Metabolism of flavonoids and lignans by lactobacilli and bifidobacteria strains improves the nutritional properties of flaxseed-enriched beverages

Characterization and stabilization of GluLm and its application to deglycosylate dietary flavonoids and lignans

This study describes the characterization of the recombinant GH3 aryl-β-glucosidase "GluLm" from Limosilactobacillus mucosae INIA P508, followed by its immobilization on an agarose support with the aim of developing an efficient application to increase the availability and concentration of flavonoid and lignan aglycones in a vegetal beverage. In previous studies, heterologous GluLm-producing strains demonstrated a great capacity to deglycosylate flavonoids. Nevertheless, the physicochemical properties and substrate spectrum of the enzyme remained unknown up to now. A high production of purified GluLm was achieved (14 mg L-1). GluLm exhibited optimal activity at broad ranges of pH (5.0-8.0) and temperature (25-60°C), as well as high affinity (Km of 0.10 mmol L-1) and specific constant (86554.0 mmol L-1 s-1) against p-nitrophenyl-β-D-glucopyranoside. Similar to other GH3 β-glucosidases described in lactic acid bacteria, GluLm exhibited β-xylosidase, β-galactosidase, and β-fucosidase activities. However, this study has revealed for the first time that a GH3 β-glucosidase is capable to hydrolyze different families of glycosylated phenolics such as flavonoids and secoiridoids. Although it exhibited low thermal stability, immobilization of GluLm improved its thermostability and allowed the development of a beverage based on soybeans and flaxseed extract with high concentration of bioactive isoflavone (daidzein, genistein), lignan (secoisolariciresinol, pinoresinol, and matairesinol), and other flavonoid aglycones. KEY POINTS: • Limosilactobacillus mucosae INIA P508 GluLm was purified and biochemically characterized • Immobilized GluLm efficiently deglycosylated flavonoids and lignans from a vegetal beverage • A viable application to produce vegetal beverages with a high content of aglycones is described.

Bioconversion of lignans in flaxseed cake by fermented tofu microbiota and isolation of Enterococcus faecium strain ZB26 responsible for converting secoisolariciresinol diglucoside to enterodiol

Human intestinal microbiota plays a crucial role in converting secoisolariciresinol diglucoside, a lignan found in flaxseed, to enterodiol, which has a range of health benefits: antioxidative, antitumor, and estrogenic/anti-estrogenic effects. Given the high secoisolariciresinol diglucoside content in flaxseed cake, this study investigated the potential of co-fermenting flaxseed cake with fermented soybean product to isolate bacterial strains that effectively convert secoisolariciresinol diglucoside to enterodiol in a controlled environment (in vitro). The co-fermentation process with stinky tofu microbiota significantly altered the lignan, generating 12 intermediate lignan metabolites as identified by targeted metabolomics. One particular promising strain, ZB26, demonstrated an impressive ability to convert secoisolariciresinol diglucoside. It achieved a conversion rate of 87.42 ± 0.33%, with secoisolariciresinol and enterodiol generation rates of 94.22 ± 0.51% and 2.91 ± 0.03%, respectively. Further optimization revealed, under specific conditions (0.5 mM secoisolariciresinol diglucoside, pH 8, 30 °C for 3 days), ZB26 could convert an even higher percentage (97.75 ± 0.05%) of the secoisolariciresinol diglucoside to generate secoisolariciresinol (103.02 ± 0.16%) and enterodiol (3.18 ± 0.31%). These findings suggest that the identified strains ZB26 have promising potential for developing functional foods and ingredients enriched with lignans.

A comparative study on flaxseed lignan biotransformation through resting cell catalysis and microbial fermentation by β-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 β-glucosidase activity has found wide application in preparing bioactive aglycone.

RESULTS

LAB strains with good β-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 β-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 β-glucosidase production L. plantarum could be potentially applied in preparing flax lignan ingredients and fermented flaxseed. © 2024 Society of Chemical Industry.

Anti-inflammatory effect of lignans from flaxseed after fermentation by lactiplantibacillus plantarum SCB0151 in vitro

Lignan, a beneficial constituent of Flaxseed (Linum usitatissimum L.) showed great interest in researchers because of its multiple functional properties. Nonetheless, a challenge arises due to the glycosidic structure of lignans, which the gut epithelium cannot readily absorb. Therefore, we screened 18 strains of Lactiplantibacillus plantarum, Lacticaseibacillus casei, Lactobacillus acidophilus, Lacticaseibacillus rhamnosus, Pediococcus pentosaceus, Pediococcus acidilactici, and Enterococcus durans to remove glycosides from flaxseed lignan extract enzymatically. Among our findings, Lactiplantibacillus plantarum SCB0151 showed the highest activity of β-glucosidase (8.91 ± 0.04 U/mL) and higher transformed efficiency of Secoisolariciresinol (SECO) (8.21 ± 0.13%). The conversion rate of Secoisolariciresinol diglucoside (SDG) and the generation rate of SECO was 58.30 ± 3.78% and 32.13 ± 2.78%, respectively, under the optimized conditions. According to the LC-HRMSMS analysis, SECO (68.55 ± 6.57 µM), Ferulic acid (FA) (32.12 ± 2.50 µM), and Coumaric acid (CA) (79.60 ± 6.21 µM) were identified in the biotransformation products (TP) of flaxseed lignan extract. Results revealed that the TP exhibited a more pronounced anti-inflammatory effect than the flaxseed lignan extract. SECO, FA, and CA demonstrated a more inhibitory effect on NO than that of SDG. The expression of iNOS and COX-2 was significantly suppressed by TP treatment in LPS-induced Raw264.7 cells. The secretion of IL-6, IL-2, and IL-1β decreased by 87.09 ± 0.99%, 45.40 ± 0.87%, and 53.18 ± 0.83%, respectively, at 60 µg/mL of TP treatment. Given these data, the bioavailability of flaxseed lignan extract and its anti-inflammatory effect were significantly enhanced by Lactiplantibacillus plantarum SCB0151, which provided a novel approach to commercializing flaxseed lignan extract for functional food.

Relationships between Habitual Polyphenol Consumption and Gut Microbiota in the INCLD Health Cohort

While polyphenol consumption is often associated with an increased abundance of beneficial microbes and decreased opportunistic pathogens, these relationships are not completely described for polyphenols consumed via habitual diet, including culinary herb and spice consumption. This analysis of the International Cohort on Lifestyle Determinants of Health (INCLD Health) cohort uses a dietary questionnaire and 16s microbiome data to examine relationships between habitual polyphenol consumption and gut microbiota in healthy adults (n = 96). In this exploratory analysis, microbial taxa, but not diversity measures, differed by levels of dietary polyphenol consumption. Taxa identified as exploratory biomarkers of daily polyphenol consumption (mg/day) included Lactobacillus, Bacteroides, Enterococcus, Eubacterium ventriosum group, Ruminococcus torques group, and Sutterella. Taxa identified as exploratory biomarkers of the frequency of polyphenol-weighted herb and spice use included Lachnospiraceae UCG-001, Lachnospiraceae UCG-004, Methanobrevibacter, Lachnoclostridium, and Lachnotalea. Several of the differentiating taxa carry out activities important for human health, although out of these taxa, those with previously described pro-inflammatory qualities in certain contexts displayed inverse relationships with polyphenol consumption. Our results suggest that higher quantities of habitual polyphenol consumption may support an intestinal environment where opportunistic and pro-inflammatory bacteria are represented in a lower relative abundance compared to those with less potentially virulent qualities.

Corinthian Currants Supplementation Restores Serum Polar Phenolic Compounds, Reduces IL-1beta, and Exerts Beneficial Effects on Gut Microbiota in the Streptozotocin-Induced Type-1 Diabetic Rat

The present study aimed at investigating the possible benefits of a dietary intervention with Corinthian currants, a rich source of phenolic compounds, on type 1 diabetes (T1D) using the animal model of the streptozotocin-(STZ)-induced diabetic rat. Male Wistar rats were randomly assigned into four groups: control animals, which received a control diet (CD) or a diet supplemented with 10% w/w Corinthian currants (CCD), and diabetic animals, which received a control diet (DCD) or a currant diet (DCCD) for 4 weeks. Plasma biochemical parameters, insulin, polar phenolic compounds, and inflammatory factors were determined. Microbiota populations in tissue and intestinal fluid of the caecum, as well as fecal microbiota populations and short-chain fatty acids (SCFAs), were measured. Fecal microbiota was further analyzed by 16S rRNA sequencing. The results of the study showed that a Corinthian currant-supplemented diet restored serum polar phenolic compounds and decreased interleukin-1b (IL-1b) (p < 0.05) both in control and diabetic animals. Increased caecal lactobacilli counts (p < 0.05) and maintenance of enterococci levels within normal range were observed in the intestinal fluid of the DCCD group (p < 0.05 compared to DCD). Higher acetic acid levels were detected in the feces of diabetic rats that received the currant diet compared to the animals that received the control diet (p < 0.05). Corinthian currant could serve as a beneficial dietary component in the condition of T1D based on the results coming from the animal model of the STZ-induced T1D rat.

Antioxidant activity and phytochemical analysis of fennel seeds and flaxseed

Natural herbs are now receiving more attention due to the growing demand for their antioxidant properties. This study compared flaxseed and fennel seeds for their nutritional composition, bioactive moieties, and antioxidant activity-the study comprised two different phases. According to methods, phase I analyzed flaxseed and fennel seeds for proximate composition, mineral profile, dietary fiber, and amino acid content. In phase II, seeds were extracted using three different solvents, i.e., ethanol 80%, acetone 80%, and distilled water, to probe the total phenolic and flavonoid content. Antioxidant activity was measured using DPPH and a FRAP in the final phase. Current study revealed that flaxseed had higher protein (17.33 ± 0.02%), fat content (36.76 ± 0.02%), potassium (763.66 ± 4.04 mg/100 g), iron (5.13 ± 0.03 mg/100 g), phosphorus (581.46 ± 4.07 mg/100 g), magnesium (406.60 ± 5.12 mg/100 g), and zinc (3.30 ± 0.49 mg/100 g), respectively. In fennel seed, high dietary fiber (53.2 ± 0.01 g/100 mg), calcium, manganese, and sodium (588.93 ± 7.77, 20.30 ± 0.95, and 57.34 ± 0.33 mg/100 g, respectively) were found. Acetone showed better extraction efficiency than acetone, ethanol, and distilled water. Moreover, acetone flaxseed extract showed higher total phenolic content (84.13 ± 7.73 mgGAE/g), flavonoid content (5.11 ± 1.50 mgQE/g), and FRAP (5031 ± 15.92 μMFe^2+/g) than fennel seed extract. This study showed that, among both herbs, flaxseed extract may have pharmacological potential in preventing illnesses and may be suggested for use in the food industry as a natural antioxidant.

Transcriptomics and metabolomics reveal tolerance new mechanism of rice roots to Al stress

The prevalence of soluble aluminum (Al) ions is one of the major limitations to crop production worldwide on acid soils. Therefore, understanding the Al tolerance mechanism of rice and applying Al tolerance functional genes in sensitive plants can significantly improve Al stress resistance. In this study, transcriptomics and metabolomics analyses were performed to reveal the mechanism of Al tolerance differences between two rice landraces (Al-tolerant genotype Shibanzhan (KR) and Al-sensitive genotype Hekedanuo (MR) with different Al tolerance. The results showed that DEG related to phenylpropanoid biosynthesis was highly enriched in KR and MR after Al stress, indicating that phenylpropanoid biosynthesis may be closely related to Al tolerance. E1.11.1.7 (peroxidase) was the most significant enzyme of phenylpropanoid biosynthesis in KR and MR under Al stress and is regulated by multiple genes. We further identified that two candidate genes Os02g0770800 and Os06g0521900 may be involved in the regulation of Al tolerance in rice. Our results not only reveal the resistance mechanism of rice to Al stress to some extent, but also provide a useful reference for the molecular mechanism of different effects of Al poisoning on plants.

Composition, processing, and quality control of whole flaxseed products used to fortify foods

Whole flaxseed (flour) as a good source of omega-3 fatty acid and phytochemicals with excellent nutritional and functional attributes has been used to enrich foods for health promotion and disease prevention. However, several limitations and contemporary challenges still impact the development of whole flaxseed (flour)-enriched products on the global market, such as naturally occurring antinutritional factors and entrapment of nutrients within food matrix. Whole flaxseed (flour) with different existing forms could variably alter the techno-functional performance of food matrix, and ultimately affect the edible qualities of fortified food products. The potential interaction mechanism between the subject and object components in fortified products has not been elucidated yet. Hence, in this paper, the physical structure and component changes of flaxseed (flour) by pretreatments coupled with their potential influences on the edible qualities of multiple fortified food products were summarized and analyzed. In addition, several typical food products, including baked, noodle, and dairy products were preferentially selected to investigate the potential influencing mechanisms of flaxseed (flour) on different substrate components. In particular, the altered balance between water absorption of flaxseed protein/gum polysaccharides and the interruption of gluten network, lipid lubrication, lipid-amylose complexes, syneresis, and so forth, were thoroughly elucidated. The overall impact of incorporating whole flaxseed (flour) on the quality and nutritional attributes of fortified food products, coupled with the possible solutions against negative influences are aimed. This paper could provide useful information for expanding the application of whole flaxseed (flour) based on the optimal edible and nutritional properties of fortified food products.

The fate of flaxseed-lignans after oral administration: A comprehensive review on its bioavailability, pharmacokinetics, and food design strategies for optimal application

Lignans are one of the most important and abundant phytochemicals found in flaxseed-diets. These have shown to possess several health-benefits, including anticancer, antioxidant, neuroprotective, cardioprotective, and estrogenic-properties etc. The potential of lignans health-promoting effects are circumscribed due to their poor-bioavailability resulting from their bound structure. Recent studies have demonstrated that various food design strategies can enhance the release of bound-lignans from agro-industrial residues, resulting in a higher bioaccessibility and bioavailability. This review focuses primarily on the bioavailability of flaxseed lignans, key factors affecting it and their pharmacokinetics, different strategies to improve the contents of lignans, their release and delivery. Present study will help to deepen our understanding of the applications of lignans and their dietary-supplements in the prevention and treatment of diseases. Several absorption issues of lignans have been observed such as impaired-bioavailability and variability in pharmacokinetics and pharmacodynamics. Therefore, the development of novel strategies for optimizing lignan bioavailability is critical to ensure its successful application, such as the delivery of lignans to biological targets via "targeted designs." In addition, some detailed examination is required to identify and understand the basis of variation in lignans bioavailability caused by interactions with the gastrointestinal system.

Secoisolariciresinol diglucoside-derived metabolite, enterolactone, attenuates atopic dermatitis by suppressing Th2 immune response

Atopic dermatitis (AD) is a severe inflammatory skin disease caused by a combination of genetic, immune, and environmental factors. Intestinal microbiome disorders and changes in the immune microenvironment are associated with AD. We observed that gut bacterial metabolite enterolactone (ENL) was significantly reduced in AD model mice. Notably, patients with early childhood-onset AD exhibited decreased sera ENL level compared to the healthy controls, and the ENL level was negatively correlated with the SCORAD index. Secoisolariciresinol-diglycoside (SDG) is a natural dietary lignan of flaxseeds that can be converted by intestinal bacteria to ENL. Repeated applications of 2,4-dinitrochlorobenzene (DNCB) were performed on the ear and dorsal skin of mice to induce AD-like symptoms and skin lesions. Oral administration of SDG significantly decreased serum IgE levels and limited skin inflammation in the DNCB-induced AD mice. In addition, SDG treatment strongly limited the Th2 responses in AD mice. Moreover, we demonstrated that the IL-4 production was significantly suppressed by ENL under Th2 polarization conditions via the JAK-STAT6 signaling pathway in a concentration-dependent manner. We concluded that SDG and its derived metabolite ENL ameliorated AD development by reducing the Th2 immune response. These results suggested that SDG and ENL might be exploited as potential therapeutic candidates for AD treatment.

In vitro gastrointestinal bioaccessibility and colonic fermentation of lignans from fresh, fermented, and germinated flaxseed

Fermented flaxseed improves lignan (SECO) bioaccessibility in the gastrointestinal phase, release and conversion to enterolactone during colon fermentation.

Strategies to achieve significant physiological concentrations of bioactive phytoestrogens in plasma

The benefits to health attributed to the intake of phytoestrogens (PEs) have been demonstrated in previous studies with significant physiological concentrations of bioactive PEs, such as genistein, equol, enterolignans and urolithins in plasma. However, the achievement of high bioactive PE levels in plasma is restricted to a select population group, mainly due to the low intake of plant PEs and/or the absence, or inhibition, of the microbiota capable of producing these bioactive forms. In this study, the intake of plant PEs, the concentration of bioactive PEs in plasma, the ability of the intestinal microbiota to produce bioactive PEs, as well as the different mechanisms used by GRAS bacteria to increase the level of bioactive PEs were evaluated concluding that the use of GRAS bacteria bioactive PE producers and the development of fermented foods enriched in bioactive PEs in addition to a high intake of plant PEs and taking care of the intestinal microbiota, are some of the different strategies to achieve significant physiological concentrations of bioactive PEs in the intestine and, subsequently, in plasma and targets organs which are essential to improve menopausal symptoms or reduce the risk of some pathologies such as breast and colon cancer, or cardiovascular disease.