Evaluation of different ionic liquid stationary phases for the analysis of carbohydrates by gas chromatography-mass spectrometry.

Five commercial ionic liquid (IL) columns have been evaluated for the first time for the gas chromatography-mass spectrometry (GC-MS) analysis of low molecular weight carbohydrate (LMWC) standards (mono-, di-, and trisaccharides, inositols, and iminosugars). A previous derivatization step was necessary to convert the LMWCs into their volatile and stable derivatives. Compared with conventional GC stationary phases, such as HP-1 and Supelcowax® 10, IL columns have shown a different selectivity in the separation of target compounds. Among the IL columns, only SLB™-IL82 allowed the elution of all the LMWCs studied. Its performance in terms of peak width and asymmetry, evaluated under different oven temperature conditions, was shown to be dependent on the carbohydrate class considered. As an example of application, a SLB™-IL82 column was successfully used to separate the complex mixtures of LMWCs in hyacinth and mulberry extracts. This column is an interesting alternative to the conventional stationary phases used in the GC analysis of LMWCs in real-world samples. Graphical abstract.

Graphical statistical approach to soil organic matter resilience using analytical pyrolysis data.

Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) of humic acids (HAs) from 30 agricultural soils from a volcanic island (Tenerife, Spain) was used to discern the molecular characteristics of soil organic matter (SOM) associated to resilience. For faster perceptual identification of the results, the yields of the pyrolysis products in the form of surface density plots were compared in an update of the Van Krevelen graphical statistical method. This approach, with respect to data reduction and visualization, was also used to collectively represent statistical indices that were obtained after simple and partial least squares (PLS) regression. The resulting plots illustrate different SOM structural domains (for example, carbohydrate- and lignin-derived and condensed lipid). The content of SOM and total mineralization coefficient (TMC) values can be well estimated from the relative abundance of 57 major pyrolysis compounds: SOM content and composition parallels the accumulation of lignin- and carbohydrate-derived structures (lignocellulosic material) and the depletion of condensed polyalkyl structures. In other words, in the volcanic ash soils that were studied, we found that the higher the amount of SOM, the lower its quality in terms of resilience. Although no cause-and-effect is inferred from this fact, it is evident that the resistance to biodegradation of the SOM is related to its molecular composition.

New methodologies for the extraction and fractionation of bioactive carbohydrates from mulberry (Morus alba) leaves.

Pressurized liquid extraction (PLE) was applied for the first time to extract bioactive low molecular weight carbohydrates (iminosugars and inositols) from mulberry ( Morus alba ) leaves. Under optimized conditions, PLE provided a similar yield to the conventional process used to extract these bioactives, but in less time (5 vs 90 min). To remove carbohydrates that interfere with the bioactivity of iminosugars from PLE extracts, two fractionation treatments were evaluated: yeast ( Saccharomyces cerevisiae ) incubation and cation-exchange chromatography (CEC). Both methods allowed complete removal of major soluble carbohydrates (fructose, glucose, galactose, and sucrose), without affecting the content of mulberry bioactives. As an advantage over CEC, the yeast treatment preserves bioactive inositols, and it is an affordable methodology that employs food grade solvents. This work found PLE followed by yeast treatment to be an easily scalable and automatable procedure that can be implemented in the food industry.

Prevention of diet-induced obesity by apple polyphenols in Wistar rats through regulation of adipocyte gene expression and DNA methylation patterns.

This study was conducted to determine the mechanisms implicated in the beneficial effects of apple polyphenols (APs) against diet-induced obesity in Wistar rats, described in a previous study from our group. Supplementation of high-fat sucrose diet with AP prevented adiposity increase by inhibition of adipocyte hypertrophy. Rats supplemented with AP exhibited improved glucose tolerance while adipocytes isolated from these rats showed an enhanced lipolytic response to isoproterenol. AP intake led to reduced Lep, Plin, and sterol regulatory element binding transcription factor 1 (Srebf1) mRNA levels and increased aquaporin 7 (Aqp7), adipocyte enhancer binding protein 1 (Aebp1), and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (Ppargc1a) mRNA levels in epididymal adipocytes. In addition, we found different methylation patterns of Aqp7, Lep, Ppargc1a, and Srebf1 promoters in adipocytes from apple-supplemented rats compared to high-fat sucrose fed rats. The administration of AP protects against body weight gain and fat deposition and improves glucose tolerance in rats. We propose that AP exerts the antiobesity effects through the regulation of genes involved in adipogenesis, lipolysis, and fatty acid oxidation, in a process that could be mediated in part by epigenetic mechanisms.

Optimisation of a biotechnological procedure for selective fractionation of bioactive inositols in edible legume extracts.

BACKGROUND: Currently, disorders such as diabetes mellitus, obesity or atherosclerosis are recognised as major global health problems. The use of inositols for treating these illnesses has attracted considerable attention and their extraction from natural sources presents added value as they are considered bioactive ingredients in the food industry. Legumes are natural and rich sources of inositols; however, the co-existence of other low molecular weight carbohydrates (LMWCs) in their extracts, which interfere in their bioactivity, might constitute an important drawback, thereby making their removal essential. RESULTS: LMWCs, including inositols, methyl-inositols and glycosyl-inositols of different legume extracts, were determined by GC-MS; the presence of bornesitol (2.35 mg g(-1) ) and lathyritol (0.27 mg g(-1) ) were reported for the first time in grass peas. The use of Saccharomyces cerevisiae for the selective removal of interfering carbohydrates was optimised. Incubation time (3-40 h) was highly dependent on the composition of the legume considered; inositol contents were generally stable along the treatment. CONCLUSION: Removal of interfering LMWCs from inositol-enriched extracts was successfully achieved using a clean and easily scalable fractionation methodology. This biotechnological procedure not only represents high interest for the production of bioactive food ingredients but for applications in other research areas.

Analysis of cyclitols in different Quercus species by gas chromatography-mass spectrometry.

BACKGROUND: The carbohydrate profile of some woods used for aging wines and spirits has been recently studied using a pressurized liquid extraction method, the main differences found being related to cyclitol content. The aim of this study was to perform a detailed study of these compounds in woods of different Quercus species in order to identify two unknown compounds which appeared in the extracts and to verify whether the obtained profile was homogeneous for other Quercus species. RESULTS: Besides the known monosaccharides and five cyclitols previously described, three deoxy-inositols (epi-, vibo- and scyllo-quercitol) were identified. The presence of these eight cyclitols was confirmed in all subgenera and species of Quercus analyzed, allowing a characteristic cyclitol profile. CONCLUSIONS: Three deoxy-inositols (quercitols) have been identified in the carbohydrate profile of oak wood. All examined Quercus species displayed a common profile consisting of four inositols and four quercitols, which represent a good dataset for characterization of this genus.