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The presence of phenolic compounds, possessing outstanding antioxidant activity corresponding to ascorbic acid, in wasted acorn shells was revealed by means of thermochemolysis-gas chromatography/mass spectrometry (thermochemolysis-GC/MS) in the presence of organic alkalis. The chromatogram of intact acorn shell samples obtained by thermochemolysis-GC/MS using tetramethylammonium hydroxide (TMAH) showed a strong peak of 3,4,5-trimethoxybenzoic acid methyl ester. This product was also clearly observed on the chromatograms of the methanol and water extracts from the acorn shells, indicating that 3,4,5-trimethoxybenzoic acid methyl ester was derived from free and/or esterified gallic acids through the thermochemolysis reaction. Based on the peak intensities, the contents of gallic acid components were determined as ca. 27 wt% for the both extracts. Furthermore, the content of free gallic acid was selectively estimated with discriminating from its esterified counterpart by using tetramethylammonium acetate (TMAAc) as a methylating reagent. These results were also correlated with high antioxidant activity of the acorn shell extracts evaluated by a DPPH radical scavenging method. [ABSTRACT FROM AUTHOR]

Subcritical water (SCW) extraction of citrus pomaces (CPs) was carried out, and antioxidant activity and nutraceutical compound levels of the SCW extracts were evaluated in detail. At first, CP samples were subjected to the SCW extraction under various conditions focusing on the extraction temperature and time. Consequently, the highest total phenol contents, radical scavenging activity, and reducing power were found when extraction was carried at 200°C and 1.4 MPa for 60 min. Furthermore, the amounts of three kinds of polymethoxylated flavones (sinensetin, nobiletin, and tangeretin) in the SCW extracts also showed the highest values under this condition. These results indicate that SCW is an effective medium for the fast and highly efficient extraction of the antioxidants and nutraceutical compounds from CPs. [ABSTRACT FROM AUTHOR]

Abstract: Reaction efficiencies of two organic alkalis, tetramethylammonium hydroxide (TMAH) and trimethylsulfonium hydroxide (TMSH), with lipids during thermally assisted hydrolysis and methylation (THM) were examined focusing on (1) the types of lipids and (2) degree of unsaturation of fatty acid moieties. Different types of lipids such as triglycerides, phospholipids, free fatty acids and cholesteryl esters containing saturated, monounsaturated or polyunsaturated fatty acid (PUFA) residues were subjected to THM-gas chromatography (GC) in the presence of TMAH or TMSH. The obtained results revealed that the THM reaction using TMAH allowed almost quantitative methylation of saturated and monounsaturated fatty acid components independently of the classes of lipids. However, strong alkalinity of TMAH brought about isomerization and/or degradation of PUFA components. In contrast, the use of TMSH was effective to highly sensitive detection of PUFA as well as saturated and monounsaturated fatty acid components contained in triglycerides, phospholipids (phosphatidylcholines) and free fatty acids. On the other hand, TMSH was proved to react hardly with any kind of fatty acid residues in cholesteryl esters due to their steric hindrance. [Copyright &y& Elsevier]

Abstract: The effect of off-line alkylation using a powerful methylating reagent of carbanion and methyl iodide on the kind and yield of degradation products of humic and fulvic acids in their pyrolysis-gas chromatography (Py-GC) was examined. The humic and fulvic acids used were prepared from three soils including a Dystric Cambisol, an Umbric Andosol, and a Podzol. The yields of aliphatic and lignin-derived phenolic compounds did not increase or decreased generally after the off-line methylation in comparison with conventional thermally assisted hydrolysis and methylation (THM) using tetramethylammonium hydroxide (TMAH) for unmethylated samples. However, benzenetetracarboxylic acid tetramethyl esters and benzenepentacarboxylic acid pentamethyl ester became detectable or increased in yield for all the three fulvic acids examined and one humic acid sample characterized by its high concentration of carboxyl groups. Benzenehexacarboxylic acid hexamethyl ester was also detected in off-line methylated fulvic acids soluble in dichloromethane and purified with Sephadex LH-20. The addition of TMAH in pyrolysis of the off-line methylated samples did not improve the yields. Hence, the conventional THM comparatively lead to lower yields of the benzenepolycarboxylic acids (BPCAs) with 4–6 carboxyl groups, and the Py-GC after the off-line methylation could give additional information on structural unit of humic substances, although its single use did not increase total yields of degradation products. [Copyright &y& Elsevier]

1. The composition of fatty acids (FA) from C14 to C18 was measured for edible seston and for individual Daphnia galeata, Diaphanosoma brachyurum and Eodiaptomus japonicus from Lake Biwa using a pyrolysis--gas chromatography (Py-GC) method. Based on the relative abundance of the FA, inter-and intraspecific differences in composition were examined. 2. Among the FA, C16 : 0 was the most abundant, both in the three zooplankton species and in edible seston smaller than 20 μm, suggesting that the composition of the zooplankton was roughly reflected by their diet. However, the abundance of C18 : 1 relative to C16 : 1 and C18 : 0 was much higher in each zooplankton species than in the diet. 3. Comparison of the relative abundance of FA among the three zooplankton species revealed that intraspecific differences in FA composition are greater than interspecific differences. These results indicate that variability in FA composition is not necessarily species-specific, and can be obscured by variation in composition between individuals. [ABSTRACT FROM AUTHOR]