In the present study, we report on the lipid classes, including fat-soluble antioxidants, and fatty acid and sterol profiles of freeze-dried Chinese yam (Dioscorea opposita Thunb., nagaimo) tubers harvested in Hokkaido. The effect of the unsaponifiables on human colon cancer Caco-2 cells was also examined. In addition to acylglycerols and free fatty acids, five glycolipids, four phospholipids and two neutral sterol lipids were found in the tubers, which had, in general, a low lipid content (0.4%). However, diosgenin, a steroidal saponin with various physiological functions, was not detected. The major lipid classes were phosphatidic acid, diglycosyldiacylglycerol, phosphatidylcholine and phosphatidylethanolamine. In relation to components showing DPPH-radical scavenging activity, α-, β- and γ- tocopherols were detected; the total amount was approximately 2μg/100g. At least 17 fatty acids were identified. Among these, linoleic, palmitic and α-linolenic acids were predominant, with significant amounts of oleic and cis-vaccenic acids. The unsaturation index of the fatty acid constituents in the major lipid classes was high in glyceroglycolipids and low in phosphatidylinositol and acyl sterylglycoside, the same tendency as found in potato tuber lipids. The principal sterol components were usually sitosterol and campesterol. Chinese yam unsaponifiables exhibited a growth-inhibitory effect against Caco-2 cells in a concentration-dependent manner, and the active principle was confirmed to be mainly sitosterol. It was also suggested that the unsaponifiables induced apoptosis in Caco-2 cells.

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Antioxidant capacities of nine rice cultivars (four red rice, four purple-black rice and ‘Koshihikari’) were evaluated in terms of oxygen radical absorbance capacity (ORAC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. All colored rice extracts showed significantly higher total ORAC (58.0-169.4 μmol of Trolox equivalent (TE) per gram dry weight) and DPPH radical scavenging abilities (10.8-52.2 μmol TE/g-dry weight) than those of extracts from ‘Koshihikari’ (24.9 and 2.5 μmol TE/g-dry weight, respectively). Total polyphenol content of rice extracts was measured using Folin-Ciocalteu assay, and showed highly positive correlations with hydrophilic (H)-ORAC (r=0.984, p<0.01) and DPPH radical scavenging abilities (r=0.948, p<0.01). Both contents of proanthocyanidin in red rice and anthocyanin in purple-black rice were associated with H-ORAC, DPPH radical scavenging ability and total polyphenol content in the colored rice groups. In addition, a strong correlation (r=0.946, p<0.01) was also found between H-ORAC and DPPH radical scavenging ability. Five cultivars of colored rice were subjected to the evaluation for 2 harvest years to investigate differences between different crop years. Although antioxidant capacity and polyphenol content values were different between the 2 crop years, the order of the values among the cultivars remained mostly unchanged. These results indicate that colored rice is a potential bio-functional food with high antioxidant capacities, which is due mainly to polyphenols in the rice.

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To investigate the influence of cyclodextrin (CD) on the pungent taste of α-lipoic acid, a 0.05% (w/v) aqueous solution of α-lipoic acid in which CD (or dextrin) was added was evaluated by a sensory test and a liquid taste analyzer. Data from the liquid taste analyzer were used to compare the taste intensities of α-lipoic acid alone and α-lipoic acid supplemented with CD. The sensory test showed that the pungent taste of α-lipoic acid reduced significantly with the addition of 1.5% α-CD and γ-CD (w/v). The liquid taste analysis demonstrated a significant reduction in the taste of α-lipoic acid in the order of α-CD > G2-β-CD^® > β-CD > dextrin > γ-CD > Isoeleat^®P, and a reduction in the taste of α-lipoic acid supplemented with 3.0% (w/v) CD in the order of α-CD > γ-CD = Isoeleat^®P. In conclusion, it was suggested that α-CD significantly reduced the pungent taste of α-lipoic acid due to the formation of a poorly water-soluble inclusion complex and the interaction between α-lipoic acid and α-CD in solution.

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A simple and rapid method for identification of rice cultivar “Koshihikari” has been developed using loop-mediated isothermal amplification (LAMP). Primers for detection of Koshihikari (positive primer) and cultivars other than Koshihikari (negative primer) were designed for blast resistant gene Pi5-1and its susceptible allele. DNA amplification analysis of the top 48 cultivars using positive and negative primers showed that both primers had approximately 90% accuracy in detecting Koshihikari and cultivars other than Koshihikari. For rapid detection from rice grains, a simple DNA extraction method using sodium hydroxide was developed. LAMP amplification using DNA extracted by this method was almost equivalent to that using column-purified DNA. Using these methods, we tested LAMP detection of Koshihikari and Hitomebore (representative of cultivars excluding Koshihikari) grain contamination, and showed that both primers could detect 1% contamination.

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Moisture distribution in “Ichidagaki” dried persimmon fruit was examined to clarify the water-related differences between sound and moldy samples by using magnetic resonance imaging (MRI). One moldy product was measured together with one or three sound samples by the spin-echo (SE) method with a small MRI system equipped with a 0.2-Tesla permanent magnet and a solenoid-type detector with a 12-cm² opening. Differences in the moisture content and water activity values of the sound and moldy samples were not significant (p > 0.05). With NMR signal intensity expressed as brightness in the images, the mesocarp and endocarp tissues of the moldy samples were brighter than those of the sound samples. Endocarp tissues of the moldy samples produced especially bright images. This difference in brightness was found in all 2-D images horizontally sliced from 3-D images. The brighter the area in an MRI image, the higher the amount of water present. The T₁ and T₂ relaxation time-weighted imaging methods revealed that water mobility distributions of the moldy samples shifted upward and endocarp tissues of the moldy samples had higher water mobility. We found that MRI can be used to detect moisture distribution differences between sound and moldy samples of “Ichidagaki” dried persimmon fruit, and expect this practical application of MRI in the quality control of the fruit to be useful.

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We established an allergic model of the late phase of type I hypersensitivity reaction to cedar pollen in mice. In this model, BALB/c mice (5-week-old females) were immunized five times with cedar pollen allergen, and eosinophil accumulation in the peritoneal cavity was elicited by an intraperitoneal injection of the allergen. We investigated the effects of the leaf of Moringa oleifera on allergen-induced eosinophil accumulation and total IgE in serum by giving freely feeding mice a powder diet containing 0.3%, 1.0%, and 3.0% M. odeifera leaf powder. Compared to the control group (normal diet), the number of total leukocytes and eosinophils accumulated in the peritoneal cavity was significantly reduced in the groups given the diet containing 0.3% and 3.0% M. oleifera leaf powder. However, there were no differences in the number of lymphocytes, monocytes, and neutrophils between all groups. Furthermore, the serum level of total IgE was reduced in the M. oleifera leaf powder-treated groups. These results provide laboratory evidence that M. oleifera leaf powder reduces eosinophil accumulation at the site of allergic inflammation and attenuates the development of IgE-mediated allergy.

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[in Japanese]

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