Structural Modifications of a Flaxseed Lignan in Pursuit of Higher Liposolubility: Evaluation of the Antioxidant and Permeability Properties of the Resulting Derivatives

Flaxseed powder supplementation in non-alcoholic fatty liver disease: a randomized controlled clinical trial

Background: Non-alcoholic fatty liver disease (NAFLD) has become a growing public health problem worldwide, and dietary interventions have important potential in the prevention and treatment of NAFLD. Moreover, previous animal studies have shown that flaxseed has a good improvement effect in animal NAFLD models. Objectives: Assess whether flaxseed powder could improve the liver lipid content in patients with NAFLD. Methods: In this 12-week randomized controlled clinical trial, 50 patients were randomly assigned to the flaxseed group (n = 25) and the control group (n = 25). The flaxseed group received 30 g d-1 flaxseed powder orally before lunch or dinner along with health education, while the control group received only health education. The primary outcome was the intrahepatic lipid content assessed by the proton density fat fraction estimated by magnetic resonance imaging, and secondary outcomes were body composition measurements, liver function, and glucolipid metabolism. Results: Patients in the flaxseed group showed significantly lower liver fat content, body fat percentage, obesity index, visceral fat area, serum total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL), aspartate aminotransferase (AST), total cholesterol (TC), and triglyceride (TG) levels after a 12-week intervention compared to pre-intervention levels, while serum apolipoprotein A1 (Apo A1) and high-density lipoprotein cholesterol (HDL-C) levels were significantly increased, with all differences being statistically significant (P < 0.05). Analysis of the gut microbiota showed that, at the phylum level, flaxseed intervention significantly increased the abundance of Bacteroides and Actinobacteria, while decreasing the ratio of Firmicutes to Bacteroidetes. At the genus level, the relative abundance of Clostridium_sensu_stricto_1, Parasutterella, Lachnospiraceae_NK4A136_group, Eubacterium_xylanophilum_group, and Bifidobacterium in the gut microbiota of the flaxseed group was significantly higher than that of the control group (P < 0.05), whereas the relative abundance of Coriobacteriaceae_UCG-002 was significantly lower than that of the control group (P < 0.05). Conclusions: Flaxseed powder intervention for 12 weeks had the effect of improving liver lipid deposition, liver function, body composition indicators, and lipid metabolism in patients with NAFLD. It also regulated the gut microbiota in NAFLD patients, increasing the abundance of beneficial bacteria while reducing harmful bacteria. This suggested that flaxseed is one of the natural and effective foods for improving NAFLD.

Unveiling the Power of Flax Lignans: From Plant Biosynthesis to Human Health Benefits

BACKGROUND

Flax (Linum usitatissimum L.) is the richest plant source of lignin secondary metabolites. Lignans from flax have been applied in the fields of food, medicine, and health due to their significant physiological activities. The most abundant lignan is secoisolariciresinol, which exists in a glycosylated form in plants.

RESULTS

After ingestion, it is converted by human intestinal flora into enterodiol and enterolactone, which both have physiological roles. Here, the basic structures, contents, synthesis, regulatory, and metabolic pathways, as well as extraction and isolation methods, of flax lignans were reviewed. Additionally, the physiological activity-related mechanisms and their impacts on human health, from the biosynthesis of lignans in plants to the physiological activity effects observed in animal metabolites, were examined.

CONCLUSIONS

The review elucidates that lignans, as phenolic compounds, not only function as active substances in plants but also offer significant nutritional values and health benefits when flax is consumed.

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.

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.

Review of lignans from 2019 to 2021: Newly reported compounds, diverse activities, structure-activity relationships and clinical applications

Lignans, with various biological activities, such as antitumor, antioxidant, antibacterial, and antiviral activities, are widely distributed in nature and mainly exist in the xylem of plants. In this paper, we summarized the structures and bioactivities of lignans reported in recent years (2019-2021) from five parts, including (1) a summary and classification of newly reported compounds; (2) the pharmacological activities of lignans; (3) molecular resources and activity distribution; (4) the structure-activity relationships; and (5) the clinical application of lignans. This review covers all undescribed compounds that were reported within the covered period of time and all bioactivity data about previously isolated lignans. The distribution of lignans in different plants and families is visualized, which improves the efficiency of searching for specific molecules. The diverse activities of different types of lignans provide an important reference for the rapid screening of these compounds. Discussion about the structure-activity relationships of lignans provides a direction for the structural modification of skeleton molecules. Combined with the clinical application of such molecules, this work will provide a valuable reference for pharmaceutical chemists.

Evaluation of the Antioxidant and Antiradical Properties of Some Phyto and Mammalian Lignans

In this study, the antioxidant and antiradical properties of some phyto lignans (nordihydroguaiaretic acid, secoisolariciresinol, secoisolariciresinol diglycoside, and α-(-)-conidendrin) and mammalian lignans (enterodiol and enterolactone) were examined by different antioxidant assays. For this purpose, radical scavenging activities of phyto and mammalian lignans were realized by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical (ABTS^•+) scavenging assay and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging assay. Additionally, the reducing ability of phyto and mammalian lignans were evaluated by cupric ions (Cu²⁺) reducing (CUPRAC) ability, and ferric ions (Fe³⁺) and [Fe³⁺-(TPTZ)2]³⁺ complex reducing (FRAP) abilities. Also, half maximal inhibitory concentration (IC₅₀) values were determined and reported for DPPH^• and ABTS^•+ scavenging influences of all of the lignan molecules. The absorbances of the lignans were found in the range of 0.150–2.320 for Fe³⁺ reducing, in the range of 0.040–2.090 for Cu²⁺ reducing, and in the range of 0.360–1.810 for the FRAP assay. On the other hand, the IC₅₀ values of phyto and mammalian lignans were determined in the ranges of 6.601–932.167 µg/mL for DPPH^• scavenging and 13.007–27.829 µg/mL for ABTS^•+ scavenging. In all of the used bioanalytical methods, phyto lignans, as secondary metabolites in plants, demonstrated considerably higher antioxidant activity compared to that of mammalian lignans. In addition, it was observed that enterodiol and enterolactone exhibited relatively weaker antioxidant activities when compared to phyto lignans or standard antioxidants, including butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), Trolox, and α-tocopherol.

Exploiting Nature's Most Abundant Polymers: Developing New Pathways for the Conversion of Cellulose, Hemicellulose, Lignin and Chitin into Platform Molecules (and Beyond)

The four most prominent forms of biomass are cellulose, hemicellulose, lignin and chitin. In efforts to develop sustainable sources of platform molecules there has been an increasing focus on examining how these biopolymers could be exploited as feedstocks that support the chemical supply chain, including in the production of fine chemicals. Many different approaches are possible and some of the ones being developed in the authors' laboratories are emphasised.