Abstract
Background:
Interest in using herbal medicines to treat the hypercholesterolemia is increasing. Cranberry extract could decrease plasma cholesterol, however, the active ingredients and the underlying mechanisms remain largely unknown.
Hypothesis:
The present study was to test the hypothesis that cranberry anthocyanins (CrA) were at least one of the active ingredients responsible for the cholesterol-lowering activity of cranberry fruits via a mechanism of increasing fecal sterol excretion.
Methods:
Forty-four hamsters were randomly divided into five groups and fed one of the five diets, namely a non-cholesterol control diet (NCD), a high-cholesterol control diet (HCD), a HCD diet supplemented with a low dose of 1% CrA (CL), a HCD diet supplemented with a high dose of 2% CrA (CH), and a HCD diet supplemented with 0.5% cholestyramine as a positive control drug (P-CTL), respectively, for six weeks. Plasma lipoprotein cholesterol was quantified using the enzymatic kits, while the gene expressions of transporters, enzymes and receptors involved in cholesterol absorption and metabolism were quantified using the quantitative RT-PCR. Fecal sterols were quantified using gas chromatography (GC).
Results:
Plasma total cholesterol and aorta atherosclerotic plaque decreased dose-dependently with the increasing amounts of CrA added into diets. This was accompanied by a dose-dependent increase in excretion of both neutral and acidic sterols. CrA had no effect on the mRNA levels of intestinal Niemann-Pick C1 like 1 protein (NPC1L1), acyl CoA:cholesterol acyltransferase2 (ACAT2), microsomal triacylglycerol transport protein (MTP), and ATP binding cassette transporter 5 (ABCG5) as well as hepatic cholesterol-7α-hydroxylase (CYP7A1), 3-Hydroxy-3-methylglutaryl reductase (HMG-CoA-R), sterol regulatory element binding protein 2 (SREBP2), LDL receptor (LDL-R), and Liver X receptor alpha (LXRα).
Conclusion:
CrA as an herbal medicine could favorably modify the lipoprotein profile in hamsters fed a high cholesterol diet by enhancing excretion of fecal neutral and acidic sterols, most likely not mediated by interaction with genes of transporters, enzymes and proteins involved in cholesterol absorption and metabolism.
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