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Foods 2018, 7(6), 94; https://doi.org/10.3390/foods7060094

Identification of Rice Koji Extract Components that Increase β-Glucocerebrosidase Levels in Human Epidermal Keratinocytes

1
Bionics Program, Tokyo University of Technology Graduate School, 1404-1 Katakuramachi, Hachioji City, Tokyo 192-0982, Japan
2
School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji City, Tokyo 192-0982, Japan
3
MARUKOME Co., Ltd., 883 Amori, Nagano-shi, Nagano 380-0943, Japan
*
Author to whom correspondence should be addressed.
Received: 21 April 2018 / Revised: 6 June 2018 / Accepted: 15 June 2018 / Published: 18 June 2018
(This article belongs to the Special Issue Functional and Bioactive Properties of Food)
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Abstract

Rice miso contains many ingredients derived from rice koji and has been a valuable source of nutrition since ancient times. We found that the consumption of rice miso led to improvements in the moisture content of cheek stratum corneum, skin viscoelasticity, and skin texture. Further, rice miso extract was found to increase the mRNA expression and activity of β-glucocerebrosidase (β-GCase), an enzyme involved in ceramide synthesis in the stratum corneum, in cultures. In this study, we identified the lipid-derived components of rice koji that increase the β-GCase activity in cultured human epidermal keratinocytes. The methanol fraction of rice koji extract induced an increase in the mRNA expression and activity of β-GCase in keratinocytes. The active fraction of rice koji was found to contain phosphatidic acid (PA) and lysophosphatidic acid (LPA). The total PA concentration in rice koji was 973.9 ng/mg dry weight, which was 17.5 times higher than that in steamed rice. Among the molecular species, PA_18:2/18:2 was the most frequently found. The total LPA concentration in rice koji was 29.6 ng/mg dry weight, and 2-LPA_18:2 was the most frequently found LPA. Since PA and LPA increase the mRNA expression and activity of β-GCase in keratinocytes, they are thought to be the active ingredients in rice koji that increase the β-GCase levels in human epidermal keratinocytes. View Full-Text
Keywords: Aspergillus oryzae; rice koji; phosphatidic acid; lysophosphatidic acid; β-glucocerebrosidase Aspergillus oryzae; rice koji; phosphatidic acid; lysophosphatidic acid; β-glucocerebrosidase
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Maeda, K.; Ogino, Y.; Nakamura, A.; Nakata, K.; Kitagawa, M.; Ito, S. Identification of Rice Koji Extract Components that Increase β-Glucocerebrosidase Levels in Human Epidermal Keratinocytes. Foods 2018, 7, 94.

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