Auswahl der wissenschaftlichen Literatur zum Thema „Lc-Hrms2“

This study describes a multistage methodology to detect minute amounts of tetrodotoxin in fishes, a plan that may be broadened to include other marine organisms. This methodology was applied to porcupinefish (Diodon hystrix) collected in Punta Chiquirín, El Salvador. A three-stage approach along with post-acquisition processing was employed, to wit: (a) Sample screening by selected reaction monitoring (HPLC-MS/MS-SRM) analyses to quickly identify possible toxin presence via a LC/MS/MS API 3200 system with a triple quadrupole; (b) HPLC-HRFTMS-full scan analyses using an ion trap-Orbitrap spectrometer combined with an MZmine 2-enhanced dereplication-like workflow to collect high-resolution mass spectra; and (c) HPLC-HRMS2 analyses. This is the first time tetrodotoxin has been reported in D. hystrix specimens collected in El Salvador.

Susceptibility to the severe Citrus tristeza virus (CTV), T36, is higher for Citrus macrophylla (CM) than for C. aurantium (CA). How host-virus interactions are reflected in host physiology is largely unknown. In this study, the profile of metabolites and the antioxidant activity in the phloem sap of healthy and infected CA and CM plants were evaluated. The phloem sap of quick decline (T36) and stem pitting (T318A) infected citrus, and control plants was collected by centrifugation, and the enzymes and metabolites analyzed. The activity of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), in infected plants increased significantly in CM and decreased in CA, compared to the healthy controls. Using LC-HRMS2 a metabolic profile rich in secondary metabolites was assigned to healthy CA, compared to healthy CM. CTV infection of CA caused a drastic reduction in secondary metabolites, but not in CM. In conclusion, CA and CM have a different response to severe CTV isolates and we propose that the low susceptibility of CA to T36 may be related to the interaction of the virus with the host’s metabolism, which reduces significantly the synthesis of flavonoids and antioxidant enzyme activity.

Glucosinolates (GSLs), crucial secondary metabolites in cruciferous vegetables, hydrolyze upon consumption or mechanical damage, forming bioactive compounds with anti-cancer properties, such as glucoraphanin (GRA). Among cruciferous vegetables, broccoli stands out for its high GSL content, which varies significantly among different genotypes. This study aimed to characterize and quantify glucosinolate compounds in broccoli using LC-HRMS2 and UPLC. We identified thirteen GSLs in 191 broccoli genotypes, including seven aliphatic, five indole, and one aromatic glucosinolate. The GSL content in these genotypes ranged from 0.1705 to 5.8174 mg/g (DW). We also explored GSL diversity and content in seven developmental organs, finding high diversity and content in seedling roots and florets. Notably, genotype No. 300 had the highest GSL content (5.8174 mg/g, DW) and GRA (3.1545 mg/g, DW), along with a larger flower bulb diameter (13.4 cm) and a shorter growth stage (11 days), demonstrating its potential for breeding GRA-rich broccoli. To our knowledge, this study encompasses the largest number of broccoli genotypes to date, broadening our understanding of GSLs’ diversity and content in broccoli. These findings may provide valuable resources for future breeding or the commercial cultivation of GRA-rich broccoli.

Plant de novo fatty acid synthesis takes place in the plastid using acetyl-coenzyme A (acetyl-CoA) as the main precursor. This first intermediate is produced from pyruvate through the action of the plastidial pyruvate dehydrogenase complex (PDH), which catalyses the oxidative decarboxylation of pyruvate to produce acetyl-CoA, CO2, and NADH. For the proper functioning of this complex, lipoic acid is required to be bound to the dihydrolipoamide S-acetyltransferase E2 subunit of PDH. Octanoyltransferase (LIP2; EC 2.3.1.181) and lipoyl synthase (LIP1; EC 2.8.1.8) are the enzymes involved in the biosynthesis of this essential cofactor. In Arabidopsis plastids, an essential lipoyl synthase (AtLIP1p) and two redundant octanoyltransferases (AtLIP2p1 and AtLIP2p2) have been described. In the present study, the lipidomic characterization of Arabidopsis octanoyltransferase mutants reveals new insight into the lipoylation functions within plastid metabolism. Lipids and fatty acids from mature seeds and seedlings from Atlip2p1 and Atlip2p2 mutants were analysed by gas chromatography (GC) and liquid chromatography–electrospray ionization high-resolution mass spectrometry (LC-ESI-HRMS2), the analysis revealed changes in fatty acid profiles that showed similar patterns in both mutant seeds and seedlings and in the lipid species containing those fatty acids. Although both mutants showed similar tendencies, the lack of the AtLIP2p2 isoform produced a more acute variation in its lipids profile. These changes in fatty acid composition and the increase in their content per seed point to the interference of octanoyltransferases in the fatty acid synthesis flux in Arabidopsis thaliana seeds.

Degradation of anthocyanins involves scission of the flavonoid skeleton yielding 2,4,6-trihydroxybenzaldehyde (phloroglucinaldehyde, PGA) and a phenolic acid. However, the process is not finished with the formation of PGA, as the consequent condensation of two PGA molecules providing colored hydroxylated anthraquinones was observed for the first time. This process was studied using a combination of preparative column chromatography, nuclear magnetic resonance, liquid chromatography/high resolution tandem mass spectrometry (LC/HRMS2), and quantum calculations using density functional theory. 1,3,5,7-tetrahydroxyanthraquinone (anthrachrysone) and its isomers were found to rise during heating (95 °C) in a buffered PGA model solution (phosphate buffer, pH 7). These compounds were detected in heated red wine after an increase of its pH value. The concentration of the identified anthrachrysone in the red wine reached 0.01 mg·L−1. Presence of those compounds could therefore indicate involvement of certain steps in the processing of plant materials rich in anthocyanins (e.g., utilization of a higher temperature and/or reduction of acidity) or long-term transformation of anthocyanins (potentially, for instance, in archaeological findings such as wine or fruit residues). Additionally, measurement of wine–soil suspensions proved an increase of their pH to the values suitable for anthocyanin cleavage (neutral to slightly alkaline; reached using soil from archaeologically well-known Bull Rock Cave). Although not found in artificially prepared samples (imitations) or authentic materials so far, according to our results the above mentioned conditions are suitable for the formation of tetrahydroxylated anthraquinone derivatives and their monitoring would be beneficial.

Dengue and Zika viruses are identified as the most medically important arthropod-borne viral pathogens. Over the past 20 years, the global dengue incidence has dramatically increased with epidemics of severe dengue where the case fatality rate can reach up to 20% in untreated patients. The association between Zika virus infection and severe congenital anomalies was first reported in 2015. Today no specific antiviral therapies are available for dengue and Zika virus infections, accentuating the need of adapted antiviral strategies based on medicinal plant drug discovery. Plants are a potential source of antiviral phytocompounds which act primarily by blocking virus entry in the host-cell. In the present study, we evaluated whether crude extracts from Stenocline ericoides DC. and Stenocline inuloides DC., two endemic plants from Madagascar, may have antiviral effects against dengue and Zika viruses. We showed that S. ericoides has virucidal action whereas S. inuloides inhibits the early steps of virus infection with a non-cytotoxic effect in human cells. The administration of S. ericoides and S. inuloides extracts in zebrafish had no effect on the behavior of animals at the active doses against dengue and Zika viruses, suggesting the absence of adverse effects at these doses. LC-HRMS2 and molecular networking analyses revealed the richness of these two plants in polyphenols and flavonoid with the presence of clusters of phytocompounds specific to each Stenocline species. Consequently, S. ericoides and S. inuloides represent potential sources for natural and safe antiviral phytocompounds against flaviviruses of medical concern.

Les écorces d’arbres, co-produit de la sylviculture, constituent une source abondante et durable de substances naturelles. Toxoplasma gondii est le parasite responsable de la toxoplasmose, présentant une menace chez les fœtus, les nouveau-nés et les personnes immunodéprimées. Les thérapies actuelles, limitées et mal tolérées, font désormais face à des phénomènes de chimiorésistance. Ce travail de thèse a pour but d’explorer l’espace chimique associé aux écorces d’essences champardennaises, et les cibles protéiques essentielles à T. gondii. Une première évaluation in silico par docking inverse (AMIDEv2.0) a été réalisée afin d’identifier la cible biologique de triterpènes dérivés de la bétulone, isolés de l’Aulne glutineux ayant montré une activité anti-toxoplasmose in vitro. La CDPK3 a été identifiée comme étant la cible la plus probable parmi 87 protéines de T. gondii. Puis, une protéothèque de 25 structures protéiques 3D essentielles à la survie du parasite, 19 ayant été modélisées par homologie, a été constituée. Les composés de la Chimiothèque Nationale Essentielle ont été évalués ensuite sur cette protéothèque en utilisant AMIDEv2.0. Deux protéines ont été identifiées comme de potentielles cibles, dont ATG3, une structure reconstruite à partir d'homologues avec un pourcentage d'identité inférieur à 50%. Deuxièmement, les écorces du Mélèze d'Europe, dont l’extrait n-heptane avait démontré une activité significative (58 % d’inhibition de croissance parasitaire à 100 µg/ml), ont été soumises à un profilage chimique impliquant un fractionnement par Chromatographie de Partage Centrifuge et de déréplication combinant les données issues de la résonance magnétique nucléaire et de la spectrométrie de masse. Les outils VersaDB et CATHEDRAL ont été développés pour faciliter la création de bases de données modulables et l’évaluation du niveau de confiance des annotations. 52 molécules ont ainsi pu être annotées et associées à un score de confiance. En parallèle, des tests in vitro ont démontré que 2 des 12 fractions CPC, majoritairement composées de terpènes, inhibaient à plus de 40% la survie du parasite à 25 µg/ml. Les composés annotés chez L. decidua ont été soumis à AMIDEv2.0. Le croisement des résultats in vitro et in silico, reposant sur le calcul d'un score d'activité biologique, a mis en évidence l'acide 7-oxo-déhydroabiétique et l'acide daniellique, fortement corrélés à l'activité inhibitrice in vitro des écorces. La CDPK1 et la protéine SET containing Protein ont été identifiées comme leurs cibles protéiques probables, fournissant ainsi de premières informations sur leurs mécanismes d'action. Ces deux hits font actuellement l’objet d’une évaluation in vitro afin d’attester l’efficacité de la démarche développée au cours de ces travaux de thèse
Tree barks, by-product of forestry industry, constitute an abundant and sustainable source of natural compounds. Toxoplasma gondii is the parasite responsible for toxoplasmosis, posing a threat to fetuses, newborns, and immunocompromised individuals. The current therapeutics, limited and poorly tolerated, are now confronted to chemoresistant phenomena. This doctoral project aims to explore the chemical space associated with tree barks from the Champagne-Ardenne region, as relevant protein targets to fight T. gondii. An initial in silico evaluation using reverse docking (AMIDEv2.0) was carried out to identify biological target for triterpenes derived from betulone, isolated from the European alder, which had exhibited in vitro anti-toxoplasmosis activity. Among 87 proteins of T. gondii, CDPK3 was identified as the most probable target. Subsequently, a bank of 25 essential 3D protein structures for parasite survival, including 19 homology-modeled structures, was compiled. Thereafter, compounds from the Essential National Chemical Library were screened against this protein bank, using AMIDEv2.0. Two proteins were identified as potential targets; one of them was ATG3, a protein structure modeled from homologs with less than 50% identity. Subsequently, the barks of European Larch, whose n-heptane extract had shown significant activity (58% inhibition of parasitic growth at 100 µg/ml), were subjected to a chemical profiling. First, through a fractionation process using Centrifugal Partition Chromatography, and then a dereplication approach combining data from nuclear magnetic resonance and mass spectrometry. Tools like VersaDB and CATHEDRAL were developed to facilitate the creation of custom-databases and assess the confidence level of annotations. 52 molecules were annotated and associated with a confidence score. Simultaneously, in vitro tests demonstrated that 2 out of the 12 CPC fractions, primarily composed of terpenic derivatives, inhibited the parasite's survival by more than 40% at 25 µg/ml. Ultimately, the annotated compounds from L. decidua were subjected to AMIDEv2.0. The overlap between in vitro and in silico results highlighted 7-oxo-dehydroabietic acid and daniellic acid, strongly correlated with the in vitro inhibitory activity of the barks. CDPK1 and the SET-containing Protein are likely protein targets for these two ligands, thereby providing initial insights into their mechanism of action. These two hits are currently undergoing in vitro evaluation to verify the efficiency of developed approach during this doctoral project