Modulation Mechanism of Proanthocyanidins from Leaves of Bayberry (Myrica rubra Sieb. Et Zucc.) on Hyperlipemic Rats Induced by High-fat-diet
Lu-ting Ye
College of Life Sciences, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
Zong-hua Dong
College of Life Sciences, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
Jun Liu
College of Life Sciences, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
Feng Guan
College of Life Sciences, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
Jian Ge *
College of Life Sciences, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
*Author to whom correspondence should be addressed.
Abstract
Aim: To investigate the lipid-lowering effect of proanthocyanidins from Bayberry leaf (BLP) in rat model of hyperlipidemia and to clarify the underlying molecular mechanism.
Study Design: The study includes in-vitro and in-vivo experiments in rat model.
Place and Duration of Study: College of Life Sciences, China Jiliang University, Zhejiang Province, China, between March 2021 to December 2021.
Methodology: BLP were preliminarily characterized. The adsorption rate of BLP was determined based on in-vitro binding to bile acids. The effect of BLP on membrane transport of bile acids was examined through Caco-2 mono-layer in trans-well. The effect of BLP on serum enzyme activity and lipid metabolism genes expression were also investigated in a high-fat diet rat model.
Results: Total poly-phenol and proanthocyanidins contents were 97.93% and 82.25% respectively, using gallic acid and Epigallocatechin-3-O-Gallate (EGCG) as equivalent. The total flavonoid content was 12.05% (quercetin as equivalent) and the average polymerization degree of BLP was determined as 4.51. And the in-vitro average binding rates of BLP to bile acids were all higher than 80%. Meanwhile, the membrane transport of bile acids in Caco-2 monolayer cells were significantly obstructed by BLP. Furthermore, the total cholesterol (TC), triglyceride (TG) and low density lipoprotein cholesterol (LDL-C) concentrations in rat serum were markedly decreased after 28-day of BLP treatment. And the hepatic steatosis was significantly ameliorated in high-dose BLP treatment group compared with high fat group. High-dose administration of BLP significantly reduced the levels of 3-hydroxy-3-3methylglutary-CoA (HMG-CoA) reductase, while the levels of ATP binding cassette transporters (ABCG-5), liver X receptor-α (LXR-α) and cholesterol-7α-hydroxylase (CYP7A1) were significantly increased.
Conclusion: BLP can mediate the serum lipid metabolism via preventing bile acids re-absorption, reducing oxidative stress and regulating the expression of lipid metabolism-related genes.
Keywords: Bayberry Leaf Proanthocyanidins (BLP), bile acids, hyperlipidemia, lipid metabolism regulation