-S433). According to a homology analysis, no amino acid sequence homology was observed between Cryj II and Cryj I, another major allergen. But Cryj II showed homology with polygalacturonase (PG) derived from tomato (40% identity) at the amino acid level. The sequence information can potentially be used to devise an effective course of immunotherapy for Japanese cedar pollinosis.

In a previous study (Oku, K.; Watanabe, H.; Kubota, M.; Fukuda, S.; Kurimoto, M.; Tujisaka, Y.; Komori, M.; Inoue, Y.; Sakurai, M. J. Am. Chem. Soc. 2003, 125, 12739), we investigated the mechanism of the antioxidant function of trehalose against unsaturated fatty acids (UFAs) and revealed that the key factor relevant to the function is the formation of OH...pi and CH...O hydrogen bonds between trehalose and the cis double bonds of the UFA. Here, we investigate whether such intriguing interactions also occur between this sugar and cis double bonds in other unsaturated compounds. For this purpose, we selected various diene compounds (1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, and 2,5-heptadiene) as interaction partners. All NMR experiments performed, including 1H-1H NOESY measurements, indicated that trehalose selectively interacts with the cis-olefin proton pair in the above diene with a 1:1 stoichiometry, and the C-3 (C-3') and C-6' (C-6) sites of the sugar are responsible for the interaction. Similar interactions were not observed for the mixtures of the diene and other saccharides (neotrehalose, kojibiose, nigerose, maltose, isomaltose, sucrose, maltitol, and sorbitol). Quantum chemical calculations revealed that the OH-3 and OH-6 groups bind to the olefin double bonds of the diene through OH...pi and CH...O types of hydrogen bonds, respectively, and the stabilization energy of the resulting complex is 5-6 kcal mol(-1). These results strongly support the above NMR results. Finally, the activation energies were calculated for the hydrogen abstraction reactions from the activated methylene group of heptadiene. In particular, when the reaction was initiated by a methyl radical, the activation energy was only 10 kcal mol(-1) for the free heptadiene, but on complexation with trehalose it drastically increased to ca. 40 kcal mol(-1). This indicates that trehalose has a significant depression effect on the oxidation of the diene compounds. These results strongly support the antioxidant mechanism deduced in the previous study and indicate that the formation of unique multiple hydrogen bonds between trehalose and cis-olefin bonds is rather a general event not confined to the case of UFA.

The antioxidative activity of trehalose on autoxidation of unsaturated fatty acid (UFA) were investigated by a water/ethanol system. The formation of hydroperoxide (HPOD) from linoleic acid (LA) was remarkably inhibited by trehalose. The inhibitory effect on the autoxidation was dependent on the amount of trehalose.Several other disaccharides, sucrose, maltose, and neotrehalose, showed negligible effect on the autoxidation, but maltitol was effective second to trehalose. Similarly to LA, the formation of HPOD from a-linolenic acid (LNA) was inhibited by trehalose and maltitol.On the other hand, when the degradation of LA-HPOD was tested under the same conditions of the autoxidation, it was found that the degradation was not influenced by the presence of all of the saccharides tested, including trehalose. Although volatile aldehydes generated from LA-HPOD was slightly reduced by trehalose and maltitol, the effect of both saccharides seemed to be weak, compared with their inhibitory effect on the autoxidation. Thus, it is clear that trehalose and maltitol inhibit the autoxidation of UFA, but negligibly supress the generation of volatile aldehydes from HPOD.

Background: Isomaltodextrin (IMD) is a novel highly branched α-glucan and its function as a soluble dietary fiber is expected.Objective: The goal of this study was to evaluate the effects of IMD on postprandial glucose excursions in healthy people and to make the mechanism clear.Design: Twenty-nine subjects ingested a solution containing maltodextrin (MD) or sucrose with or without IMD. Fourteen subjects ingested a solution containing glucose with or without IMD. Blood glucose concentrations were then compared between the groups. Furthermore, in vitro digestion, inhibition of digestive enzymes, and glucose absorption tests were conducted.Results: IMD attenuated blood glucose elevation in the subjects with blood glucose excursions at the high end of normal following the ingestion of MD or sucrose or glucose alone. This effect of 5 g IMD was most clear. IMD was digested partially only by small intestinal mucosal enzymes, and maltase and isomaltase activities were weakly inhibited. Furthermore, IMD inhibited the transport of glucose from mucosal side to serosal side.Conclusions: IMD attenuated postprandial blood glucose, after the ingestion of MD or sucrose or glucose. As one of the mechanism, it was suggested that IMD inhibited the absorption of glucose on small intestinal mucosal membrane.

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