mêmes arbres quel la 2ème étude et a été axée sur l’étude de l’expression des génomes, complétée par des analyses hormonales et du métabolome. Les résultats des dosages hormonaux ont montré qu’en relation avec la littérature, le taux d’acide salicylique (hormone clé de la résistance systémique acquise) augmentait considérablement chez les plants infectés par la bactérie responsable du HLB. Enfin, bien que les résultats du métabolome soient préliminaires, les résultats montrent un impact de la maladie sur les composés synthétisés en lien avec la ploïdie du porte-greffe et qu’il existait des interactions spécifiques entre greffon et porte-greffes
Considered as the most devastating bacterial disease in cultivated citrus, Huanglongbing (HLB), also called citrus greening or yellow dragon disease in French is present all over the world except in the Mediterranean basin and in the Middle East. The bacterium responsible for this disease is a non-cultivable gram-negative bacillus-like alphaproteobacteria called Candidatus Liberibacter transmitted by psyllids Diaphorina citri and Trioza erytreae. There are three strains of this bacterium, Candidatus Liberibacter asiaticus (CLas; Las), Candidatus Liberibacter americanus (CLam; Lam) and Candidatus Liberibacter africanus (CLaf; Laf). Once infected by the HLB bacterium, the tree's response is to induce callose synthesis in the phloem pores, thus preventing the transfer of the elaborated sap to the sink organs such as fruit or roots. The consequence of this blockage will be asymmetric mottling in leaves of infected trees due to the accumulation of photosynthetic products such as starch. In addition, HLB will induce oxidative stress, characterized by the synthesis of reactive oxygen species (ROS), which will be detrimental to the trees. Contrary to the leaves, no deposition of callose can be observed in the roots, justifying the fact that they are considered as a reservoir because they would be the place of multiplication and development of the bacteria. Therefore, the degradation of the roots observed would be due to a direct action of the bacterium and not indirectly as at the leaf level. Altogether, this will lead to the drop of leaves, fruit but also to the degradation of the roots, thus leading to a decrease in fruit production. Citrus are usually diploid (n = 9 or 18 chromosomes). Nevertheless, it does exist citrus polyploid, which behave better in abiotic stress condition than diploid varieties. Polyploidy is a phenomenon that has shown advantages in the plant kingdom notably in term of adaptation. Indeed, in polyploid, cells and organs are larger than in their respective diploids. Their defense systems against oxidative stresses generated by biotic or abiotic stresses are usually more efficient. In this thesis, the first study focuses on the impact of ploidy regarding HLB disease, using two varieties of lime trees: Mexican lime diploid (2x) and the triploid Persian (3x) grafted with a 2x rootstock by doing physiological, microscopic and biochemical analyses.The second study of this thesis was performed on citrumelo Swingle 2x and tetraploid (4x) rootstocks grafted with the same 2x and 3x varieties of the first study. The study was focused at the root level.The third study was performed on the same experimental design of the 2nd study and focused on the study of the expression of the genomes, completed by hormonal and metabolome analyses.Finally, although the metabolome results are preliminary, the results showed that there was an impact of the disease on the synthetized compounds depending of the ploidy of the rootstock and that there were specific relationship between the graft and rootstock