Protective Effects of Black Raspberry (Rubus occidentalis) Extract against Hypercholesterolemia and Hepatic Inflammation in Rats Fed High-Fat and High-Choline Diets.

Taehwan Lim,Kiuk Lee,Keum Taek Hwang,Sun Young Park,Juhee Ryu

doi:10.3390/nu12082448

Abstract

Choline is converted to trimethylamine by gut microbiota and further oxidized to trimethylamine-N-oxide (TMAO) by hepatic flavin monooxygenases. Positive correlation between TMAO and chronic diseases has been reported. Polyphenols in black raspberry (BR), especially anthocyanins, possess various biological activities. The objective of this study was to determine the effects of BR extract on the level of choline-derived metabolites, serum lipid profile, and inflammation markers in rats fed high-fat and high-choline diets. Forty female Sprague-Dawley (SD) rats were randomly divided into four groups and fed for 8 weeks as follows: CON (AIN-93G diet), HF (high-fat diet), HFC (HF + 1.5% choline water), and HFCB (HFC + 0.6% BR extract). Serum levels of TMAO, total cholesterol, and low-density lipoprotein (LDL)-cholesterol and cecal trimethylamine (TMA) level were significantly higher in the HFC than in the HFCB. BR extract decreased mRNA expression of pro-inflammatory genes including nuclear factor-κB (NF-κB), interleukin (IL)-1β, IL-6, and cyclooxygenase-2 (COX-2), and protein expression of NF-κB and COX-2 in liver tissue. These results suggest that consistent intake of BR extract might alleviate hypercholesterolemia and hepatic inflammation induced by excessive choline with a high-fat diet via lowering elevated levels of cecal TMA and serum TMAO in rats.

Highlights

Choline, one of the components of phospholipids in cell membrane and neurotransmitter, is regarded as an essential nutrient [1]
A previous study reported that the major component of the black raspberry (BR) extract using ethanol solution was carbohydrates and small amounts of soluble proteins, ash, and anthocyanins [26]
Since biological properties of BR and its extract have been largely related to their phenolic-type phytochemicals [27,28], bioactive compounds in the BR extract used in this study would most likely be polyphenols

Summary

Introduction

One of the components of phospholipids in cell membrane and neurotransmitter, is regarded as an essential nutrient [1]. Choline is a precursor of trimethylamine-N-oxide (TMAO), which has been reported to act as a putative promoter of chronic diseases in human [2,3,4,5,6]. A part of excessive dietary choline is metabolized by gut microbiota to produce trimethylamine (TMA). Since various epidemiological studies revealed connection between TMAO and cardiovascular diseases (CVD) [5,7,8], studies on TMAO and its precursors, such as choline, lecithin, and L-carnitine, have focused on vascular inflammation, endothelial dysfunction, and cholesterol homeostasis [3,4,5,9,10,11,12].

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