Safety evaluation of the human-identical milk monosaccharide, l-fucose

Research progress on the functions, preparation and detection methods of l-fucose

l-fucose is a six-carbon sugar that has potential applications in many fields. It exerts antitumor effects and could relieve intestinal disease. It exhibits potential as an emulsifier in the food industry. It is also used as a functional food and in anti-aging skincare products. However, at present, it is not possible to prepare high-purity l-fucose on a large scale, and its preparation needs further development. This review summarizes the preparation methods of l-fucose including chemical synthesis, enzymatic synthesis, microbial fermentation, and separation and purification from algae. The detection methods of l-fucose are also introduced in detail, such as l-fucose-specific lectin, detection l-fucose dehydrogenase, cysteine-sulfuric acid method, high-performance liquid chromatography, gas chromatography, and biosensors. In this review, the properties and pharmacological effects of l-fucose; preparation methods, and the commonly used detection methods of l-fucose are reviewed to serve as a reference material.

Exogenous l-fucose attenuates neuroinflammation induced by lipopolysaccharide

α1,6-Fucosyltransferase (Fut8) catalyzes the transfer of fucose to the innermost GlcNAc residue of N-glycan to form core fucosylation. Our previous studies showed that lipopolysaccharide (LPS) treatment highly induced neuroinflammation in Fut8 homozygous KO (Fut8-/-) or heterozygous KO (Fut8+/-) mice, compared with the WT (Fut8+/+) mice. To understand the underlying mechanism, we utilized a sensitive inflammation-monitoring mouse system that contains the human interleukin-6 (hIL6) bacterial artificial chromosome transgene modified with luciferase (Luc) reporter cassette. We successfully detected LPS-induced neuroinflammation in the central nervous system by exploiting this bacterial artificial chromosome transgenic monitoring system. Then we examined the effects of l-fucose on neuroinflammation in the Fut8+/- mice. The lectin blot and mass spectrometry analysis showed that l-fucose preadministration increased the core fucosylation levels in the Fut8+/- mice. Notably, exogenous l-fucose attenuated the LPS-induced IL-6 mRNA and Luc mRNA expression in the cerebral tissues, confirmed using the hIL6-Luc bioluminescence imaging system. The activation of microglial cells, which provoke neuroinflammatory responses upon LPS stimulation, was inhibited by l-fucose preadministration. l-Fucose also suppressed the downstream intracellular signaling of IL-6, such as the phosphorylation levels of JAK2 (Janus kinase 2), Akt (protein kinase B), and STAT3 (signal transducer and activator of transcription 3). l-Fucose administration increased gp130 core fucosylation levels and decreased the association of gp130 with the IL-6 receptor in Fut8+/- mice, which was further confirmed in BV-2 cells. These results indicate that l-fucose administration ameliorates the LPS-induced neuroinflammation in the Fut8+/- mice, suggesting that core fucosylation plays a vital role in anti-inflammation and that l-fucose is a potential prophylactic compound against neuroinflammation.

COVID-19 mRNA vaccine-mediated antibodies in human breast milk and their association with breast milk microbiota composition

Newborns can acquire immunological protection to SARS-CoV-2 through vaccine-conferred antibodies in human breast milk. However, there are some concerns around lactating mothers with regards to potential short- and long-term adverse events and vaccine-induced changes to their breast milk microbiome composition, which helps shape the early-life microbiome. Thus, we sought to explore if SARS-CoV-2 mRNA vaccine could change breast milk microbiota and how the changes impact the levels of antibodies in breast milk. We recruited 49 lactating mothers from Hong Kong who received two doses of BNT162b2 vaccine between June 2021 and August 2021. Breast milk samples were self-collected by participants pre-vaccination, one week post-first dose, one week post-second dose, and one month post-second dose. The levels of SARS-CoV-2 spike-specific IgA and IgG in breast milk peaked at one week post-second dose. Subsequently, the levels of both antibodies rapidly waned in breast milk, with IgA levels returning to baseline levels one month post-second dose. The richness and composition of human breast milk microbiota changed dynamically throughout the vaccination regimen, but the abundances of beneficial microbes such as Bifidobacterium species did not significantly change after vaccination. Additionally, we found that baseline breast milk bacterial composition can predict spike-specific IgA levels at one week post-second dose (Area Under Curve: 0.72, 95% confidence interval: 0.58-0.85). Taken together, our results identified specific breast milk microbiota markers associated with high levels of IgA in the breast milk following BNT162b2 vaccine. Furthermore, in lactating mothers, BNT162b2 vaccines did not significantly reduce probiotic species in breast milk.

Safety of 3-fucosyllactose (3-FL) produced by a derivative strain of Escherichia coli K-12 DH1 as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 3-fucosyllactose (3-FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 3-FL, but it also contains d-lactose, l-fucose, 3-fucosyllactulose and a small fraction of other related saccharides. The NF is produced by fermentation by a genetically modified strain (Escherichia coli K-12 DH1 MDO MAP1834) of E. coli K-12 DH1 (DSM 4235). The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow-on formula, food for special medical purposes and food supplements (FS). The target population is the general population. The anticipated daily intake of 3-FL from both proposed and combined (authorised and proposed) uses at their respective maximum use levels in all population categories does not exceed the highest intake level of 3-FL from human milk in infants on a body weight basis. The intake of 3-FL in breastfed infants on a body weight basis is expected to be safe also for other population groups. The intake of other carbohydrate-type compounds structurally related to 3-FL is also considered of no safety concern. FS are not intended to be used if other foods with added 3-FL or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Effect of Marine-Derived Saccharides on Human Skin Fibroblasts and Dermal Papilla Cells

The skin is the largest organ of the human body, composed of a diverse range of cell types, non-cellular components, and an extracellular matrix. With aging, molecules that are part of the extracellular matrix undergo qualitative and quantitative changes and the effects, such as a loss of skin firmness or wrinkles, can be visible. The changes caused by the aging process do not only affect the surface of the skin, but also extend to skin appendages such as hair follicles. In the present study, the ability of marine-derived saccharides, L-fucose and chondroitin sulphate disaccharide, to support skin and hair health and minimize the effects of intrinsic and extrinsic aging was investigated. The potential of the tested samples to prevent adverse changes in the skin and hair through stimulation of natural processes, cellular proliferation, and production of extracellular matrix components collagen, elastin, or glycosaminoglycans was investigated. The tested compounds, L-fucose and chondroitin sulphate disaccharide, supported skin and hair health, especially in terms of anti-aging effects. The obtained results indicate that both ingredients support and promote the proliferation of dermal fibroblasts and dermal papilla cells, provide cells with a supply of sulphated disaccharide GAG building blocks, increase ECM molecule production (collagen and elastin) by HDFa, and support the growth phase of the hair cycle (anagen).

Therapeutic interventions target the NLRP3 inflammasome in ulcerative colitis: Comprehensive study

One of the significant health issues in the world is the prevalence of ulcerative colitis (UC). UC is a chronic disorder that mainly affects the colon, beginning with the rectum, and can progress from asymptomatic mild inflammation to extensive inflammation of the entire colon. Understanding the underlying molecular mechanisms of UC pathogenesis emphasizes the need for innovative therapeutic approaches based on identifying molecular targets. Interestingly, in response to cellular injury, the NLR family pyrin domain containing 3 (NLRP3) inflammasome is a crucial part of the inflammation and immunological reaction by promoting caspase-1 activation and the release of interleukin-1β. This review discusses the mechanisms of NLRP3 inflammasome activation by various signals and its regulation and impact on UC.

Microbial Synthesis of l-Fucose with High Productivity by a Metabolically Engineered Escherichia coli

l-Fucose is a natural deoxy hexose found in a variety of organisms. It possesses many physiological effects and has potential applications in pharmaceutical, cosmetic, and food industries. Microbial synthesis via metabolic engineering attracts increasing attention for efficient production of important chemicals. Previously, we reported the construction of a metabolically engineered Escherichia coli strain with high 2'-fucosyllactose productivity. Herein, we further introduced Bifidobacterium bifidum α-l-fucosidase via both plasmid expression and genomic integration and blocked the l-fucose assimilation pathway by deleting fucI, fucK, and rhaA. The highest l-fucose titers reached 6.31 and 51.05 g/L in shake-flask and fed-batch cultivation, respectively. l-Fucose synthesis was little affected by lactose added, and there was almost no 2'-fucosyllactose residue throughout the cultivation processes. The l-fucose productivity reached 0.76 g/L/h, indicating significant potential for large-scale industrial applications.

L-Fucose Suppresses Lipid Accumulation via the AMPK Pathway in 3T3-L1 Adipocytes

L-fucose (Fuc), a monosaccharide with different biological functions in various organisms, exhibits potent anti-obesity effects in obese mice. However, the mechanisms underlying its anti-obesity effects remain largely unknown. In this study, we aimed to investigate the effects of Fuc on lipid metabolism and insulin signaling in 3T3-L1 adipocytes. We found that Fuc treatment suppressed lipid accumulation during adipocyte differentiation. Additionally, Fuc treatment enhanced the phosphorylation of AMP-activated kinase (AMPK) and its downstream pathways, responsible for the regulation of fatty acid oxidation and lipolysis. Furthermore, Fuc-induced activation of the AMPK pathway was diminished by the AMPK inhibitor Compound C, and Fuc treatment considerably promoted glucose uptake via Akt activation in an insulin-resistant state. These findings provide a basis for elucidating the mechanism underlying the anti-obesity effect of Fuc, which may, in the future, be considered as a therapeutic compound for treating obesity and related diseases.

Safety of 2'-fucosyllactose (2'-FL) produced by a derivative strain (APC199) of Corynebacterium glutamicumATCC 13032 as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 2'-fucosyllactose (2'-FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 2'-FL, but it also contains d-lactose, l-fucose, 3-fucosyllactose, difucosyllactose, d-glucose and d-galactose. The NF is produced by fermentation with a genetically modified strain (APC199) of Corynebacterium glutamicum ATCC 13032. 2'-FL, when chemically synthesised or produced by fermentation with derivative strains of Escherichia coli K-12 DH1 or E. coli BL21 (DE3), is already authorised and included in the EU list of NFs. This application refers to a change in the production process and specifications, while target population, conditions of use and consequently, the anticipated intake remain unchanged. The information provided on the identity, production process, composition and specifications of the NF does not raise safety concerns. The intake of other carbohydrate-type compounds structurally related to 2'-FL is also considered of no safety concern. In line with other milk oligosaccharides that are natural components of human milk, the safety assessment of this NF is mainly based on the comparison between the intake of breastfed infants and the estimated intake as NF. Given that the NF would be consumed at the same extent as the already authorised 2'-FL, the Panel considers that the consumption of the NF at the proposed uses and use levels does not raise safety concerns. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of 3-fucosyllactose (3-FL) produced by a derivative strain of Escherichia coli BL21 (DE3) as a Novel Food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 3‐fucosyllactose (3‐FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human‐identical milk oligosaccharide (HiMO) 3‐FL, but it also contains d‐lactose, l‐fucose, d‐glucose and d‐galactose, and a small fraction of other related saccharides. The NF is produced by fermentation with a genetically modified strain of Escherichia coli BL21 (DE3). The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow‐on formula, food for infants and young children, food for special medical purposes and food supplements. The target population is the general population. The anticipated daily intake of 3‐FL from both proposed and combined (authorised and proposed) uses at their respective maximum use levels in all population categories does not exceed the highest intake level of 3‐FL from human milk in infants on a body weight basis. The intake of 3‐FL in breastfed infants on a body weight basis is expected to be safe also for other population groups. The intake of other carbohydrate‐type compounds structurally related to 3‐FL is also considered of no safety concern. Food supplements are not intended to be used if other foods with added 3‐FL or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of 3-FL (3-Fucosyllactose) as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 3-fucosyllactose (3-FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 3-FL but also contains D-lactose and its monomers, L-fucose and a small fraction of other related saccharides. The NF is produced by fermentation with a genetically modified strain of Escherichia coli K-12. The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF in a variety of foods, including infant and follow-on formula, foods for infants and toddlers, foods for special medical purposes and food supplements. The target population is the general population, except for food supplements for which the target population is individuals above 1 year of age. The anticipated daily intake of 3-FL from the NF at the maximum proposed use levels is unlikely to exceed the intake level of breastfed infants on a body weight basis. The intake of 3-FL in breastfed infants on a body weight basis is expected to be safe also for other population groups. In infants below 1 year of age, a possible exceedance of a natural intake was observed, but the degree of this exceedance is not considered of safety concern in view of the wide range of 3-FL concentrations in human milk. Food supplements are not intended to be used if other foods with the added NF (as well as human milk for young children) are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

The Effects of Brown Algae-Derived Monosaccharide L-Fucose on Lipid Metabolism in C57BL/6J Obese Mice

Obesity is a global public health problem and a risk factor for several metabolic disorders as well as cancer. In this study, we investigated the effects of L-fucose on lipid metabolism through chronic and acute in vivo experiments in mice. In the chronic test, mice were fed a high-calorie diet (HCD) containing 0.0001%, 0.001%, 0.01%, and 0.1% L-fucose for one month. The L-fucose supplementation inhibited body weight and visceral fat mass gain in HCD-fed mice. The results of the acute test showed that L-fucose increased the ratio of serum high molecular weight adiponectin and enhanced glucose and lipid catabolism. Furthermore, L-fucose also decreased the expression of adipogenic genes (peroxisome proliferator-activated receptor γ and cluster of differentiation 36). In conclusion, this study provides a new approach to combat obesity and the related diseases.

Macrophage M1/M2 polarization

Macrophages can be affected by a variety of factors to change their phenotype and thus affect their function. Activated macrophages are usually divided into two categories, M1-like macrophages and M2-like macrophages. Both M1 macrophages and M2 macrophages are closely related to inflammatory responses, among which M1 macrophages are mainly involved in pro-inflammatory responses and M2 macrophages are mainly involved in anti-inflammatory responses. Improving the inflammatory environment by modulating the activation state of macrophages is an effective method for the treatment of diseases. In this review, we analyzed the mechanism of macrophage polarization from the tumor microenvironment, nanocarriers, nuclear receptor PPARγ, phagocytosis, NF-κB signaling pathways, and other pathways.

Genotoxic potential of cellobiose

Cellobiose is a naturally occurring only slightly sweet disaccharide that may be used as a novel food ingredient. As part of the safety evaluation of cellobiose, produced from sucrose by an enzymatic process, an Ames test and an in-vitro micronucleus test with human peripheral lymphocytes were performed according to the respective OECD Guidelines. The results demonstrate that cellobiose lacks a genotoxic potential under the conditions of these standardized assays.

Carbocatalysed hydrolytic cleaving of the glycosidic bond in fucoidan under microwave irradiation

Biomass valorization involves breaking down naturally occurring long chain polysaccharides into their constituent monomers. The polysaccharide chain consists of monomers adjoined via C (carbon)–O (oxygen) glycosidic linkages that are typically cleaved via hydrolytic scission. In this study, we aimed to recover fucose from the polysaccharide fucoidan, which can be extracted from seaweed biomass. We investigated the depolymerisation behavior of fucoidan sourced from two different species of seaweeds, namely Undaria pinnatifida (F-UP) and Fucus vesiculosus (F-FV). Catalytic depolymerisation experiments were performed using four different carbon-based catalysts – graphene, multiwalled carbon nanotubes (MWCNT), graphene oxide (GO), and reduced graphene oxide (rGO) – under microwave (MW) irradiation. Our results showed that the depolymerisation of fucoidan was best achieved using GO, which was attributed to the abundance of oxygen functionalities on its surface. Furthermore, based on gel permeation chromatography analyses, the depolymerisation of fucoidan was found to follow a two-step process: (1) random scission leading to the production of short-chain oligosaccharides and (2) acid-catalysed hydrolysis of the oligosaccharides to fucose. Because of the longer chain length of F-UP (61 kDa), the highest fucose yield of 17.4% using this species was obtained at a higher temperature of 120 °C in a closed vessel. Meanwhile, in the case of F-FV (1.1 kDa), the highest yield of 54.0% was obtained under reflux conditions at a lower temperature of 104 °C. Our mechanistic study based on semi-empirical quantum calculations also revealed that the recovery of fucose from F-FV is more energetically favoured than from F-UP as a result of their structural differences.

Fucose recovery from Undaria pinnatifida (F-UP) and Fucus vesiculosus (F-FV) via microwave-carbocatalysis consist of random scission leading to the production of short-chain oligosaccharides followed by acid-catalysed hydrolysis.

L-Fucose ameliorates DSS-induced acute colitis via inhibiting macrophage M1 polarization and inhibiting NLRP3 inflammasome and NF-kB activation

Previous studies reported that L-fucose had anti-inflammatory effects in respiratory and cutaneous system. However, the effect of L-fucose on colitis and the underlying mechanism is poorly understood. We studied the anti-inflammatory effects of L-fucose on Dextran sulfate sodium (DSS)-induced acute colitis in vivo and on LPS/ATP-induced bone marrow derived macrophages (BMDMs) damage in vitro. Our results show that L-fucose significantly alleviated weight loss and disease activity index (DAI) scores in colitis and reduced the infiltration of macrophages and neutrophils. In addition, L-fucose can inhibit macrophage M1 polarization, inactivate the NLRP3 inflammasome and reduce the release of TNFα, IL1β, IL6 pro-inflammatory cytokines. In vitro studies showed that L-fucose ameliorated cell damage resulting from the administration of LPS with ATP in BMDMs, inhibited NLRP3 inflammasome activation and reduced the release of corresponding pro-inflammatory cytokines. Finally, L-fucose can inhibit the expression of p-NF-kB in vivo and in vitro. Overall, our results show that L-fucose can attenuate colitis by inhibiting macrophage M1 polarization, inhibiting NLRP3 inflammasome and NF-kB activation, and down-regulation of pro-inflammatory cytokines.

L-Fucose ameliorates high-fat diet-induced obesity and hepatic steatosis in mice

Background

l-Fucose (Fuc), a six-deoxy hexose monosaccharide, is present endogenously in humans and animals and has a wide range of biological functions. In the present study, we aimed to examine the effect of Fuc on obesity and hepatic steatosis in mice fed a high-fat diet (HFD).

Methods

C57BL/6 mice were fed a normal chow (NC) or HFD for 18 weeks to induce obesity and fatty liver. Fuc was administered intragastrically from the 8th week to the end of the experiment (18 weeks).

Results

Metagenomic analysis showed that HFD altered the genomic profile of gut microbiota in the mice; specifically, expression of alpha-l-fucosidase, the gene responsible for Fuc generation, was markedly reduced in the HFD group compared with that in the NC group. Fuc treatment decreased body weight gain, fat accumulation, and hepatic triglyceride elevation in HFD-fed mice. In addition, Fuc decreased the levels of endotoxin-producing bacteria of the Desulfovibrionaceae family and restored HFD-induced enteric dysbiosis at both compositional and functional levels.

Conclusion

Our findings suggest that Fuc might be a novel strategy to treat HFD-induced obesity and fatty liver.