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Evidence-Based Complementary and Alternative Medicine
Volume 2013, Article ID 921012, 8 pages
http://dx.doi.org/10.1155/2013/921012
Research Article

Citrus junos Tanaka Peel Extract Exerts Antidiabetic Effects via AMPK and PPAR- both In Vitro and In Vivo in Mice Fed a High-Fat Diet

1Korea Food Research Institute, 1201 Anyangpangyoro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-746, Republic of Korea
2Department of Food Science & Technology, Gyeongsang National University, 501 Jinjudaero, Jinju, Gyeongnam 660-701, Republic of Korea

Received 23 January 2013; Accepted 7 April 2013

Academic Editor: Per Bendix Jeppesen

Copyright © 2013 Sung Hee Kim et al. 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.

Abstract

The antidiabetic effect of the Citrus junos Tanaka (also known as yuja or yuzu) was examined. Ethanol extract of yuja peel (YPEE) significantly stimulated 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG) uptake in C2C12 myotubes. However, ethanol extract of yuja pulp (YpEE) and water extract of yuja peel (YPWE) or pulp (YpWE) did not stimulate glucose uptake. In addition, peroxisome proliferator-activated receptor gamma (PPAR- ) and AMP-activated protein kinase (AMPK) activities were increased by YPEE in a dose-dependent manner. Pretreatment of AMPK inhibitor decreased the glucose uptake stimulated by YPEE in C2C12 myotubes. We confirmed the anti-diabetic effect of YPEE in mice fed a high fat-diet (HFD). Compared with control mice on a normal diet (ND), these mice showed increased body weight, liver fat, insulin resistance, triacylglycerol (TG), and total cholesterol content. Addition of 5% YPEE significantly reduced the weight gain and rise in liver fat content, serum triacylglycerol (TG), total cholesterol, and insulin resistance found in mice fed a high-fat diet (HFD). Moreover, YPEE reduced the secretion of HFD-induced adipocytokines such as leptin and resistin. YPEE also resulted in increased phosphorylation of AMPK in muscle tissues. These results suggest that ethanol extract of yuja peel exerts anti-diabetic effects via AMPK and PPAR- in both cell culture and mouse models.