Yukikazu Yamasaki

Effect of flavonol glycoside in mulberry (Morus alba L.) leaf on glucose metabolism and oxidative stress in liver in diet-induced obese mice.

BACKGROUND Mulberry therapies on type 2 diabetic patients or streptozotocin-induced diabetic rats have been reported to improve fasting blood glucose levels. We investigated the effects of dietary consumption of mulberry-leaf powder and purified quercetin 3-(6-malonylglucoside), the quantitatively major flavonol glycoside in mulberry leaves, on glucose and lipid metabolism in high-fat diet-induced obese mice. Male C57BL/6J mice aged 8 weeks were assigned to three groups (control, mulberry leaf powder (MLP), and quercetin 3-(6-malonylglucoside) (Q3MG)) and treated with their respective diets for 8 weeks. RESULTS We found that dietary supplementation of 10 g MLP kg(-1) or 1 g Q3MG kg(-1) in high-fat diet effectively suppressed blood glucose levels. We also noted increased expression of glycolysis-related genes and suppression of thiobarbituric acid reactive substances concentrations in the liver of Q3MG group compared to control mice. CONCLUSION Dietary consumption of Q3MG, the quantitatively major flavonol glycoside in mulberry leaves, improved hyperglycemia in obese mice and reduced oxidative stress in the liver.

Anti-obesity effects of hot water extract from Wasabi (Wasabia japonica Matsum.) leaves in mice fed high-fat diets

The anti-obesity effects of a hot water extract from wasabi (Wasabia japonica Matsum.) leaves (WLE), without its specific pungent constituents, such as allyl-isothiocyanate, were investigated in high fat-diet induced mice. C57J/BL mice were fed a high-fat diet (control group) or a high-fat diet supplemented with 5% WLE (WLE group). Physical parameters and blood profiles were determined. Gene expression associated with lipid metabolism in liver and white adipose tissue were analyzed. After 120 days of feeding, significantly lower body weight gain, liver weight and epididymal white adipose tissue weight was observed in the WLE group compared to the control group. In liver gene expression within the WLE group, PPARα was significantly enhanced and SREBP-1c was significantly suppressed. Subsequent downstream genes controlled by these regulators were significantly suppressed. In epididymal white adipose tissue of the WLE group, expression of leptin, PPARγ, and C/EBPα were significantly suppressed and adiponectin was significantly enhanced. Acox, related to fatty acid oxidization in adipocytes, was also enhanced. Our results demonstrate that the WLE dietary supplement induces mild suppression of obesity in a high-fat diet induced mice, possibly due to suppression of lipid accumulation in liver and white adipose tissue.

Molecular cloning, nucleotide sequencing, and regulation of the chiA gene encoding one of chitinases from Enterobacter sp. G-1

The chiA gene encoding a chitinase of 60-kDa has been cloned from Enterobacter sp. G-1 by PCR using synthetic oligonucleotides corresponding to the amino acid sequences of the purified enzyme and subsequently genomic library screening was performed. The products of the positive clones were found to degrade water-insoluble chitin. The primary structure of the chiA gene consisted of 1,686-bp encoding 562 amino acid residues. Comparison of the deduced amino acid sequence of the cloned chitinase gene product (chiA) with other chitinases revealed a high homology (95.7% identity) with chitinase A from Serratia marcescens QMB1466. The coding region of the chiA gene for higher expression in Escherichia coli was identified using deletion and sequence analysis. The expression of the chiA gene in Enterobacter sp. G-1 was controlled by presence of chitin, as determined by Northern blotting hybridization analysis. We found that the expression of the chiA gene in E. coli was controlled by an inverted repeat sequence located in the upstream region from a promoter region.

Development of a Food Manufacturing System with Near Infrared Method.

本研究では魚の調味漬工程において,近赤外分光分析計により調味液成分をリアルタイムで測定し,ファジィ制御技術で調味液濃度を一定に保つ工程管理システムの開発を行った.開発にあたって,まずビーカー規模で調味漬実験を行い,工程中における成分濃度の変化等について検討した.調味液を繰り返し使用する場合,減少した成分を補うことで,魚肉への吸収を一定に保ち,漬け時間の短縮が可能となった.また生菌数の増加を抑え,繰り返し使用が可能であった.よって濃度調整システムを使うことで,より品質の安定した製品を製造することができると考えられた.近赤外分光法による調味液各成分の分析では,キャリブレーションにおいてスペクトルを二次微分処理し,各二波長を採用することで,精度の高い検量線を得ることができた.この検量線は,その精度から考えて工程管理に十分応用可能であった.濃度調整システムの制御用ソフトは,パソコン画面や濃度の設定等,実際の使いやすさを工夫しており,誰でも簡単に使える様になっている.また濃度調整の手法として,ファジィ制御技術を用い,正確な濃度調整を可能にした.実際に濃度調整システムを用いて,100l規模で調味漬実験を行ったところ,調味液中の各成分濃度はほぼ一定に保たれ,本システムが有効に機能していることが示された.従来の静置方式では,魚肉から溶出する水分量の違い等により,製品にばらつきがでやすかった.本システムの使用は,品質の安定した製品の製造につながり,また調味液の効率的な使用により,コストの削減と環境保全にも役立つと考えられた.