Eduardo Vioque

Amino acid analysis by high-performance liquid chromatography after derivatization with diethyl ethoxymethylenemalonate

Amino acids were determined by precolumn derivatization with diethyl ethoxymethylenemalonate and reversed-phase high-performance liquid chromatography (HPLC) with spectrophotometric detection at 280 nm. The reaction time was 50 min and the derivatives were stable at room temperature. Chromatographic resolution of a mixture of the derivatives of seventeen amino acids, including proline and cystine, was achieved within 35 min using a binary gradient system. The detection limit was 3 pmol. Amino acid analyses of acid hydrolysates of two proteins gave results equivalent to those obtained by conventional ion-exchange-based amino acid analysis. The simplicity of the procedure allows its use on any multi-purpose HPLC system.

Leaf wax alkanes in the genus coincya

Abstract Leaf wax alkanes in the genus Coincya vary between C 22 and C 31 . This series is dominated by alkanes with an odd number of carbon atoms. The most abundant alkanes are C 29 , C 31 and C 27 . The main one, C 29 , ranges from 53.3% in C. monensis subsp. nevadensis to 95.0% in C. monensis subsp. recurvata var. setigera . A positive correlation between the content of C 29 and the glaucous character was observed. Likewise, there was a negative correlation between the availability of water and the amount of C 29 .

Leaf wax alcohols inCoincya (Brassicaceae)

Free and ester alcohol compositions have been determined for leaf waxes in ten taxa belonging to the genusCoincya (Brassicaceae) on the Iberian Peninsula (Spain and Portugal). Size of leaf wax alcohols in the genusCoincya varies between 20 and 31 carbon atoms. This series is dominated by alcohols with an even number of carbon atoms. The most abundant alcohols are C24, C26 and C28 among even and C25, C27 and C29 among odd alcohols, both in free alcohols and in wax esters.

Epoxidation of ethyl (Z)-9-(Z)-12-(Z)-15-octadecatrienoate with m-chloroperbenzoic acid

Abstract The expoxidation of ethyl linolenate (ethyl (Z)-9-(Z)-12-Z-15-octadecatrienoate (I) with m-chloroperbenzoic acid is described. When the reaction was performed using one mole of peracid per mole of (I), the three monoepoxides of (I), namely, ethy cis-9,10-epoxy-(Z)-12-(Z)-15-octadecadienoate (II), ethyl cis-12,13-epoxy-(Z)-9-(Z)-15-octadecadienoate (III) and ethyl cis-15,16-epoxy-(Z)-9-(Z)-12-octadecadienoate (IV) were the main products; these compounds were isolated by thin-layer chromatography. Using 3 mol peracid/mol of (I), ethyl cis-9,10-cis-12,13-cis-15,16-triepoxy-octadecanoate (XIV) was obtained. The compounds were characterized by spectroscopic techniques and derivative preparation.

Syntheses and reactions of methyl (Z)-9,10-epoxy-13-oxo-(E)-11-octadecenoate and methyl (E)-9,10-epoxy-13-oxo-(E)-11-octadecenoate

Abstract The syntheses and reactions of two epoxyketoacids (methyl (Z)-9,10-epoxy-13-oxo-(E)-11-octadecenoate (IV) and methyl (E)-9,10-epoxy-13-oxo-(E)-11-octadecenoate (V)) are described. The synthetic method is based on the stereoselective oxidation of linoleic acid by soybean lipoxygenase to produce the corresponding 13-hydroperoxide. Reduction of the hydroperoxide with sodium borohydride followed by oxidation, esterification and epoxidation yielded the compounds IV and V with a global yield of 14% and 3%, respectively, referred to the diasteromerically pure isolated compounds. Confirmation of the structures was carried out by reduction of the ketone group with sodium borohydride and by the opening of the oxirane ring with methanolic boron trifluoride. The reduction of compounds IV and V with hydrogen mainly yielded the tetrahydrofuranoid fatty acid, methyl 10,13-epoxyoctadecanoate. This reaction may be considered a new procedure to obtain tetrahydrofuranoid fatty acids.

Fatty acid composition of seed oil triglycerides inCoincya (Brassicaceae)

Oil and triglyceride contents and fatty acid composition were determined for seeds in nine taxa belonging to the genusCoincya (Brassicaceae) on the Iberian Peninsula (Spain and Portugal). The oil content ranges from 11.1 to 24.6%, triglycerides from 68.7 to 88.5%. The major fatty acids were erucic (24.6–30.5%), linolenic (17.7–27.7%), linoleic (13.9–24.6%) and oleic acid (12.3–21.8%).

Study of the neutral lipids of sunflower meal and isolates

Two types of sunflower protein isolates have been obtained from prepress and solvent extracted sunflower meal. The first was obtained by precipitation (at the isoelectric point) of the alkaline extract of the meal, and washing the curd with water. In the second, the alkaline extraction was carried out in the presence of sodium sulfite, and the curd was washed with water, ethanol and acetone. Both isolates were air-dried and then dried under vacuum at 50 C. From the total lipids, obtained with 86% ethanol, the neutral lipids were separated using a column of Florisil. The lipids studied were those of the two isolates mentioned above as well as those of the original meal. The following types of compounds were separated, identified and quantified: hydrocarbons, waxes, methyl esters, triglycerides, free fatty acids, diglycerides, free sterols, and hydroxy fatty acids.

Leaf wax ketones in the genus Coincya

Abstract Leaf wax ketones in the genus Coincya vary between C 22 and C 31 , and is dominated by those with an odd number of carbon atoms. The most abundant ketones are C 25 , C 27 and C 29 . The main one, C 29 , ranges from 57.7% in C. monensis subsp. cheiranthos var. setigera to 21.2% in C. monensis subsp. nevadensis . A positive correlation between the content of C 29 and the glaucous character was observed.

Synthesis of 9,12-epoxyoctadeca-9,11-dienoic acid

Abstract The oxidation of 12-oxo-(Z)-9-octadecenoic acid with potassium permanganate in an alkaline medium is described, erythro -9,10-Dihydroxy-12-oxooctadecanoic acid and 9,12-epoxyoctadeca-9,11-dienoic acid are obtained as minor and major products, respectively. The furanoid structure of the latter acid is confirmed by spectroscopic techniques and by the preparation of derivatives.

Polar lipids of sunflower meal and isolates

The polar lipids present in the 86% ethanol extract obtained from sunflower meal and isolates were studied. The isolates were obtained in 2 ways: (a) by precipitation at the isoelectric point of the alkaline extract of the meal and further washing of the curd with water, and (b) by precipitation at the isoelectric point of the extract obtained with a 0.25% sodium sulfite solution and washing the curd with water, ethanol and acetone, successively. The polar lipids eluted from a Florisil column with chloroform/acetone (1:1) and with methanol, glycolipids and phospholipids, respectively, were studied both qualitatively and quantitatively. The components found were glycolipids, including sterol glycosides and esterified sterol glycosides, and phospholipids, including phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and sphingomyelin.