Analysis and screening of hypoglycemic compounds from the extract of Cucurbita moschata and Momordica charantia wild variant
| Autor: | Chen-Chen Lin, 林禎楨 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 Insulin resistance, the reduced tissue sensitivity to circulating insulin, plays a key role in the development of type 2 diabetes. It leads to decreased glucose utilization by cells and results in hyperglycemia. A cell-based screening system for hypoglycemic compounds able to improve insulin resistance was established previously in this laboratory. We have treated mouse liver cells with tumor necrosis factor-α for the induction of insulin resistance. We used the insulin resistrance cells to test which compounds could improve this insulin resistance and increase the glucose uptake of cells. We considered materials with abilities as hypoglycemic potential. This established system for the screening of hypoglycemic compounds from Cucurbitaceae plants. It was revealed that the crude extracts of Cucurbita moschata(pumpkin) contained hypoglycemic effects. Thus, in this study, it was attempted to screen the crude extracts from the stems of Cucurbita moschata by the cell-based screening system. Stems of pumpkins were extracted by methanol first, followed by serial partitioning with ethyl acetate and butanol. The methanol extract, ethyl acetate layer, butanol layer and final water layer were screened. The methanol extract, ethyl acetate layer and butanol layer showed hypoglycemic activities. The ethyl acetate layer was further divided into twenty three fractions by chromatographies. It was found that fractions 2, 3, 5, 6, 7, 8, 10, 13, 16, 17, 18, 19, 20, 21, 22 and 23were with obvious acute hypoglycemic activities. Among them, fraction 19 and fraction 22 were tested for in vivo hypoglycemic effects in animal models. Hyperglycemic mice were fed with 200 mg/kg of fraction 19 or fraction 22 for 3 days. Both fractions showed hypoglycemic activities in vivo and capabilities to activate AMPK(AMP-activated protein kinase). The latter indicated that both fractions contained compounds able to activate AMPK. Thus, purification of compounds from fraction 19 and fraction 22 is undertaking. Meanwhile, hypoglycemic compounds screened from the extract of Momordica charantia wild variant in our previous study were characterized. We found RA2-19 was with the most significant ability to activate AMPK than the others, but may not inhibit PP2C expression. Thus, other activation of AMPK mechanisms still waited for further confirms. Furthermore, pro-inflammation cytokine, TNF-α was secreted by inflammation is closely associated with insulin resistance. RA2-19 may reduce iNOS, and was found to reduce inflammatory reactions caused by TNF-α. This may be an important mechanism underlying it effect on ameliorating cellular insulin resistance. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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