Effects of dietary flaxseed oil on cholesterol metabolism of hamsters

High-fat/cholesterol diets (HFCD) formulated by addition of butter (BU), coconut oil (CO), or flaxseed oil (FX) enhanced (P < 0.05) serum lipids of hamsters compared to the low-fat/cholesterol diet (Control). However, FX groups showed a hypocholesterolaemic effect compared to CO and BU groups. Lower (P < 0.05) hepatic triacylglycerol and cholesterol contents were measured in FX groups than those of CO and BU groups; whereas, higher (P < 0.05) faecal triacylglycerol and cholesterol contents were observed in FX groups. HMG-CoA reductase mRNA expression was upregulated (P < 0.05) by HFCD, whilst FX groups showed no (P > 0.05) influence on LDL-receptor mRNA expression compared to that of Control groups; however, higher (P < 0.05) than those of CO and BU groups. Meanwhile, there was a tendency towards higher CYP7A1 expression in the CO or FX group than the BU group. Thus, the hypocholesterolaemic effect of FX might result from increases of LDL-receptor mRNA expression, and cholesterol catabolism/output.     

Taurine alleviates dyslipidemia and liver damage induced by a high-fat/cholesterol-dietary habit

Eight male hamsters per group were assigned randomly to one of the following diets: chow diet (Control); high-fat/cholesterol diet (HFCD); HFCD supplemented with 1% Tau (HFCD/1% Tau); HFCD supplemented with 2% Tau (HFCD/2% Tau). Tau supplementation improved (P < 0.05) serum lipids and cholesterol profile in the high-fat/cholesterol-dietary hamsters. Although hepatic cholesterol/triacylglycerol in the high-fat/cholesterol-dietary hamsters were not (P > 0.05) changed by Tau supplementation, faecal cholesterol and bile acid outputs were increased (P < 0.05). Two percent Tau supplementation unregulated (P < 0.05) HMG-CoA reductase and cholesterol 7-α hydroxylase (CYP7A1) expressions in the high-fat/cholesterol-dietary hamsters. Besides, Tau supplementation also increased (P < 0.05) LDL receptor mRNA expressions in high-fat/cholesterol-dietary hamsters. Tau supplementation also reduced serum GPT and GOT values and C-reactive protein (CRP) levels in the high-fat/cholesterol-dietary hamsters. Results clearly indicated that Tau could alleviate blood lipids and hepatic damage induced by a high-fat/cholesterol-dietary diet.     

Protective effect of a litchi (Litchi chinensis Sonn.)-flower-water-extract on cardiovascular health in a high-fat/cholesterol-dietary hamsters

Cardiovascular disease (CVD) is the major cause of death in the developed countries. Litchi-flower-water-extract (LFWE) contains plenty of phytochemicals, i.e. phenols, flavonoids, tannins which may own cardio-protection. Ten male hamsters per group were assigned randomly to one of the following dietary groups: chow diet and normal distilled water (LFCD/NDW); high-fat/cholesterol diet and normal distilled water (HFCD/NDW); HFCD and 2.5% litchi-flower-water-extract (HFCD/2.5% LFWE); HFCD and 5% LFWE (HFCD/5% LFWE). Serum lipids, cardiac index, and hepatic lipids were lowered (p < 0.05) in high-fat/cholesterol-dietary hamsters by drinking 2.5% and 5% LFWE which may result from higher (p < 0.05) LDL receptor and peroxisome proliferator-activated receptor-alpha (PPAR-α) gene expressions and lower (p < 0.05) fatty acid synthase (FAS) gene expression, as well as increased (p < 0.05) faecal lipid and bile acid excretions. Drinking LFWE also lowered (p < 0.05) serum malondialdehyde (MDA) contents in high-fat/cholesterol-dietary hamsters, and even showed the same (p > 0.05) serum MDA contents as the LFCD/NDW group’s which could be due to increased (p < 0.05) serum trolox equivalent antioxidant capacity (TEAC). Therefore, this study indicated that LFWE indeed characterises a protective effect on cardiovascular health in vivo.     

Choosing hamsters but not rats as a model for studying plasma cholesterol‐lowering activity of functional foods

Rats and hamsters are commonly used rodents to test the efficacy of cholesterol‐lowering functional foods. In general, a diet containing 1% cholesterol for rats whereas a diet containing 0.1% cholesterol for hamsters is used to induce the hypercholesterolemia. The present study was carried out to compare hamsters with rats as a hypercholesterolemia model. Golden Syrian hamsters and Sprague Dawley rats were randomly divided into four groups and fed one of the four diets containing 0–0.9% cholesterol. Results demonstrated that serum total cholesterol (TC) in hamsters was raised 73–81% higher than that in rats fed the same cholesterol diets. Unlike rats in which HDL‐C accounted very little for serum TC, the lipoprotein profile in hamsters was closer to that in humans. We investigated interaction of higher cholesterol diets with 3‐hydroxy‐3‐methylglutary‐CoA (HMG‐CoA) reductase, low‐density lipoprotein receptor (LDL‐R) and cholesterol‐7α‐hydroxylase (CYP7A1), sterol regulatory element binding protein‐2 (SREBP‐2), and liver X receptor (LXR‐α). Results showed hamsters and rats metabolized cholesterol differently. In view that hamsters synthesize and excrete cholesterol and bile acids in a manner similar to that in humans, it is concluded that hamsters but not rats shall be chosen as a model to study efficacy of cholesterol‐lowering functional foods.     

Dietary calcium decreases plasma cholesterol by down‐regulation of intestinal Niemann–Pick C1 like 1 and microsomal triacylglycerol transport protein and up‐regulation of CYP7A1 and ABCG 5/8 in hamsters

Scope: It has been shown that calcium supplementation favorably modifies plasma lipoprotein profile in postmenopausal women. The present study investigated the interaction of dietary calcium with genes of transporters, receptors and enzymes involved in cholesterol metabolism. Methods and results: Forty‐eight ovariectomized hamsters were fed one of the four diets containing 0, 2, 6 and 8 g calcium per kg. Plasma total cholesterol (TC), triacylglycerols (TG), and non‐high density lipoprotein cholesterol were dose‐dependently decreased, whereas high‐density lipoprotein cholesterol (HDL‐C) was dose‐dependently increased with the increasing dietary calcium levels. Dietary calcium had no effect on protein mass of hepatic sterol regulatory element binding protein‐2 (SREBP), liver X receptor‐alpha (LXR), 3‐hydroxy‐3‐methylglutaryl‐CoA reductase (HMGR), LDL receptor (LDLR) and cholesterol‐7α‐hydroxylase (CYP7A1). However, dietary calcium up‐regulated the mRNA levels of hepatic CYP7A1 and intestinal ATP binding cassette transporters (ABCG5/8) whereas it down‐regulated the intestinal Niemann‐Pick C1 like 1 (NPC1L1) and microsomal triacylglycerol transport protein (MTP). In addition, dietary calcium increased the activity of intestinal acyl coenzyme A: cholesterol acyltransferase 2, while it decreased plasma cholesteryl ester transport protein (CETP). Conclusion: Beneficial modification of lipoprotein profile by dietary calcium was mediated by sequestering bile acid absorption and enhancing excretion of fecal cholesterol, via up‐regulation of mRNA CYP7A1 and intestinal ABCG 5/8 with down‐regulation of mRNA NPC1L1 and MTP.     

牛磺酸对肥胖大鼠甘油三酯和胆固醇代谢的影响

目的 探讨长期经饮水方式补充牛磺酸对高脂膳食所致肥胖大鼠降脂减重作用,对甘油三酯合成关键分子和胆固醇7α羟化酶(cholesterol 7α-hydroxylase, CYP7A1)表达调控关键分子的影响。方法 根据血清胆固醇水平和体重, SD大鼠被分为3组,为对照组(normal, N)饲喂基础维持饲料,肥胖组(high fat, HF)和牛磺酸组(high fat taurine, HFT)饲喂高脂饲料。N组和HF组自由饮水,而HFT组给予牛磺酸溶液代替水,持续12周。结果 与HF组相比,给予牛磺酸的HFT组大鼠体重、附睾周围脂肪重量、血清总胆固醇和低密度脂蛋白胆固醇、游离脂肪酸、固醇调节元件结合蛋白-1c (sterol regulatory element-binding protein-1c, SREBP-1c)和脂肪酸合成酶(fatty acid synthase, FAS)基因表达显著降低,粪便胆汁酸水平、脂蛋白脂肪酶(lipoprotein lipase, LPL)活性以及CYP7A1和Ser63p-c-Jun的蛋白表达显著增加,但肝细胞核因子4α(hepatocyte...     

Comparative effects of safflower oil and perilla oil on serum and hepatic lipid levels, fatty acid compositions of serum and hepatic phospholipids, and hepatic mRNA expressions of 3-hydroxy-3-methylglutaryl CoA reductase, LDL receptor, and cholesterol 7alpha-hydroxylase in young and adult rats

Male Wistar rats, 4 and 33 weeks of age, were fed the diets containing safflower oil (SO-diet, 77.3% linoleic acid) or perilla oil (PO-diet, 58.4% -linolenic acid) for 7 days. Serum total cholesterol was lower on the PO-diet in both ages. On the other hand, hepatic cholesterol and phospholipids were significantly higher in the PO group than in the SO group of the adult rats. The PO group showed significantly lower 20:4 n-6 but higher 18:2 n-6 in hepatic phosphatidylcholine compared with the SO group in both ages. Hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase mRNA was significantly lower on the PO-diet than on the SO-diet irrespective of age. The present results show that -linolenic acid has a higher hypocholesterolemic ability than linoleic acid in rats irrespective of age and these fatty acids behaved differently in affecting hepatic mRNA expressions of HMG-CoA reductase, LDL receptor, and cholesterol 7-hydroxylase.     

Camellia sinensis tea melanin suppresses transformation of the aryl hydrocarbon receptor and prevents against dioxin-induced toxicity in mice

The suppressive effects of Camellia sinensis tea melanin (CSTM) on transformation of aryl hydrocarbon receptor (AhR) induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were disclosed for the first time. CSTM strongly inhibited TCDD-induced toxicity with IC₅₀ equalling 20.4 μg mL⁻¹. Daily administration of CSTM (40 mg kg⁻¹, p.o.) prevented TCDD-induced body weight loss, ameliorated TCDD-induced mortality and prevented TCDD-induced hepatomegaly and thymic atrophy. Co-administration of CSTM significantly inhibited TCDD-induced hepatic CYP1 A1 activity. CSTM retarded transformation of AhR in vitro. In animals treated with CSTM, the antibody-secreting cells produced significantly (P < 0.05) more antibodies (32–34%) than the antigen control. Administration of TCDD caused a suppression of antibody-forming cells of 29–33% against the antigen control level. Co-administration of CSTM restored immunity to the control level. We demonstrated that CSTM directly competed with TCDD during the transformation of AhR and suppressed the downstream activation of genes associated with TCDD toxicity.     

Regulation of lipid disorders by ethanol extracts from Zingiber zerumbet in high-fat diet-induced rats

The aim of this study was to investigate the antihyperlipidaemic effects of the ethanol extract of Zingiber zerumbet (L) Smith (EEZZ). After being fed a high-fat diet (HFD) for 2 weeks, rats were dosed orally with EEZZ (100, 200 or 300 mg/kg) or fenofibrate (100 mg/kg) once daily for 8 weeks. EEZZ (300 mg/kg/day) produced effects similar to fenofibrate in reducing body weight gain, visceral fat-pad weights and plasma lipid levels. EEZZ caused reductions in hepatic triglyceride and cholesterol content, and lowered hepatic lipid droplet accumulation and the size of epididymal adipocytes. HFD-induced reductions in the hepatic proteins of peroxisome proliferator-activated receptor (PPAR) α, acyl-CoA oxidase (ACO) and cytochrome P450 isoform 4A1 (CYP4A1) were reversed by EEZZ. These results suggest that EEZZ reduced the accumulation of visceral fat and improved hyperlipidaemia in HFD-fed rats by increasing fatty acid oxidation, an effect which is likely to be mediated via up-regulation of hepatic PPARα.     

Effects of diet enriched with restructured meats,containing Himanthalia elongata, on hypercholesterolaemic induction,CYP7A1 expression and antioxidant enzyme activity and expression in growing rats

Meat and pork consumptions are very high in Spain. Seaweeds are rich in fibre, minerals, and bioactive substances. Due to the growing demand for healthier meats, this work studied the effect of diets containing restructured pork (RP) enriched with Himanthalia elongata (Sea Spaghetti) on: (1) cholesterolaemia; (2) liver cytochrome P450 7A1 (CYP7A1) expression; (3) liver antioxidant enzyme activities and gene expression; (4) the liver antioxidant substrate concentrations. Four groups of 10 Wistar rats each were fed a mix of 85% AIN-93 M rodent diet and 15% freeze-dried RM for 35 days. The control group (C) consumed control RP; the Sea Spaghetti (SS) group, RP with 5% Sea Spaghetti. Animals on added cholesterol diets (CholC and CholSS) consumed their basal C and SS diets enriched with cholesterol and cholic acid as hypercholesterolaemic agent. Food intake was significantly affected by the alga × cholesterol interaction and by dietary cholesterol (both p < 0.001). Plasma cholesterol was significantly affected by the cholesterol × alga interaction (p < 0.05). CholC rats showed significantly higher plasma cholesterol (p < 0.001) than did their C counterparts, whilst serum cholesterol of CholSS was significantly lower (p < 0.05) than that of CholC. The glutathione peroxide (GSSG) concentrations and all mRNA expressions were significantly affected by the cholesterol × alga interaction (at least p < 0.05). SS vs C group showed significant (at least p < 0.05) increases in superoxide dismutase (Mn-SOD and Cu,Zn-SOD), glutathione peroxidase (GPx) and decrease of glutathione reductase (GR) expressions, and increased GR activity, GSSG and the redox index. CholSS vs CholC showed significant (at least p < 0.05) increases of CYP7A1, GR and Cu,Zn-SOD expression but decreases in catalase, Mn-SOD and GPx expression, and increase of GR activity. In conclusion, Sea Spaghetti could be widely used in RP design. Its addition to non-cholesterol enriched RP diet reduced oxidation mechanisms. SS-RP partially blocked the effect of the hypercholesterolaemic agent, giving rise to a new balance of the antioxidant enzyme expression.     

Phytochemistry, traditional uses and pharmacology of Eugenia jambolana Lam. (black plum): A review

Eugenia jambolana Lam. (syn. Syzigium cumini (L.) SKEELS; S. jambolana DC; Family: Myrtaceae), commonly known as black plum or Jamun is a plant native to India. Annually the trees produce oblong or ellipsoid fruits (berries). They are green when raw and purplish black when fully ripe. The ripe fruits are sweetish sour to taste and are used to prepare health drinks, squashes, juices, jellies and wine. Studies have shown that the berries contain carbohydrates, minerals and the pharmacologically active phytochemicals like flavonoids, terpenes, and anthocyanins. Jamun is a plant with known ethnomedicinal uses. Before the discovery of insulin, Jamun was useful in the treatment of diabetes and is an integral part in the various alternative systems of medicine. Scientific studies have shown that the various extracts of Jamun possess a range of pharmacological properties such as antibacterial, antifungal, antiviral, anti-genotoxic, anti-inflammatory, anti-ulcerogenic, cardioprotective, anti-allergic, anticancer, chemopreventive, radioprotective, free radical scavenging, antioxidant, hepatoprotective, anti-diarrheal, hypoglycemic and antidiabetic effects. The present paper reviews these aspects and also addresses the lacunas in the existing knowledge.     

A review of botanical characteristics, phytochemistry, clinical relevance in efficacy and safety of Lycium barbarum fruit (Goji)

Lycium barbarum has been used as a traditional Chinese medicine (TCM) to nourish liver and kidney, and brighten the eye. The fruits are dried or freshly squeezed for their juice and concentrated for beverages. Among various constituents, a group of polysaccharides (LBP) with a Glycan-O-Ser glycopeptide structure has been most researched and considered to be important for the efficacy of L. barbarum. Studies indicate effects of L. barbarum on aging, neuroprotection, general well-being, fatigue/endurance, metabolism/energy expenditure, glucose control in diabetics, glaucoma, anti-oxidant properties, immunomodulation, anti-tumor activity and cytoprotection. In addition to TCM, L. barbarum can be sold as a dietary supplement or classified as a food based upon the long and safe traditional usage. This review is to provide background and updated information of chemical constituents and efficacies with safety including a new direction for research and current regulatory situation of L. barbarum.