Protective Effect of Saponins-Enriched Fraction of Gynostemma pentaphyllum against High Choline-Induced Vascular Endothelial Dysfunction and Hepatic Damage in Mice.

Choline as a quaternary amine nutrient is metabolized to trimethylamine by gut microbiota and subsequently oxidized to circulating trimethylamine-N-oxide (TMAO), a gut-derived metabolite associated with liver toxicity and cardiovascular disease. The study was to probe the possible vasoprotective and hepatoprotective effects of total saponins of Gynostemma pentaphyllum (TSGP) in 3% high-choline water-feeding mice. The purified TSGP was obtained with content of 83.0% saponins, and its antioxidant activities were evaluated in vitro. Furthermore, the mice fed with high choline for 8 weeks significantly expressed vascular endothelial dysfunction and liver oxidative stress (p < 0.01 vs. Normal). Administration of TSGP at 400 and 800 mg/kg·body weight (b.w.) significantly lowered the serum total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), endothelin-1 (ET-1) and thromboxane A2 (TXA2) levels, as well as hepatic malondialdehyde (MDA) formation, but effectively elevated the serum nitric oxide (NO), endothelial nitric oxide synthase (eNOS) and prostaglandin I2 (PGI2) levels, as well as alanine aminotransferase (ALT), aspartate aminotransferase (AST), T-superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in high choline-fed mice. Hematoxylin-eosin (H&E) and oil red O staining also suggested that TSGP could exert the significant protection against endothelial dysfunction and liver injury in high choline-treated mice. These findings suggest that TSGP is of the saponins-enriched extract, and is a good candidate of dietary supplement and therapeutic application in vascular and hepatic oxidative injury.