Myricetin derived from Hovenia dulcis Thunb. ameliorates vascular endothelial dysfunction and liver injury in high choline-fed mice.

The present study was conducted to explore the protective effects of myricetin (MYR) purified from Hovenia dulcis Thunb. against vascular endothelial dysfunction and liver injury in mice fed with 3% dietary choline water. MYR was shown to possess strong scavenging activities against DPPH˙, HO˙, and O2˙(-) and ferric-reducing antioxidant power in vitro. Mice fed 3% dietary choline water for 8 weeks significantly displayed vascular endothelial dysfunction and liver oxidative stress (p < 0.01). Furthermore, continuous administration of MYR at 400 and 800 mg per kg bw in choline-fed mice could significantly decrease the high choline diet-induced elevation of serum total cholesterol (TC), total triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), endothelin 1 (ET-1) and thromboxane A2 (TXA2) levels as well as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, while the choline-induced decline of serum high density lipoprotein-cholesterol (HDL-C), endothelin nitric oxide synthase (eNOS), nitric oxide (NO) and prostaglandin I2 (PGI2) levels could be markedly elevated in mice (p < 0.05, p < 0.01). Meanwhile, MYR at 400 and 800 mg per kg bw also increased hepatic total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activities and decreased hepatic malonaldehyde (MDA) and non-esterified fatty acid (NEFA) levels in mice, relative to choline-treated mice (p < 0.05, p < 0.01). These results together with conventional haematoxylin and eosin (H&E) and Oil Red O staining observation of the liver and vascular tissues suggested that MYR exerted a significant protective role against high choline diet-induced endothelial dysfunction and liver injury in mice. This is the first report showing that high intake of dietary choline can induce liver damage and that MYR can ameliorate choline-induced vascular endothelial dysfunction and liver injury.