Flaxseed Lignans Secoisolariciresinol Diglucoside Research Articles

Short-term exposure to synthetic flaxseed lignan LGM2605 alters gut microbiota in mice.

LGM2605 is a synthetic version of the naturally occurring flaxseed lignan secoisolariciresinol diglucoside (SDG), with known anti‐inflammatory and antioxidant properties; however, its effects on gut microbial composition have not previously been evaluated. In the present study, we sought to determine how the 10‐day oral administration of LGM2605 alters the gut microbiota of mice. Eight‐week‐old female C57BL/6 mice were treated with either LGM2605 or saline, administered daily via oral gavage over a 10‐day treatment period. Upon termination of treatment, mouse cecums (n = 31) were collected, and cecal DNA was isolated. 16S rRNA genes were sequenced and analyzed in Mothur to identify changes in gut microbial composition induced by LGM2605 treatment (v. saline control). We then assessed community composition, performed indicator taxa analysis, and measured alpha and beta diversity. Overall, LGM2605 significantly altered the gut microbiota of mice; we reported alterations in 3 bacterial phyla and 22 genera as a result of treatment. The study here identifies for the first time significant alterations in the gut microbiota of mice following oral administration of LGM2605, in general shifting toward a more anti‐inflammatory composition. These findings lay the foundation for future investigations utilizing LGM2605 to control gut dysbiosis and, by extension, systemic inflammation.

Protective role of flaxseed lignan secoisolariciresinol diglucoside against lead-acetate-induced oxidative-stress-mediated nephrotoxicity in rats

BackgroundLead (Pb) is a toxic heavy metal that causes kidney injury and oxidative tissue damage. Current drugs to treat nephrotoxicity have multiple side-effects. Therefore, the development of novel therapeutic approaches is urgently required. PurposeWe investigated the nephroprotective efficacy of flaxseed lignan secoisolariciresinol diglucoside (SDG) against lead acetate (PbAc)-induced renal toxicity in rats. MethodsThe therapeutic activity of SDG was determined using a Wistar Albino rat model. Rats were administered with lead acetate (20 mg/kg b.w.) to induce nephrotoxicity and treated with SDG (10 mg/kg b.w.) or vehicle for 5 days. Biochemical parameters were measured and histopathological studies were carried out to evaluate the nephroprotective effects of SDG. ResultsThere were significant changes in relative kidney weight and reduced PbAc accumulation in the kidney after treatment with SDG compared to the control. SDG treatment also led to significant decreases in the levels of blood urea and creatinine and restored levels of albumin. There was also a marked improvement in the concentration of enzymes in the group treated with SDG. Histopathological examination of renal tissues confirmed that the nephritic changes due to PbAc were ameliorated by SDG treatment. ConclusionIn conclusion, our study suggests the protective role of SDG in limiting renal cytotoxicity induced by lead acetate as a model for lead toxicity.

The anti-cancer effect of flaxseed lignan derivatives on different acute myeloid leukemia cancer cells

Flaxseeds have been known for their anti-cancerous effects due to the high abundance of lignans released upon ingestion. The most abundant lignan, secoisolariciresinol diglucoside (SDG), is ingested during the dietary intake of flax, and is then metabolized in the gut into two mammalian lignan derivatives, Enterodiol (END) and Enterolactone (ENL). These lignans were previously reported to possess anti-tumor effects against breast, colon, and lung cancer.This study aims to investigate the potential anti-cancerous effect of the flaxseed lignans SDG, END and ENL on acute myeloid leukemia cells (AML) in vitro and to decipher the underlying molecular mechanism. AML cell lines, (KG-1 and Monomac-1) and a normal lymphoblastic cell line were cultured and treated with the purified lignans. ENL was found to be the most promising lignan, as it exhibits a significant selective dose- and time-dependent cytotoxic effect in both AML cell lines, contrary to normal cells. The cytotoxic effects observed were attributed to apoptosis induction, as revealed by an increase in Annexin V staining of AML cells with increasing ENL concentrations. The increase in the percentage of cells in the pre-G phase, in addition to cell death ELISA analysis, validated cellular and DNA fragmentation respectively. Analysis of protein expression using western blots confirmed the activation of the intrinsic apoptotic pathway upon ENL treatment. This was also accompanied by an increase in ROS production intracellularly. In conclusion, this study demonstrates that ENL has promising anti-cancer effects in AML cell lines in vitro, by promoting DNA fragmentation and the intrinsic apoptotic pathway, highlighting the protective health benefits of flax seeds in leukemia.

Evaluation of protective efficacy of flaxseed lignan-Secoisolariciresinol diglucoside against mercuric chloride-induced nephrotoxicity in rats.

The toxicity of heavy metals such as mercury (Hg) in humans and animals is well documented. The kidney is the primary deposition site of inorganic-Hg and target organ of its toxicity. The present study investigated the protective efficacy of flaxseed lignan-Secoisolariciresinol diglucoside (SDG) on nephrotoxicity induced by mercuric chloride (HgCl2). Rats were intraperitoneally injected with HgCl2 (2mg/kg/day) and renal toxicity was induced. Subcutaneous administration of rats with SDG (5mg/kg/day) as a pre-treatment caused a significant reversal of HgCl2 induced increase in blood urea, creatinine, glutathione s-transferase and catalase (CAT). On the other hand, administration of SDG with HgCl2 restored normal levels of albumin and superoxide dismutase (SOD). Histological examination of kidneys confirmed that pre-treatment of SDG before HgCl2 administration significantly reduced its pathological effects. Thus, the results of the present investigation suggest that SDG can significantly reduce renal damage, serum and tissue biochemical profiles caused by HgCl2 induced nephrotoxicity. Hence, SDG may be recommended for clinical trials in the treatment of kidney disorders caused by exposure to Hg.

The flaxseed lignan secoisolariciresinol diglucoside decreases local inflammation, suppresses NF\u03baB signaling, and inhibits mammary tumor growth

PurposeExposure to the polyphenolic plant lignan secoisolariciresinol diglucoside (SDG) and its metabolite enterolactone (ENL) has been associated with reduced breast cancer progression, particularly for estrogen receptor alpha (ERα)-negative disease, and decreased preclinical mammary tumor growth. However, while preclinical studies have established that SDG and ENL affect measures of progression in models of triple-negative breast cancer (TNBC, a subset of ERα-negative disease), the molecular mechanisms underlying these effects remain unclear.MethodsC57BL/6 mice were fed a control diet (control, 10% kcal from fat) or control diet + SDG (SDG, 100 mg/kg diet) for 8 weeks, then orthotopically injected with syngeneic E0771 mammary tumor cells (a model of TNBC); tumor growth was monitored for 3 weeks. The role of reduced NF-κB signaling in SDG’s anti-tumor effects was explored in vitro via treatment with the bioactive SDG metabolite ENL. In addition to the murine E0771 cells, the in vitro studies utilized MDA-MB-231 and MCF-7 cells, two human cell lines which model the triple-negative and luminal A breast cancer subtypes, respectively.ResultsSDG supplementation in the mice significantly reduced tumor volume and expression of phospho-p65 and NF-κB target genes (P < 0.05). Markers of macrophage infiltration were decreased in the distal-to-tumor mammary fat pad of mice supplemented with SDG relative to control mice (P < 0.05). In vitro, ENL treatment inhibited viability, survival, and NF-κB activity and target gene expression in E0771, MDA-MB-231, and MCF-7 cells (P < 0.05). Overexpression of Rela attenuated ENL’s inhibition of E0771 cell viability and survival.ConclusionsSDG reduces tumor growth in the E0771 model of TNBC, likely via a mechanism involving inhibition of NF-κB activity. SDG could serve as a practical and effective adjuvant treatment to reduce recurrence, but greater understanding of its effects is needed to inform the development of more targeted recommendations for its use.

Protective Role of Flaxseed Oil and Flaxseed Lignan Secoisolariciresinol Diglucoside Against Oxidative Stress in Rats with Metabolic Syndrome.

We report that the antioxidant effects attributed to flaxseed are mainly due to its high lignan content, especially that of secoisolariciresinol diglucoside. This is significant because suggests that this compound can be used in isolation to prevent oxidative stress associated with MS. Furthermore, this study was the only one to perform a comparison of the abilities of 2 components of flaxseed to protect against oxidative stress in an MS model, which brings a great advance in the medicine's field, since it indicates another alternative for improve the health and the quality of life of patients with this disorder.

Flaxseed lignan secoisolariciresinol diglucoside ameliorates experimental colitis induced by dextran sulphate sodium in mice

The effect of flaxseed lignan secoisolariciresinol diglucoside (SDG) on ulcerative colitis was examined. Experimental colitis was induced in mice by administering 5% dextran sulphate sodium (DSS). SDG in doses of 100 and 200 mg/kg/day and 5-aminosalicylic acid (positive control) were given orally for 3 days before and during DSS administration. Oral SDG treatment significantly decreased the disease activity index and increased colon length. Histological examination revealed that the oral administration of SDG suppressed DSS-induced erosion, ulceration, crypt abscesses and oedema. Furthermore, colonic myeloperoxidase activity and TNF-α expression declined remarkably following treatment with SDG. Additionally, oral SDG treatment significantly increased the expression of several mucoprotection markers, to include zona occludens-1, Tollip and trefoil factor 3, and thus restored intestinal permeability. These results suggested that oral SDG treatment can alleviate DSS-induced colitis and might be a promising supplement for the amelioration of inflammatory bowel disease.

Flaxseed lignans alleviate high fat diet-induced hepatic steatosis and insulin resistance in mice: Potential involvement of AMP-activated protein kinase

Hepatic steatosis and insulin resistance are highly prevalent and play a vital role in the development of nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM). The present study examined the protective effects of naturally occurring flaxseed lignan secoisolariciresinol diglucoside (SDG) on these metabolic disorders resulting from high fat diet (HFD). SDG (0.05%, w/w) supplementation for 16 weeks attenuated body weight gain, hyperlipidaemia and hepatic steatosis in HFD (60% kcal from fat)-challenged C57BL/6J mice. Moreover, SDG lowered fasting serum glucose and insulin, and improved homeostasis model assessment of insulin resistance (HOMA-IR) index, glucose tolerance, and insulin response in HFD-fed mice. Furthermore, SDG prevented HFD-induced inhibition of protein kinase B, insulin receptor substrate-1 and AMP-activated protein kinase activation in the liver of HFD-fed mice. These findings indicate that SDG supplementation alleviates hepatic steatosis and insulin resistance, at least in part, by enhancing insulin signalling and AMPK activation.

Flaxseed lignan secoisolariciresinol diglucoside improves insulin sensitivity through upregulation of GLUT4 expression in diet-induced obese mice

The efficacy and mechanism of flaxseed lignan secoisolariciresinol diglucoside (SDG) on glucose hemostasis in obese mice were examined. Male C57BL/6J mice fed on a high-fat diet (60 kcal% fat) for 15 weeks were divided into four groups and treated by oral gavage with 0, 10, 100, or 1000 mg/kg/d of SDG dissolved in water for 6 weeks. Age-matched mice fed with a low-fat diet (10% kcal fat) were used as the normal control. SDG lowered fasting blood glucose, insulin, and free fatty acid levels and improved oral glucose tolerance, insulin response, and homeostatic model assessment-estimated insulin resistance index in mice fed the high-fat diet. Flaxseed SDG also increased GLUT4 expression and tended to increase phosphorylated AKT to total AKT ratio in the muscle tissue. The data demonstrated that flaxseed SDG improved glycaemic control, at least in part, by enhancing insulin signalling and sensitivity in diet-induced obese mice.

Flaxseed lignan secoisolariciresinol diglucoside improves insulin sensitivity through upregulating GLUT4 expression in diet‐induced obese mice (829.25)

Flaxseed Lignan Secoisolariciresinol Diglucoside Improves Insulin Sensitivity through Upregulating GLUT4 Expression in Diet‐Induced Obese Mice Yanwen Wang1, Bourlaye Fofana2, Moumita Roy1, and Kaushik Ghose 2 1 Aquatic and Crop Resource Development, National Research Council of Canada, Charlottetown, PE, Canada C1A 4P3 2 Agriculture and Agri‐Food Canada, Charlottetown, PE, Canada C1A 4P3 The objective of this study was to determine the anti‐diabetic effect and underlying mechanisms of flaxseed lignans in diet‐induced obese and insulin resistant mice. Male C57BL/6J mice, at the age of 8 wk, were provided with a high‐fat diet to induce insulin resistance. The age‐matched male C57BL/6J mice fed in parallel with a low‐fat diet were used as the normal control. After 12 wk, the high‐fat diet‐fed mice were randomized into 4 groups and treated by gavage feeding once a day with 0 (high‐fat/insulin resistant control), 10, 100, and 1,000 mg/kg/d of secoisolariciresinol diglucoside (SDG, 60% pure) lignan dissolved in water, respectively, for 6 weeks. The high‐fat and low‐fat control groups were gavaged with the vehicle. It was demonstrated that oral administration of SDG lowered body weight, serum insulin, total cholesterol and free fatty acid levels. SDG also improved oral glucose tolerance and insulin tolerance. Further molecular experiments showed that SDG increased muscle GLUT4 protein expression. The results suggest that flaxseed SDG lignan protects from insulin resistance in diet‐induced obese mice and has potential to be used as a natural product for the prevention and treatment of obesity‐related insulin resistance or diabetes.Grant Funding Source: TUFGEN 604381

The Comparison of Rat and Human Intestinal and Hepatic Glucuronidation of Enterolactone Derived from Flaxseed Lignans

Enterolactone (EL) is a gut microbe metabolite of the flaxseed lignan secoisolariciresinol diglucoside (SDG). Studies suggest a correlation between EL systemic levels and protective effects against cancer and cardiovascular disease. EL's oral bioavailability is low and highly variable due to extensive first-pass metabolism. To better understand the contribution of liver and intestine to first-pass glucuronidation we conducted an in vitro enzyme kinetic analysis of EL glucuronidation in liver and intestinal microsomes from both human and rat. An intrinsic clearance (CLint) value was calculated using the substrate depletion approach. In addition to monitoring substrate depletion, HPLC analysis allowed detection of EL glucuronides which were further substantiated by LC-MS/MS. EL monoglucuronide was identified in human and rat liver and intestinal microsomes. Enzyme kinetic studies indicated the extent of hepatic microsomal glucuronidation exceeded intestinal glucuronidation in both human and rat, while the human liver CLint value was slightly higher than that of rat liver. The CLint value generated in human intestinal microsomes was only one third of human liver, whereas the CLint of rat jejunum or colon was one-twentieth of rat liver suggesting the human intestine makes a greater contribution to EL glucuronidation than rat intestine. Our results suggest that both liver and intestine contribute to EL glucuronidation and the human intestine may exert a greater influence on the first-pass glucuronidation of EL than rat intestine. The rat might underestimate the extent of intestinal metabolism of EL relative to human. Keywords: Enterolactone, flaxseed, glucuronidation, intestine, liver, lignan.

Anti‐Diabetic Potential of Flaxseed Lignan Secoisolariciresinol Diglucoside in Diet‐Induced Obese Mice

The current study was to determine the anti‐diabetic potential of semi‐purified (~ 60% pure) flaxseed SDG lignan in obese mice. Sixty male C57BL/6J mice were fed a high‐fat diet to induce insulin resistance and 11 male C57BL/6J mice fed a low‐fat diet were used as the normal control. After 12 weeks, mice on the high‐fat diet were treated by oral gavage with 0, 10, 100, and 1,000 mg/kg/d of flaxseed SDG lignan, respectively, for 6 weeks. The two control groups were gavaged with the vehicle. The results showed that oral administration of SDG lignan lowered body weight and improved blood glucose levels. SDG lignan treatment significantly lowered insulin levels and improved insulin tolerance. The treatment of SDG lignan also improved oral glucose tolerance. Moreover, the serum total cholesterol and free fatty acids were lowered due to SDG lignan treatment. The results suggest that flaxseed SDG lignan is a promising natural product for improving or preventing obesity‐related insulin resistance. Further experiments are underway to determine the mechanisms of action. (Supported by Genome Canada/TUFGEN grant 6003321).

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.

Flaxseed lignan attenuates high-fat diet-induced fat accumulation and induces adiponectin expression in mice

Flaxseed lignan secoisolariciresinol diglucoside (SDG) has been reported to prevent and alleviate lifestyle-related diseases including diabetes and hypercholesterolaemic atherosclerosis. This study assesses the effect of SDG on the development of diet-induced obesity in mice and the effect of the SDG metabolite enterodiol (END) on adipogenesis in 3T3-L1 adipocytes. We compared body weight, visceral fat weight, liver fat content, serum parameters, mRNA levels of lipid metabolism-related enzymes and adiponectin in mice fed either a low-fat diet (5 % TAG), high-fat diet (30 % TAG) or high-fat diet containing 0.5 and 1.0 % (w/w) SDG for 4 weeks. Administration of SDG to mice significantly reduced high-fat diet-induced visceral and liver fat accumulation, hyperlipaemia, hypercholesterolaemia, hyperinsulinaemia and hyperleptinaemia. SDG also suppressed sterol regulatory element binding protein 1c mRNA level in the liver and induced increases in the adiponectin mRNA level in the white adipose tissue and carnitine palmitoyltransferase I mRNA level in the skeletal muscle. Differentiated 3T3-L1 adipocytes were treated with 0, 5, 10 and 20 mumol/l END and then assayed for mRNA expression of adipogenesis-related genes and DNA binding activity of PPARgamma to the PPAR response element consensus sequence. END induced adipogenesis-related gene mRNA expression including adiponectin, leptin, glucose transporter 4 and PPARgamma, and induced PPARgamma DNA binding activity in 3T3-L1 adipocytes. In conclusion, SDG induced adiponectin mRNA expression and showed beneficial effects on lipid metabolism in diet-induced obesity in mice. Flaxseed lignans are suggested to regulate adipogenesis-related gene expressions through an increase in PPARgamma DNA binding activity.

Antioxidant activities of the flaxseed lignan secoisolariciresinol diglucoside, its aglycone secoisolariciresinol and the mammalian lignans enterodiol and enterolactone in vitro

The flaxseed lignan secoisolariciresinol diglucoside (SDG) and mammalian lignans enterodiol (ED) and enterolactone (EL) were previously shown to be effective antioxidants against DNA damage and lipid peroxidation. Others reported inhibition of activated cell chemiluminescence by supra-physiological concentrations of secoisolariciresinol (SECO), ED and EL. Thus, we evaluated the antioxidant efficacy of potential physiological concentrations of SDG, SECO, ED and EL against 1,1-diphenyl-2-picrylhydrazyl (DPPH ), and 2,2′-azo-bis(2-amidinopropane) dihydrochloride (AAPH)-initiated peroxyl radical plasmid DNA damage and phosphatidylcholine liposome lipid peroxidation. SDG and SECO were effective ( p < 0.01) antioxidants against DPPH at 25–200 μM; whereas, ED and EL were inactive. Efficacy of lignans and controls against AAPH peroxyl radical-induced DNA damage was: SDG > SECO = 17α-estradiol > ED = EL > genistein > daidzein. Lignan efficacy against AAPH-induced liposome lipid peroxidation was: SDG > SECO = ED = EL. Plant lignan antioxidant activity was attributed to the 3-methoxy-4-hydroxyl substituents of SDG and SECO, versus the meta mono-phenol structures of ED and EL. Benzylic hydrogen abstraction and potential resonance stabilization of phenoxyl radicals in an aqueous environment likely contributed to the antioxidant activity of the mammalian lignans. These represent likely extra- and intracellular antioxidant activities of flax-derived lignans at concentrations potentially achievable in vivo.