Hiroe Kikuzaki
Nara Women's University
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Publication
Featured researches published by Hiroe Kikuzaki.
Journal of Nutritional Science and Vitaminology | 2016
Keiko Kobayashi; Yuki Ishizaki; Shosuke Kojo; Hiroe Kikuzaki
Sphingomyelinases (SMases) are key enzymes involved in many diseases which are caused by oxidative stress, such as atherosclerosis, diabetes mellitus, nonalcoholic fatty liver disease, and Alzheimers disease. SMases hydrolyze sphingomyelin to generate ceramide, a well-known pro-apoptotic lipid. SMases are classified into five types based on pH optimum, subcellular localization, and cation dependence. Previously, we demonstrated that elevation of secretory sphingomyelinase (sSMase) activity increased the plasma ceramide concentration under oxidative stress induced by diabetes and atherosclerosis in murine models. These results suggest that sSMase inhibitors can prevent the progress of these diseases. The present study demonstrated that sSMase activity was activated by oxidation and inhibited by reduction. Furthermore, we examined whether catechins inhibited the sSMase activity in a physiological plasma concentration. Among catechins, (-)-epicatechin 3-O-gallate (ECg) exhibited strong inhibitory effect on sSMase (IC50=25.7 μM). This effect was attenuated by methylation at the 3″- or 4″-position. On the other hand, (-)-epigallocatechin 3-O-gallate (EGCg) and (-)-catechin 3-O-gallate (Cg) exhibited weaker inhibitory activity than ECg, and (-)-epicatechin and (-)-epigallocatechin did not affect sSMase activity. Additionally, one synthetic catechin, (-)-3-O-methylepigallocatechin 3-O-gallate (EGCg-3-O-Me), showed the strongest inhibitory effect (IC50=1.7 μM) on sSMase. This phenomenon was not observed for (-)-4-O-methylepigallocatechin 3-O-gallate. These results suggest that the reduction potential, the presence of the galloyl residue at the C-3 position, and the steric requirement to interact with sSMase protein are important for effective inhibition of sSMase.
Acta Physiologiae Plantarum | 2017
Yuichi Uno; Yoko Nitta; Misaki Ishibashi; Yuji Noguchi; Hiroe Kikuzaki
Strawberry fruit contains many constituents, some of which have the potential to inhibit histidine decarboxylase (HDC) activity. HDC converts l-histidine to histamine, which is associated with allergic and other biological reactions in the human body. The HDC inhibition levels were different and the component ratios varied by genotype in strawberry. Among the 11 cultivars collected locally in Japan, ‘Tokun’ had an approximately ten times higher inhibition ratio than the lowest cultivar. The reproducibility was confirmed using five cultivars under the same conditions in a glass greenhouse, suggesting that genotypic variation is a major factor of HDC inhibition. The potential inhibitors of HDC might be polyphenols because they showed moderate correlations with HDC inhibition rates. Among the polyphenols, the anthocyanin content possessed a moderate negative correlation. Ascorbic acid, which contributes to the overestimation of total polyphenol, did not independently inhibit HDC activity. These findings will support the identification of potential HDC inhibitors in strawberry and indicated that genotypic differences would make useful probes for inhibitor identification.
Food Hydrocolloids | 2014
Zheng Wang; Kun Yang; Tom Brenner; Hiroe Kikuzaki; Katsuyoshi Nishinari
Food Chemistry | 2012
Shin-ichi Kayano; Yoko Matsumura; Yoko Kitagawa; Mayumi Kobayashi; Asuka Nagayama; Nami Kawabata; Hiroe Kikuzaki; Yoshimi Kitada
Food Hydrocolloids | 2015
Kun Yang; Zheng Wang; Tom Brenner; Hiroe Kikuzaki; Yapeng Fang; Katsuyoshi Nishinari
Food Hydrocolloids | 2015
Kun Yang; Zheng Wang; Tom Brenner; Hiroe Kikuzaki; Yapeng Fang; Katsuyoshi Nishinari
Journal of Functional Foods | 2015
Shoko Kobayashi; Taro Kato; Toshiaki Azuma; Hiroe Kikuzaki; Keiko Abe
Biological & Pharmaceutical Bulletin | 2013
Keiko Kobayashi; Eri Nagata; Kazuki Sasaki; Mariko Harada-Shiba; Shosuke Kojo; Hiroe Kikuzaki
Natural Product Communications | 2016
Yosie Andriani; Desy Fitrya Syamsumir; Tee Ching Yee; Faizah Shaharom Harisson; Gan Ming Herng; Siti Aishah Abdullah; Christine Abellana Orosco; Abdul Manaf Ali; Jalifah Latip; Hiroe Kikuzaki; Habsah Mohamad
Free Radical Biology and Medicine | 2018
Keiko Kobayashi; Hiroe Kikuzaki; Shosuke Kojo; Hiroshi Ichikawa; Yukiko Minamiyama