Lignan Secoisolariciresinol Research Articles

Flaxseed: its bioactive components and their cardiovascular benefits.

Cardiovascular disease remains the leading cause of mortality and morbidity worldwide. The inclusion of functional foods and natural health products in the diet are gaining increasing recognition as integral components of lifestyle changes in the fight against cardiovascular disease. Several preclinical and clinical studies have shown the beneficial cardiovascular effects of dietary supplementation with flaxseed. The cardiovascular effects of dietary flaxseed have included an antihypertensive action, antiatherogenic effects, a lowering of cholesterol, an anti-inflammatory action, and an inhibition of arrhythmias. Its enrichment in the ω-3 fatty acid α-linolenic acid and the antioxidant lignan secoisolariciresinol diglucoside as well as its high fiber content have been implicated primarily in these beneficial cardiovascular actions. Although not as well recognized, flaxseed is also composed of other potential bioactive compounds such as proteins, cyclolinopeptides, and cyanogenic glycosides, which may also produce biological actions. These compounds could also be responsible for the cardiovascular effects of flaxseed. This article will not only summarize the cardiovascular effects of dietary supplementation with flaxseed but also review its bioactive compounds in terms of their properties, biological effects, and proposed mechanisms of action. It will also discuss promising research directions for the future to identify additional health-related benefits of dietary flaxseed.

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.

Influence of Flaxseed Lignan Supplementation to Older Adults on Biochemical and Functional Outcome Measures of Inflammation

ABSTRACT Evidence from the literature suggests that dietary flaxseed lignans have the ability to modulate inflammation, which is recognized as the underlying basis of multiple chronic human diseases in older adults. Our objective was to determine the effects of oral lignan supplementation on biochemical and functional indicators of inflammation as well as safety and tolerability in older healthy adults. We designed a randomized, double-blind, placebo-controlled clinical trial in older healthy adults (60–80 years) to assess flaxseed lignan–enriched complex (∼38% secoisolariciresinol diglucoside [SDG]; 600 mg SDG dose) oral supplementation effects on biochemical and functional indicators of inflammation and safety and tolerability in older healthy adults after 6 months of once-daily oral administration. The clinical trial confirmed that plasma concentration of total flaxseed lignans (free and conjugated forms) secoisolariciresinol (SECO), enterodiol (ED), and enterolactone (ENL) were significantly associated with daily oral supplementation of flaxseed lignan–enriched complex (p < 0.05). A significant decrease in systolic blood pressure (SBP; from a mean of 155 ± 13 mm Hg at baseline to 140 ± 11 mm Hg at 24 weeks) was observed in lignan-supplemented participants stratified into an SBP ≥140 mm Hg subcategory (p = 0.04). No differences were found between treatment or placebo groups in terms of cognition, pain, activity, physical measurements (calf, waist, and upper arm circumstances), and grip strength. With respect to blood inflammatory markers, lipid profiles, and biochemical parameters, no significant differences were found between treatment and placebo groups at the end of the 6-month supplementation. No adverse effects were reported during supplementation. These data further support the safety and tolerability of long-term flaxseed lignan–enriched complex supplementation in older adults and identify an ability to favorably modulate SBP, an important risk factor in cardiovascular disease.

Short communication: The mammalian lignan enterolactone is absorbed by newborn dairy calves fed enterolactone-enriched milk

Flaxseed is the richest source of the plant lignan secoisolariciresinol diglucoside, which is converted to the mammalian lignans enterolactone (EL) and enterodiol by the gut microbiota of ruminants and humans. Enterolactone has been associated with improved animal and human health due to its antioxidant and anticarcinogenic properties. The objective of this study was to determine the pharmacokinetics of EL in newborn dairy calves fed milk replacer or EL-enriched milk. We hypothesized that newborn Holstein calves fed EL-enriched milk would have greater area under the curve and plasma concentration of EL compared with those fed milk replacer. On d 5 of life, calves were administered 2 L of milk replacer (n = 10; low-EL treatment: 123 nmol/L of EL) or 2 L of EL-enriched milk (n = 10; high-EL treatment: 481 nmol/L of EL) during the morning feeding (0700 h). Blood samples were taken from the jugular vein before (0 h) and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 24, and 48 h after oral administration of treatments. The area under the curve for the plasma concentration of EL was analyzed according to the trapezoidal rule between 0 and 12 h after treatment administration, and it was greater in high- (26 nmol/L × h) than low-EL calves (4.30 nmol/L × h). Similarly, the maximum concentration of EL in plasma was greater in high- (5.06 nmol/L) versus low-EL calves (1.95 nmol/L). Furthermore, the time after treatment intake to reach maximum plasma concentration of EL was faster in high- (4.31 h) compared with low-EL (4.44 h) treatment. Calves were able to absorb EL, indicating that EL-enriched milk can potentially be used as source of EL to pre-weaned ruminants.

Abstract 231: The polyphenolic plant lignan secoisolariciresinol diglycoside reduces mammary tumor growth, possibly via inhibition of local inflammatory signaling

Abstract Background: Secoisolariciresinol diglycoside (SDG) is a polyphenolic plant lignan found in flax and sesame seeds as well as legumes, whole grains, fruits and vegetables. It is metabolized by the gut bacteria into two major enterolignans: enterolactone (ENL) and enterodiol (END). These enterolignans have been associated with reduced breast cancer risk and progression in population studies as well as decreased tumor growth in preclinical models of breast cancer. Methods: The impact of SDG supplementation on tumor growth in a mouse model of basal-like breast cancer was examined. C57BL/6 mice were fed a control diet (10% kcal from fat) or control diet with SDG supplementation (100 mg/kg food) for eight weeks, then both groups were orthotopically injected with E0771 mammary tumor cells. An inflammatory signaling qPCR array (Qiagen) was performed on mammary tissue distal to tumor. Tumors were stained by immunohistochemistry (IHC) for Ki67 to measure proliferation levels and phospho-p65 to determine inflammatory signaling pathway activation. Tumors and mammary tissue were also stained for F4/80 to quantify macrophage infiltration. Serum level of hormones, adipokines, and cytokines were measured via luminex assay (Bio-Rad). Results: SDG supplementation significantly decreased tumor weight (p&amp;lt;0.05). SDG did not affect body weight or body fat percentage but did significantly decrease expression of F4/80, CRP, and other pro-inflammatory markers in the mammary tissue. IHC staining revealed no difference in tumor proliferation; however, SDG supplementation did reduce inflammatory signaling in the tumors, indicated by a significant decrease in phospho-p65 staining. However, serum cytokine levels were not significantly different between the groups. Tumors are currently being stained by IHC for cleaved caspase 3 to measure levels of apoptosis. In addition, cell culture experiments will be conducted to define the impact of ENL treatment on protumorigenic cross-talk between tumor cells, adipocytes, and macrophages. Specifically, the effects of conditioned media from adipocyte/macrophage co-cultures (with +/- ENL treatment) on mouse E0771 and human MDA-MB-231 tumor cell proliferation, migration and invasion will be examined. Conclusions: SDG supplementation reduced mammary tumor growth in association with SDG’s effects on local, but not systemic, inflammatory signaling. Citation Format: Claire G. Lineberger, Laura W. Bowers, Nikki A. Ford, Emily L. Rossi, Bruce K. Kimler, Carol J. Fabian, Stephen D. Hursting. The polyphenolic plant lignan secoisolariciresinol diglycoside reduces mammary tumor growth, possibly via inhibition of local inflammatory signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 231. doi:10.1158/1538-7445.AM2017-231

Enterolactone Induces G1-phase Cell Cycle Arrest in Nonsmall Cell Lung Cancer Cells by Downregulating Cyclins and Cyclin-dependent Kinases

ABSTRACTFlaxseed is a rich source of the plant lignan secoisolariciresinol diglucoside (SDG), which is metabolized into mammalian lignans enterodiol (ED) and enterolactone (EL) in the digestive tract. The anticancer properties of these lignans have been demonstrated for various cancer types, but have not been studied for lung cancer. In this study, we investigated the anticancer effects of EL for several nonsmall cell lung cancer (NSCLC) cell lines of various genetic backgrounds. EL inhibited the growth of A549, H441, and H520 lung cancer cells in concentration- and time-dependent manners. The antiproliferative effects of EL for lung cancer cells were not due to enhanced cell death, but rather due to G1-phase cell cycle arrest. Molecular studies revealed that EL decreased mRNA or protein expression levels of the G1-phase promoters cyclin D1, cyclin E, cyclin-dependent kinases (CDK)-2, -4, and -6, and p-cdc25A; decreased phosphorylated retinoblastoma (p-pRb) protein levels; and simultaneously increased levels of p21WAF1/CIP1, a negative regulator of the G1 phase. The results suggest that EL inhibits the growth of NSCLC cell lines by downregulating G1-phase cyclins and CDKs, and upregulating p21WAF1/CIP1, which leads to G1-phase cell cycle arrest. Therefore, EL may hold promise as an adjuvant treatment for lung cancer therapy.

The Synthetic Lignan Secoisolariciresinol Diglucoside Prevents Asbestos-Induced NLRP3 Inflammasome Activation in Murine Macrophages.

Background The interaction of asbestos with macrophages drives two key processes that are linked to malignancy: (1) the generation of reactive oxygen species (ROS)/reactive nitrogen species (RNS) and (2) the activation of an inflammation cascade that drives acute and chronic inflammation, with the NLRP3 inflammasome playing a key role. Synthetic secoisolariciresinol diglucoside (SDG), LGM2605, is a nontoxic lignan with anti-inflammatory and antioxidant properties and was evaluated for protection from asbestos in murine peritoneal macrophages (MF). Methods MFs were exposed to crocidolite asbestos ± LGM2605 given 4 hours prior to exposure and evaluated at various times for NLRP3 expression, secretion of inflammasome-activated cytokines (IL-1β and IL-18), proinflammatory cytokines (IL-6, TNFα, and HMGB1), NF-κB activation, and levels of total nitrates/nitrites. Results Asbestos induces a significant (p < 0.0001) increase in the NLRP3 subunit, release of proinflammatory cytokines, NLRP3-activated cytokines, NF-κB, and levels of nitrates/nitrites. LGM2605 significantly reduced NLRP3 ranging from 40 to 81%, IL-1β by 89–96%, and TNFα by 67–78%, as well as activated NF-κB by 48-49% while decreasing levels of nitrates/nitrites by 85–93%. Conclusions LGM2605 reduced asbestos-induced NLRP3 expression, proinflammatory cytokine release, NF-κB activation, and nitrosative stress in MFs supporting its possible use in preventing the asbestos-induced inflammatory cascade leading to malignancy.

Secoisolariciresinol Diglucoside and Cyanogenic Glycosides in Gluten-free Bread Fortified with Flaxseed Meal.

Flaxseed (Linum usitatissimum L.) meal contains cyanogenic glycosides (CGs) and the lignan secoisolariciresinol diglucoside (1). Gluten-free (GF) doughs and baked goods were produced with added flaxseed meal (20%, w/w) then 1, and CGs were determined in fortified flour, dough, and bread with storage (0, 1, 2, and 4 weeks) at different temperatures (-18, 4, and 22-23 °C). 1 was present in flour, dough, and GF bread after baking. 1 was stable with extensive storage (up to 4 weeks) and was not affected by storage temperature. CGs in flaxseed meal and fortified GF samples were analyzed by 1H NMR of the cyanohydrins. Linamarin and/or linustatin were the primary CGs in both flaxseed meal and fortified flour. CGs decreased with storage in dough fortified with flaxseed meal or GF bread after baking. GF bakery food products fortified with flaxseed meal had reduced CGs but remained a good source of dietary 1.

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.

Plant lignan secoisolariciresinol suppresses pericardial edema caused by dioxin-like compounds in developing zebrafish: Implications for suppression of morphological abnormalities

Dioxins and dioxin-like compounds (DLCs) enter the body mainly through diet and cause various toxicological effects through activation of the aryl hydrocarbon receptor (AhR), a ligand activated transcription factor. Some plant extracts and phytochemicals are reported to suppress this transformation. However, most of these reports have been from in vitro experiments and few reports have been from in vivo experiments. In addition, there has been no report of foodstuffs that effectively prevent AhR-associated morphological abnormalities such as deformities caused by dioxins and DLCs in vivo. In this study, we show that secoisolariciresinol (SECO), a natural lignan-type polyphenolic phytochemical found mainly in flaxseed, has a rescuing effect, actually suppressing morphological abnormalities (pericardial edema) in zebrafish embryos exposed to 3,3′,4,4′,5-pentachlorobiphenyl (PCB126), a dioxin-like PCB congener. Importantly, the rescuing effect of SECO was still evident when it was applied 16 h after the beginning of exposure to PCB126. This study suggests that SECO may be useful as a natural suppressive agent for morphological abnormalities caused by dioxins and DLCs.

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.

Asbestos Induces Oxidative Stress and Activation of Nrf2 Signaling in Murine Macrophages: Chemopreventive Role of the Synthetic Lignan Secoisolariciresinol Diglucoside (LGM2605)

The interaction of asbestos fibers with macrophages generates harmful reactive oxygen species (ROS) and subsequent oxidative cell damage that are key processes linked to malignancy. Secoisolariciresinol diglucoside (SDG) is a non-toxic, flaxseed-derived pluripotent compound that has antioxidant properties and may thus function as a chemopreventive agent for asbestos-induced mesothelioma. We thus evaluated synthetic SDG (LGM2605) in asbestos-exposed, elicited murine peritoneal macrophages as an in vitro model of tissue phagocytic response to the presence of asbestos in the pleural space. Murine peritoneal macrophages (MFs) were exposed to crocidolite asbestos fibers (20 µg/cm2) and evaluated at various times post exposure for cytotoxicity, ROS generation, malondialdehyde (MDA), and levels of 8-iso Prostaglandin F2α (8-isoP). We then evaluated the ability of LGM2605 to mitigate asbestos-induced oxidative stress by administering LGM2605 (50 µM) 4-h prior to asbestos exposure. We observed a significant (p < 0.0001), time-dependent increase in asbestos-induced cytotoxicity, ROS generation, and the release of MDA and 8-iso Prostaglandin F2α, markers of lipid peroxidation, which increased linearly over time. LGM2605 treatment significantly (p < 0.0001) reduced asbestos-induced cytotoxicity and ROS generation, while decreasing levels of MDA and 8-isoP by 71%–88% and 41%–73%, respectively. Importantly, exposure to asbestos fibers induced cell protective defenses, such as cellular Nrf2 activation and the expression of phase II antioxidant enzymes, HO-1 and Nqo1 that were further enhanced by LGM2605 treatment. LGM2605 boosted antioxidant defenses, as well as reduced asbestos-induced ROS generation and markers of oxidative stress in murine peritoneal macrophages, supporting its possible use as a chemoprevention agent in the development of asbestos-induced malignant mesothelioma.

Abstract IA25: Nutritional intervention for prevention of ovarian cancer in a natural model: The laying hen.

Abstract Ovarian cancer is a lethal disease with poor prognosis due to the late stage at which it is usually detected. Research has been hampered by lack of suitable animal models. With the exception of the laying hen, no other accessible animal model recapitulates the human disease hens get ovarian cancer spontaneously, present with same gross and histological pathology, and provide feasible model for conducting large scale dietary interventions. Moreover, each of the histological subtypes of ovarian cancer seen in the human disease are observed in the hen with varying frequency. We have shown that the up-regulation of E-cadherin (CDH1) is an early defining step in ovarian cancer hens, analogous to the human disease. Rigidity of the tissue, discerned by touch, and positive E-cadherin staining, assist in the diagnosis of early ovarian cancer from hens with no apparent pathology. Flaxseed is the richest vegetable source of the potent anti-inflammatory omega-3 polyunsaturated fats (OM3) in the germ and the phytoestrogen lignan secoisolariciresinol diglucoside (SDG) in the hull. Cancer-prone old laying hens were fed a diet enriched with flaxseed for one year and we observed a significant reduction in ovarian cancer severity, but not a reduction in ovarian cancer incidence. However, a significant decrease in the incidence of ovarian cancer, as well as severity, was seen when hens were provided flaxseed throughout their whole egg laying life. These long term feeding studies which are initiated when hens are at different ages have helped us to define the window of therapeutic intervention which enables significant amelioration and prevention of ovarian cancer. We hypothesize that the two biologically active constituents of flaxseed work in concert to reduce the incidence and severity of ovarian cancer resulting in suppression and prevention of this deadly disease. Feeding hens specific diets enriched with the individual components of flaxseed (OM3, SDG) vs. OMG6 (corn oil) provides insight into their separable actions. OM3 enriched diets reduce systemic oxidative stress while OM6 caused an increase in systemic oxidative stress. The reduction in cancer severity and incidence was correlated to a reduction in cyclooxygenase (COX) enzymes and prostaglandin E2 (PGE2). The phytoestrogen lignan SDG reduced pro-proliferative estrogen signaling and estrogen mediated genotoxicity, contributing to the preventative effects. Alteration in the pattern of estrogen metabolites provides a read-out of the therapeutic effectiveness and may provide the basis for development of a biomarker for early disease. Research on dietary intervention not only provides development of therapeutic modalities, but provides new insights into basic biology of ovarian cancer. These studies provide the foundation for a new flax meal-based clinical trial on progression-free remission in ovarian cancer. {NIH/NCCAM AT005295 and NIH/NCI CA162511} Citation Format: Dale Buck Hales. Nutritional intervention for prevention of ovarian cancer in a natural model: The laying hen. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr IA25.

Effect of bovine ABCG2 polymorphism Y581S SNP on secretion into milk of enterolactone, riboflavin and uric acid

The ATP-binding cassette transporter G2/breast cancer resistance protein (ABCG2/BCRP) is an efflux protein involved in the bioavailability and milk secretion of endogenous and exogenous compounds, actively affecting milk composition. A limited number of physiological substrates have been identified. However, no studies have reported the specific effect of this polymorphism on the secretion into milk of compounds implicated in milk quality such as vitamins or endogenous compounds. The bovine ABCG2 Y581S polymorphism is described as a gain-of-function polymorphism that increases milk secretion and decreases plasma levels of its substrates. This work aims to study the impact of Y581S polymorphism on plasma disposition and milk secretion of compounds such as riboflavin (vitamin B2), enterolactone, a microbiota-derived metabolite from the dietary lignan secoisolariciresinol and uric acid. In vitro transport of these compounds was assessed in MDCK-II cells overexpressing the bovine ABCG2 (WT-bABCG2) and its Y581S variant (Y581S-bABCG2). Plasma and milk levels were obtained from Y/Y homozygous and Y/S heterozygous cows. The results show that riboflavin was more efficiently transported in vitro by the Y581S variant, although no differences were noted in vivo. Both uric acid and enterolactone were substrates in vitro of the bovine ABCG2 variants and were actively secreted into milk with a two-fold increase in the milk/plasma ratio for Y/S with respect to Y/Y cows. The in vitro ABCG2-mediated transport of the drug mitoxantrone, as a model substrate, was inhibited by enterolactone in both variants, suggesting the possible in vivo use of this enterolignan to reduce ABCG2-mediated milk drug transfer in cows. The Y581S variant was inhibited to a lesser extent probably due to its higher transport capacity. All these findings point to a significant role of the ABCG2 Y581S polymorphism in the milk disposition of enterolactone and the endogenous molecules riboflavin and uric acid, which could affect both milk quality and functionality.

Abstract 5542: Flaxseed and its lignan component protect from asbestos-induced inflammation in mice

Abstract Introduction/Background: Malignant mesothelioma (MM) is a highly lethal form of thoracic cancer with high mortality and poor treatment options. Development of MM has been linked directly to exposure to asbestos fibers, but with a long latency period. Recent studies have indicated that the pathogenesis of asbestos-induced cancers is due, in part, to chronic inflammation and oxidative tissue damage caused by persistent asbestos fibers. Whole grain flaxseed (FS) has known antioxidant, anti-inflammatory and cancer chemopreventive properties. Rationale: As a prelude to future chemoprevention studies, we tested the ability of oral FS and its lignan component, FLC which is enriched in the lignan secoisolariciresinol diglucoside (SDG), to prevent acute asbestos-induced inflammation and inflammatory cytokine release in MM-prone Nf2+/mut;Cdkn2a+/mut mice. Methods: Mice were given a single ip bolus of 400 mM of crocidolite asbestos. They were then placed on 10% FS or 10% FLC supplemented diets 1 day prior (-1) to or after (+1) asbestos instillation. All mice were evaluated 3 days after injection of asbestos for abdominal inflammation and proinflammatory cytokine release. The Nf2+/mut;Cdkn2a+/mut model was selected as it develops an accelerated form of MM when exposed to asbestos. Results: Using liquid chromatography and tandem mass spectrometry (LC/MS/MS), we showed that systemic levels (plasma) of flaxseed lignan metabolites (such as the mammalian lignans Enterolactone (EL) and Enterodiol (ED)) were comparable to those in other mouse models where FS was shown to be an effective chemopreventive agent. The numbers of macrophages (MF) and neutrophils (PMN) in peritoneal lavage fluid indicated that both FS and FLC blunted acute abdominal inflammation induced by asbestos. In addition, the levels of pro-inflammatory cytokines TNF alpha and IL-1 beta in lavage fluid were also decreased by the dietary agents. Conclusions: Our findings suggest that the known chemopreventive properties of FS and its lignan component appear to reduce short-term asbestos-induced inflammation and may thus prove to be a promising dietary agent in the chemoprevention of MM. Funding: This study was supported in part by Penn's SRP Center Grant (P42 ES027320), “Asbestos fate, exposure, remediation and adverse health effects” from the National Institute of Environmental Health (NIEHS) and 1R03CA180548-02 (MCS). Citation Format: Steven M. Albelda, Ralph A. Pietrofesa, Craig W. Menges, Joseph R. Testa, Melpo Christofidou-Solomidou. Flaxseed and its lignan component protect from asbestos-induced inflammation in mice. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5542. doi:10.1158/1538-7445.AM2015-5542

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.

Effects of Flaxseed Lignan Secoisolariciresinol Diglucosideon Preneoplastic Biomarkers of Cancer Progression in a Model of Simultaneous Breast and Ovarian Cancer Development

Breast cancer prevention efforts are focused increasingly on potentially beneficial dietary modifications due to their ease of implementation and wide acceptance. Secoisolariciresinol diglucoside (SDG) is a lignan found in high concentration in flaxseed that may have selective estrogen receptor modulator-like effects resulting in antiestrogenic activity in a high estrogen environment. In parallel with a human phase II prevention trial, female ACI rats (n = 8–10/group) received 0, 10, or 100 ppm SDG in the feed. The 100 ppm SDG treatment produced similar blood lignan levels as those observed in our human pilot study. Mammary and ovarian cancer progression were induced using local ovarian DMBA treatment and subcutaneous sustained release 17β-estradiol administered starting at 7 weeks of age. Mammary gland and ovarian tissues were collected at 3 mo after initiation of treatment and examined for changes in epithelial cell proliferation (Ki-67, cell counts), histopathology, and dysplasia scores, as well as expression of selected genes involved in proliferation, estrogen signaling, and cell adhesion. Treatment with SDG normalized several biomarkers in mammary gland tissue (dysplasia, cell number, and expression of several genes) that had been altered by carcinogen. There is no indication that SDG promotes preneoplastic progression in the ovarian epithelium.

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

Bioconversion of Pinoresinol into Matairesinol by Use of Recombinant Escherichia coli

Lignans, a class of dimeric phenylpropanoid derivative found in plants, such as whole grains and sesame and flax seeds, have anticancer activity and can act as phytoestrogens. The lignans secoisolariciresinol and matairesinol can be converted in the mammalian proximal colon into enterolactone and enterodiol, respectively, which reduce the risk of breast and colon cancer. To establish an efficient bioconversion system to generate matairesinol from pinoresinol, the genes encoding pinoresinol-lariciresinol reductase (PLR) and secoisolariciresinol dehydrogenase (SDH) were cloned from Podophyllum pleianthum Hance, an endangered herb in Taiwan, and the recombinant proteins, rPLR and rSDH, were expressed in Escherichia coli and purified. The two genes, termed plr-PpH and sdh-PpH, were also linked to form two bifunctional fusion genes, plr-sdh and sdh-plr, which were also expressed in E. coli and purified. Bioconversion in vitro at 22°C for 60 min showed that the conversion efficiency of fusion protein PLR-SDH was higher than that of the mixture of rPLR and rSDH. The percent conversion of (+)-pinoresinol to matairesinol was 49.8% using PLR-SDH and only 17.7% using a mixture of rPLR and rSDH. However, conversion of (+)-pinoresinol by fusion protein SDH-PLR stopped at the intermediate product, secoisolariciresinol. In vivo, (+)-pinoresinol was completely converted to matairesinol by living recombinant E. coli expressing PLR-SDH without addition of cofactors.

Bioaccessibility of lignans from flaxseed (Linum usitatissimumL.) determined by single-batchin vitrosimulation of the digestive process

Flaxseed is an important source of lignan secoisolariciresinol diglucoside (SDG) and its aglycone, secoisolariciresinol (SECO). These phenolic compounds can be metabolized to the mammalian lignans enterodiol (ED) and enterolactone (EL) by human intestinal microflora. Flaxseed lignans are known for their potential health benefits, which are attributed to their antioxidant and phytoestrogenic properties. The focus of this study was to determine the bioaccessibility of plant and mammalian lignans in whole flaxseed (WF) and flaxseed flour (FF) throughout the entire digestive process. Moreover, the metabolic activity of intestinal microflora was evaluated. A single-batch in vitro simulation of the digestive process was performed, including fermentation by the intestinal microflora in the colon. Bioaccessibility was calculated as (free lignan)/(total lignan). In digested WF, the bioaccessibility values of SECO, ED and EL were 0.75%, 1.56% and 1.23%, respectively. Conversely, in digested FF, the bioaccessibility values of SDG, ED and EL were 2.06%, 2.72% and 1.04%, respectively. The anaerobic count and short-chain fatty acids indicate that bacteria survival and carbohydrate fermentation occurred. The contents of both SDG and ED were significantly higher in digested FF than in digested WF. FF facilitated the action of intestinal bacteria to release SDG and metabolize ED.