| Gynostemma pentaphyllum Makino (Cucurbitaceae), an edible and medicinal plant in China, is widely supplied as the herbal tea, named'Jiao-Gu-Lan Tea'. Due to rich in saponins and polysaccarchieds, higher health-promoting property such as the prevention and treatment of metabolic and cardiovascular diseases, and non-toxic side effects in long-term consumption, G. pentaphyllum was well known as the "southern ginseng". However, the protective effect of saponin-enriched Gynostemma tea extracts (GTSE) on the diet-induced vascular endothelial and liver injury was poorly understood.Therefore, in this study G.pentaphyllum tea from Pingli County of Shaanxi was used to yield GTSE by hot water extraction and D101 macroporous adsorption resin, and then the vitro antioxidant capacities and potential protective effect on the choline-induced vascular endothelial and liver injury were systematically evaluated. The main results of this study were as follows:(1) The optimum extraction conditions of GTSE were achieved by the orthogonal method, and the optimum extraction yield of GTSE was 3.9% when the ratio of material to liquid was 1:35 (W/V), the extraction time was 90 min, extraction temperature was 85 ?. The GTSE was further enriched by D101 macroporous adsorption resin with a increase of saponin content from 26.2% to 83.0%.(2) The results of antioxidant assays indicated that GTSE displayed considerable radical scavenging activities against DPPH·, HO·, O2·- and also high total reducing power, showing that the clearance rate of GTSE (3 mg/mL) on HO'and O2·- can reach 82% and 73%, respectively, and the clearance rate of GTSE (4 mg/mL) on DPPH· can reach 92%. The results showed that GTSE had good antioxidant activities.(3) After consecutive 8 weeks, compared with normal group, the high choline diet-treated mice serum of endothelin nitric oxide synthase (eNOS), nitric oxide (NO) and prostaglandin I2 (PGI2) and high density lipoprotein-cholesterol (HDL-C) levels were significantly reduced to 18.57 ± 3.17 U/L,0.94 ± 0.20 ?mol/L,19.41 ± 3.41 pg/mL and 0.65 ± 0.09 mmol/L from 25.07 ± 4.26 U/L,2.30 ± 0.35 ?mol/L,50.7 ± 5.2 pg/mL and 1.11 ± 0.16 mmol/L (p<0.01), respectively. Endothelin-1 (ET-1), thromboxane A2 (TXA2), total cholesterol (TC), triglyceride (TG), and low density lipoprotein-cholesterol (LDL-C) levels were dramatically increased to 90.65 ± 8.80 pg/mL,546.82 ± 47.85 pg/mL,4.71 ± 0.33 mmol/L,1.42 ± 0.09 mmol/L and 1.83 ± 0.13 mmol/L (p<0.01) from 68.69 ± 5.04 pg/mL,121.0 ± 15.1 pg/mL,3.19 ± 0.56 mmol/L,0.84 ± 0.09 mmol/L and 1.15 ± 0.15 mmol/L, respectively. The above results showed that 3% high dietary choline caused the mice dyslipidemia and vascular endothelial cell disorder. However, giving mice with different doses of GTSE, the situation can obviously improved, and the improvement effect is more obvious with the increase of GTSE dose. At the same time, the biochemical indicators with histopathological observation of H&E staining of the thoracic aorta in mice showed high choline diet caused some degree of injuries happened in the endothelium of the aorta wall, which was characterized by obvious proliferation of the wall and incrassation of media of the thoracic aorta.So, we could fully proved that 3% dietary choline caused vascular endothelial damage in mice, and GTSE protected vascular tissue from dietary choline-induced vessel injury and vascular endothelial dysfunction.(4) At the same time, high choline diet induced different degrees of liver injury in mice compared with normal mice for consecutive 8 weeks, which was characterized by increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. The ALT and AST activities significantly increased to 66.47 ± 5.80 U/L and 37.62 ± 3.24 U/L from 43.21 ± 2.49 U/L and 23.95 ± 3.34 U/L (p<0.01), respectively. And the total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activities was reduced by 66.43% and 66.43% (p<0.01), respectively, and malonaldehyde (MDA) level was increased by 60.08%(p<0.01). However, GTSE could improve liver damage degree in a dose-dependent manner. At the same time, the mice liver tissue which observed by H&E and Oil Red O staining observation indicated the obvious disorder of parenchyma in mice, such as cellular degeneration, karyopyknosis of cells, cytoplasmic vacuolation, massive fatty changes, hepatocyte necrosis and the loss of cellular boundaries and so on. The above symptom index and histopathological observation consistently showed high dietary choline caused different degree of liver injury in mice. However, after treated with different doses of GTSE, the damage had been improved, and showed good dose-effect relationship.This study revealed the GTSE had good antioxidant activity, and the first time showed that intake of dietary high choline water induced vascular dysfunction and liver injury, and GTSE had the obvious improvement against choline-induced vascular dysfunction and liver injury in mice. All these findings provided scientific basis for the use of GTSE as a promising dietary supplement in the therapy of vascular and liver disorders. |
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