Hypocholesterolaemic effect of whole-grain highland hull-less barley in rats fed a high-fat diet

Abstract

Whole-grain highland hull-less barley (WHLB) contains high amounts of bioactive compounds that potentially exhibit cholesterol-lowering effects. This study investigated the hypocholesterolaemic effect of WHLB. A total of seventy-two male Sprague-Dawley rats were divided into four groups and were fed with the normal control diet, high-fat diet (HFD) and HFD containing low or high dose (10 or 48·95 %) of WHLB. High dose of WHLB significantly decreased the organ indexes of liver and abdominal fat and lipid levels of plasma and liver in HFD rats. The lipid regulation effect of WHLB, which was reconfirmed through hepatocyte morphologic observation, was accompanied by a large excretion of bile acids in the small intestinal contents and the faeces. Real-time PCR analyses, which were further reconfirmed through Western blot analyses, revealed that a high dose of WHLB significantly enhanced the hepatic expressions of AMP-activated protein kinase α, cholesterol 7α-hydroxylase, LDL receptor, liver X receptor, and PPARα and decreased the expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase. It also enhanced the ileal expression of farnesoid X receptor and resulted in the decrease of expression of apical sodium-dependent bile acid transporter. WHLB exhibited hypocholesterolaemic effects mainly by inhibiting cholesterol synthesis, cholesterol accumulation in peripheral tissue, and bile acid reabsorption and by stimulating bile acid synthesis.

Molecular Mechanism of Functional Ingredients in Barley to Combat Human Chronic Diseases

“…Barley bran 5% and 10% in diet to the hypercholesterolaemic rats improved the level of lipids, lactate dehydrogenase, liver enzymes, and creatine kinase-MB [120]. Whole grain hulless barley has hypocholesterolaemic effects by promoting bile acid synthesis and reabsorption, controlling cholesterol synthesis and accumulation in peripheral tissue, decreasing the expression of 3-hydroxy-3methylglutaryl coenzyme A reductase, while increasing the hepatic expressions of AMP-activated protein kinase α, cholesterol 7α-hydroxylase, LDL receptor, liver X receptor, and PPARα [118].…”

“…Kernel position Mean ± SD Range References β-glucan (%) Whole grains 4:61 ± 0:45 2.40~11.00 [21,29,39] Resistant starch (%) Whole grains 3:63 ± 2:32 0.2~24.0 [73][74][75] Arabinoxylan (%) Endosperms 0:67 ± 0:06 0.53~0.90 [55] Barley bran 4:66 ± 3:35 1.97~8.42 [29,30] Grains flour 1:31 ± 0:73 0.70~2.13 [29,30] Polyphenols (mg/100 g) Whole grains 231:61 ± 34:26 150.0~300.0 [37,118] Barley bran 421:84 ± 24:46 376.1~443.5 [30] Grains flour 140:41 ± 10:21 129.9~160.7 [30] Phenolic acids (mg/100 g) Whole grains 414:70 ± 32:86 336.29~453.94 [39] Total flavones (mg/100 g) Whole grains 80:64 ± 17:15 37.93~236.91 [37,39,75] Flavonoids (mg/100 g) Whole grains 12:51 ± 10:14 6.20~30.08 [18] Catechin (mg/100 g) Whole grains 2:25 ± 0:94 0.90~4.27 [18,227] Quercetin (mg/100 g) Purple grains 3:51 ± 2:24 2.00~6.08 [18,227] Kaempferol (mg/100 g) Whole grains 3:66 ± 14:87 1.27~6.31 [18,227] Myricetin (mg/100 g) Whole grains 11:07 ± 22:25 0~73.30 [227] Total alkaloid (mg/100 g) Whole grains 25:96 ± 1:41 6.36~44.63 [228] Total anthocyanin (mg/100 g) Whole grains 35:50 ± 23:82 4.9~103.7 [229] Barley bran 256:05 ± 137:67 158~353.4 [54] Refined flours 39:15 ± 25:67 21.0~57.3 [54] Proanthocyanidin (mg/100 g) Whole grains 6:97 ± 3:84 1.58~13.18 [18] Total tocols (mg/100 g) Whole grains 5:85 ± 3:51 0.85~12.49 [21,66,70,71] Antioxidant activity (%) Whole grains 41:55 ± 7:82 24.10~82.00 [37]…”

“…Hypocholesterolaemic effects. Cholesterol is a synthesis lipid in the body [118]. Dietary β-glucan of hulless barley reduces the plasma LDL cholesterol content (see Table 3) by promoting the excretion of faecal lipids and regulating the activities of 3-hydroxy-3-methyl glutaryl-coenzyme A 8…”

“…The free phenolic extract in barley added the hepatic levels of antioxidant enzymes [130]. Whole grain hulless barley had significantly lower liver lipid levels (total phenolic and pentosan) [118]. Barley sprout extract protects liver cells under oxidative stress by activating Nrf2 and adding glutathione synthesis, especially against alcohol-induced liver injury, as it inhibits glutathione depletion and hepatic lipid accumulation, reduces serum biochemical markers of liver injury, and inhibits inflammatory responses [131].…”

“…Black barley sprouting stimulates the phenolic biosynthesis by upregulating proline-associated pentose phosphate pathway to support structure of sprouts with antioxidant capacity [153]. Total phenolic and pentosan in hulless barley grains have antioxidant activity by downregulated expression of heat shock protein 60 and phosphatidylethanolamine binding protein 1 but upregulated expression of enoyl-coenzyme A hydratase and peroxiredoxin 6 [118]. The total polyphenol (flavonoid) content and the 2,2-diphenyl-1-picrylhydrazyl and ABTS radical scavenging abilities increased as the barley added to the food mixture [154].…”