Hypocholesterolemic and antiatherosclerotic effect of flax lignan complex isolated from flaxseed

Amelioration of cholesterol induced atherosclerosis by normalizing gene expression, cholesterol profile and antioxidant enzymes by Vigna unguiculata

Cardiovascular diseases, especially atherosclerosis, have found to be the dreadful diseases worldwide and therapeutic interventions using plant sources have wide therapeutic value. Vigna unguiculata (VU) leaves have been used as food and therapeutics. Hence, our study was designed to evaluate the hypolipidemic as well as anti-atherogenic potential of VU leaves in normalizing atherogenic gene expression, cholesterol profile, generation of reactive oxygen species (ROS) and antioxidant enzyme system on cholesterol fed rabbit model. For the study New Zealand white rabbits were randomly divided into four groups of six animals each and experimental period was three months; group -i - ND [normal diet (40 g feed)], group-ii- ND (normal diet) +EAVU [ethyl acetate fraction of Vigna unguiculata (150 mg/kg body weight)], group -iii- ND [normal diet ]+ CFD [cholesterol fed diet (cholesterol 1 % of 40 g feed and cholic acid 0.5 % of 40 g feed)] and group-iv - ND [normal diet] +CFD [cholesterol fed diet ]+EAVU [ethyl acetate fraction of Vigna unguiculata (150 mg/kg body weight)]. Atherosclerosis was induced by feeding the rabbit with cholesterol (1 % of 40 g feed) and cholic acid (0.5 % of 40 g feed). Supplementation of EAVU normalized cholesterol profile, generation of reactive oxygen species (ROS), lipid peroxidation products like thiobarbituric acid reactive substance (TBARS), antioxidant system and important genes of cardiovascular diseases like interleukin-10 (IL 10), paraoxanase-1 (PON I), interleukin-6 (IL 6), and cyclooxygenase-2 (Cox 2) to near normal level as compared with normal diet. The result obtained showed the antioxidant as well as anti-atherogenic potential of Vigna unguiculata leaves in ameliorating cholesterol induced atherosclerosis, and thus it is good task to include VU leaves in daily diet for the prevention of cardiovascular diseases especially atherosclerosis.

Beneficial effect of flax seeds in streptozotocin (STZ) induced diabetic mice: isolation of active fraction having islet regenerative and glucosidase inhibitory properties

Diabetes mellitus is a metabolic disorder that affects millions of people worldwide. Present study highlights the antidiabetogenic property of Linum usitassimum active fraction (LU6) in streptozotocin (STZ) induced diabetic Swiss mice. Treatment with LU6 fraction showed improved glucose utilization with increase in liver glucose-6-phosphate dehydrogenase enzyme activity and normal glycogenesis in hepatic and muscle tissues. Reduction in pancreatic and intestinal glucosidase inhibitory activity was observed with LU6 treatment, indicating beneficial effects in reducing postprandial hyperglycemia (PPHG). Normalization of plasma insulin and C-peptide levels were observed in diabetic mice, indicating endogenous insulin secretion after the treatment with LU6. The histochemical and immunohistochemical analysis on pancreatic islets suggests the role of LU6 fraction in islet regeneration and insulin secretion as evident in increase functional pancreatic islets producing insulin. Furthermore, significant insulin producing islet formation was also observed in in vitro PANC-1 cells after LU6 treatment, indicating the cellular aggregates to be newly formed islets. This suggests the potential of LU6 fraction in the formation of new islets in vitro, as well as in vivo. Thus, LU6 can be used as a neutraceutical-based first-line treatment for diabetes.

Antidiabetic effect of secoisolariciresinol diglucoside in streptozotocin-induced diabetic rats

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycaemia. Its complications such as neuropathy, cardiopathy, nephropathy, and micro and macro vascular diseases are believed to be due to the increase in oxidative stress and decrease in the level of antioxidants. The aim of this study was to determine the antihyperglycemic activity of synthetic Secoisolariciresinol diglucoside (SDG) in streptozotocin (STZ)-induced diabetic rats. The synthetic SDG in a single-dose (20 mg/kg b.w.) two-day study showed dose-dependent reduction in glucose levels with maximum effect of 64.62% at 48 h post drug treatment (p<0.05), which is comparable to that of the standard drug tolbutamide (20 mg/kg b.w.). In a multi-dose fourteen-day study, lower doses of SDG (5 and 10 mg/kg b.w.) exhibited moderate reduction in glucose levels, lipid profile, restoration of antioxidant enzymes and improvement of the insulin and c-peptide levels which shows the regeneration of β-cell which secretes insulin. Altered levels of lipids and enzymatic antioxidants were also restored by the SDG to the considerable levels in diabetic rats. Results of the present investigation suggest that diabetes is associated with an increase in oxidative stress as shown by increase in serum malondialdehyde (MDA), decreased levels of catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH). Also, diabetes is associated with an increase in serum total cholesterol as well as triglycerides levels and decrease in insulin and c-peptide levels. SDG is effective in retarding the development of diabetic complications. We propose that synthetic SDG exerts anti hyperglycemic effect by preventing the liver from peroxidation damage through inhibition of ROS level mediated increased level of enzymatic and non-enzymatic antioxidants. And, also maintaining tissue function which results in improving the sensitivity and response of target cells in STZ-induced diabetic rats to insulin.

Characterization of apigenin and luteolin derivatives from oil palm (Elaeis guineensis Jacq.) leaf using LC-ESI-MS/MS

The palm oil industry generates several byproducts, and more than half of the dry weight of the waste is of oil palm leaf whereby the tissue is underutilized. Recently, several research studies found promising potential of oil palm fronds as a source of nutraceutical due to its bioactive properties. However, the chemical composition of the tissue is still not deciphered. Using reversed-phase liquid chromatography (LC) electrospray mass spectrometry (ESI-MS), glycosylated apigenin and luteolin were separated and identified from oil palm (Elaeis guineensis Jacq.) leaf and structures of the constituents were elucidated by collision-induced dissociation (CID) tandem MS. From 28 derivatives of the flavones, 9 compounds were conjugated with hydroxymethylglutaric (HMG) acid. Improved knowledge on oil palm especially on bioactive component of the leaf tissue will allow correlation of its beneficial effects and further promotes efficient utilization of this agriculture byproduct.

Effect of flaxseed supplementation and exercise training on lipid profile, oxidative stress and inflammation in rats with myocardial ischemia

Background

Flaxseed has recently gained attention in the area of cardiovascular disease primarily because of its rich contents of α-linolenic acid (ALA), lignans, and fiber. Although the benefits of exercise on any single risk factor are unquestionable, the effect of exercise on overall cardiovascular risk, when combined with other lifestyle modifications such as proper nutrition, can be dramatic.

This study was carried out to evaluate the protective role of flaxseed and exercise on cardiac markers, lipids profile and inflammatory markers in isoproterenol (ISO)-induced myocardial ischemia in rats.

Methods

The research was conducted on 40 male albino rats, divided into 4 groups (n=10): group I served as control, group II has acute myocardial ischemia induced by isoproterenol, groups III and IV have acute myocardial ischemia induced by isoproterenol pretreated with flaxseed supplementation orally for 6 weeks, additionally group IV practiced muscular exercise through swimming.

Results

Alterations of lipid profile, cardiac and inflammatory markers (Il-1β, PTX 3 and TNF- α) were observed in myocardial ischemia group. Flaxseed supplementation combined with exercise training showed significant increase of HDL and PON 1, on the other hand cardiac troponin, Il- 1β and TNF- α levels significantly decreased as compared to myocardial ischemic group. Receiver Operating Characteristics (ROC) analysis of cTnI, PTX 3, Il-1β and TNF- α revealed a satisfactory level of sensitivity and specificity.

Conclusion

Regular exercise enhances the improvement in plasma lipoprotein levels and cardiovascular protection that results from flaxseed supplementation by mitigating the pathophysiology of atherosclerosis. Elevation of HDL, the antioxidant PON 1 and the cardioprotective marker PTX 3 emphasizes the protective effects of flaxseed and muscular exercise mutually against the harmful effects of acute myocardial ischemia.

Flaxseed oil as a neuroprotective agent on lead acetate-induced monoamineric alterations and neurotoxicity in rats

Lead remains a considerable occupational and public health problem, which is known to cause a number of adverse effects in both man and animals. Here, the neuroprotective effect of flaxseed oil (1,000 mg/kg) on lead acetate (20 mg/kg) induced alternation in monoamines and brain oxidative stress was examined in rats. The levels of lead, dopamine (DA), norepinephrine (NE), serotonin (5-HT), lipid peroxidation, nitrite/nitrate (NO), and glutathione (GSH) were determined; also, the activity of acetylcholinesterase (AChE) and Na(+)-K(+)-ATPase were estimated on different brain regions of adult male albino rats. The level of lead was markedly elevated in different brain regions of rats. This leads to enhancement of lipid peroxidation and NO production in brain with concomitant reduction in AChE activity and GSH level. In addition, the levels of DA, NE, and 5-HT were decreased in the brain. These findings were associated with BAX over expression. Treatment of rats with flaxseed oil induced a marked improvement in most of the studied parameters as well as the immunohistochemistry features. These data indicated that dietary flaxseed oil provide protection against lead-induced oxidative stress and neurotoxic effects.

Serum biochemical changes in rabbits on a regular diet with and without flax lignan complex following a high-cholesterol diet

BACKGROUND

Flax lignan complex (FLC) isolated from flaxseed suppresses development of hypercholesterolemic atherosclerosis. It does not produce regression of atherosclerosis, but prevents its regular diet-induced acceleration following a high-cholesterol diet. It is not known if replacement of a high-cholesterol diet with a regular diet has deleterious effects on body organs.

OBJECTIVES

To determine if short-term use of a high-cholesterol diet, and a regular diet with or without FLC following the high-cholesterol diet, have any adverse effects on serum electrolytes, glucose and enzymes related to the liver, kidneys, skeletal muscle and intestines.

METHODS

Blood samples were collected from the rabbits before and at various intervals during the high-cholesterol diet, and while on the regular diet with or without FLC, following the high-cholesterol diet. Measurements of serum total cholesterol, glucose, aspartate aminotransferase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), albumin, creatinine, electrolytes (sodium [Na], potassium [K], chloride [Cl]) and carbon dioxide (CO(2)) were taken.

RESULTS

The high-cholesterol diet produced hypercholesterolemia, which was associated with reductions in serum glucose and no significant changes in serum Na, K, Cl, CO(2), ALT, ALP, AST, GGT, albumin or creatinine. Regular diet with or without FLC, following the high-cholesterol diet, reduced serum total cholesterol and glucose, increased serum Na, Cl and creatinine, but produced no significant alterations in serum K, CO(2), ALT, AST, GGT or albumin. FLC reduced serum ALP, but regular diet produced no significant change.

CONCLUSION

Short-term use of a high-cholesterol diet, or a regular diet with or without FLC following the high-cholesterol diet, does not produce deleterious effects in the liver, kidneys, skeletal muscle, intestine or bone, as shown by changes in serum electrolytes, glucose and enzymes.

Dietary flaxseed oil supplementation ameliorates the effect of cisplatin on brush border membrane enzymes and antioxidant system in rat intestine

Cisplatin (CP; cis-diamminedichloroplatinum II) is a drug widely used against different types of solid tumors. Patients receiving CP, however, experience very profound and long lasting gastrointestinal symptoms. Recently, ω-3 polyunsaturated fatty acid-enriched flaxseed/flaxseed oil (FXO) has shown numerous health benefits. The present study was undertaken to investigate whether FXO can prevent CP-induced adverse biochemical changes in the small intestine of rats. A single intraperitoneal dose of CP (6 mg/kg body weight) was administered to male Wistar rats fed with control diet (CP group) and FXO diet (CPFXO group). Administration of CP led to a significant decline in the specific activities of brush border membrane enzymes both in the mucosal homogenates and in the isolated membrane vesicles. Lipid peroxidation and total sulfhydryl groups were altered upon CP treatment, indicating the generation of oxidative stress. The activities of SOD, catalase and glutathione peroxidase also decreased in CP-treated rats. In contrast, dietary supplementation of FXO prior to and following CP treatment significantly attenuated the CP-induced changes in all these parameters. FXO feeding markedly enhanced resistance to CP-elicited adverse gastrointestinal effects. The results suggest that FXO owing to its intrinsic biochemical/antioxidant properties is an effective agent in reducing the adverse effects of CP on intestine.

Antiatherosclerotic Effect of Canarium odontophyllum Miq. Fruit Parts in Rabbits Fed High Cholesterol Diet

The effect of C. odontophyllum (CO) fruit parts was investigated in hypercholesterolemic rabbits. Forty-nine rabbits, which were randomly divided into seven groups of seven animals (n = 7), received a diet containing different parts of CO fruit parts for 8 weeks. The groups were as follows: (1) normal diet: NC group and (2) hypercholesterolemic diet: PC, HS (10 mg/kg/day simvastatin), HPO (20 g kg(-1) oil extracted from the pulp of CO), HKO (20 g kg(-1) oil extracted from the kernel of CO), HF (50 g kg(-1) fullfat pulp of CO), and HD (50 g kg(-1) defatted pulp of CO). Among these groups, rabbits receiving defatted pulp of CO showed the greatest cholesterol lowering effect as it had reduced plasma LDL-C, TC, and thiobarbiturate reactive substance (TBARS) levels as well as atherosclerotic plaques. The presence of high dietary fiber and antioxidants activity are potential factors contributing to the cholesterol lowering effect. Consequently, these results indicate the potential use of CO defatted pulp as a cholesterol lowering and antioxidant agent.

Vitamin E slows the progression of hypercholesterolemia-induced oxidative stress in heart, liver and kidney

Vitamin E suppresses the hypercholesterolemia-induced oxidative stress in the heart. The objectives were to investigate if: (a) hypercholesterolemia-induced oxidative stress is similar in heart, liver, and kidney, and is dependent upon duration of hypercholesterolemia; and (b) vitamin E slows the progression of oxidative stress in these organs. The rabbits were assigned to 4 groups: I, regular diet (2 months); II, 0.25 % cholesterol diet (2 months); III, 0.25 % cholesterol diet (4 months); and IV, 0.25 % cholesterol diet (2 months) followed by 0.25 % cholesterol diet plus vitamin E (2 months). Blood samples were collected before and at the end of protocol for the measurement of total cholesterol (TC). Hearts, livers, and kidneys were removed at the end of the protocol under anesthesia for the measurement of oxidative parameters, malondialdehyde (MDA), and chemiluminescence (CL). The basal MDA levels in the heart, liver, and kidney of rabbits in Group I were similar, but increased to 14.65-, 3.18-, and 10.35-fold, respectively, with hypercholesterolemia. The increases in MDA levels were dependent upon the duration of hypercholesterolemia. Vitamin E did not alter the TC levels, but reduced the MDA levels in all organs. Hypercholesterolemia and vitamin E had variable effects on CL activity. In conclusion, (i) hypercholesterolemia induces oxidative stress in heart, liver, and kidney, the heart being the most and the liver the least susceptible to oxidative stress; (ii) oxidative stress is positively associated with duration of hypercholesterolemia; and (iii) vitamin E slows the progression of oxidative stress in these organs.

Do edible oils reduce bacterial colonization of enamel in situ?

OBJECTIVE

Edible oils are an empiric approach for the prevention of oral diseases. The present in situ study investigated the effect of edible oils on initial bacterial colonization of enamel surfaces.

METHODS AND MATERIALS

Initial biofilm formation was performed on enamel specimens mounted on maxillary splints and carried by eight subjects. After 1 min of pellicle formation, rinses with safflower oil, olive oil and linseed oil were performed for 10 min. Application of chlorhexidine for 1 min served as positive control. Afterwards, the slabs were carried for 8 h overnight. Samples carried for 8 h without any rinse served as negative controls. The amount of adherent bacteria was determined by DAPI staining (4',6-diamidino-2-phenylindole) and live-dead staining (BacLight). Additionally, determination of colony forming units was performed after desorption of the bacteria. TEM evaluation was carried out after application of the rinses.

RESULTS

The number of adherent bacteria on control samples was 6.1 ± 8.1 × 10(5)/cm(2) after 8 h (DAPI). Fluorescence microscopic data from DAPI staining and live-dead staining as well as from the determination of CFU revealed no significant effects of rinsing with oils on the amount of adherent bacteria compared to the non-rinsed control samples. However, with chlorhexidine a significant reduction in the number of bacteria by more than 85 % was achieved (DAPI, chlorhexidine: 8.2 ± 17.1 × 10(4)/cm(2)). The ratio of viable to dead bacteria was almost equal (1:1) irrespective of the rinse adopted as recorded with BacLight. TEM indicated accumulation of oil micelles at the pellicle's surface and modification of its ultrastructure.

CONCLUSION

Rinses with edible oils have no significant impact on the initial pattern and amount of bacterial colonization on enamel over 8 h.

CLINICAL RELEVANCE

Rinses with edible oils cannot be recommended for efficient reduction of oral biofilm formation.

The α-linolenic acid content of flaxseed can prevent the atherogenic effects of dietary trans fat

Dietary intake of industrially hydrogenated trans fatty acids (TFA) has been associated with coronary heart disease. Dietary flaxseed can inhibit atherosclerosis induced by dietary cholesterol. The aim of this study was to determine whether supplementing the diet with flaxseed could protect against atherosclerosis induced by a diet enriched in TFA. Low-density lipoprotein receptor-deficient (LDLr−/−) mice were fed 1 of 14 experimental diets for 14 wk containing one of two fat sources [regular (pork/soy) or trans fat] at two concentrations (4 or 8%) and supplemented with or without dietary cholesterol (2%), whole ground flaxseed, or one of the components of flaxseed [α-linolenic acid (ALA), defatted fiber, or lignan]. Adding flaxseed to the diet partially mitigated the rise in circulating cholesterol levels induced by the cholesterol-enriched diet. Atherosclerosis was stimulated by TFA and/or cholesterol. Including milled flaxseed to an atherogenic diet significantly reduced atherosclerosis compared with the groups that consumed cholesterol and/or TFA. ALA was the only component within flaxseed that could inhibit the atherogenic action of cholesterol and/or TFA on its own. Dietary flaxseed protects against atherosclerotic development induced by TFA and cholesterol feeding through its content of ALA.

Effects of flaxseed oil on lead acetate-induced neurotoxicity in rats

It is well known that chronic exposure to lead (Pb(+2)) alters a variety of behavioral tasks in rats and mice. Here, we investigated the effect of flaxseed oil (1,000 mg/kg) on lead acetate (20 mg/kg)-induced brain oxidative stress and neurotoxicity in rats. The levels of Pb(+2), lipid peroxidation, nitric oxide (NO), and reduced glutathione (GSH) and the activity of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione-S-transferase (GST), and glutathione peroxidase (GPx) were determined in adult male albino rats. The level of Pb(+2) was markedly elevated in brain and blood of rats. This leads to enhancement of lipid peroxidation and NO production in brain with concomitant reduction in GSH, CAT, SOD, GR, GST, and GPx activities. These findings were associated with DNA fragmentation. In addition, lead acetate induced brain injury as indicated by histopathological changes of the brain. Treatment of rats with flaxseed oil resulted in marked improvement in most of the studied parameters as well as histopathological features. These findings suggest to the conclusion that flaxseed oil significantly decreased the adverse harmful effects of lead acetate exposure on the brain as well as Pb(+2)-induced oxidative stress.

Do statins have a role in reduction/prevention of post-PCI restenosis?

The pathophysiology of post-PCI restenosis involves neointimal formation that consists of three phases: thrombosis (within 24 h), recruitment (3-8 days), and proliferation, which starts on day 8 of PCI. Various factors suggested to be predictors/risks for restenosis include C-reactive protein (CRP), inflammatory mediators (cytokines and adhesion molecules), oxygen radicals, advanced glycation end products (AGEs) and their receptors (RAGE), and soluble RAGE (sRAGE). The earlier noted factors produce thrombogenesis, vascular smooth muscle cell proliferation, and extracellular matrix formation. Statins have pleiotropic effects. Besides lowering serum cholesterol, they have various other biological effects including antiinflammatory, antithrombotic, CRP-lowering, antioxidant, antimitotic, and inhibition of smooth muscle cell proliferation. They inhibit matrix metalloproteinase and cyclooxygenase-2, lower AGEs, decrease expression of RAGE and increase levels of serum sRAGE. They also increase the synthesis of nitric oxide (NO) by increasing endothelial NO synthase expression and activity. Preprocedural statin therapy is known to reduce peri- and post-PCI myonecrosis and reduce the need for repeat revascularization. There is evidence that statin-eluting stents inhibit in-stent restenosis in animal models. It is concluded that because of the above attributes of statins, they are suitable candidates for reduction of post-PCI restenosis and post-PCI myonecrosis. The future directions for the use of statins in reduction of post-PCI restenosis and myonecrosis have been discussed.

The redox status in rats treated with flaxseed oil and lead-induced hepatotoxicity

Lead is a persistent environmental pollutant, and its toxicity continues to be a major health problem due to its interference with natural environment. In the present study, we have evaluated the effect of flaxseed oil on lead acetate-mediated hepatic oxidative stress and toxicity in rats. Lead acetate enhanced lipid peroxidation and nitric oxide production in both serum and liver with concomitant reduction in glutathione, catalase, superoxide dismutase, glutathione reductase, glutathione-S-transferase, and glutathione peroxidase activities, these findings were associated with DNA fragmentation. In addition, lead acetate caused liver injury as indicated by histopathological changed of the liver with an elevation in total bilirubin, serum alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transpeptidase, and alkaline phosphatase. Treatment of rats with flaxseed oil resulted in marked improvement in most of the studied parameters as well as histopathological features. On the basis of the above results it can hypothesized that flaxseed oil is a natural product can be protect against lead acetate-mediated hepatic cytotoxicity.

Release of angiotensin I-converting enzyme inhibitory peptides from flaxseed (Linum usitatissimum L.) protein under simulated gastrointestinal digestion

The scope of this study was to determine the ability of flaxseed (Linum usitatissimum L.) proteins to release angiotensin I-converting enzyme inhibitory (ACEI) peptides during simulated gastrointestinal (GI) digestion using a static (SM; no absorption in the intestinal phase) and a dynamic model (DM; simultaneous absorption of digested products in the intestinal phase via passive diffusion). Gastric and gastric + small intestinal digests of flaxseed proteins of both models possessed ACEI activity. The ACEI activity of the gastric + small intestinal digest in the DM (IC(50) unabsorbed, 0.05 mg N/mL; IC(50) absorbed, 0.04 mg N/mL) was significantly higher (p < 0.05) than that of the SM (IC(50), 0.39 mg N/mL). Two peptides, a pentapeptide (Trp-Asn-Ile/Leu-Asn-Ala) and a hexapeptide (Asn-Ile/Leu-Asp-Thr-Asp-Ile/Leu), were identified in the most active ACEI fraction (0.5-1 kDa) of the absorbable flaxseed protein digest by de novo sequencing.

Effects of linseed consumption for a short period of time on lipid profile and atherosclerotic lesions in rabbits fed a hypercholesterolaemic diet

Linseed contains biologically active substances, such as lignans, fibres and linoleic acid, which are believed to provide cardioprotective effects. The objective of the present study was to assess the potential hypolipaemic, anti-atherogenic and anti-inflammatory effects of linseed consumption using an experimental animal model, with rabbits fed a hypercholesterolaemic diet (1 % cholesterol extracted from lyophilised egg). A total of twenty white male rabbits were selected and divided into two groups: group I (GI), control group, ten rabbits; group II (GII), ten rabbits. The animals were fed a hypercholesterolaemic diet for 56 d. For the GII diet, ground linseed was added from day 29 through to day 56. Animals underwent aortic arch and descending aorta dissection on day 56 for histological, morphometric and immunohistochemical analysis. At the end of the experiment, GII animals presented with lower levels of total cholesterol (TC, 10 068·3 v. 16 767·0 mg/l; P < 0·05) and lower levels of LDL-cholesterol (LDL-C; 10 743·2 v. 15 961·2 mg/l; P < 0·05) when compared with the GI control group. There was no significant difference in serum HDL-cholesterol and TAG between the two groups. Almost all animals exhibited type III atherosclerotic lesions in the descending aorta. There was no statistically significant difference between the intima area and the intima:media layer area ratio in both groups. There was no difference between the positive areas for vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 molecules between the groups. Linseed consumption showed hypolipaemic action by reducing LDL-C and TC levels; however, this cholesterol-lowering effect did not reduce the atherosclerotic lesions induced by a hypercholesterolaemic diet (1 % cholesterol) for a short period of time.

Suppression of inflammatory response and endothelial nitric oxide synthase downregulation in hyperlipidaemic C57BL/6J mice by eugenosedin-A

Objectives

Eugenosedin-A has been found to ameliorate high-fat diet (HFD)-induced hyperglycaemia and hyperlipidaemia in C57BL/6J mice. This study aimed to investigate the mechanisms of action of eugenosedin-A on endothelial function and inflammation in hyperlipidaemic mice.

Methods

C57BL/6J mice were randomly divided into two control groups and two treatment groups. The control mice received either a regular diet or HFD, and the treatment groups were fed HFD with either 5 mg/kg eugenosedin-A or atorvastatin for eight weeks.

Key findings

Mice fed a HFD had higher concentrations of nitrate (NO) but not prostaglandin E2 (PGE2), increased tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) mRNA and inducible nitric oxide synthase (iNOS) proteins, but decreased endothelial nitric oxide synthase (eNOS) proteins. HFD-induced upregulation of iNOS is associated with p38, extracellular signal-regulated kinase (ERK), c-Jun-N-terminal kinase (JNK), PI3K and Akt/IKKα/p65. Eugenosedin-A and atorvastatin reduced HFD-induced TNF-α and IFN-γ mRNA, NO generation, upregulation of iNOS protein, and down-regulation of eNOS protein. Both agents inhibited p38, ERK, JNK and Akt/IKKα/p65 protein levels in the aorta. However, eugenosedin-A did not significantly reduce p38 in the liver.

Conclusions

Our results showed an association between obesity-induced inflammation and altered levels of TNF-α, IFN-γ, p38, ERK, JNK and Akt/IKKα/p65. Eugenosedin-A, like atorvastatin, could inhibit p38, ERK, JNK, Akt/IKKα/p65 proteins, as well as TNF-α and IFN-γ mRNA during the regulation of the obesity-induced inflammatory process.

Dietary lignans: physiology and potential for cardiovascular disease risk reduction

The present review of the literature on lignan physiology and lignan intervention and epidemiological studies was conducted to determine if lignans decrease the risks of cardiovascular disease in Western populations. Five intervention studies using flaxseed lignan supplements indicated beneficial associations with C-reactive protein, and a meta-analysis that included these studies also suggested lignans have a lowering effect on plasma total and low-density lipoprotein cholesterol. Three intervention studies using sesamin supplements indicated possible lipid- and blood pressure-lowering associations. Eleven human observational epidemiological studies examined dietary intakes of lignans in relation to cardiovascular disease risk. Five showed decreased risk with either increasing dietary intakes of lignans or increased levels of serum enterolactone (an enterolignan used as a biomarker of lignan intake), five studies were of borderline significance, and one was null. The associations between lignans and decreased risk of cardiovascular disease are promising, but they are yet not well established, perhaps due to low lignan intakes in habitual Western diets. At the higher doses used in intervention studies, associations were more evident.

Synthesis of Threo-(±)-9,9-Dibenzoylsecoisolariciresinol and its Isomer

The total synthesis of threo-(±)-9,9-dibenzoylsecoisolariciresinol and its isomer based on two Stobbe reactions as C–C bond-forming steps used a protected vanillin and diethyl; succinate to give the skeleton of lignan, followed by reduction to afford threo- and meso-(±)-secoisolariciresinol Both were treated with benzoyl chloride to obtain the natural product threo-(±)-9,9-dibenzoylsecoisolariciresinol and Its isomer meso-(±)-9,9-dibenzoylsecoisolariciresinol for the first time.

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.

Bacterial transformation of dietary lignans in gnotobiotic rats

The bioactivity of lignans depends on their transformation by gut bacteria. The intestinal bacteria Clostridium saccharogumia, Eggerthella lenta, Blautia producta and Lactonifactor longoviformis convert the plant lignan secoisolariciresinol diglucoside via secoisolariciresinol (SECO) into the bioactive enterolignans enterodiol (ED) and enterolactone (EL). While the in vitro conversion of lignans by these bacteria has already been demonstrated, it is unclear whether this defined community is also capable of catalysing lignan transformation in vivo. We therefore associated germ-free rats with these four species. Germ-free rats served as a control. All animals were fed a diet containing 5% ground flaxseed. The caecal contents of rats associated with the four lignan-activating bacteria (ALB rats) contained SECO, ED and EL. The maximal EL formation rate from lignans in the pooled caecal contents of ALB rats was 7.52 nmol min(-1) g(-1) dry matter. The ALB rats excreted EL, but no SECO and ED, in their urine. The caecal contents of germ-free rats contained SECO, but no ED and EL. Their urine was devoid of lignans. Hence, the presence of enterolignans in the ALB rats, but not in the germ-free rats, demonstrates that this defined microbial community is capable of transforming plant lignans into EL in vivo.

Health effects with consumption of the flax lignan secoisolariciresinol diglucoside

Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside (SDG). After ingestion, SDG is converted to secoisolariciresinol, which is further metabolised to the mammalian lignans enterodiol and enterolactone. A growing body of evidence suggests that SDG metabolites may provide health benefits due to their weak oestrogenic or anti-oestrogenic effects, antioxidant activity, ability to induce phase 2 proteins and/or inhibit the activity of certain enzymes, or by mechanisms yet unidentified. Human and animal studies identify the benefits of SDG consumption. SDG metabolites may protect against CVD and the metabolic syndrome by reducing lipid and glucose concentrations, lowering blood pressure, and decreasing oxidative stress and inflammation. Flax lignans may also reduce cancer risk by preventing pre-cancerous cellular changes and by reducing angiogenesis and metastasis. Thus, dietary SDG has the potential to decrease the incidence of several chronic diseases that result in significant morbidity and mortality in industrialised countries. The available literature, though, makes it difficult to clearly identify SDG health effects because of the wide variability in study methods. However, the current evidence suggests that a dose of at least 500 mg SDG/d for approximately 8 weeks is needed to observe positive effects on cardiovascular risk factors in human patients. Flaxseed and its lignan extracts appear to be safe for most adult populations, though animal studies suggest that pregnant women should limit their exposure. The present review discusses the potential health benefits of SDG in humans, with supporting evidence from animal studies, and offers suggestions for future research.

Experimental and clinical research findings on the cardiovascular benefits of consuming flaxseed

Functional foods and nutraceuticals are becoming popular alternatives to pharmacological treatments by providing health benefits and (or) reducing the risk of chronic diseases. Flaxseed is a rich source of 3 components with demonstrated cardioprotective effects: the omega-3 fatty acid α-linolenic acid (ALA), dietary fibre, and phytoestrogen lignans. Multiple clinical dietary intervention trials report that consuming flaxseed daily can modestly reduce circulating total cholesterol (TC) by 6%–11% and low-density lipoprotein (LDL) cholesterol by 9%–18% in normolipemic humans and by 5%–17% for TC and 4%–10% for LDL cholesterol in hypercholesterolemic patients, as well as lower various markers associated with atherosclerotic cardiovascular disease in humans. Evidence to date suggests that the dietary fibre and (or) lignan content of flaxseed provides the hypocholesterolemic action. The omega-3 ALA found in the flaxseed oil fraction also contributes to the antiatherogenic effects of flaxseed via anti-inflammatory and antiproliferative mechanisms. Dietary flaxseed may also protect against ischemic heart disease by improving vascular relaxation responses and by inhibiting the incidence of ventricular fibrillation.

Soy constituents: modes of action in low-density lipoprotein management

Reviewed here are the modes of action of soy components used as ingredients in foods, which can lower plasma levels of low-density lipoprotein (LDL) and cholesterol, which are markers for the risk for atherosclerosis. Soy ingredients act via more than one mode of action including the following: LDL absorption suppression, cholesterol efflux stimulation, LDL resorption stimulation, LDL oxidation prevention, LDL particle size increase, cholesterol synthesis reduction, and bile secretion increase. Individual genetics, lifestyle, and nutrition habits alter LDL management and a better understanding of the various modes of actions of soy ingredients may facilitate the composition of effective ingredient cocktails. The optimization of food components offers further alternatives to LDL management to augment drug therapy for patients who are unable to reach their target LDL cholesterol levels or who are suffering from side effects or drug insensitivity.

A randomized controlled trial of the effects of flaxseed lignan complex on metabolic syndrome composite score and bone mineral in older adults

A randomized double-blind placebo controlled study design was used to assess the effects of flaxseed lignan complex supplementation during exercise training on a metabolic syndrome composite score and osteoporosis risk in older adults. A total of 100 subjects (>or=50 years) were randomized to receive flaxseed lignan (543 mg.day-1 in a 4050 mg complex) or placebo while completing a 6 month walking program (30-60 min.day-1, 5-6 days.week-1). Fasting serum glucose, triacylglycerol (TAG), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, total cholesterol, interleukin-6, and tumor necrosis factor-alpha were measured every 2 months, while body composition, bone mineral density, and resting blood pressure were assessed at baseline and at 6 months. A composite Z score of 6 risk factors for metabolic syndrome (fasting glucose, HDL cholesterol, TAG, abdominal adiposity, blood pressure, and inflammatory cytokines) was calculated at baseline and at 6 months. Men taking placebo increased metabolic syndrome composite Z score (p < 0.05), but there were no changes in the other groups. A significant group x sex x time interaction was noted for TAG (p = 0.017) and diastolic blood pressure (p = 0.046), with men taking flaxseed lignan decreasing diastolic blood pressure relative to men taking placebo, and men taking placebo increasing TAG relative to men taking flax lignan. There were no differences between groups for change in bone measures, body composition, lipoproteins, or cytokines. Males taking the flaxseed lignan complex reduced metabolic syndrome score relative to men taking placebo, but a similar trend was not seen in females. Flaxseed lignan had no effect on bone mineral density or content, body composition, lipoproteins, glucose, or inflammation.

Quantitative aspects of the metabolism of lignans in pigs fed fibre-enriched rye and wheat bread

A diet rich in lignans has been suggested to be protective against a range of chronic diseases. The distribution and metabolic fate of lignans is, however, very poorly understood. We fed high-fibre wheat breads low in lignans (n 8) or high-fibre rye breads (n 9) rich in plant lignans to pigs for 58-67 d, and analysed the content of plant lignans and their metabolites in the diet, blood, bile, faeces, urine and selected tissues. Apparent faecal digestibility of dietary precursors was higher than of total (plant- and entero-) lignans due to conversion to enterolactone and enterodiol. The digestibility of lariciresinol and matairesinol was lower than that of the sum of plant lignans. This suggests that interconversion of plant lignans during digestion and enterohepatic circulation occur without complete conversion to enterolignans. The majority of lignans present in plasma and urine was in the form of enterolignans, but up to 23 % in the plasma, and 11 % in the urine of the rye-fed pigs were in the form of plant lignans. There was a very high concentration of lignans in bile from the rye-fed pigs with as much as 77 % in the form of plant lignans. Lignans were detected in the tissue of colon, liver, breast and brain at a much higher level with rye than with wheat, but only in the form of enterolactone. The importance and implications of systemic exposure to plant lignans remain to be elucidated.

Flax Lignan Complex Slows Down the Progression of Atherosclerosis in Hyperlipidemic Rabbits

Flax lignan complex suppresses the development of hypercholesterolemic atherosclerosis. However, it is not known whether flax lignan complex would slow down the progression of hypercholesterolemic atherosclerosis. This study was carried out to determine whether flax lignan complex slows down the progression of already developed atherosclerosis, and whether this effect is associated with reductions in serum lipids and oxidative stress. The studies were conducted in 4 groups of rabbits: group I, regular diet (2 months); group II, 0.25% cholesterol diet (2 months); group III, 0.25% cholesterol diet (4 months); group IV, 0.25% cholesterol diet (2 months) followed by 0.25% cholesterol diet plus flax lignan complex (2 months). Serum lipids and oxidative stress parameters (malondialdehyde, antioxidant reserve, white blood cell chemiluminescence) were measured before and at monthly intervals thereafter on their respective diets. Aortas were removed at the end of the protocol for assessment of atherosclerosis and oxidative stress. Atherosclerosis in group II was associated with hyperlipidemia and increased oxidative stress. Significant areas of the aortic intimal surfaces from group II (37.76% + 7.96%), group III (76.6% + 9.04%), and group IV (52.95% + 10.29%) were covered with atherosclerotic plaques. Group IV rabbits had 40% more atherosclerotic lesions than group II but 31% fewer lesions than group III. The flax lignan complex—induced reduction in the progression of atherosclerosis was associated with reductions in oxidative stress. In conclusion, flax lignan complex was effective in slowing down the progression of atherosclerosis by 31%, and this effect was associated with a reduction in oxidative stress.

Effects of the flaxseed lignans secoisolariciresinol diglucoside and its aglycone on serum and hepatic lipids in hyperlipidaemic rats

The present study involved a comparative analysis of the effects of purified flaxseed lignans, secoisolariciresinol diglucoside (SDG) and its aglycone metabolite (SECO), in hyperlipidaemic rats. For hypercholesterolaemia, female Wistars (six rats per group) were fed a standard or 1 % cholesterol diet and orally administered 0, 3 or 6 mg SDG/kg or 0, 1·6 or 3·2 mg SECO/kg body weight once daily for 4 weeks. Hypertriacylglycerolaemia was induced in male Sprague–Dawley rats (ten rats per group) by supplementing tap water with 10 % fructose. These rats were orally administered 0, 3 or 6 mg SDG/kg body weight once daily for 2 weeks. Fasting blood samples (12 h) were collected predose and at the end of the dosing period for serum lipid analyses. Rats were killed and livers rapidly excised and sectioned for lipid, mRNA and histological analyses. Chronic administration of equimolar amounts of SDG and SECO caused similar dose-dependent reductions in rate of body-weight gain and in serum total and LDL-cholesterol levels and hepatic lipid accumulation. SDG and SECO failed to alter hepatic gene expression of commonly reported regulatory targets of lipid homeostasis. SDG had no effect on serum TAG, NEFA, phospholipids and rate of weight gain in 10 % fructose-supplemented rats. In conclusion, our data suggest that the lignan component of flaxseed contributes to the hypocholesterolaemic effects of flaxseed consumption observed in humans. Future studies plan to identify the biochemical mechanism(s) through which flaxseed lignans exert their beneficial effects and the lignan form(s) responsible.

Effects of soluble dietary fiber on low-density lipoprotein cholesterol and coronary heart disease risk

Strong epidemiologic and experimental data suggest that increasing dietary fiber may help to lower low-density lipoprotein cholesterol (LDL-C) and decrease the risk of coronary heart disease. Recent studies have highlighted the role of dietary fiber, particularly water-soluble varieties, in decreasing the risk of cardiovascular disease. Several types of soluble fiber, including psyllium, beta-glucan, pectin, and guar gum, have been shown to decrease LDL-C in well-controlled intervention studies, whereas the soluble fiber content of legumes and vegetables has also been shown to decrease LDL-C. Current investigations continue to explore this area in depth and examine potential synergies between dietary fiber and other phytochemicals that may lower cholesterol. These studies, along with recent analyses of ongoing prospective cohort studies, have provided new insights into the probable protective role of dietary fiber in the development of coronary heart disease and other cardiovascular diseases.

Determination of lignans in flaxseed using liquid chromatography with time-of-flight mass spectrometry

A new method of flaxseed-derived lignan determination was developed using HPLC with high-resolution time-of-flight MS (TOF-MS), optimized, and compared to two existing methods (HPLC/MS/MS and GC/MS). The limits of detection (LODs) for HPLC/TOF-MS (0.002-0.043 pg) were comparable with those of the optimized and improved HPLC/MS/MS (0.001-0.015 pg), whereas the LODs for the optimized GC/MS were higher (0.02-3.0 pg, yet lower than reported before). Using the newly developed detection and separation methods, several key flaxseed sample preparation parameters (including extraction, hydrolysis, and sample purification) were evaluated resulting in the development of efficient protocol for lignan quantification from flaxseed hulls and embryos. The results confirmed the importance of quantification of both aglycones and unhydrolyzed glucosides in order to obtain the total lignan estimates.

The effect of a lignan complex isolated from flaxseed on inflammation markers in healthy postmenopausal women

BACKGROUND AND AIM

Plant lignans are metabolised by the colonic micro-flora to the mammalian lignans enterodiol and enterolactone, which are hypothesized to be cardioprotective. The aim of this study was to investigate the effects of a plant lignan complex isolated from flaxseed, providing 500 mg/d of secoisolariciresinol diglucoside, on inflammatory markers.

METHODS AND RESULTS

Healthy postmenopausal women (n=22) completed a randomised double-blind, placebo-controlled crossover study. Women consumed daily a low-fat muffin, with or without a lignan complex, for 6 weeks, separated by a 6-week washout period. A significant difference of approximately 15% (P=0.028) was observed for C-reactive protein (CRP) concentration between the lignan complex intervention period and placebo period. CRP concentrations (median; 25th, 75th percentiles) were 0.88 (0.63, 2.05) mg/L at baseline and 0.92 (0.59, 1.49) mg/L after the lignan complex intervention period compared with 0.80 (0.62, 1.62) mg/L at baseline and 1.10 (0.72, 1.62) mg/L after placebo. No significant differences in interleukin-6, tumor necrosis factor-alpha, soluble intracellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, and monocyte chemoattractant protein-1 were found between the lignan complex intervention period and placebo period.

CONCLUSION

Daily consumption for 6 week of a low-fat muffin enriched with a lignan complex may reduce CRP concentrations compared to a low-fat muffin with no lignans added.

The in vitro and ex vivo antioxidant properties, hypolipidaemic and antiatherosclerotic activities of water extract of Moringa oleifera Lam. leaves

Moringa oleifera is used in Thai traditional medicine as cardiotonic. Recent studies demonstrated its hypocholesterolaemic effect. However, to be clinically useful, more scientific data are needed.

AIM OF THE STUDY

We investigated the antioxidant, hypolipidaemic and antiatherosclerotic activities of Moringa oleifera leaf extract.

MATERIALS AND METHODS

Scavenging activity of the extract on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), and the inhibitory effect on Cu(2+)-induced low-density lipoprotein (LDL) oxidation were determined in in vitro experiment. The effects of the extract on cholesterol levels, conjugated diene (CD) and thiobarbituric acid reactive substances (TBARS) and plaque formations in cholesterol-fed rabbits were investigated.

RESULTS

We found that in scavenging DPPH radicals the extract and Trolox had IC(50) of 78.15+/-0.92 and 2.14+/-0.12microg/ml, respectively. The extract significantly (P<0.05) prolonged the lag-time of CD formation and inhibited TBARS formation in both in vitro and ex vivo experiments in a dose-dependent manner. In hypercholesterol-fed rabbits, at 12 weeks of treatment, it significantly (P<0.05) lowered the cholesterol levels and reduced the atherosclerotic plaque formation to about 50 and 86%, respectively. These effects were at degrees comparable to those of simvastatin.

CONCLUSIONS

The results indicate that this plant possesses antioxidant, hypolipidaemic and antiatherosclerotic activities and has therapeutic potential for the prevention of cardiovascular diseases.

Dietary flaxseed lignan extract lowers plasma cholesterol and glucose concentrations in hypercholesterolaemic subjects

Lignans, derived from flaxseed, are phyto-oestrogens being increasingly studied for their health benefits. An 8-week, randomised, double-blind, placebo-controlled study was conducted in fifty-five hypercholesterolaemic subjects, using treatments of 0 (placebo), 300 or 600 mg/d of dietary secoisolariciresinol diglucoside (SDG) from flaxseed extract to determine the effect on plasma lipids and fasting glucose levels. Significant treatment effects were achieved (P < 0.05 to < 0.001) for the decrease of total cholesterol (TC), LDL-cholesterol (LDL-C) and glucose concentrations, as well as their percentage decrease from baseline. At weeks 6 and 8 in the 600 mg SDG group, the decreases of TC and LDL-C concentrations were in the range from 22.0 to 24.38 % respectively (all P < 0.005 compared with placebo). For the 300 mg SDG group, only significant differences from baseline were observed for decreases of TC and LDL-C. A substantial effect on lowering concentrations of fasting plasma glucose was also noted in the 600 mg SDG group at weeks 6 and 8, especially in the subjects with baseline glucose concentrations > or = 5.83 mmol/l (lowered 25.56 and 24.96 %; P = 0.015 and P = 0.012 compared with placebo, respectively). Plasma concentrations of secoisolariciresinol (SECO), enterodiol (ED) and enterolactone were all significantly raised in the groups supplemented with flaxseed lignan. The observed cholesterol-lowering values were correlated with the concentrations of plasma SECO and ED (r 0.128-0.302; P < 0.05 to < 0.001). In conclusion, dietary flaxseed lignan extract decreased plasma cholesterol and glucose concentrations in a dose-dependent manner.

Effects of a flaxseed-derived lignan supplement in type 2 diabetic patients: a randomized, double-blind, cross-over trial

BACKGROUND

Flaxseed consumption has been shown to improve blood lipids in humans and flaxseed-derived lignan has been shown to enhance glycemic control in animals. The study aimed to investigate the effect of a flaxseed-derived lignan supplement on glycemic control, lipid profiles and insulin sensitivity in type 2 diabetic patients.

METHODOLOGY/PRINCIPAL FINDINGS

This was a randomized, double-blind, placebo-controlled, cross-over trial and it was conducted between April and December 2006 in Shanghai, China. Seventy-three type 2 diabetic patients with mild hypercholesterolemia were enrolled into the study. Patients were randomized to supplementation with flaxseed-derived lignan capsules (360 mg lignan per day) or placebo for 12 weeks, separated by an 8-week wash-out period. HbA1c, lipid profiles, insulin resistance index and inflammatory factors were measured. Sixty-eight completed the study and were included in the analyses. The lignan supplement significantly improved glycemic control as measured by HbA(1c) (-0.10+/-0.65 % vs. 0.09+/-0.52 %, P = 0.001) compared to placebo; however, no significant changes were observed in fasting glucose and insulin concentrations, insulin resistance and blood lipid profiles. Urinary excretion of lignan metabolites (enterodiol and enterolactone) was significantly higher after the lignan supplement intervention compared to baseline (14.2+/-18.1 vs. 1.2+/-2.4 microg/mL, P<0.001). Data also suggested minimal competition between lignan and isoflavones for bioavailability when measured by the excretion concentrations.

CONCLUSIONS/SIGNIFICANCE

Daily lignan supplementation resulted in modest, yet statistically significant improvements in glycemic control in type 2 diabetic patients without apparently affecting fasting glucose, lipid profiles and insulin sensitivity. Further studies are needed to validate these findings and explore the efficacy of lignans on type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00363233.