Puckering Free Energy of Pyranoses: an NMR and Metadynamics--Umbrella Sampling Investigation

We present the results of a combined metadynamics--umbrella sampling investigation of the puckered conformers of pyranoses described using the gromos 45a4 force field. The free energy landscape of Cremer--Pople puckering coordinates has been calculated for the whole series of alpha and beta aldohexoses, showing that the current force field parameters fail in reproducing proper puckering free energy differences between chair conformers. We suggest a modification to the gromos 45a4 parameter set which improves considerably the agreement of simulation results with theoretical and experimental estimates of puckering free energies. We also report on the experimental measurement of altrose conformers populations by means of NMR spectroscopy, which show good agreement with the predictions of current theoretical models

Vibrational properties of inclusion complexes: the case of indomethacin-cyclodextrin

Vibrational properties of inclusion complexes with cyclodextrins are studied by means of Raman spectroscopy and numerical simulation. In particular, Raman spectra of the non-steroidal, anti-inflammatory drug indomethacin undergo notable changes in the energy range between 1600 and 1700 cm$^{-1}$ when inclusion complexes with cyclodextrins are formed. By using both \emph{ab initio} quantum chemical calculations and molecular dynamics, we studied how to relate such changes to the geometry of the inclusion process, disentangling single-molecule effects, from changes in the solid state structure or dimerization processes.Comment: 14 file figure

Absorption et désorption du dioxyde de souffre par des gouttes d'eau de fort diamètre en chute.

Cet article concerne l’absorption et la désorption du SO2 par des gouttes d’eau de diamètre supérieur à 1mm en chute libre dans un mélange air-SO2 à faible et moyenne concentrations. Dans ce cas, le transfert résulte du couplage des résistances interne et externe à la goutte. Dans la phase liquide, un modèle local basé sur la vitesse de frottement inter faciale et le diamètre de la goutte permet le calcul du coefficient de transfert interne kl. Le coefficient de transfert externe kg dans la phase gazeuse est déterminé à l’aide d’une expression plus classiqueAfin de valider le modèle, des investigations expérimentales sont menées en absorption et en désorption sur une colonne de 2.3 m de hauteur dans laquelle le temps de séjour des gouttes est de l’ordre de la seconde. Le présent modèle simule fort bien l’ensemble de ces expériences réalisées pour différents diamètres de goutte [2.04 ; 4.31] mm et différentes concentrations [100 ; 2000] ppm. Le modèle proposé est aussi comparé avec succès à des résultats expérimentaux de la littérature à faible et moyenne concentrations pour des temps de contact beaucoup plus grands.Son domaine d’application couvre donc désormais l’absorption et la désorption du SO2 pour des concentrations comprises entre quelques ppm et quelque %.Mass transfer in dispersed media is of interest to fields such as nuclear engineering, process engineering and environmental engineering. It occurs when two phases, not under chemical equilibrium, are in contact. Knowledge of mass transfer mechanisms in the case of gas absorption from and/or into droplets is necessary to understand the scavenging of trace gases in clouds, rain and wet scrubbers. Our studies focus on absorption and desorption phenomena involving free falling water droplets in a mixture of air and gas. For example, acid rain is formed when a drop of rain falls through an atmosphere contaminated with gaseous acid precursors. A similar phenomenon occurs in specific atmospheric scrubbers, where pollution is trapped at the source. In all cases, the transfer of trace gases from the air into the falling droplets is controlled by molecular diffusion and by convection outside and inside the drops.For droplets, falling inside a soluble gas medium, the main transfer resistance is located in the gas phase. A survey of published studies shows that a number of good numerical models exist, as well as experimental correlations for predictions of the mass transfer coefficient in the gas film. For the liquid phase controlled resistance, Saboni (1991) proposed a model based on local scales, interfacial liquid friction velocity and drop diameter. The model was validated experimentally by Amokrane et al. (1994). The experimental study and model validation in the case of sulfur dioxide absorption by water droplets falling through air with a high gas concentration (few %) has been described previously in detail by Amokrane et al. (1994).The purpose of the present article was to extend our previous model to predict SO2 absorption and desorption by droplets (1-5 mm) falling in air with a low gas concentration. In the liquid phase, a model based on local scales, interfacial liquid friction velocity and droplet size diameter was used. In the continuous gas phase a more classical model was applied. To support the model, two types of experiments were carried out. The first type was adapted to measure the absorption of gas by droplets of known diameter. A second set of experiments gave the desorption rate from droplets with an initial concentration of sulfur dioxide falling through SO2 -free air. Absorption occurred during the fall through a 2.3 m long column for various gas concentrations and for various droplet diameters. A sketch of the experimental equipment is presented schematically in Figure 1. It consists of a cylindrical column 2.3 m in height and 0.104 m in diameter. Before each experiment, a gas mixture with the desired SO2 concentration in air, ranging between 100 and 2000 ppm, was introduced into the column. The SO2 concentration was set at the desired value by regulating the volumetric flow rates of sulfur dioxide and air with calibrated rotameters. The gas concentration in the column was measured continuously by a chemical cell analyzer. The air temperature and humidity were continually measured at the top, in the middle and at the bottom of the column. They ranged from 18°C to 20°C and from 40% to 50%, respectively. Droplets were generated using a specific injector consisting of a demineralized water tank at the base of which identical thin needles were placed. In the case of the smallest droplets, seven needles, 300 µm in diameter, were used. For the largest droplets, one needle of about 1 mm was used. The artificial rain was started by exerting an overpressure in the tank and it was stopped by exerting a depression. This device allowed the generation of almost identical water drops at a controlled rate. Droplets fell with zero initial velocity. Their diameters were determined by collecting a known number of droplets and weighing them on a precision balance. The droplets were collected in a special glass cup placed at the bottom of the rain shaft. This collector initially contained a known volume of kerosene. The presence of this organic compound allowed the creation of a film to prevent additional absorption of SO2 during the experiment and natural desorption of sulfur after the experiment. An experiment consisted of dropping 10 to 20 mL of rain. This amount is enough to precisely measure the sulfur concentration.For reversible desorption, experimentation was undertaken directly in a lab atmosphere. For these experiments, the 4.31 mm diameter droplets free fall occurred over 16.3 m. Three intermediate levels were also examined with falling times varying from 0.7 to 2.4 s. The ambient temperature was measured in the surrounding area of both the injector and the collector and the maximum variation was 2°C. Various initial sulfurous acid concentrations were obtained as a result of various contact times of demineralized water with air-SO2 mixtures. Initial concentrations ranged from 0.5 10-3 mol·L-1 to 1.8 10-3 mol·L-1. In this case, the collector initially contained a known volume of hydrogen peroxide to immediately convert sulfurous acid into sulfuric acid. This avoided additional desorption of sulfurous acid during and after the experiments. In this case, the presence of the organic film was not necessary.The results achieved with the theoretical model were compared to the experimental results. The present model was successful in correlating the experimental results carried out for various droplet diameters ranging between 2.04 and 4.31 mm, and gas concentrations ranging between 100 and 2000 ppm. The model also compared successfully with experimental results from the literature in the case of much longer contact times. The applicability of the model thus covers the absorption and desorption of SO2 for concentrations ranging between ppm to a few %

Methyl salicylate glycosides in some Italian varietal wines

Glycosides are ubiquitous plant secondary metabolites consisting of a non-sugar component called an aglycone, attached to one or more sugars. One of the most interesting aglycones in grapes and wine is methyl salicylate (MeSA), an organic ester naturally produced by many plants, particularly wintergreens. To date, nine different MeSA glycosides from plants have been reported, mainly spread over the genera Gaultheria, Camellia, Polygala, Filipendula, and Passiflora. From a sensorial point of view, MeSA has a balsamic-sweet odor, known as Wintergreen. MeSA was found in Vitis riparia grapes, in Vitis vinifera sp. and in the Frontenac interspecific hybrid. We found that the MeSA glycosides content in Verdicchio wines and in some genetically related varieties (Trebbiano di Soave and Trebbiano di Lugana) was very high. In order to understand which glycosides were present in wine, the methanolic extract of Verdicchio wine was injected into a UPLC-Q-TOF-HDMS and compared to the extracts of different plants rich in such glycosides. Using pure standards, we confirmed the existence of two glycosides in wine: MeSA 2-O-β-d-glucoside and MeSA 2-O-β-d-xylopyranosyl (1-6) β-d-glucopyranoside (gaultherin). For the first time, we also tentatively identified other diglycosides in wine: MeSA 2-O-α-l-arabinopyranosyl (1-6)-β-d-glucopyranoside (violutoside) and MeSA 2-O-β-d-apiofuranosyl (1-6)-β-d-glucopyranoside (canthoside A), MeSA 2-O-β-d-glucopyranosyl (1-6)-O-β-d-glucopyranoside (gentiobioside) and MeSA 2-O-α-l-rhamnopyranosyl (1-6)-β-d-glucopyranoside (rutinoside). Some of these glycosides have been isolated from Gaultheria procumbens leaves by preparative liquid chromatography and structurally annotated by 1H- and 13C-NMR analysis. Two of the peaks isolated from Gaultheria procumbens leaves, namely MeSA sambubioside and MeSA sophoroside, were herein observed for the first time. Six MeSA glycosides were quantified in 64 Italian white wines, highlighting the peculiar content and pattern in Verdicchio wines and related cultivars. The total concentration in bound and free MeSA in Verdicchio wines varied in the range of 456–9796 μg/L and 5.5–143 μg/L, respectively, while in the other wines the bound and free MeSA was below 363 μg/L and 12 μg/L, respectively. As this compound’s olfactory threshold is between 50 and 100 μg/L, our data support the hypothesis that methyl salicylate can contribute to the balsamic scent, especially in old Verdicchio wine

Evidence for Gene Duplication and Allelic Codominance (not Hierarchical Dominance) at the Mating-Type Locus of the Ciliate, Euplotes crassus.

The high-multiple mating system of Euplotes crassus is known to be controlled by multiple alleles segregating at a single locus and manifesting relationships of hierarchical dominance, so that heterozygous cells would produce a single mating-type substance (pheromone). In strain L-2D, now known to be homozygous at the mating-type locus, we previously identified two pheromones (Ec-α and Ec-1) characterized by significant variations in their amino acid sequences and structure of their macronuclear coding genes. In this study, pheromones and macronuclear coding genes have been analyzed in strain POR-73 characterized by a heterozygous genotype and strong mating compatibility with L-2D strain. It was found that POR-73 cells contain three distinct pheromone coding genes and, accordingly, secrete three distinct pheromones. One pheromone revealed structural identity in amino acid sequence and macronuclear coding gene to the Ec-α pheromone of L-2D cells. The other two pheromones were shown to be new and were designated Ec-2 and Ec-3 to denote their structural homology with the Ec-1 pheromone of L-2D cells. We interpreted these results as evidence of a phenomenon of gene duplication at the E. crassus mating-type locus, and lack of hierarchical dominance in the expression of the macronuclear pheromone genes in cells with heterozygous genotypes

Humoral and T-Cell Mediated Response after the Third Dose of mRNA Vaccines in Patients with Systemic Lupus Erythematosus on Belimumab

Objective: To evaluate humoral and T-cell cellular-mediated immune response after three doses of SARS-CoV-2 mRNA vaccines in patients with systemic lupus erythematosus (SLE) under Belimumab. Patients and methods: 12 patients on Belimumab and 13 age-matched healthy volunteers were recruited. Patients were in remission or in low disease activity, and they were taking no corticosteroids or only low doses. None of the patients and controls had detectable anti-SARS-CoV-2 antibodies due to previous exposure to the virus. All the patients received three doses of mRNA anti-SARS-CoV-2 vaccines and the humoral and cellular-mediated response were tested 4 weeks after the second dose (T0), 6 months after the second dose (T1) and 4 weeks after the third dose (T2). Comparison with the control group was performed at time T0 (i.e., 4 weeks after the second dose). Total anti-SARS-CoV-2 RBD antibodies were analyzed using a diagnostic assay, while cellular-mediated response was evaluated using the interferon-gamma release assay (IGRA). Results: A humoral response was documented in all the patients at T0 (median 459; IQR 225.25–758.5), but the antibody titer significantly declined from T0 to T1 (median 44.7; IQR: 30.3–202; p = 0.0066). At T2, the antibody titer significantly increased from T1 (median 2500; IQR: 2500–2500), and it was not different from T0 (respectively p < 0.0001, p = 0.66). Cellular-mediated response significantly declined from T0 to T1 (p = 0.003) but not from T0 to T2 (p = 0.3). No differences were found between patients and controls at T0 as regards both humoral and cellular responses (p = 1.0 and p = 0.09 for humoral and cellular responses, respectively). Conclusion: The third dose of mRNA COVID-19 vaccine can restore both humoral and cellular immune response in SLE patients on Belimumab

Complexing the Marine Sesquiterpene Euplotin C by Means of Cyclodextrin-Based Nanosponges: A Preliminary Investigation

Euplotin C is a sesquiterpene of marine origin endowed with significant anti-microbial and anti-tumor properties. Despite the promising functional profile, its progress as a novel drug candidate has failed so far, due to its scarce solubility and poor stability in aqueous media, such as biological fluids. Therefore, overcoming these limits is an intriguing challenge for the scientific community. In this work, we synthesized β-cyclodextrin-based nanosponges and investigated their use as colloidal carriers for stably complex euplotin C. Results obtained proved the ability of the carrier to include the natural compound, showing remarkable values of both loading efficiency and capacity. Moreover, it also allowed us to preserve the chemical structure of the loaded compound, which was recovered unaltered once extracted from the complex. Therefore, the use of β-cyclodextrin-based nanosponges represents a viable option to vehiculate euplotin C, thus opening up its possible use as pharmacologically active compound

FUNCTIONAL STUDY OF LIPOXYGENASE-MEDIATED RESISTANCE AGAINST ASPERGILLUS FLAVUS AND FUSARIUM VERTICILLIOIDES INFECTION IN MAIZE

Mycotoxin contamination of maize kernels by fungal pathogens Aspergillus flavus (Af) and Fusarium verticillioides (Fv) is a chronic global challenge impacting food security, health and trade. Current disease management practices are proven inadequate and strategies gearing towards hostmediated resistance can be an effective and sustainable approach to strengthen efforts to control the pathogens. Lipid modification into a diverse array of compounds, oxylipins, are recognized in response of plants to fungal pathogens. Lipoxygenase genes (LOXs) play a crucial role in the enzymatic oxidation of polyunsaturated fatty acids (PUFAs) into 9(S)- and 13(S)-hydroperoxides that are further metabolized into different oxylipins including jasmonates, oxo- and keto-fatty acids and volatiles. The involvement of maize LOXs (ZmLOXs) in this respect has been a subject of studies and their genetic manipulation resulted in the alteration of resistance or susceptibility to fungal pathogens in maize. However, the maize genome encodes six 9-LOX and seven 13-LOX isoforms and the specific role of each isoform remains elusive. The current study investigated the role of ZmLOXs in host resistance against the fungi Af and Fv using in silico and in planta approaches. The phylogenetic relationship, sequence similarity, protein domain structures, and transcript level structural variations were explored by comparing publicly available maize pan-genomes. Furthermore, the role of ZmLOXs against Af and Fv infection was investigated through their expression analysis along with further key genes involved in oxylipin biosynthesis, mycotoxin accumulation and lipid profiles in a ZmLOX4 mutant line (UFMulox4) together with W22, Mo17 and Tzi18 inbred lines at 3- and 7-days post-inoculation (dpi). ZmLOX proteins showed considerable variations in their sequences, functional domain structure and transcript structural variations among the pan-genome members. Among the studied lines, Tzi18 showed the highest resistance to the pathogens coupled with the lowest mycotoxin accumulation, while the mutant, UFMulox4, was highly susceptible to both pathogens with the most elevated content of mycotoxins. Fv inoculation determined a stronger induction of ZmLOXs and maize allene oxide synthase genes as compared to Af . Higher constitutive levels of 9-LOXs genes, ZmLOX1 and ZmLOX2 and an induction of ZmLOX4 were recorded in Tzi18, while the upregulation of ZmLOX1 and ZmLOX4 observed in Mo17 might have larger active role in resistance against Fv. Liquid chromatography-mass spectrometry further revealed an increased accumulation of the linoleic (18:2) derived 9-cyclopentenone, 10- oxo-11-phytoenoic acid (10-OPEA), in Fv inoculated kernels of Tzi18 and Mo17, which was previously identified to inhibit fungal growth in vitro. Hence, the results confirm the pivotal role of ZmLOXs in controlling the resistance mechanisms against these two pathogens

Functional Study of Lipoxygenase-Mediated Resistance against Fusarium verticillioides and Aspergillus flavus Infection in Maize

Mycotoxin contamination of maize kernels by fungal pathogens like Fusarium verticillioides and Aspergillus flavus is a chronic global challenge impacting food and feed security, health, and trade. Maize lipoxygenase genes (ZmLOXs) synthetize oxylipins that play defense roles and govern host-fungal interactions. The current study investigated the involvement of ZmLOXs in maize resistance against these two fungi. A considerable intraspecific genetic and transcript variability of the ZmLOX family was highlighted by in silico analysis comparing publicly available maize pan-genomes and pan-transcriptomes, respectively. Then, phenotyping and expression analysis of ZmLOX genes along with key genes involved in oxylipin biosynthesis were carried out in a maize mutant carrying a Mu transposon insertion in the ZmLOX4 gene (named UFMulox4) together with Tzi18, Mo17, and W22 inbred lines at 3- and 7-days post-inoculation with F. verticillioides and A. flavus. Tzi18 showed the highest resistance to the pathogens coupled with the lowest mycotoxin accumulation, while UFMulox4 was highly susceptible to both pathogens with the most elevated mycotoxin content. F. verticillioides inoculation determined a stronger induction of ZmLOXs and maize allene oxide synthase genes as compared to A. flavus. Additionally, oxylipin analysis revealed prevalent linoleic (18:2) peroxidation by 9-LOXs, the accumulation of 10-oxo-11-phytoenoic acid (10-OPEA), and triglyceride peroxidation only in F. verticillioides inoculated kernels of resistant genotypes