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C Barbas

Publications and source records attributed to C Barbas.

48 records · Page 3Linked to original sources
PubMed1999

Determination of alpha-tocopherol and alpha-tocopherol acetate in diets of experimental animals. Study of stability in the diets.

A simple method is described which permits, avoiding saponification, alpha-tocopherol and alpha-tocopheryl acetate measurement in semi-synthetic diets for experimental animals by HPLC, with both UV and fluorescence detection. Phenyldodecane was chosen as internal standard with remarkable performances, and EDTA and BHT were added to prevent oxidation in aqueous and non-aqueous phases respectively. The mobile phase was methanol-water (94:6 v/v) at a flow-rate of 2 ml/min. Samples were homogenized and extracted twice with n-hexane by probe sonication. Extracts were evaporated to dryness and redissolved with chloroform-methanol (1:1, v/v). Validation parameters were studied between 25 ng and 6 micrograms for alpha-tocopherol and between 3 and 24.2 micrograms for alpha-tocopheryl acetate, which corresponds to the range of values in the existing diets. Results had correlation coefficients > 0.99; recoveries > 85%; R.S.D. < 6%, so the method is adequate to control vitamin E intake in animals as well as vitamin E stability in food during storage.

Animal Feed↗
PubMed1999

Alpha-tocopherol concentration in fetal and maternal tissues of pregnant rats supplemented with alpha-tocopherol.

We wanted to determine whether alpha-tocopherol supplementation to pregnant rats could increase the concentration of alpha-tocopherol in maternal and fetal plasma and tissues. Pregnant rats were treated with alpha-tocopherol on days 18 and 19 gestation and studied at day 20. A control group was studied in parallel. Treatment of pregnant rats with alpha-tocopherol increased its concentration in maternal and fetal plasma, in all maternal plasma lipoprotein fractions, in maternal and fetal liver and in the placenta. The fetal and maternal concentration of alpha-tocopherol were positively correlated.

Animals↗
PubMed1998

Simplified method for vitamin E determination in rat adipose tissue and mammary glands by high-performance liquid chromatography.

A method for vitamin E (alpha-tocopherol) measurement in rat adipose tissue and mammary gland has been developed and validated. Tissues were homogenized in ethanol-water (1:1) and extracted with n-hexane. Vitamin K1 was used as internal standard. Separation was performed by HPLC with methanol-water (96.5:3.5) as eluent in a Nucleosil C18 column (15 x 0.46 cm) at 40 degrees C. Detection was by fluorescence with excitation at 295 nm and emission at 350 nm for vitamin E and at 330 and 440 nm for vitamin K1. Standards and tissue extracts were checked for linearity giving correlation coefficients over 0.99 in a range of concentrations from 0.56 to 4.51 nmol/g in adipose tissue and from 2.18 to 17.4 nmol/g in mammary gland tissue. Intra-assay precision (R.S.D.) varied between 3 and 4%, whereas inter-assay precision was between 8 and 9%. Recoveries ranged between 95 +/- 3% and 98 +/- 11% for the two tissues, respectively. Vitamin E was measured in rats that had previously received one oral dose of this vitamin. Whereas vitamin E content in adipose tissue did not differ between late-pregnant and virgin rats, it was significantly higher in mammary gland of pregnant rats, and this difference could be related to the enhanced lipoprotein lipase activity in this group.

Adipose Tissue↗
PubMed1998

Lipid composition and vitamin E content in human colostrum and mature milk.

Lipidic components, as well as fatty acid composition and vitamin E content were determined in colostrum (days 3-5 of postpartum) and mature milk (day 21) in 8 women from Murcia (Spain). Triglycerides concentration was higher and cholesterol and esterified cholesterol were lower in mature milk than in colostrum, whereas phospholipid content was similar. These differences indicate that the diameter of milk fat globules increases in mature milk. The percentage of medium-chain fatty acids (12:0 and 14:0) increased in mature milk as compared to colostrum, reflecting de novo synthesis of fatty acids. With the only exception of stearic acid which was lower in mature milk than in colostrum, the remaining long-chain fatty acids was similar. The proportion of both linoleic (18:2) and eicosapentaenoic (20:5) acids found in mature milk and colostrum is higher than in studies from other countries and may reflect the intake of high proportions of polyunsaturated fat from vegetable oils and fish in the studied women. Both vitamin E content and vitamin E/linoleic acid ratio in mature milk are lower than in colostrum, evidencing the efficient mechanism of mammary gland vitamin E uptake around parturition.

Adult↗
PubMed1998

Capillary electrophoresis for rapid profiling of organic acidurias.

Organic acids analysis is a powerful technique in the diagnosis of inborn errors of metabolism. Clinically, patients present with severe symptoms, and early detection and appropriate treatment are often lifesaving. Most of the existing methods are based on gas chromatography in combination with mass spectrometry and require sophisticated equipment and complex sample pretreatment and derivatization. We propose a rapid, simple, and automated capillary electrophoretic method for routine analysis of urine to detect 27 organic acids related to metabolic diseases. With this method, direct measurements are performed on samples after initial centrifugation and dilution, if needed. Separation is performed in pH 6.0 phosphate buffer with methanol added as an organic modifier, -10 kV applied potential, and ultraviolet detection at 200 nm. The assay is completed in <15 min, and alternative separation conditions are proposed in case of overlapping peaks. The developed method allows the identification and quantitation of methylmalonic, pyroglutamic, and glutaric acids in samples of patients with diseases related to these acids.

Carboxylic Acids↗
PubMed1997

Simultaneous determination of vitamins A and E in rat tissues by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method to determine vitamins A, Ap and E simultaneously was developed with direct extraction of vitamins from rat tissues with n-hexane and probe sonicating. The dry residue was redissolved in chloroform-methanol. Vitamins A and Ap were detected by UV-Vis and vitamin E by fluorescence. Vitamin K, used as internal standard, was detected both the UV-Vis and by fluorescence. Standards and samples were checked for linearity giving correlation coefficients that were higher than 0.99 in the concentration range of 3.1-9.4 for vitamin A, 8.2-24.7 for vitamin Ap and 0.6-1.7 nmol/g in the case of liver extracts and 0.5-3.0 nmol/g in the case of placenta. The inta-assay precision (R.S.D) varied between 1.48 and 7.25, whereas inter-assay precision was between 4.99 and 7.03. Recoveries ranged between 94 +/- 8 and 107 +/- 5%. Results from the application of this method to different rat tissues having wide range of vitamin content are presented.

Animals↗
PubMed1996

In vitro effects of a flavonoid-rich extract on LDL oxidation.

Flavonoids are phenolic compounds of vegetable origin with antioxidant effects. The present study aimed to determine their properties as LDL antioxidants. LDL were incubated with increasing concentrations of flavonoids (0-16 micrograms/ml) and LDL oxidation was started by adding CuCl2 (2 microM) to the media. When flavonoids were present in the media, vitamin E consumption, the lag phase of conjugated diene formation, LDL electrophoretic mobility in agarose gels and the appearance of thiobarbituric acid reacting substances (TBARS) were delayed in a concentration-dependent manner. To determine whether flavonoids could terminate LDL oxidation once initiated, two sets of experiments were performed. In the first, LDL oxidation was initiated as described above. At 2 or 4 h of incubation, flavonoids were added (4 micrograms/ml) and their effect compared to samples where butylated hydroxytoluene or EDTA were added. At 5 h, in the LDL samples where flavonoids were added, the electrophoretic mobility and TBARS production were the same as those present in LDL samples incubated for the whole period in the absence of flavonoids. However, when either butylate hydroxytoluene or EDTA was added, as would be expected, the LDL oxidation process was completely arrested as shown by a reduction in the appearance of TBARS and a lower LDL electrophoretic mobility. In the second experiment, LDL oxidation was initiated as described above and at 0, 10 and 20 min, flavonoids were added (4 micrograms/ml). When vitamin E was still present in the LDL solution, the flavonoids were able to both increase the lag phase in the formation of conjugated dienes and to delay the consumption of vitamin E. The present results show that in vitro, flavonoids prevent LDL oxidation in a concentration-dependent manner, delaying the consumption of vitamin E, but they cannot terminate or delay LDL oxidation once vitamin E in LDL is consumed.

Antioxidants↗
PubMedDate not supplied

Low molecular weight organic acids and fatty acids in root exudates of two Lupinus cultivars at flowering and fruiting stages.

Low molecular weight organic acids (LOAs) and fatty acids in root exudates of two lupin cultivars, Lupinus albus cv. Multolupa and L. luteus cv. Tremosilla, were determined at flowering and fruiting stages. LOAs were analysed by capillary electrophoresis. Acetic and citric acids were the most abundant, especially the latter in L. luteus at the flowering stage (5922.79 micrograms/g dry root). The significant decrease in acid content of both cultivars from flowering to fruiting stages was also striking. The highest levels of acetic acid were detected in L. luteus at fruiting stage (1542.03 micrograms/g dry root). The significant citrate production in L. luteus could be related to the low phosphorus concentration in the studied soils but not to proteoid roots, which were detected only in L. albus. The source of the LOAs detected in these exudates is also discussed, since they may be produced either by the plant or by the associated rhizobacteria. The profile of phospholipid fatty acids was determined by high-resolution GC. A high level of 18:2 omega 6 (a fatty-acid specific to fungi) was found in exudates of L. luteus (a mycorrhizal plant) in contrast to L. albus (a non-mycorrhizal plant).

Acids↗