Effect of Galla chinensis on prevention and improvement of type 2 diabetes mellitus
Date Issued
2009
Date
2009
Author(s)
Huang, Yu-Zhu
Abstract
Diabetes mellitus is one of the ten leading causes of death in Taiwan. Chronic hyperglycemic is the main symptom of type 2 diabetes, and it not only increases body oxidative stress but also accumulates advanced glycation end products (AGEs) and causes the insulin sensitive cells to decrease glucose uptake ability. here is still limitation in current available therapeutic treatments for type 2 diabetes. A novel approach to treat type 2 diabetes is using DPP-4 inhibitors to improve the duration of endogenous GLP-1 (Glucagon-like peptide-1) activity. GLP-1 is a gut hormone, it stimulates the secretion of insulin and inhibits glucagon release in a glucose dependent manner. This decreases the glycemic excursion, and would not cause hypoglycemic side effect.ntil now, all of DPP-4 inhibitors are chemically synthesized. Hence, we tried to use DPP-4 inhibition as a model to find out the materials from nature substances which are able to prevent and improve the conditions of diabetic patients.he results of the study showed that hot water extract of Galla chinensis at 121℃ for 60 min was able to inhibit DPP-4 activity (inhibition ratio is 49.6 ± 2.3% at 100 μg/mL ). Furthermore, the hot water extract was separated by Sephadex LH-20 into A~J fractions. All fractions and hot water extract were examined by antioxidative assays (DPPH free radical scavenging effect and inhibition of Cu2+-induced oxidation of human low-density lipoprotein assay), DPP-4 inhibition assay, and diabetes symptoms related assays (inhibit AGEs formation, stimulate cells glucose uptake ability) for their anti-diabetes abilities.t was found that G fraction had the superior IC50 of antioxidant activity and showed positive effect during diabetes symptoms related assays. It’s DPPH free radical scavenging activity was 52.9 ± 0.5 μg/mL, the delaying LDL oxidation effect was 1.7 times better than Trolox at the same concentration (0.5 μg/mL), it’s ability of inhibiting AGEs formation is the same with positive control quercetin at the same concentration (20 μg/mL), it stimulates insulin resistant cells uptake glucose 2.5 ± 0.4 times, improving glucose uptake of the insulin resistance cells. In DPP-4 inhibition assay, J, H, I fractions are better than other fractions (Inhibition ratio are 49.6 ± 2.3% ~ 57.8 ± 2.0% at 100 μg/mL). Consequently, we purified G、H、I、J fractions via High Performance Liquid Chromatography and identified their molecular weights by Mass Spectrometry. The mass spectra data were compared with the data in literatures, and indicated that major compounds in G fraction were methyl gallate and digallic acid. While, H, I, J fractions maybe 1,2,6-tri-O-galloyl-β-d-glucose, 1,2,3,6-tetra-O-galloyl-β-d-glucose, 1,2,3,4,6-penta-O-galloyl-β-d-glucose, respectively.o the best of our knowledge is the first time that DPP-4 inhibitors is discovered from nature substances, and the active compounds probably are 1,2,6-tri-O-galloyl-β-d-glucose、1,2,3,6-tetra-O-galloyl-β-d-glucose、 1,2,3,4,6-penta-O-galloyl-β-d-glucose. However, the chemical structures of these compounds should be further identified by NMR and/or IR. This study showed that Galla chinensis is able to inhibit DPP-4 activity, scavenges DPPH free radical, delays Cu2+-induced oxidation of human LDL, and stimulates insulin resistant cells uptake glucose. Thus, it is able to prevent and improve the conditions of diabetic symptoms via different ways. Therefore, Galla chinensis has potential to be developed as an anti-diabetes products.
Subjects
diabetes mellitus
Galla chinensis
SDGs
Type
thesis
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