A cautionary note on thermal runaway reactions in mixtures of 1-alkyl-3-methylimidazolium ionic liquids and N-methylmorpholine-N-oxide

Nicht verfügbarN-Methylmorpholine-N-oxide (NMMO) cannot be completely separated by extraction from mixtures with common 1,3-dialkylimidazolium ionic liquids (ILs) due to strong ionic interactions between the two components. At elevated temperatures, above approx. 90 C, especially under dry conditions and in the presence of acid, alkylating or acylating agents, remaining NMMO in ILs tends to undergo autocatalytic degradation. This is a highly exothermic, unstoppable process that results in explosions, flames, and complete charring of the reaction mixtures. Thus, caution must be exercised when drying or heating ILs that were in previous contact with NMMO, and the absence of amine oxide must be confirmed to avoid potential danger.(VLID)192930

Involvement of UDP-Glucuronosyltransferases and Sulfotransferases in the Excretion and Tissue Distribution of Resveratrol in Mice.

Resveratrol is a naturally occurring polyphenolic compound with various pharmacological activities. It is unknown whether the expression of metabolizing enzymes correlates with resveratrol levels in organs and tissues. Therefore, we investigated the metabolism and tissue distribution of resveratrol in mice and assessed its association with the expression of UDP-glucuronosyltransferase (Ugt) and sulfotransferase (Sult) genes. Plasma, urine, feces, and various organs were analyzed using high-performance liquid chromatography at up to 8 h after intragastric resveratrol administration. The metabolism of resveratrol was pronounced, leading to the formation of resveratrol glucuronides and sulfates. Concentrations of resveratrol and its metabolites were high in the gastrointestinal organs, urine, and feces, but low in the liver and kidneys. In lung, heart, thymus, and brain tissues, parent resveratrol levels exceeded the sulfate and glucuronide concentrations. The formation of resveratrol conjugates correlated with the expression of certain Ugt and Sult genes. Reverse transcription quantitative PCR (RT-qPCR) analysis revealed high mRNA expression of Ugt1a1 and Ugt1a6a in the liver, duodenum, jejunum, ileum, and colon, leading to high concentrations of resveratrol-3-O-glucuronide in these organs. Strong correlations of resveratrol-3-O-sulfate and resveratrol-3-O-4'-O-disulfate formation with Sult1a1 mRNA expression were also observed, particularly in the liver and colon. In summary, our data revealed organ-specific expression of Sults and Ugts in mice that strongly affects resveratrol concentrations; this may also be predictive in humans following oral uptake of dietary resveratrol

The Lipoxygenase Lox1 Is Involved in Light‐ and Injury-Response, Conidiation, and Volatile Organic Compound Biosynthesis in the Mycoparasitic Fungus Trichoderma atroviride

18 páginas, 10 figuras. -- The first publication by Frontiers Media is avalilable at https://www.frontiersin.org/articles/10.3389/fmicb.2020.02004/fullThe necrotrophic mycoparasite Trichoderma atroviride is a biological pest control agent frequently applied in agriculture for the protection of plants against fungal phytopathogens. One of the main secondary metabolites produced by this fungus is 6-pentyl-α-pyrone (6-PP). 6-PP is an organic compound with antifungal and plant growth-promoting activities, whose biosynthesis was previously proposed to involve a lipoxygenase (Lox). In this study, we investigated the role of the single lipoxygenase-encoding gene lox1 encoded in the T. atroviride genome by targeted gene deletion. We found that light inhibits 6-PP biosynthesis but lox1 is dispensable for 6-PP production as well as for the ability of T. atroviride to parasitize and antagonize host fungi. However, we found Lox1 to be involved in T. atroviride conidiation in darkness, in injury-response, in the production of several metabolites, including oxylipins and volatile organic compounds, as well as in the induction of systemic resistance against the plant-pathogenic fungus Botrytis cinerea in Arabidopsis thaliana plants. Our findings give novel insights into the roles of a fungal Ile-group lipoxygenase and expand the understanding of a light-dependent role of these enzymes.This research was supported by the Austrian Science Fund (FWF; grant P32179-B), Tyrolean Science Fund (TWF; grant number AP718021) and the doctoral program BioApp from the University of InnsbruckPeer reviewe

Monosaccharide profile and antioxidant activities of sulphated polysaccharide extracted from Indonesian brown seaweed (Sargassum sp.)

This research was conducted to determine the monosaccharide profile and antioxidant activities of the sulphated polysaccharide fucoidan, extracted from Sargassum sp. harvested in Batam, Indonesia. Crude fucoidan (Fsar) was extracted using low pH (pH 2) acid method, obtaining a yield of 5.5% (w/w), and the chemical properties of Fsar were subsequently compared to commercial fucoidan (Fcomm), obtained from Japan. Sulphate contents were determined using spectrophotometric analysis, where Fsar (5.21±0.35%) and Fcomm (8.80±0.19%) differed significantly (p<0.05). Monosaccharide profiling was performed using methanolysis and gas chromatography-flame ionisation detector (GC-FID). Fsar contained fucose (138.34 µg/g), 4-O-methyl-glucuronic acid (105.39 µg/g), galactose (70.49 µg/g) and glucuronic acid (30.60 µg/g) while Fcomm contained fucose (520 µg/g) and glucuronic acid (62.93 µg/g) as its main composition. Antioxidant activities were analysed through 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide anion (SOA) and hydroxyl radical (·OH) scavenging activities. DPPH scavenging activity of Fsar (40.67±4.0%) was significantly higher (p<0.05) than Fcomm (10.11±1.0%), while SOA and ·OH scavenging activities showed no significant difference (p>0.05) between Fsar and Fcomm. Fsar showed significant differences (p<0.05) in chemical properties and DPPH scavenging activities compared to that of Fcomm. Fucoidan from Southeast Asia waters has the potential for application as functional ingredients

Studies into fundamentals of ortho-quinone methide chemistry

Durch Oxidation entstehen aus Tocopherolen ("Vitamin E") komplexe Substanzgemische, das ortho-Chinonmethid ist dabei ein Schlüsselintermediat. Der Übergang vom bisher nur vermuteten intermediären aromatischen Zwitterion zum olefinischen ortho-Chinonmethid sollte lediglich an eine Drehung um eine Einfachbindung gekoppelt sein. Anhand spezieller Tocopherolderivate konnte nun die zwitterionischen Stufe spektroskopisch (NMR) eingehend untersucht und erstmalig direkt nachgewiesen werden. Durch dieses Ergebnis müssen bisherige Lehrmeinungen zur Entstehung und Chemie von ortho-Chinonmethiden revidiert werden. Erst kürzlich wurde durch mögliche chemotherapeutische Anwendungen großes Interesse an der Stoffklasse der Tocopheramine die phenolische OH-Gruppe der Tocopherole ist hierbei durch eine Aminogruppe ersetzt geweckt. Das Wissen um das Reaktionsverhalten und um die Reaktionsprodukte dieser Verbindungen ist eine Vorraussetzung für jede Art von Anwendung. Daher wurde erstmal systematisch das Reaktionsverhalten der Tocopheramine in Einelektronen- und Zweielektronen-Oxidationsprozessen erforscht, wobei methodisch ESR und Abfangreaktionen zur Anwendung kamen. Die Bromierung von Tocopherolen kann nach zwei unterschiedlichen Mechanismen verlaufen: entweder es erfolgt eine klassische elektrophile Substitution am Aromaten, oder das Tocopherol wird über ein ortho-Chinonmethid oxidiert. Anhand der Produktverhältnisse und durch quantenchemische Berechnungen wurden die Aktivierungsenergien bestimmt und der jeweils bevorzugte Reaktionsmechanismus erklärt. Die Bromierungsprodukte aller vier Tocopherole wurden synthetisiert und vollständig charakterisiert, um eine verlässliche Grundlage für zukünftige Studien zu bilden. In den letzten Jahren hat sich herausgestellt, daß die traditionellen Lehrmeinungen zur Oxidationschemie der Tocopherole teilweise falsch und mißverständlich sind. Einige Oxidationsprodukte, die mit Reaktionen des Tocopherylradikals erklärt wurden, entstehen in Wirklichkeit aus dem ortho-Chinonmethid. Ebenso wurde der detaillierte Bildungsmechanismus der ortho-Chinonmethide revidiert. Um den derzeitigen Stand des Wissens darzustellen und die neuen Entwicklungen einzubinden, wurde im Rahmen der Arbeit ein umfassender Review verfasst.Oxidation of tocopherols ("vitamin E") produces complex mixtures of compounds, with the ortho-quinone methide being a key intermediate. The conversion of the hitherto hypothetical aromatic zwitterion to the olefinic ortho-quinone methide would simply be controlled by bond rotation. In the present work, special tocopherol derivatives were synthesized that allowed detailed spectroscopic studies (NMR) on the zwitterionic intermediate, and thus a direct proof of its existence for the first time. Conventional, decade-old teaching on formation and chemistry of ortho-quinone methides will now have to be revised. Most recently the almost completely neglected class of tocopheramines tocopherols that bear an amino group instead of the phenolic hydroxyl group have undergone a surge of interest due to their potential in chemotherapy. A comprehensive knowledge about their chemistry, reactivity and products is a prerequisite to any application. Making use of EPR spectroscopy and chemical trapping, for the first time the one-electron and two-electron oxidation chemistry of tocopheramines was established. The bromination of different tocopherols can proceed, in principle, according to two different mechanisms, either by a classical electrophilic substitution at the aromatic core or by an oxidation-addition sequence leading to a bromomethyl derivative. The bromination behaviour of all four tocopherols was thoroughly studied. Based on the product ratios and computational studies, activation energies were calculated and the preferred pathways were identified. All bromination products were synthesized and fully analytically characterized, clarifying contradictory data in the pertinent literature and providing a reliable set of standard compounds for future studies. Over the past several years, some traditional teaching on the oxidation chemistry of tocopherols has proved to be erroneous. Oxidation products that so far have been explained based on tocopheroxyl radical chemistry are actually formed involving the ortho-quinone methide as key intermediate. The general mechanism of ortho-chinone methide formation was revised as well. To update the current knowledge of ortho-quinone methide chemistry related to tocopherols, also considering the new results of the present thesis, this topic was comprehensively reviewed.eingereicht von Stefan BöhmdorferAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in dt. SpracheWien, Univ. für Bodenkultur, Diss., 2009OeBB(VLID)193051

Gellan residues on paper: quantification and implication for paper conservation

Abstract Gels prepared from the polysaccharide gellan are used for aqueous poulticing treatments in paper conservation when the application of water must be restricted. Optimal use of the rigid, yet shapeable gel requires direct contact with the paper surface, which carries the risk of gel residues on the treated surface. We used acid methanolysis as a destructive analytical method to detect rhamnose as a component of gellan, which was undetectable with ATR-FTIR spectroscopy. We show that there is a significant probability of leaving gellan residues on the paper. Conservators should be aware of this potential side effect when considering the use of gellan poultices in direct contact with paper objects

Profiling and quantification of grain anthocyanins in purple pericarp × blue aleurone wheat crosses by high-performance thin-layer chromatography and densitometry

Abstract Background Anthocyanins are abundant secondary metabolites responsible for most blue to blue-black, and red to purple colors of various plant organs. In wheat grains, anthocyanins are accumulated in the pericarp and/or aleurone layer. Anthocyanin pigmented wheat grains can be processed into functional foods with potential health benefits due to the antioxidant properties of the anthocyanins. The grain anthocyanin content can be increased by pyramidizing the different genes responsible for the accumulation of anthocyanins in the different grain layers. Our objective was to develop a high-performance thin-layer chromatography (HPTLC) method that allows the determination of both the anthocyanin profile and the total pigment concentration. Thereby, selection of breeding lines with significantly higher grain anthocyanin content from purple pericarp × blue aleurone wheat crosses should become more efficient than selection based on only visual scoring of grain color and the unspecific determination of anthocyanin concentration by UV/Vis spectroscopy. Results A wide variability in the grain anthocyanin content was observed in breeding lines and check varieties. The highest concentration of anthocyanins was observed in deep purple (i.e. combination of the purple pericarp and blue aleurone genetics) grained breeding lines, followed by blue aleurone and purple pericarp genotypes. Determination of the total anthocyanin content was included into the chromatographic analysis, rendering an additional photometric analysis unnecessary. Ten target zones were identified in anthocyanin pigmented wheat grains; four of these zones were typically for blue aleurone types, five for purple pericarp types, and one (i.e. kuromanin glucoside) was characteristic for both. Chemometrics applied to the anthocyanin profile recorded by scanning densitometry revealed that peak heights and peak areas are highly correlated and that seven out of the ten target zones were responsible for about 90% of the total variation in the germplasm. Multivariate analysis of these seven target zones allowed not only a separation of the genetic material into purple, blue and deep purple grained genotypes, but also the identification of genotypes with a specific anthocyanin pattern. Thereby, the original classification by visual scoring was overruled in about one-third of the breeding lines. Conclusions The presented HPTLC method with à côté calibration allowed the profiling of the pigments and quantification of wheat grain anthocyanin content in a single analysis, replacing UV/Vis spectroscopy with subsequent HPLC analysis. Moreover, no sample preparation apart from extraction and filtration is required, and more than 15 samples can be evaluated in one analysis run, corresponding to several dozens of samples per day. Hence, the method fulfills the requirements for screening methods in early generations of a plant breeding program such as high-throughput, small sample size, high repeatability, fast determination, and reasonable costs per sample. Combined with multivariate statistical analysis, the anthocyanin pattern allowed the validation of the genetic background in the offspring of purple × blue wheat crosses and, therefore, the efficient selection of genotypes exhibiting both the cyanidin and delphinidin aglycon

Facile Preparation of Mechanically Robust and Functional Silica/Cellulose Nanofiber Gels Reinforced with Soluble Polysaccharides

Nanoporous silica gels feature extremely large specific surface areas and high porosities and are ideal candidates for adsorption-related processes, although they are commonly rather fragile. To overcome this obstacle, we developed a novel, completely solvent-free process to prepare mechanically robust CNF-reinforced silica nanocomposites via the incorporation of methylcellulose and starch. Significantly, the addition of starch was very promising and substantially increased the compressive strength while preserving the specific surface area of the gels. Moreover, different silanes were added to the sol/gel process to introduce in situ functionality to the CNF/silica hydrogels. Thereby, CNF/silica hydrogels bearing carboxyl groups and thiol groups were produced and tested as adsorber materials for heavy metals and dyes. The developed solvent-free sol/gel process yielded shapable 3D CNF/silica hydrogels with high mechanical strength; moreover, the introduction of chemical functionalities further widens the application scope of such materials

Acetylation of cellulose – Another pathway of natural cellulose aging during library storage of books and papers

Gaseous acetic acid is formed under conditions of storage of historic paper objects. Its presence not only promotes hydrolytic cleavage of cellulose, but also causes acetylation of the cellulosic material to very small degree. The acetylation reaction proceeds under ambient conditions and without catalyst. Different analytical methods were used to prove the presence of organic acetates on cellulosic paper matrices. DESI-MS in combination with 2H-isotopic labeling showed the presence of sugar fragments with different acetylation patterns. A method based on Zemplen saponification was applied and worked also in the presence of a large excess of acetic acid and/or inorganic acetates. The acetylation effect was quantified for model papers and original, naturally aged paper samples. While cellulose acetylation was clearly proven to be another general pathway of paper aging, further studies of this acetylation phenomenon are needed with regard to conservational aspects and suitable paper storage conditions