Mass Spectrometric Identification of Metabolites after Magnetic-Pulse Treatment of Infected Pyrus communis L. Microplants

The major goal of this study is to create a venue for further work on the effect of pulsed magnetic fields on plant metabolism. It deals with metabolite synthesis in the aforementioned conditions in microplants of Pyrus communis L. So far, there have been glimpses into the governing factors of plant biochemistry in vivo, and low-frequency pulsed magnestatic fields have been shown to induce additional electric currents in plant tissues, thus perturbing the value of cell membrane potential and causing the biosynthesis of new metabolites. In this study, sixty-seven metabolites synthesized in microplants within 3-72 h after treatment were identified and annotated. In total, thirty-one metabolites were produced. Magnetic-pulse treatment caused an 8.75-fold increase in the concentration of chlorogenic acid (RT = 8.33 ± 0.0197 min) in tissues and the perturbation of phenolic composition. Aucubin, which has antiviral and antistress biological activity, was identified as well. This study sheds light on the effect of magnetic fields on the biochemistry of low-molecular-weight metabolites of pear plants in vitro, thus providing in-depth metabolite analysis under optimized synthetic conditions. This study utilized high-resolution gas chromatography-mass spectrometry, metabolomics methods, stochastic dynamics mass spectrometry, quantum chemistry, and chemometrics, respectively. Stochastic dynamics uses the relationships between measurands and molecular structures of silylated carbohydrates, showing virtually identical mass spectra and comparable chemometrics parameters.

Regioselective degradation of [beta] 1,3 glucan by ferrous ion and hydrogen peroxide (Fenton oxidation)

Many species use Fe⁺² and H₂O₂ to oxidize a wide variety of compounds to simpler molecules. Both pathogen killing by leukocytes (neutrophils and lymphocytes) and degradation of cellulose by brown rot fungi rely on excretion of Fe⁺² ions and H₂O₂, the Fenton reagent. To elucidate the mechanism of Fenton oxidation of carbohydrates, β1,3 glucan (laminaran), a major fungal wall polysaccharide, was oxidized using a molar ratio of monomer/Fe⁺²/H₂O₂ of 10:1:1 (primarily). We labeled the reaction products and profiled them as fluorescent-labeled molecules in polyacrylamide gels and as hydrophobic-tagged molecules using reverse phase liquid chromatography/mass spectrometry (HPLC/MS). Sub-stoichiometric concentrations of Fe⁺² and H₂O₂ fragmented laminaran into smaller molecules containing carbonyl and carboxylic acid groups visible on fluorescent-labeled carbohydrate polyacrylamide gel electrophoresis. HPLC/MS analysis of glucan fragments showed masses consistent with six classes of molecules: aldoses, dialdoses, uronic acids, hexosuloses, aldonic acids, and hexulosonic acids. The results were consistent with published mechanisms where hydrogen radical (H•) abstraction from a C-H or O-H bond begins a cascade of reactions leading to 1) C-C bond cleavage to produce aldose/dialdose pairs; 2) oxo-group (O = ) addition to produce uronic and aldonic acids; 3) hydroxyl group (HO-) addition to produce gluconolactone and hexosuloses; and 4) hexulosonic acids. Most products resulted from regioselective H• abstractions characteristic of oxidations by ferryl-oxo ion [(FeO)⁺²] or perferryl-oxo ion [(FeO)⁺³] in close contact with specific positions in the glycan. Therefore, oxidations initiated by regioselectively-bound Fe ions were the predominant initiators of polysaccharide degradations.

Isolation and characterization of 3-deoxypentulose and its determination in heated milk

The presence of 3-deoxypentulose in heated milk is reported. This compound has been isolated from alkaline solutions of lactose and characterized by spectroscopic and Chromatographie techniques. Gas Chromatographic analysis of free monosaccharides of milk revealed two peaks corresponding to 3-deoxypentulose in commercial sterilized milk samples, in a concentration range of 30–50 mg/1. Its concentration increased with temperature and length of time of processing.

gamma-Radiolysis of DNA in oxygenated aqueous solutions: alterations at the sugar moiety

On gamma-irradiation of DNA in N2O/O2-saturated aqueous solutions alterations at the sugar moiety are observed. In the present study three new lesions were recognized: (i) 2-deoxytetrodialdose bound via a phosphoric acid ester linkage to a (broken) DNA strand, (ii) 2-deoxypentos-4-ulose bound to DNA via one (or two?) phosphoric acid ester linkage(s), and (iii) 2-deoxy-D-erythro-pentose bound to DNA via two phosphoric acid ester linkages. Lesion (i) is directly connected with a DNA strand break. Lesion (ii) might be related to a DNA strand break if bound via only one phosphoric acid ester linkage, or has to be considered as an alkali-labile site if bound via two phosphoric acid ester linkages. Lesion (iii) results from base damage, when the damaged base is hydrolysed from the sugar. This lesion is an alkali-labile site which turns into a strand break on alkali treatment. Attempts have been made to quantify these lesions. A lower limit of sugar damage (including lesions observed in preceding studies, but not lesion (iii) of G = 0.25 has been estimated.

Radiation-induced DNA strand breaks in deoxygenated aqueous solutions. The formation of altered sugars as end groups

Gamma irradiation of DNA in deoxygenated, N2O-saturated aqueous solution leads to three bound altered sugars present as end groups in broken DNA strands. These sugars are linked to the DNA by phosphoric acid ester bonds. Two of the end groups have the structures (4) and (5). (Formula: see text) The third end group after dephosphorylation has structure (3). The formation of the bound sugars (4) and (5) is explained by a mechanism postulated earlier for the formation of free altered sugars. Except for the phosphoric acid ester linkage, the free altered sugars have the same chemical structures as the bound altered sugars.

gamma-radiolysis of N2O-saturated aqueous solutions of trehalose and trehalose/amino acid mixtures

gamma-radiolysis of aqueous N2O-saturated solutions of alpha, alpha-trehalose (10(-2) M) with doses of 500 krad yielded glucose (G = 2.3), gluconic acid lactone (G = 0.25) and--after reduction--iditol (G = 0.15), mannitol (G = 0.05), 5-deoxy-glucitol (G = 0.34) and 2-deoxy-glucitol (G = 0.14). The decomposition of trehalose (G = -5.9) was reduced, if equimolar amounts of amino acids (alanine, leucine, phenylalanine, methionine or cysteine) were present during irradiation. The extent of this reduction has been correlated with the .OH radical-scavenging properties of the added amino acids. Cysteine also protected trehalose by the repair of initially formed trehalose radicals and almost completely suppressed the formation of products. The addition of the remaining amino acids led to an increase of molar product yields (glucose, 5-deoxy-glucitol and 2-deoxy-glucitol), which was related to the decomposition of trehalose. This finding was explained by hydrogen transfer from the amino acids to precursor radicals of the products.