Hypoglycemic Constituents Isolated from Trapa natans L. Pericarps.
Trapa natans L., called water chestnut or water caltrop, is a floating aquarium plant. Its fruits are widely used as food. Two new tannins, 1 and 2, one new neolignan, 14, one new norlignan, 17, and 20 known compounds, 3-13, 15, 16, and 18-24 were isolated from T. natans pericarps in this study. The 1, 2, 14, and 17 structures were elucidated using a chemical method and extensive spectral evidence. A series of hydrolyzable tannins, 1-8, a lignin, 13, a flavonoid, 16, a norlignan, 17, and phenolic compounds, 18, 20, 21, and 24 resulted in the enhanced glucose uptake activity in C2C12 myotubes. Compounds 4 and 5 significantly increased GLUT4 protein expression in C2C12 myotubes. In addition, 4 and 5 improved the phosphorylation of AMPK, AKT(S473), and AKT(T308). The involvement of AMPK and PI3K in the mechanism of action of compounds 4 and 5 was confirmed by use of AMPK and PI3K inhibitors, which completely suppressed the 4- and 5-mediated activities of glucose uptake in C2C12 myotubes. We also demonstrated that 4 and 5 could increase GLUT4 protein levels in plasma membranes.
Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University , Taichung 404, Taiwan.|Tsuzuki Institute for Traditional Medicine, China Medical University , Taichung 404, Taiwan.
Hui-Chi
HC
Huang
Graduate Institute of Life Sciences, National Defense Medical Center , Taipei 114, Taiwan.
Chien-Liang
CL
Chao
Research and Development Department, Starsci Biotech Co., Ltd. , Taipei 112, Taiwan.
Chia-Ching
CC
Liaw
Endemic Species Research Institute , Council of Agriculture, Nantou 552, Taiwan.
Syh-Yuan
SY
Hwang
Division of Chinese Material Medica Development, National Research Institute of Chinese Medicine, Ministry of Health and Welfare , Taipei 112, Taiwan.|Graduate Institute of Integrated Medicine, China Medical University , Taichung 404, Taiwan.
Yao-Haur
YH
Kuo
Graduate Institute of Life Sciences, National Defense Medical Center , Taipei 114, Taiwan.|Department of Biochemistry, National Defense Medical Center , Taipei 114, Taiwan.
Tsu-Chung
TC
Chang
School of Pharmacy, China Medical University , Taichung 404, Taiwan.|Chinese Medicine Research and Development Center, China Medical University Hospital , Taichung 404, Taiwan.
Chih-Hua
CH
Chao
Graduate Institute of Integrated Medicine, China Medical University , Taichung 404, Taiwan.|Proteomics Core Laboratory, Department of Medical Research, China Medical University Hospital , Taichung 404, Taiwan.
Chao-Jung
CJ
Chen
Department of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, China Medical University , Taichung 404, Taiwan.|Tsuzuki Institute for Traditional Medicine, China Medical University , Taichung 404, Taiwan.|Department of Biotechnology, Asia University , Taichuang 413, Taiwan.
Yueh-Hsiung
YH
Kuo
D000818:Animals; D051379:Mice; D000263:Adenylate Kinase / Q000378:metabolism; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D005947:Glucose / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D013057:Spectrum Analysis / Q000379:methods; D029561:Lythraceae
D000263:Adenylate Kinase; D005947:Glucose; D007004:Hypoglycemic Agents; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt
AMPK; PI3K; Trapa natans L.; glucose uptake in C2C12 myotubes; hydrolyzable tannins