Secoisolariciresinol diglucoside attenuates neuroinflammation and cognitive impairment in female Alzheimer's disease mice via modulating gut microbiota metabolism and GPER/CREB/BDNF pathway.

BACKGROUND: Gender is a significant risk factor for late-onset Alzheimer's disease (AD), often attributed to the decline of estrogen. The plant estrogen secoisolariciresinol diglucoside (SDG) has demonstrated anti-inflammatory and neuroprotective effects. However, the protective effects and mechanisms of SDG in female AD remain unclear. METHODS: Ten-month-old female APPswe/PSEN1dE9 (APP/PS1) transgenic mice were treated with SDG to assess its potential ameliorative effects on cognitive impairments in a female AD model through a series of behavioral and biochemical experiments. Serum levels of gut microbial metabolites enterodiol (END) and enterolactone (ENL) were quantified using HPLC-MS. Correlation analysis and broad-spectrum antibiotic cocktail (ABx) treatment were employed to demonstrate the involvement of END and ENL in SDG's cognitive improvement effects in female APP/PS1 mice. Additionally, an acute neuroinflammation model was constructed in three-month-old C57BL/6J mice treated with lipopolysaccharide (LPS) and subjected to i.c.v. injection of G15, an inhibitor of G protein-coupled estrogen receptor (GPER), to investigate the mediating role of the estrogen receptor GPER in the cognitive benefits conferred by SDG. RESULTS: SDG administration resulted in significant improvements in spatial, recognition, and working memory in female APP/PS1 mice. Neuroprotective effects were observed, including enhanced expression of CREB/BDNF and PSD-95, reduced ß-amyloid (Aß) deposition, and decreased levels of TNF-α, IL-6, and IL-10. SDG also altered gut microbiota composition, increasing serum levels of END and ENL. Correlation analysis indicated significant associations between END, ENL, cognitive performance, hippocampal Aß-related protein mRNA expression, and cortical neuroinflammatory cytokine levels. The removal of gut microbiota inhibited END and ENL production and eliminated the neuroprotective effects of SDG. Furthermore, GPER was found to mediate the inhibitory effects of SDG on neuroinflammatory responses. CONCLUSION: These findings suggest that SDG promotes the production of gut microbial metabolites END and ENL, which inhibit cerebral ß-amyloid deposition, activate GPER to enhance CREB/BDNF signaling pathways, and suppress neuroinflammatory responses. Consequently, SDG exerts neuroprotective effects and ameliorates cognitive impairments associated with AD in female mice.

Dietary secoisolariciresinol diglucoside crude extract improves growth through modulating rumen bacterial community and epithelial development in lambs.

BACKGROUND: Flaxseed lignans, types of polyphenolic compounds, primarily consist of secoisolariciresinol diglucoside (SDG). Natural plant extracts are becoming increasingly important as feed for ruminant animals. An underutilized plant bioactive component, SDG shows promising benefits for young ruminant production. The objective of this study was to assess the impact of SDG on rumen fermentation using an in vitro rumen simulation technology. Additionally, we tested the effects of SDG (0.20 g kg-1 body weight) on rumen development and production performance of lambs in a production setting. RESULTS: The in vitro addition of 100 mg L-1 SDG demonstrated significant regulatory effects, with a notable decrease in the acetate/propionate ratio (P < 0.05). Feeding trials revealed that SDG significantly increased average daily feed intake and average daily weight gain (P < 0.05), and reduced the acetate/propionate ratio (P < 0.05). This led to a significant increase in the relative abundance of Eubacterium ruminantium (P = 0.038) and Butyrivibrio (P = 0.002). Furthermore, it promoted rumen development and upregulated the relative expression of mRNA of Cyclin E1 and CDK2 in rumen epithelial cells (P < 0.05). CONCLUSION: The SDG extract optimizes the composition of rumen microbiota and the development of rumen epithelial cells, promoting the growth of pre-weaning lambs. The SDG additive exhibits potential as a novel growth promoter for ruminant animals, offering a promising solution for sustainable livestock production. © 2024 Society of Chemical Industry.

A comparative study on flaxseed lignan biotransformation through resting cell catalysis and microbial fermentation by ß-glucosidase production Lactiplantibacillus plantarum.

BACKGROUND: Flax lignan has attracted much attention because of its potential bioactivities. However, the bioavailability of secoisolariciresinol diglucoside (SDG), the main lignan in flaxseed, depends on the bioconversion by the colon bacteria. Lactic acid bacteria (LAB) with ß-glucosidase activity has found wide application in preparing bioactive aglycone. RESULTS: LAB strains with good ß-glucosidase activity were isolated from fermented tofu. Their bioconversion of flax lignan extract was investigated by resting cell catalysis and microbial fermentation, and the metabolism of SDG by Lactiplantibacillus plantarum C5 following fermentation was characterized by widely targeted metabolomics. Five L. plantarum strains producing ß-glucosidase with broad substrate specificity were isolated and identified, and they all can transform SDG into secoisolariciresinol (SECO). L. plantarum C5 resting cell reached a maximum SDG conversion of 49.19 ± 3.75%, and SECO generation of 21.49 ± 1.32% (0.215 ± 0.013 mm) at an SDG substrate concentration of 1 mM and 0.477 ± 0.003 mm SECO was produced at 4 mm within 24 h. Although sixteen flax lignan metabolites were identified following the fermentation of SDG extract by L. plantarum C5, among them, four were produced following the fermentation: SECO, demethyl-SECO, demethyl-dehydroxy-SECO and isolariciresinol. Moreover, seven lignans increased significantly. CONCLUSION: Fermentation significantly increased the profile and level of flax lignan metabolites, and the resting cell catalysis benefits from higher bioconversion efficiency and more straightforward product separation. Resting cell catalysis and microbial fermentation of flax lignan extract by the isolated ß-glucosidase production L. plantarum could be potentially applied in preparing flax lignan ingredients and fermented flaxseed. © 2024 Society of Chemical Industry.

Availability of dietary secoisolariciresinol diglucoside on borderline blood cholesterol level in men: a randomized, parallel, controlled, double-blinded clinical trial.

Borderline low-density lipoprotein cholesterol levels (120-139 mg/dl) increase the risk of cardiovascular disease. Therefore, the use of functional dietary nutrients is expected to control blood low-density lipoprotein cholesterol levels. This study aimed to evaluate the effect of dietary secoisolariciresinol diglucoside on blood cholesterol in healthy adults with borderline low-density lipoprotein cholesterol levels. A randomized, parallel, controlled, double-blinded clinical trial was performed for participants with borderline low-density lipoprotein cholesterol levels, for 12 weeks with secoisolariciresinol diglucoside (60 mg/day) or placebo. Lipid profile [low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio, total cholesterol, and triglycerides] and liver disease risk markers were measured at weeks 0, 4, 8, and 12. Analyzing 36 participants in each group revealed a significant interaction between treatment and time, indicating reduced low-density lipoprotein cholesterol (p = 0.049) and total cholesterol (p = 0.020) levels in secoisolariciresinol diglucoside-receiving men but not women. However, no significant differences were observed in other markers regardless of gender. The results suggest that a daily intake of 60 mg of secoisolariciresinol diglucoside lowers low-density lipoprotein cholesterol and total cholesterol levels in men with borderline low-density lipoprotein cholesterol, proposing secoisolariciresinol diglucoside potential as a functional dietary nutrient for cardiovascular disease prevention. This study was registered in the UMIN-CTR database (UMIN000046202).

Comparison of Yield Characteristics, Chemical Composition, Lignans Content and Antioxidant Potential of Experimentally Grown Six Linseed (Linum usitatissimum L.) Cultivars.

Linseed represents a rich source of nutritional, functional and health-beneficial compounds. Nevertheless, the chemical composition and content of bioactive compounds may be quite variable and potentially affected by various factors, including genotype and the environment. In this study, the proximate chemical composition, lignans content and antioxidant potential of six experimentally grown linseed cultivars were assessed and compared. A diagonal cultivation trial in the University of South Bohemia Experimental Station in Ceské Budejovice, Czech Republic, was established in three subsequent growing seasons (2018, 2019 and 2020). The results showed that the cultivar and growing conditions influenced most studied parameters. The lack of precipitation in May and June 2019 negatively affected the seed yield and the level of secoisolariciresinol diglucoside but did not decrease the crude protein content, which was negatively related to the oil content. The newly developed method for lignans analysis allowed the identification and quantification of secoisolariciresinol diglucoside and matairesinol. Their content correlated positively with the total polyphenol content and antioxidant assays (DPPH and ABTS radical scavenging activity), indicating the significant contribution to the biofunctional properties of linseed. On the other hand, we did not detect minor linseed lignans, pinoresinol and lariciresinol. The results of this study showed the importance of cultivar and growing conditions factors on the linseed chemical composition and the lignans content, determining its nutritional and medicinal properties.

[Suppression effect of secoisolariciresinol diglucoside against trans fatty acids-induced oxidative damage and inflammatory in brain of offspring mice].

OBJECTIVE: To probe into the protective effect of different dose of secoisolariciresinol diglucoside(SDG) on brain of offspring of mice anainst oxidative damage and inflammatory reaction induced by maternal exposure to trans fatty acids(TFA) during gestation, and observe the the changes of regulating Nrf2/Keap1 pathway in the course. METHODS: 30 healthy female mice(C57BL/6) were divided into 5 groups randomly, they are respectively control group, TFA-exposed group, and three SDG-intervention groups(low-(TFA+LSDG), medium-(TFA+MSDG) and high-(TFA+HSDG)). The pregnancy mice of control group and TFA group were treated with distilled water and 60 mg/kg·d TFA by gavage, in the same time, the mice of three SDG-intervention groups were treated with 60 mg/kg·d TFA by gavage and fed with feed included SDG(10, 20 and 30 mg/kg). The treatment to pregnancy mice continued to birth of offspring. After 21 days of lactation, the offspring were killed under anesthesia and the experiment was ended. The coefficient of brain was calculated. The levels of superoxide dismutase(SOD), glutathione peroxidase(GSH-Px), malondialdehyde(MDA), tumor necrosis factor-α(TNF-α), interferon-γ(IFN-γ) and amyloid-ß(Aß)of brain were detected. RT-PCR and Western Blot was used to detected gene expression and protein levels of nuclear factor erythroid-2 related factor 2(Nrf2), kelch-like ECH-associated protein 1(Keap1), quinone oxidoreductase 1(NQO1) and hemeoxygenase-l(HO-1). RESULTS: Compared with control group, the brain coefficient and Aß1-40 of offspring of TFA-group had no significant changes(P>0.05), the activity of SOD and GSH-Px reduced, the content of MDA, IFN-γ, TNF-α and Aß1-42 increased, the level of mRNA and protein expression of Nrf2, NQO1 and HO-1 decreased and the level of mRNA and protein expression of Keap1 increase because of the exposion to TFA during gestation and all the differences were statistically significant(P<0.05). Compared with TFA-group, the brain coefficient, Aß1-40 and the level of NQO1 mRNA of offspring of three SDG-intervention groups had no significant changes(P>0.05), the activity of SOD(the middle and high dose SDG intervention groups) and GSH-Px(three SDG-intervention groups) increased, the content of MDA(the middle and high dose SDG intervention groups), IFN-γ(the middle and high dose SDG intervention groups), TNF-α(three SDG-intervention groups) and Aß1-42(the middle and high dose SDG intervention groups) decreased, the mRNA expression of Nrf2 and HO-1(the middle and high dose SDG intervention groups) was up-regulated, the mRNA expression of Keap1(the middle and high dose SDG intervention group) decreased, proteic expression of Nrf2, NQO1 and HO-1 of three SDG-intervention groups increase and the level of protein of Keap1 decreased because of the intervention of SDG during gestation(P<0.05). CONCLUSION: These result suggest that maternal TFA exposure during gestation can result in oxidative stress and inflammation to brain of offspring in a way. SDG can protect brain of mice of offspring from TFA-induced oxidative injury by up-regulating the expression of mRNA and protein of Nrf2, down-regulating the expression of Keap1, accelerating expression of protein of NQO1 and HO-1 which are antioxidant protein lying downstream of pathway of Nrf2/Keap1.

Availability of bioactive flax lignan from foods and supplements.

Hyperlipidemia, high levels of blood lipids including cholesterol and triglycerides, is a major risk factor for cardiovascular disease. Traditional treatments of hyperlipidemia often include lifestyle changes and pharmacotherapy. Recently, flaxseed has been approved as a nutrient that lowers blood lipids. Several metabolites of flaxseed lignan secoisolariciresinol diglucoside (SDG), have been identified that reduce blood lipids. SDG is present in flaxseed hull as an ester-linked copolymer with 3-hydroxy-3-methylglutaric acid (HMGA). However, purification processes involved in hydrolysis of the copolymer and enriching SDG are often expensive. The natural copolymer of SDG with HMGA (SDG polymer) is a source of bioactive compounds useful in prophylaxis of hypercholesterolemia. After consumption of the lignan copolymer, SDG and HMGA are released in the stomach and small intestines. SDG is metabolized to secoisolariciresinol, enterolactone and enterodiol, the bioactive forms of mammalian lignans. These metabolites are then distributed throughout the body where they accumulate in the liver, kidney, skin, other tissues, and organs. Successively, these metabolites reduce blood lipids including cholesterol, triglycerides, low density lipoprotein cholesterol, and lipid peroxidation products. In this review, the metabolism and efficacies of flaxseed-derived enriched SDG and SDG polymer will be discussed.

Amelioration of oxidative kidney damage in offspring by maternal trans-fatty acid exposure in mice by secoisolariciresinol diglucoside. / äºšéº»æœ¨é šç´ å¯¹æ¯é¼ åå¼è„‚è‚ªé ¸æš´éœ²è‡´å­ä»£è‚¾æ°§åŒ–æŸä¼¤çš„ä¿æŠ¤ä½œç”¨.

OBJECTIVES: Trans-fatty acids (TFAs), primarily derived from the food industry's production processes, have become a globally recognized public health issue due to the detrimental impact they have on human well-being. Secoisolariciresinol diglucoside (SDG) is a polyphenolic compound derived from flax lignans, possessing antioxidative properties. This study aims to investigate the protective effect of SDG on kidney oxidative damage in offspring of mice caused by maternal exposure to TFA during pregnancy and lactation. METHODS: A total of 30 c57BL/6 female rats were randomly divided into 5 groups: a control group, a TFA-exposed group, a low-(TFA+LSDG) group, a medium-(TFA+MSDG) group, and a high-(TFA+HSDG) group (n=6 in each group). With the exception of the control group, the maternal mice in the remaining 4 groups received a daily oral gavage of TFA at a dosage of 60 mg/(kg·BW) throughout the experimental period. The mothers in the control group were administered physiological saline via oral gavage once daily. Meanwhile, the 3 SDG intervention groups were provided with ad libitum access to SDG feed containing 10 mg/kg (low), 20 mg/kg (medium), and 30 mg/kg (high) of SDG. The female mice were conceived overnight. If the vaginal plug appeared in the next morning, the female mice were conceived and included in the experimental stage until the end of the 21th day lactation period. The body weight and kidney mass of offspring were recorded, and the kidney coefficient was calculated. The kidney was detected by HE staining to observe the histopathological changes, and the level of reactive oxidative species (ROS) was detected by fluorescence probe-dihydroethidium (DHE) staining; the expression levels of total superoxide dismutase (T-SOD) and malondialdehyde (MDA) in renal homogenate were detected, and the expression of nuclear factor E2-related fator2 (Nrf2) and hemeoxygenase-1 (HO-1) protein was analyzed by immunohistochemistry (IHC) staining. The mRNA expressions of Nrf2 and HO-1 were detected by real-time PCR, and the protein expression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD), Mn-superoxide dismutase (Mn-SOD), glutathione peroxidase-1 (GPx-1), Nrf2 and HO-1 were detected by Western blotting. RESULTS: Compared with the control group, the kidney coefficient in the TFA-exposed group was increased, the morphology and structure of kidney tissue was abnormal; the activity of T-SOD enzyme was decreased, and the content of MDA was increased, the level of ROS was increased; the expressions of Cu/Zn-SOD, Mn-SOD, GPx1 protein were decreased, and the mRNA and protein expressions of Nrf2 and HO-1 were decreased, there were all significant difference (all P<0.05). Compared with the TFA-exposed group, the ROS levels were reduced, and the T-SOD enzyme activity as well as the protein expression of Cu/Zn-SOD, GPx-1, Mn-SOD, Nrf2 and HO-1 were up-regulated in the low, middle and high dose SDG intervention groups; the kidney coefficient and MDA content were decreased in the middle and high dose SDG groups; the Nrf2 mRNA expression in the high dose SDG group was up-regulated, there were all significant difference (all P<0.05). CONCLUSIONS: Maternal exposure to TFA during pregnancy and lactation can lead to oxidative damage in the kidney of offspring, and the SDG intervention may alleviate TFA-induced oxidative damage by up-regulating the expression of Nrf2 and HO-1 signal pathway.

A review of flaxseed lignan and the extraction and refinement of secoisolariciresinol diglucoside.

Lignan is a class of diphenolic compounds that arise from the condensation of two phenylpropanoid moieties. Oilseed and cereal crops (e.g., flaxseed, sesame seed, wheat, barley, oats, rye, etc.) are major sources of plant lignan. Methods for commercial isolation of the lignan secoisolariciresinol diglucoside (SDG) are not well reported, as most publications describing the detection, extraction, and enrichment of SDG use methods that have not been optimized for commercial scale lignan recovery. Simply scaling up laboratory methods would require expensive infrastructure to achieve a marketable yield and reproducible product quality. Therefore, establishing standard protocols to produce SDG and its derivatives on an industrial scale is critical to decrease lignan cost and increase market opportunities. This review summarizes the human health benefits of flaxseed lignan consumption, lignan physicochemical properties, and mammalian lignan metabolism, and describes methods for detecting, extracting, and enriching flaxseed lignan. Refining and optimization of these methods could lead to the development of inexpensive lignan sources for application as an ingredient in medicines, dietary supplements, and other healthy ingredients.

Secoisolariciresinol diglucoside induces pyroptosis by activating caspase-1 to cleave GSDMD in colorectal cancer cells.

Secoisolariciresinol diglucoside (SDG) is the main component of lignans with various biological activities, including anticancer activity. However, whether SDG has obvious anticancer effects on colorectal cancer (CRC) is unclear. Pyroptosis, a form of programmed cell death, has received increasing attention in cancer-related research. In this study, we aimed to test the anticancer properties and relatecd functional mechanisms of SDG. we found that SDG not only inhibited the cell viability of HCT116 cells, but also induced HCT116 cells to swell with apparent large bubbles, which are typical signs of pyroptosis. Furthermore, SDG induced cell pyroptosis by enhancing cleavage of the N-terminal fragment of gasdermin D (GSDMD) in CRC cells, accompanied by increased caspase-1 cleavage. Consistent with this, SDG-induced GSDMD-N-terminal fragment cleavage and pyroptosis were reduced by siRNA-mediated silencing of caspase-1 or treatment with the specific caspase-1 inhibitor VX-765 treatment, suggesting that active caspase-1 further induces pyroptosis. A mechanistic study showed that SDG induced reactive oxygen species (ROS) accumulation and inhibits phosphatidylinositol 3-kinase (PI3K) phosphorylation and increases pyroptosis, while increasing GSDMD and caspase-1 cleavage and enhancing expression of BCL2-associated X (BAX), which could be rescued by the ROS scavenger (NAC), suggesting that SDG-induced GSDME-dependent pyroptosis is related to the ROS/PI3K/AKT/BAX-mitochondrial apoptotic pathway. In vivo results showed that SDG significantly inhibited tumor growth and induced pyroptosis in the HCT116-CRC nude mouse model. In conclusion, our findings suggest that the anticancer activity of SDG in CRC is associated with the induction of GSDMD-dependent pyroptosis by SDG through the generation of ROS/P13K/AKT/BAK-mitochondrail apoptosis pathway, providing insights into SDG in its potential new application in cancer treatment.