Active coatings based on oxidized chitin nanocrystals and silk fibroins for the control of anthracnose in 'Hass' avocados.

Postharvest avocado losses are mainly due to anthracnose disease caused by Colletotrichum gloeosporioides. Chemical fungicides are effective, but their negative effects on health and the environment have led to the search for sustainable alternatives such as biopolymer-based coatings and natural compounds. Therefore, chitin nanocrystals (NCChit) were extracted using a sustainable deep eutectic solvent (DES) and chemically modified into oxidized chitin nanocrystals (O-NCChit) or deacetylated chitin nanocrystals (D-NCChit) to modulate and increase the charge surface density and the dispersibility of the crystals. The modified NCChits were dispersed with silk fibroins (SF), essential oil (EO), melatonin (MT) and/or phenylalanine (Phe) to elaborate active coatings. Antioxidant and antifungal in vitro analyses showed that the O-NCChit/SF-based coating had the best performance. In addition, in vivo tests were carried out through the artificial inoculation of C. gloeosporioides on coated avocados. O-NCChit/SF/MT-based coatings reduced the severity of anthracnose by 45 %, the same effect as the chemical fungicide (Prochloraz®). Moreover, avocado quality parameters during cold storage and the shelf-life period were also evaluated, where nonsignificant differences were observed. Therefore, this study demonstrates the great potential of O-NCChit and SF in combination with active compounds for the control of anthracnose in 'Hass' avocados.

Copper-uptake mediated by an ecofriendly zwitterionic ionic liquid: A new challenge for a cleaner bioeconomy.

This study aims to investigate the ability of an imidazolium biobased Zwitterionic Ionic Liquids (ZILs) in enhancing the phytoavailability of copper from garden (G) and vineyard (V) soils using the model plant ryegrass. Uncontaminated and artificially contaminated CuSO4 soils, unamended and ZIL-amended soil modalities were designed. The copper/ZIL molar ratio (1/4) introduced was rationally established based on molecular modeling and on the maximal copper concentration in artificially contaminated soil. Higher accumulation of copper in the shoots was detected for the uncontaminated and copper contaminated ZIL amended V soils (18.9 and 23.3 mg/kg, respectively) contrary to G soils together with a ZIL concentration of around 3% (W/W) detected by LC-MS analyses. These data evidenced a Cu-accumulation improvement of 38% and 66% compared to non-amended V soils (13.6 and 13.9 mg/kg respectively). ZIL would be mainly present under Cu(II)-ZIL4 complexes in the shoots. The impact on the chemical composition of shoot was also studied. The results show that depending on the soils modalitity, the presence of free copper and/or ZIL led to different chemical compositions in lignin and monomeric sugar contents. In the biorefinery context, performances of enzymatic hydrolysis of shoots were also related to the presence of both ZIL and copper under free or complex forms. Ecotoxicity assessment of the vineyard soil samples indicated that the quantity of copper and ZIL remaining in the soils had no significant toxicity. ZIL amendment in a copper-contaminated soil was demonstrated as being a promising way to promote the valorization of phytoremediation plants.

IL versus DES: Impact on chitin pretreatment to afford high quality and highly functionalizable chitosan.

Chitin is mainly extracted from crustaceans, but this resource is seasonally dependent and can represent a major drawback to satisfy the traceability criterion for high valuable applications. Insect resources are valuable alternatives due to their lower mineral content. However, the deacetylation of chitin into chitosan is still an expensive process. Therefore, we herein compare the impact of both DES/IL-pretreatments on the efficiency of the chemical deacetylation of chitin carried out over two insect sources (Bombyx eri, BE and Hermetia illucens, HI) and shrimp shells (S). The results showed that chitosans obtained from IL-pretreated chitins from BE larva, present lower acetylation degrees (13-17%) than DES-pretreated samples (18-27%). A selective N-acylation reaction with oleic acid has also been performed on the purest and most deacetylated chitosans leading to high substitution degrees (up to 27%). The overall approach validates the proper chitin source and processing methodology to achieve high quality and highly functionalizable chitosan.

Straightforward extraction and selective bioconversion of high purity chitin from Bombyx eri larva: Toward an integrated insect biorefinery.

Chitins of different purity grades (45%, 89.7% and 93.3%) were efficiently extracted from Bombyx eri larva and fully physico-chemically characterized. Compared to commercially available and extracted α-chitin from shrimp shell, the collected data showed that insect chitins had similar characteristics in terms of crystallographic structures (α-chitin), thermal stability and degree of acetylation (>87%). The major differences lay in the crystallinity indexes (66% vs 75% for shrimp chitin) and in the morphological structures. Furthermore, low ash contents were determined for the insect chitins (1.90% vs 21.73% for shrimp chitin), making this chitin extraction and purification easier, which is highly valuable for an industrial application. Indeed, after only one step (deproteinization), the obtained chitin from Bombyx eri showed higher purity grade than the one extracted from shrimp shells under the same conditions. Insect chitins were then subjected to room temperature ionic liquid (RTIL) pretreatment prior to enzymatic degradation and presented a higher enzymatic digestibility compared to commercial one whatever their purity grade and would be thus a more relevant source for the selective production of N-acetyl-D-glucosamine (899.2 mg/g of chitin-2 stepsvs 760 mg/g of chitin com). Moreover, for the first time, the fermentescibility of chitin hydrolysates was demonstrated with Scheffersomyces stipitis used as ethanologenic microorganism.

Effect of standard light illumination on electrolyte's stability of lithium-ion batteries based on ethylene and di-methyl carbonates.

Combining energy conversion and storage at a device and/or at a molecular level constitutes a new research field raising interest. This work aims at investigating how prolonged standard light exposure (A.M. 1.5G) interacts with conventional batteries electrolyte, commonly used in the photo-assisted or photo-rechargeable batteries, based on 1 mol.L-1 LiPF6 EC/DMC electrolyte. We demonstrate the intrinsic chemical robustness of this class of electrolyte in absence of any photo-electrodes. However, based on different steady-state and time-resolved spectroscopic techniques, it is for the first time highlighted that the solvation of lithium and hexafluorophosphate ions by the carbonates are modified by light exposure leading to absorbance and ionic conductivity modifications without detrimental effects onto the electrochemical properties.

Interface stability of a TiO2/3-methoxypropionitrile-based electrolyte: first evidence for solid electrolyte interphase formation and implications.

We report an in-depth study focusing on the stability of a benchmark electrolyte composition based on a low-volatile 3-methoxypropionitrile (MPN) solvent employed in dye-sensitized solar cells. In the presence of TiO2, the semi-conductor surface plays a catalytic role in the thermal degradation of the electrolyte, which induces, among other effects, the nucleation and growth of a uniform solid electrolyte interphase (SEI) layer that wraps TiO2. On the basis of our actual understanding, we argue that SEI formation is responsible for triiodide depletion in the electrolyte during ageing and also has a simultaneous impact on TiO2 optoelectronic properties through the onset of a visible-light absorption tail, energy modification of intraband trap states, and the induction of an increase in both electron lifetime and transport time in TiO2. In-depth characterization of this layer by using XPS and ToF-SIMS indicates that the chemical composition of this SEI results from solvent and additive degradation, that is, iodide, sulfur, cyano, nitrogen, carbon, and imidazolium rings. The SEI thickness, its content, and the concentration profile strongly vary depending on the ageing conditions. The outcome of this new finding is discussed in comparison with literature observations and stresses the difficulties in reaching long-term stability at 85 °C by using MPN-based electrolytes unless new interfacial engineering is accomplished to impede pinholes between dye molecules on TiO2.

Glycosylation mediated-BAIL in aqueous solution.

The use of Brønsted acid ionic liquid (BAIL) as a catalyst for the activation of unreactive and unprotected glycosyl donors has been demonstrated for the first time in aqueous solution.

Click reactions as a key step for an efficient and selective synthesis of D-xylose-based ILs.

D-Xylose-based ionic liquids have been prepared from D-xylose following a five steps reaction sequence, the key step being a click cycloaddition. These ionic liquids (ILs) have been characterized through classical analytical methods (IR, NMR, mass spectroscopy, elemental analysis) and their stability constants, Tg and Tdec, were also determined. Considering their properties and their hydrophilicity, these compounds could be alternative solvents for chemical applications under mild conditions.

A new tool to study ribavirin-induced haemolysis.

BACKGROUND: Today, treatment of chronic hepatitis C is based on a synergistic combination of pegylated interferon and ribavirin with antiprotease inhibitors. Haemolytic anaemia, which is the major side effect of ribavirin treatment, disrupts ribavirin treatment compliance and varies significantly from one patient to another. There is an individual susceptibility to ribavirin haemolysis. With a view to studying haemolysis, and thus optimizing the treatment response, we have developed a new in vitro tool for analysing the ribavirin-induced lysis of red blood cells. METHODS: Resuspended red blood cells were incubated with isotonic buffer and a range of concentrations of ribavirin. Haemolysis was quantified by spectrophotometric measurement of the supernatant at 540 nm. The assay was used to test the effects of various compounds and to investigate the susceptibility of patients to haemolytic anaemia. RESULTS: In our assay, the degree of haemolysis is dependent on the ribavirin concentration used and can be inhibited by the addition of dipyridamole (50% inhibitory concentration [IC(50)] 30 µM), ATP or glutathione (IC(50) 1.63 mM and 767 µM, respectively). We observed a strong decrease in red blood cell haemolysis in the presence of the ribavirin prodrug viramidine (Taribavirin(®)). When testing the performance of this assay with blood from 24 patients before treatment, we observed a strong correlation between in vitro haemolysis before treatment and the decrease in haemoglobin levels seen in vivo during subsequent treatment (P<0.001). CONCLUSIONS: With this new tool it is possible to better evaluate individual susceptibility to ribavirin-induced haemolysis before the start of treatment. In addition, this model will enable the mechanism of ribavirin-induced anaemia to be further explored and allow molecules that could reduce ribavirin haemolysis to be screened and tested in vitro. This approach could help optimize current and future therapeutic strategies involving ribavirin in the treatment of chronic hepatitis C.

Synthesis of variously coupled conjugates of D-glucose, 1,3,4-oxadiazole, and 1,2,3-triazole for inhibition of glycogen phosphorylase.

5-(O-Perbenzoylated-ß-D-glucopyranosyl)tetrazole was obtained from O-perbenzoylated-ß-D-glucopyranosyl cyanide by Bu(3)SnN(3) or Me(3)SiN(3)-Bu(2)SnO. This tetrazole was transformed into 5-ethynyl- as well as 5-chloromethyl-2-(O-perbenzoylated-ß-D-glucopyranosyl)-1,3,4-oxadiazoles by acylation with propiolic acid-DCC or chloroacetyl chloride, respectively. The chloromethyl oxadiazole gave the corresponding azidomethyl derivative on treatment with NaN(3). These compounds were reacted with several alkynes and azides under Cu(I) catalysed cycloaddition conditions to give, after removal of the protecting groups by the Zemplén protocol, ß-D-glucopyranosyl-1,3,4-oxadiazolyl-1,2,3-triazole, ß-D-glucopyranosyl-1,2,3-triazolyl-1,3,4-oxadiazole, and ß-D-glucopyranosyl-1,3,4-oxadiazolylmethyl-1,2,3-triazole type compounds. 5-Phenyltetrazole was also transformed under the above conditions into a series of aryl-1,3,4-oxadiazolyl-1,2,3-triazoles, aryl-1,2,3-triazolyl-1,3,4-oxadiazoles, and aryl-1,3,4-oxadiazolylmethyl-1,2,3-triazoles. The new compounds were assayed against rabbit muscle glycogen phosphorylase b and the best inhibitors had inhibition constants in the upper micromolar range (2-phenyl-5-[1-(ß-D-glucopyranosyl)-1,2,3-triazol-4-yl]-1,3,4-oxadiazole 36: K(i)=854µM, 2-(ß-D-glucopyranosyl)-5-[1-(naphthalen-2-yl)-1,2,3-triazol-4-yl]-1,3,4-oxadiazole 47: K(i)=745µM).

A theoretical analysis of the Ti(IV)-catalyzed glycoaminocyanation reaction.

The chelation of the Lewis acid Ti(OiPr)(4) provides the necessary conformational control to induce pi-facial selectivity on the cyanation process. The steric hindrance imposed by the alpha-substituent restrains the addition for l-amino acid derivatives.

M4 agonists/5HT7 antagonists with potential as antischizophrenic drugs: serominic compounds.

Chronic low-dose treatment of rats with the psychomimetic drug, phencyclidine, induces regionally specific metabolic and neurochemical changes in the CNS that mirror those observed in the brains of schizophrenic patients. Recent evidence suggests that drugs targeting serotoninergic and muscarinic receptors, and in particular 5-HT(7) antagonists and M(4) agonists, exert beneficial effects in this model of schizophrenia. Compounds that display this combined pattern of activity we refer to as serominic compounds. Based upon leads from natural product screening, we have designed and synthesised such serominic compounds, which are principally arylamidine derivatives of tetrahydroisoquinolines, and shown that they have the required serominic profile in ligand binding assays and show potential antipsychotic activity in functional assays.

Synthesis of 4-amino-5-H-2,3-dihydroisothiazole-1,1-dioxide ring systems on sugar templates via carbanion-mediated sulfonamide intramolecular cyclization reactions (CSIC protocols) of glyco-alpha-sulfonamidonitriles.

The carbanion-mediated sulfonate intramolecular cyclizations (CSIC protocols) of glyco-alpha-sulfonamidonitriles derived from readily available monosaccharides have been extensively investigated using potassium carbonate, cesium carbonate, n-BuLi, and LDA as bases. As a result, a series of enantiomerically pure spiro(4-amino-5-H-2,3-dihydroisothiazole-1,1-dioxide) derivatives have been prepared efficiently and isolated in good yield. The synthesis of these new bicyclic systems is key to accessing a novel range of aza analogues of TSAO nucleosides (ATSAOs).