Characterization of cyclitol glycosides by gas chromatography coupled to mass spectrometry.

Several cyclitol glycosides have been characterised as trimethylsilyl derivatives by their gas chromatographic (GC) retention data (linear retention indices) and electron impact mass spectrometric (MS) profiles. Both GC-MS results have been related to cyclitol glycosides structural features. Abundance ratios of characteristic m/z ions 133/129 and 260/265 have been proposed to distinguish glycosyl-inositols from glycosyl-methyl-inositols. These ratios in combination with the presence or absence of m/z 375 ion allowed the unequivocal characterization of cyclitol glycosides. These criteria have been applied to the characterization of new cyclitol glycosides in chickpea (Cicer arietinum) and adzuki bean (Vigna angularis) and in leaves of Coriaria myrtifolia and Coriaria ruscifolia.

Optimization of pressurized liquid extraction of inositols from pine nuts (Pinus pinea L.).

Pressurized liquid extraction (PLE) has been used for the first time to extract bioactive inositols from pine nuts. The influence of extraction time, temperature and cycles of extraction in the yield and composition of the extract was studied. A quadratic lineal model using multiple linear regression in the stepwise mode was used to evaluate possible trends in the process. Under optimised PLE conditions (50°C, 18 min, 3 cycles of 1.5 mL water each one) at 10 MPa, a noticeable reduction in extraction time and solvent volume, compared with solid-liquid extraction (SLE; room temperature, 2h, 2 cycles of 5 mL water each one) was achieved; 5.7 mg/g inositols were extracted by PLE, whereas yields of only 3.7 mg/g were obtained by SLE. Subsequent incubation of PLE extracts with Saccharomyces cerevisiae (37°C, 5h) allowed the removal of other co-extracted low molecular weight carbohydrates which may interfere in the bioactivity of inositols.

Development of a carbohydrate silylation method in ionic liquids for their gas chromatographic analysis.

This paper reports on the feasibility of silylation of low molecular weight carbohydrates dissolved in different ionic liquids (ILs) for their further analysis by gas chromatography (GC). Derivatization reagents (nature and amounts), temperature and time of reaction and stirring conditions were evaluated for different carbohydrates (i.e., glucose, mannose, fructose and lactose) dissolved in 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA]. Evaluation of conformational isomerism of glucose dissolved in [EMIM][DCA] revealed the effect of the time of dissolution in the equilibration of α- and ß-furanoses (up to 3% and 6%, respectively, after 70 h of incubation) and that 21 h sufficed to obtain results similar to those provided by the reference method involving pyridine. Once optimized, the proposed derivatization procedure provided satisfactory yields (i.e., close to 100%) using 100 µL of trimethylsilylimidazole (TMSI) at mild conditions (25°C) for a relatively short time (1h) for most of the investigated carbohydrates. Under these experimental conditions, linear responses (i.e., R(2) better than 0.974) were obtained in the tested range of 0.25-1mg of the derivatized target compounds. Other reagents, such as N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)+1% trimethylchlorosilane (TMCS), were successfully used under ultrasonic conditions for aldose monosaccharides and disaccharides derivatization, while BSTFA was useful for ketose monosaccharides. The possibility of using the proposed method for the derivatization of selected carbohydrates dissolved in different ILs and the efficiency of the method applied to the analysis of carbohydrates present in real samples (fruit juices) have also been investigated.

Low molecular weight carbohydrates in pine nuts from Pinus pinea L.

Low molecular weight carbohydrates in pine nuts from Pinus pinea L. (n = 7) have been studied by gas chromatography-mass spectrometry as their trimethylsilyl oximes. Besides previously reported components, such as glucose, fructose, sucrose, and raffinose, several soluble carbohydrates have been identified for the first time in this product, including saccharides (galactose, maltose, and planteose) and cyclitols (pinitol, galactinol, galactopinitol A1, fagopyritol B1, and other glycosyl-inositols). Most abundant cyclitols were chiro-inositol, fagopyritol B1, and pinitol, with concentrations ranging from 126.7 to 222.1 mg (100 g)(-1), 94.2 to 177.1 mg (100 g)(-1), and 51.2 to 282.8 mg (100 g)(-1), respectively.