Application de la CCM à l'étude des produits obtenus dans la démucilagination des huiles de germe de maïs

Résumé Lorsque l'on traite des huiles végétales brutes par de l'eau, de la vapeur d'eau, des solutions salines ou des solutions acides, dans des conditions que la technique industrielle précise, il se sépare une phase aqueuse dite phase de démucilagination. Celle-ci contient des substances dotées de propriétés tensioactives comparables, mais de constitutions chimiques très différentes: des polyholosides qui représentent les mucilages proprement dits, mais aussi des phosphoaminolipides de natures diverses. De plus, des lipides simples: glycérides, acides gras libres et matières insaponifiables peuvent être entraînés dans ce milieu doté de propriétés émulsives.La présente étude est consacrée à l'analyse des produits de démucilagination, obtenus au laboratoire par action d'une quantité d'eau limitée sur l'huile brute extraite du germe de maïs.On sépare d'abord les glucides de l'ensemble lipidique en solubilisant celui-ci par un lavage avec de l'hexane. La solution est séchée, évaporée sous pression réduite et soumise à l'analyse chromatographique sur plaque de Kieselgel de Merck. Après les manipulations d'usage, la mise en évidence des taches pouvait être obtenue au moyen de la vapeur d'iode ou par pulvérisation d'acide sulfurique. Nous avons préféré utiliser la rhodamine B qui nous a permis de mettre en évidence, près de la base, une série de quatre tâches correspondant à des lécithines, (ce fait a été vérifié en soumettant la matière première à l'hydrolyse, ce qui a permis de mettre en évidence la seule choline sans trace d'éthanolamine, constituant caractéristique des céphalines), et près de la ligne de front d'autres dépôts, qui repris, ont été identifiés à des stérols. Il a été vérifié que glycérides et acides gras ne migrent pas dans nos conditions expérimentales.En complément de la chromatographie sur plaques, la chromatographie gazeuse a permis de connaître l'identité des acides gras consituant les lécithines et celle des stérols.

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Summary When raw vegetable oils are treated by water, vapour, solutions of salts or acids, in conditions that are defined by industrial technique, an aqueous phase, called de gumming phase is separated. This phase contains substances possessing compared surface-active properties but differing by their chemical constitutions: poly holosides, which are the gums proper, but also phospho aminolipids of various nature. Furthermore, simple lipids: glycerides, free fatty acids, unsaponifiables may be drawn into this medium endowed with emulsifying properties.The present study is concerned with the analysis of the products of degumming obtained in the laboratory by the action of a limited quantity of water on the raw oil extracted from corn germ.First the carbohydrates are separated from by the complex of lipids by solubilizing it with a washing by hexane. The solution is dried, evaporated under reduced pressure, and chromatographically analyzed on aMerck Kieselgel plate. After the usual manipulations the evidencing of the spots could be obtained with the help of iodine vapours or by spraying with sulphuric acid. We preferred to use Rhodamin B which enabled us to show, near the base, a series of four spots corresponding to lecithins (this fact was verified by the hydrolysis of the raw material which enabled us to isolate only the choline, without any trace of ethanolamine, a characteristic constituant of cephalins), and near the front line, other spots, which, when redissolved, were identified as sterols. It was verified that in our experimental conditions the glycerides and fatty acids do not migrate.As a supplement for plate chromatography, gas-chromatography has enabled us to identify the fatty acids constituting the lecithins, and also to identify the sterols.

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Zusammenfassung Wenn man die rohen Pflanzenöle mit Wasser, Wasserdampf, Salzlösungen oder Säurelösungen unter den Bedingungen der präzisen industriellen Technik behandelt, scheidet sich eine wässerige, sogenannte Entschleimungsphase aus. Diese enthält Stoffe, die vergleichbare tensioaktive Eigenschaften haben, aber deren chemische Beschaffenheit sehr verschieden ist: Polykolloide, welche die eigentlichen Schleime bilden, aber auch Phospho-amino-Lipide verschiedener Natur und auch einfache Lipide: Glyceride, freie Fettsäuren und nicht verseifbare Stoffe, die in diesem mit emulgierenden Eigenschaften ausgestattetem Medium weggespült werden können. Diese Arbeit ist der Analyse der Entschleimungsprodukte gewidmet, die im Laboratorium durch Einwirkung einer beschränkten Menge Wassers auf rohes Öl aus Maiskeimen entstanden ist.Man scheidet zuerst die Kohlenhydrate aus der Gesamtheit der Lipide aus, die durch Waschen mit Hexan lösbar gemacht werden. Die Lösung wird getrocknet, unter reduziertem Druck verdampft und der chromatographischen Analyse auf Kieselgel vonMerck unterworfen. Nach den üblichen Behandlungen wurden die Substanzflecken durch Joddampf oder Besprühen mit Schwefelsäure sichtbar gemacht. Wir bevorzugten Rhodamin B weil wir mit diesem Entwicklungsreagenz eine Reihe von vier Flecken in Startnähe erkennen konnten, die den Lecithinen zugeordnet wurden. (Es handelt sich um Lecithin, da bei der Hydrolyse des Rohmaterials nur Cholin und keine Spur Äthanolamin, dem charakteristischen Bestandteil der Kephaline, gefunden wurde.) In der Nähe der Front lagen Substanzflecken, die sich als Sterole identifizieren ließen. Es konnte nachgewiesen werden, daß Glyceride und Fettsäuren unter den Versuchsbedingungen nicht wandern.Als Ergänzung zur Chromatographie auf Platten hat die Gaschromatographie die Identifizierung der Fettsäuren, welche die Lecithine bilden, und der Sterole ermöglicht.

     

Structural Characterization of New Microcystins Containing Tryptophan and Oxidized Tryptophan Residues

Microcystins are cyclic peptides produced by cyanobacteria, which can be harmful to humans and animals when ingested. Eight of the (more than) 90 microcystin variants presently characterized, contain the amino acid tryptophan. The well-researched oxidation products of tryptophan; kynurenine, oxindolylalanine, and N-formylkynurenine, have been previously identified in intact polypeptides but microcystin congeners containing oxidized tryptophan moieties have not been reported. Liquid chromatography-tandem mass spectrometric analysis of an extract of Microcystis CAWBG11 led to the tentative identification of two new tryptophan-containing microcystins (MC‑WAba and MC-WL), as well as eight other microcystin analogs containing kynurenine, oxindolylalanine and N‑formylkynurenine (Nfk). Investigation of one of these congeners (MC‑NfkA) by nuclear magnetic resonance spectroscopy was used to verify the presence of Nfk in the microcystin. Liquid chromatography-mass spectrometry analysis of a tryptophan oxidation experiment demonstrated that tryptophan-containing microcystins could be converted into oxidized tryptophan analogs and that low levels of oxidized tryptophan congeners were present intracellularly in CAWBG11. MC-NfkR and MC-LNfk were detected in standards of MC-WR and MC-LW, indicating that care during storage of tryptophan-containing microcystins is required.     

Topical effect of various agents on gelatinase activity in the tear film of normal dogs

OBJECTIVE: To evaluate the topical effect of various agents, currently used in the treatment of melting ulcers, on gelatinase activity present in the tear film of normal dogs. ANIMAL STUDIED: Eight normal adult beagles. PROCEDURES: Each animal received the following agents: cyclosporine A 1%, N-acetylcysteine 10%, ciprofloxacin 0.3%, ethylenediaminetetraacetic acid (EDTA) 1%, doxycycline 0.001%, polysulfated glycosaminoglycans (PSGAG) 5%, autoserum, and artificial tears during a 48-h period following a Latin square design. Tear samples were collected with micro-capillary pipettes following a corneal surface irrigation of each eye with sterile saline on four different occasions. Basal and total gelatinase activities were evaluated by optical density after processing in a commercial gelatinase activity assay. From the optical density ratio, a semi-quantitative measure of gelatinase activity was obtained. Basal and total activities were measured in all samples. RESULTS: The lowest total gelatinase activity, representing a percent decline in the enzyme activity although not significant, was observed 1 h after the last treatment in seven out of the eight ophthalmic agents; EDTA (68%), ciprofloxacin (76%), cyclosporine A (68%), doxycycline (47%), artificial tears (26%), PSGAG (25%), and N-acetylcysteine (20%). However, only the reduction observed with EDTA 6 h after the last treatment was significantly lower compared to the reduction observed with the artificial tears. CONCLUSION: This study indicated that only EDTA was able to significantly reduce the gelatinase activity in a persistent manner in the tear film of normal canine eyes. Further studies will be required to evaluate the effect of EDTA under ulcerative conditions and to more accurately ascertain the potential in vivo effect of the other agents.     

Influence of fertilization, mulch color, early forcing, fruit order, planting date, shading, growing Environment, and genotype on the contents of selected phenolics in strawberry (Fragaria x ananassa Duch.) fruits

The influence of agricultural practices (fertilization, mulch color, early forcing, and planting date), environment (light and growing area), cultivar, and fruit order on the selected phenolic content and antioxidant activity in strawberry (Fragaria x ananassa Duch.) fruits was studied. Three different levels of fertilization were given to plants in the fertilization experiment. The lowest fertilization level increased the contents of flavonols and ellagic acid from 19 to 57%. Between cultivars, up to 4-fold differences were found in the flavonol content, and it also varied according to growing environment. Planting date in glasshouse production was important for the phenolic content, and a statistically significant interaction was found between planting date and fruit order. Fruit order caused at highest 1.5-2.0-fold differences in the contents of phenolics. Interestingly, compared with other phenolics, anthocyanins were affected differently by many factors. Thus, the findings show that minor cultivation changes can increase the content of phenolics, especially in under-glass production where conditions can be easily manipulated.     

Der Einflu\ variierter Düngung, einer Pflanzenschutzmittel-Anwendung und der Lagerung auf den Glykoalkaloid-Gehalt in Kartoffelknollen zweier Sorten

Zusammenfassung Es wurden Feldversuche in drei Jahren mit zwei Speisekartoffelsorten, verschiedenen Mengen an Mineraldüngern und der Anwendungen eines Pflanzenschutzmittelns gegenPhytophthora infestans angelegt. Die Knollen wurden direkt nach der Ernte sowie nach einer sechsmonatigen Lagerung auf Glykoalkaloidgehalt untersucht. Zwischen den Sorten treten statistisch gesicherte Unterschiede im Gehalt an Glykoalkaloiden auf. Die Anwendung von Pflanzenschutzmitteln w?hrend der Vegetation erh?ht den Gesamtgehalt an Glykoalkaloiden (TGA) in den Kartoffelknollen kurz nach der Ernte. Eine variierte Mineraldüngung hat keinen statistisch signifikanten Einfluss auf den TGA-Gehalt in den Proben kurz nach der Ernte, N- und K-Düngung ver?ndern diesen jedoch im Laufe der Lagerung. Unabh?ngig von den übrigen Bedingungen erh?ht sich der TGA-Gehalt in diesem Versuch w?hrend der Lagerung im Mittel von 5,8 auf 7,7 mg/100g Frischsubstanz.

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Summary Field experiments were carried out for three years to study the effect of various magnesium, potassium and nitrogen fertilization rates on two medium-early edible potato cultivars. Additionally, one of the experimental areas was sprayed againstPhytophthora infestans to ascertain the effect of fungicides on the content of total glycoalkaloids (TGA) in potato tubers after harvest and after six months of storage. The applied fungicide treatments increased total glycoalkaloids (TGA) of potato tubers (Fig. 4). Fertilization with mineral nitrogen caused different reactions in both cultivars. There was a tendency for cv. Beryl to accumulate more glycoalkaloids with increasing nitrogen fertilization rates, while the opposite was observed for cv. Mila (Fig. 7). Fertilization with potassium and magnesium did not affect the results. On the basis of these results there was no conclusive evidence that the TGA content in the tubers was dependent on cultivar or on the weather during the growing season (Figs 1,2 and 3). The TGA content increased during storage, independently of previous treatments, (Figs 4–7).

     

Content of chalconaringenin and chlorogenic acid in cherry tomatoes is strongly reduced during postharvest ripening

The contents of chalconaringenin, chlorogenic acid, rutin, ascorbic acid, lycopene, and beta-carotene were analyzed during postharvest and vine ripening of cherry tomatoes (Lycopersicon esculentumMill.) (cv. Jennita) produced in a greenhouse. A remarkable decrease in the content of chalconaringenin took place during postharvest ripening. The tomatoes were found to contain 15.26 mg 100 g(-1) fresh weight (FW) at harvest but held only 0.41 mg after 3 weeks at 20 degrees C in darkness. Chalconaringenin did not convert into naringenin. The content of chlorogenic acid fell from 0.51 to 0.06 mg 100 g(-1) FW at the same conditions. The content of rutin and that of total phenolics remained stable during postharvest ripening. The amounts of lycopene as well as beta-carotene and ascorbic acid increased during postharvest ripening. No significant change in the amount of methanol soluble antioxidants or total soluble solids was found during postharvest ripening of the tomato fruits. During vine ripening, the total amount of phenolics and that of soluble solids (% Brix) increased. The content of phenolics correlated well with the content of methanol soluble antioxidants (p < 0.001). The amount of ascorbic acid increased from 9.7 mg in green-yellow tomatoes to 17.1 mg 100 g(-1) FW in red tomatoes. The amount of chalconaringenin decreased to 8.16 mg 100 g(-1) FW, whereas no significant change was observed for chlorogenic acid or rutin. Possible causes for the decrease in chalconaringenin are discussed.     

Apoptosis, programmed cell death and the hypersensitive response

Apoptosis is typically a morphologically identifiable form of programmed cell death in mammals that is regulated by genes with homologues in other animal Phyla. Although both plants and fungal plant pathogens exhibit forms of developmental programmed cell death, demonstrated morphological or genetic homologies with mammalian apoptosis are still generally lacking. Because of its ubiquity and the involvement of signal transduction pathways in its induction, a strong case is developing that the hypersensitive response is a specific form of plant programmed cell death evolved as a defense against microbial parasites. Data suggest that separate signalling pathways may lead to the cell death and the defense gene activation that characterize this response and that parasite-specific resistance genes represent only one of many types of genes involved in response regulation. However, despite some biochemical similarities between the hypersensitive response, forms of developmental programmed cell death in plants, and animal apoptosis, no unique and consistent markers for the hypersensitive response (or plant programmed cell death in general) have yet been found. Whether any of these forms of plant cell death should be called apoptosis depends on how the term is defined. Assuming the hypersensitive response is a form of programmed cell death and is the default state upon pathogen entry into a cell, it seems likely that intracellular biotrophic plant pathogens resemble some animal viruses in being able to suppress this response in susceptible hosts.     

Efficacy of omeprazole paste for prevention of gastric ulcers in horses in race training

OBJECTIVE: To determine the minimal effective dosage of omeprazole oral paste for the prevention of naturally occurring ulcers in horses starting race training. DESIGN: Prospective study. ANIMALS: 175 horses. PROCEDURE: Horses in the dose selection portion of the study were sham dose treated or received 1 mg (0.45 mg/lb) or 2 mg (0.9 mg/lb) of omeprazole/kg, PO, every 24 hours for 28 days or 4 mg of omeprazole/kg (1.8 mg/lb; loading dose), PO, every 24 hours for 4 days, then 1 or 2 mg of omeprazole/kg, PO, every 24 hours for 24 days. Horses in the dose confirmation portion of the study were sham dose treated or received 1 mg of omeprazole/kg, PO, every 24 hours for 28 days. Gastric ulcer scores at the beginning and end of the study were compared. RESULTS: Sham-dose-treated horses had significantly higher ulcer scores than did horses treated with any of the omeprazole dosages evaluated. Among horses treated with omeprazole, there was no significant interaction of dose (1 or 2 mg/kg) and loading dose; therefore, the lowest effective dose (1 mg/kg) was evaluated in the dose confirmation portion of the study. In the dose confirmation study, 4 of 39 (10%) sham-dose-treated horses remained ulcer free, which was significantly different from the proportion of horses (31/38 [82%]) receiving 1 mg of omeprazole/kg that remained ulcer free. CONCLUSIONS AND CLINICAL RELEVANCE; Results indicated that omeprazole administered at a dosage of 1 mg/kg, PO, every 24 hours for 28 days was effective for prevention of gastric ulcers in horses starting race training.     

Evaluation of the bioavailability of the herbicide prosulfocarb through adsorption on soils and model soil colloids, and through a simple bioassay

Adsorption isotherms of prosulfocarb were determined on soils with different physicochemical properties. The extent of adsorption increased with the organic carbon content, but the results also suggested the involvement of some inorganic soil surfaces. In order better to understand the role of each soil surface, adsorption-desorption isotherms were determined on model soil colloids consisting of a soil humic acid, a montmorillonite, a synthetic aluminium hydroxide and their associations. The highest adsorption was observed on the humic acid, but it was also confirmed that the montmorillonite interacted with prosulfocarb. In contrast, the aluminium hydroxide was not active and its association with montmorillonite provoked a decrease in adsorption compared with montmorillonite alone. Except for humic acid, the highest adsorption took place on the ternary association montmorillonite-aluminium hydroxide-humic acid. On each surface tested, the adsorption was largely reversible and decreased at increasing pH. The herbicidal activity of prosulfocarb was tested by the determination of the germination and growth of a typical weed, Lolium multiflorum Lam, in contact with prosulfocarb solutions at different concentrations. The herbicide did not prevent the germination of the seeds but inhibited the growth of the roots and leaves. The same test was performed in the presence of the ternary system to evaluate the influence of adsorption on the plant bioavailability. It was concluded that the presence of an adsorptive surface reduced the herbicidal activity and that the simple bioassay proposed could be useful in predicting the extent of adsorption in a given soil.     

Dietary iron-initiated lipid oxidation and its inhibition by polyphenols in gastric conditions

The gastric tract may be the first site where food is exposed to postprandial oxidative stress and antioxidant activity by plant micronutrients. After food intake, dietary iron, dioxygen, and emulsified lipids come into close contact and lipid oxidation may take place. This study investigated lipid oxidation and its inhibition by dietary polyphenols in gastric-like conditions. Lipid oxidation induced by heme and nonheme iron was studied in acidic sunflower oil-in-water emulsions. The emulsifier type (bovine serum albumin, phospholipids), pH, and iron form were found to be factors governing the oxidation rates. Quercetin, rutin, and chlorogenic acid highly inhibited the metmyoglobin-initiated lipid oxidation in both emulsified systems at pH 5.8. Additionally, quercetin inhibited nonheme iron-initiated processes, while it was inefficient with hematin as an initiator. The presence of human gastric juice did not influence lipid oxidation, although it diminished the antioxidant activity of phenolics. Model emulsions may thus be valuable tools to study the gastric stability of polyunsaturated lipids.