Elucidation of the mechanism underlying the sequential catalysis of inulin by fructotransferase.

Glycoside hydrolase family 91 (GH91) inulin fructotransferase (IFTases) enables biotransformation of fructans into sugar substitutes for dietary intervention in metabolic syndrome. However, the catalytic mechanism underlying the sequential biodegradation of inulin remains unelusive during the biotranformation of fructans. Herein we present the crystal structures of IFTase from Arthrobacter aurescens SK 8.001 in apo form and in complexes with kestose, nystose, or fructosyl nystose, respectively. Two kinds of conserved noncatalytic binding regions are first identified for IFTase-inulin interactions. The conserved interactions of substrates were revealed in the catalytic center that only contained a catalytic residue E205. A switching scaffold was comprised of D194 and Q217 in the catalytic channel, which served as the catalytic transition stabilizer through side chain displacement in the cycling of substrate sliding in/out the catalytic pocket. Such features in GH91 contribute to the catalytic model for consecutive cutting of substrate chain as well as product release in IFTase, and thus might be extended to other exo-active enzymes with an enclosed bottom of catalytic pocket. The study expands the current general catalytic principle in enzyme-substrate complexes and shed light on the rational design of IFTase for fructan biotransformation.

Combined Supplementation of Inulin and Bacillus coagulans Lactospore Demonstrates Synbiotic Potential in the Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME®) Model.

Prebiotic and probiotic combinations may lead to a synbiotic effect, demonstrating superior health benefits over either component alone. Using the Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME®) model, the effects of repeated supplementation with inulin (prebiotic, which is expected to provide a source of nutrition for the live microorganisms in the gut to potentially support optimal digestive health), Bacillus coagulans lactospore (probiotic), and a low and high dose of a synbiotic combination of the two on the gut microbial community activity and composition were evaluated. Test product supplementation increased the health-promoting short-chain fatty acids acetate and butyrate compared with levels recorded during the control period, demonstrating a stimulation of saccharolytic fermentation. This was likely the result of the increased abundance of several saccharolytic bacterial groups, including Megamonas, Bifidobacterium, and Faecalibacterium, following test product supplementation. The stimulation of acetate and butyrate production, as well as the increased abundance of saccharolytic bacterial groups were more evident in treatment week 3 compared with treatment week 1, demonstrating the value of repeated product administration. Further, the synbiotic formulations tended to result in greater changes compared with prebiotic or probiotic alone. Overall, the findings demonstrate a synbiotic potential for inulin and B. coagulans lactospore and support repeated administration of these products, indicating a potential for promoting gut health.

Metastatic Colon Cancer in an Individual Following Prolonged Daily Inulin Consumption.

Studies in rodents suggest that inulin supplements may be carcinogenic. We present a case implicating that this risk extends to humans. A healthy male from a family lacking history of cancer had his first cancer-screening colonoscopy at age 56. No intestinal polyps/abnormalities were detected. A second colonoscopy, performed 7 years later, revealed a tumor in the cecum, with evidence of metastasis to lymph nodes. The only known change in patient's lifestyle during that seven-year period was the addition of 4g of inulin powder as a daily supplement during the last 2 years. Such inulin consumption is a plausible contributor to his disease.

Multistrategy Engineering of an Inulosucrase to Enhance the Activity and Thermostability for Efficient Production of Microbial Inulin.

Inulin has found commercial applications in the pharmaceutical, nutraceutical, and food industries due to its beneficial health effects. The enzymatic biosynthesis of microbial inulin has garnered increasing attention. In this study, molecular modification was applied to Lactobacillus mulieris UMB7800 inulosucrase, an enzyme that specifically produces high-molecular weight inulin, to enhance its catalytic activity and thermostability. Among the 18 variable regions, R5 was identified as a crucial region significantly impacting enzymatic activity by replacing it with more conserved sequences. Site-directed mutagenesis combined with saturated mutagenesis revealed that the mutant A250 V increased activity by 68%. Additionally, after screening candidate mutants by rational design, four single-point mutants, S344D, H434P, E526D, and G531P, were shown to enhance thermostability. The final combinational mutant, M5, exhibited a 66% increase in activity and a 5-fold enhancement in half-life at 55 °C. These findings are significant for understanding the catalytic activity and thermostability of inulosucrase and are promising for the development of microbial inulin biosynthesis platforms.

Preparation and characterization of fish-derived protein gel as a potential dysphagia food: Co-mingling effects of inulin and konjac glucomannan mixtures.

The study aimed to create a fish-derived protein gel with inulin/konjac glucomannan (KGM) mixture for dysphagia. The inulin/KGM complex improved the swallowing properties of myofibrillar protein (MP) emulsion gel. Interactions, physicochemical, and flavor properties were analyzed. Inulin/KGM mixture inhibited hydrophobic groups exposure, and maintained MP structure during thermal induction. Inulin/KGM-protein gels exhibited shear-thinning behavior, low deformation resistance and hardness. IDDSI test also indicated inulin/KGM gels is suitable for dysphagia. Inulin/KGM mixture improved flavor by increasing ethanol and 2-octen-ol while decreasing ichthyological substances such as hexanal and nonanal, enhancing the sensory experience of patients with dysphagia. An 8% inulin/KGM mixture effectively modulated mechanical, swallowing, and sensory properties of MP emulsion gels, offering insights for future marine-derived dysphagia foods development.

Inulin Supplementation Alleviates Ochratoxin A-Induced Kidney Injury through Modulating Intestinal Microbiota.

Ochratoxin A (OTA) is a prevalent mycotoxin found in feed that causes significant kidney injury in animals. Further investigation was needed to devise strategies for treating OTA-induced kidney damage through the gut-kidney axis. Evidence indicates the crucial role of intestinal microbiota in kidney damage development. Inulin, a dietary fiber, protects kidneys by modulating intestinal microbiota and promoting short-chain fatty acid (SCFA) production. However, its precise mechanism in OTA-induced kidney damage remained unclear. In this study, chickens were orally administered OTA and inulin for 2 weeks to investigate inulin's effects on OTA-induced kidney damage and underlying mechanisms. The alteration of intestinal microbiota, SCFAs contents, and SCFA receptors was further analyzed. Results demonstrated that inulin supplementation influenced intestinal microbiota, increased SCFAs production, and mitigated OTA-induced kidney damage in chickens. The importance of microbiota in mediating inulin's renal protection was further confirmed by antibiotic and fecal microbiota transplantation experiments. Additionally, inulin exhibited antioxidant and anti-inflammatory properties, alleviating NLRP3 inflammasome activation and pyroptosis. In summary, inulin protected chickens from OTA-induced kidney damage, which might provide a potential strategy to mitigate the harmful effects of mycotoxins through prebiotics and safeguard renal health.

Advantages of Spray Drying over Freeze Drying: A Comparative Analysis of Lonicera caerulea L. Juice Powders-Matrix Diversity and Bioactive Response.

The study investigated the impact of Lonicera caerulea L. juice matrix modification and drying techniques on powder characteristics. The evaluation encompassed phenolics (514.7-4388.7 mg/100 g dry matter), iridoids (up to 337.5 mg/100 g dry matter), antioxidant and antiglycation capacity, as well as anti-ageing properties of powders produced using maltodextrin, inulin, trehalose, and palatinose with a pioneering role as a carrier. Spray drying proved to be competitive with freeze drying for powder quality. Carrier application influenced the fruit powder properties. Trehalose protected the phenolics in the juice extract products, whereas maltodextrin showed protective effect in the juice powders. The concentrations of iridoids were influenced by the matrix type and drying technique. Antiglycation capacity was more affected by the carrier type in juice powders than in extract products. However, with carrier addition, the latter showed approximately 12-fold higher selectivity for acetylcholinesterase than other samples. Understanding the interplay between matrix composition, drying techniques, and powder properties provides insights for the development of plant-based products with tailored attributes, including potential health-linked properties.

Reply to "Stribling & Ibrahim 2023: Commentary to the Editor".

In response to "Stribling & Ibrahim 2023: Commentary to the Editor", we wish to thank all authors for their interest in our work. The sole motive behind our narrative review, after learning the lesson from the trans-fat history and its impact on the science and food industry, is to prevent harm before it is too late. We agree with the authors regarding the importance of a worldwide unified definition of dietary fibre, but this should not have potential to worsen symptoms of those with functional bowel disorders nor cause more confusion among the public regarding the health benefits of dietary fibre. Thus, we aim to address the authors' views and concerns, and to provide future recommendations, which will be summarised below. The following abbreviations will be used: FBDs, functional bowel disorders; DF, dietary fibre; LMW DF, low molecular weight dietary fibre; HMW DF, high molecular weight dietary fibre.

Colorectal cancer and inulin supplementation: the good, the bad, and the unhelpful.

The prebiotic inulin has been vaunted for its potential to reduce the risk of colorectal cancer. Inulin fermentation resulting in the production of short-chain fatty acids, primarily butyrate, has been reported to be associated with properties that are beneficial for gut health and has led to an increased consumption of inulin in the Western population through processed food and over-the-counter dietary supplements. However, in clinical trials, there is limited evidence of the efficacy of inulin in preventing colorectal cancer. Moreover, recent data suggest that improper inulin consumption may even be harmful for gastro-intestinal health under certain circumstances. The main objective of this review is to provide insight into the beneficial and potentially detrimental effects of inulin supplementation in the context of colorectal cancer prevention and enhancement of treatment efficacy.

Inulin: a multifaceted ingredient in pharmaceutical sciences.

Inulin, a naturally occurring polysaccharide derived from plants such as chicory root, has emerged as a significant ingredient in pharmaceutical sciences due to its diverse therapeutic and functional properties. This review explores the multifaceted applications of inulin, focusing on its chemical structure, sources, and mechanisms of action. Inulin's role as a prebiotic is highlighted, with particular emphasis on its ability to modulate gut microbiota, enhance gut health, and improve metabolic processes. The review also delves into the therapeutic applications of inulin, including its potential in managing metabolic health issues such as diabetes and lipid metabolism, as well as its immune-modulating properties and benefits in gastrointestinal health. Furthermore, the article examines the incorporation of inulin in drug formulation and delivery systems, discussing its use as a stabilizing agent and its impact on enhancing drug bioavailability. Innovative inulin-based delivery systems, such as nanoparticles and hydrogels, are explored for their potential in controlled release formulations. The efficacy of inulin is supported by a review of clinical studies, underscoring its benefits in managing conditions like diabetes, cardiovascular health, and gastrointestinal disorders. Safety profiles, regulatory aspects, and potential side effects are also addressed. This comprehensive review concludes with insights into future research directions and the challenges associated with the application of inulin in pharmaceutical sciences.

Structural Insights into the Catalytic Cycle of Inulin Fructotransferase: From Substrate Anchoring to Product Releasing.

Carbohydrate degradation is crucial for living organisms due to their essential functions in providing energy and composing various metabolic pathways. Nevertheless, in the catalytic cycle of polysaccharide degradation, the details of how the substrates bind and how the products release need more case studies. Here, we choose an inulin fructotransferase (SpIFTase) as a model system, which can degrade inulin into functionally difructose anhydride I. At first, the crystal structures of SpIFTase in the absence of carbohydrates and complex with fructosyl-nystose (GF4), difructose anhydride I, and fructose are obtained, giving the substrate trajectory and product path of SpIFTase, which are further supported by steered molecular dynamics simulations (MDSs) along with mutagenesis. Furthermore, structural topology variations at the active centers of inulin fructotransferases are suggested as the structural base for product release, subsequently proven by substitution mutagenesis and MDSs. Therefore, this study provides a case in point for a deep understanding of the catalytic cycle with substrate trajectory and product path.

The effect and potential mechanism of inulin combined with fecal microbiota transplantation on early intestinal immune function in chicks.

Our previous research found that fecal microbiota transplantation (FMT) and inulin synergistically affected the intestinal barrier and immune system function in chicks. However, does it promote the early immunity of the poultry gut-associated lymphoid tissue (GALT)? How does it regulate the immunity? We evaluated immune-related indicators in the serum, cecal tonsil, and intestine to determine whether FMT synergistic inulin had a stronger impact on gut health and which gene expression regulation was affected. The results showed that FMT synergistic inulin increased TGF-ß secretion and intestinal goblet cell number and MUC2 expression on day 14. Expression of BAFFR, PAX5, CXCL12, and IL-2 on day 7 and expression of CXCR4 and IL-2 on day 14 in the cecal tonsils significantly increased. The transcriptome indicated that CD28 and CTLA4 were important regulatory factors in intestinal immunity. Correlation analysis showed that differential genes were related to the immunity and development of the gut and cecal tonsil. FMT synergistic inulin promoted the development of GALT, which improved the early-stage immunity of the intestine by regulating CD28 and CTLA4. This provided new measures for replacing antibiotic use and reducing the use of therapeutic drugs while laying a technical foundation for achieving anti-antibiotic production of poultry products.

Inulin and Freeze-Dried Blueberry Intervention Lead to Changes in the Microbiota and Metabolites within In Vitro Studies and in Cognitive Function within a Small Pilot Trial on Healthy Children.

The relationship between the gut microbiota and cognitive health is complex and bidirectional, being significantly impacted by our diet. Evidence indicates that polyphenols and inulin can impact cognitive function via various mechanisms, one of which is the gut microbiota. In this study, effects of a wild blueberry treatment (WBB) and enriched chicory inulin powder were investigated both in vitro and in vivo. Gut microbiota composition and metabolites, including neurotransmitters, were assessed upon faecal microbial fermentation of WBB and inulin in a gut model system. Secondly, microbiota changes and cognitive function were assessed in children within a small pilot (n = 13) trial comparing WBB, inulin, and a maltodextrin placebo, via a series of tests measuring executive function and memory function, with faecal sampling at baseline, 4 weeks post-intervention and after a 4 week washout period. Both WBB and inulin led to microbial changes and increases in levels of short chain fatty acids in vitro. In vivo significant improvements in executive function and memory were observed following inulin and WBB consumption as compared to placebo. Cognitive benefits were accompanied by significant increases in Faecalibacterium prausnitzii in the inulin group, while in the WBB group, Bacteroidetes significantly increased and Firmicutes significantly decreased (p < 0.05). As such, WBB and inulin both impact the microbiota and may impact cognitive function via different gut-related or other mechanisms. This study highlights the important influence of diet on cognitive function that could, in part, be mediated by the gut microbiota.

The Influence of Technological Factors on the Structure and Chemical Composition of Tuberous Dahlia Roots Determined Using Vibrational Spectroscopy.

This research investigated the structural and chemical modifications of Dahlia 'Kennemerland' across different technological conditions and throughout the vegetation period. Using FT-IR imaging, this study focused on the changes in the inulin, lignin, and suberin contents of tuberous roots. FT-IR maps were generated to visualize the distribution of these compounds across scanned areas, highlighting variations across cultivation methods and seasonal stages. The key compounds analyzed included inulin, lignin, and suberin, which were identified in different root zones. The results showed that inulin was distributed in all analyzed areas, predominantly in zone 1 (periderm), with a distribution that increased with forced cultivation, while lignin and suberin distributions varied with zone and season. Forced tuberous root lignin was detected in all four areas analyzed, in the fall accumulating mainly in area 4 and in suberin starting from summer until autumn. Based on the evaluation of the maps obtained by representing the area ratios of specific bands (inulin/lignin and inulin/suberin), we established where the inulin was present in the highest quantity and concluded that suberin was the constituent with the lowest concentration in tuberous Dahlia roots. These findings emphasize the influence of technological factors and seasonal changes on the biochemical makeup of tuberous Dahlia roots. This detailed biochemical mapping provides insights for optimizing Dahlia cultivation and storage for various industrial applications. This study concludes that FT-IR spectroscopy is an effective tool for monitoring and understanding the biochemical dynamics of Dahlia roots, aiding their agricultural and industrial utilization.

Serum Metabolomics Uncovers the Mechanisms of Inulin in Preventing Non-Alcoholic Fatty Liver Disease.

Inulin may be a promising therapeutic molecule for treating non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanisms of its therapeutic activity remain unclear. To address this issue, a high-fat-diet-induced NAFLD mouse model was developed and treated with inulin. The NAFLD phenotype was evaluated via histopathological analysis and biochemical parameters, including serum levels of alanine aminotransferase, aspartate aminotransferase, liver triglycerides, etc. A serum metabolomics study was conducted using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The results revealed that inulin mitigated NAFLD symptoms such as histopathological changes and liver cholesterol levels. Through the serum metabolomics study, 347 differential metabolites were identified between the model and control groups, and 139 differential metabolites were identified between the inulin and model groups. Additionally, 48 differential metabolites (such as phosphatidylserine, dihomo-γ-linolenic acid, L-carnitine, and 13-HODE) were identified as candidate targets of inulin and subjected to pathway enrichment analysis. The results revealed that these 48 differential metabolites were enriched in several metabolic pathways such as fatty acid biosynthesis and cardiolipin biosynthesis. Taken together, our results suggest that inulin might attenuate NAFLD partially by modulating 48 differential metabolites and their correlated metabolic pathways, constituting information that might help us find novel therapies for NAFLD.

Effect of Intake of Bifidobacteria and Dietary Fiber on Resting Energy Expenditure: A Randomized, Placebo-Controlled, Double-Blind, Parallel-Group Comparison Study.

Bifidobacterium animalis subsp. lactis GCL2505 in combination with inulin has been shown to have several health benefits, including an improvement in the intestinal microbiota and a reduction in human visceral fat. Previous studies have suggested that the visceral fat reduction of GCL2505 and inulin may be achieved by improving daily energy expenditure. This parallel, placebo-controlled, randomized, double-blind study was conducted to evaluate the effects of GCL2505 and inulin on resting energy expenditure (REE) in overweight or mildly obese Japanese adults (n = 44). Participants ingested 1 × 1010 colony forming units of GCL2505 and 5.0 g of inulin daily for 4 weeks. REE score at week 4 was set as the primary endpoint. At week 4, the REE score of the GCL2505 and inulin group was significantly higher than that of the placebo group, with a difference of 84.4 kcal/day. In addition, fecal bifidobacteria counts were significantly increased in the GCL2505 and inulin group. Our results indicated that the intake of GCL2505 and inulin improves energy balance, which is known to be a major factor of obesity, by modulating the microbiota in the gut. This is the first report to demonstrate the effects of probiotics and dietary fiber on REE in humans.

Synthesis and characterization of novel carboxymethyl inulin derivatives bearing cationic Schiff bases with antioxidant potential.

This study aimed to enhance the antioxidant activity of carboxymethyl inulin (CMI) by chemical modification. Therefore, a series of cationic Schiff bases bearing heteroatoms were synthesized and incorporated into CMI via ion exchange reactions, ultimately preparing 10 novel CMI derivatives (CMID). Their structures were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The radical scavenging activities and reducing power of inulin, CMI, and CMID were studied. The results revealed a significant enhancement in antioxidant activity upon the introduction of cationic Schiff bases into CMI. Compared to commercially available antioxidant Vc, CMID demonstrated a broader range of antioxidant activities across the four antioxidant systems analyzed in this research. In particular, CMID containing quinoline (6QSCMI) exhibited the strongest hydroxyl radical scavenging activity, with a scavenging rate of 93.60 % at 1.6 mg mL-1. The CMID bearing imidazole (2MSCMI) was able to scavenge 100 % of the DPPH radical at 1.60 mg mL-1. Furthermore, cytotoxicity experiments showed that the products had good biocompatibility. These results are helpful for evaluating the feasibility of exploiting these products in the food, biomedical, and cosmetics industries.

Inulin enhanced rifaximin-inhibited colon cancer pulmonary metastasis by flora-regulated bile acid pathway.

Inulin as a natural polysaccharide regulates intestinal microorganisms, and improves the immune and gastrointestinal function. In order to explore the effect of inulin on pulmonary metastasis of colon cancer, we set up a CT26 injected pulmonary metastatic model. The results showed that inulin used alone did not improve pulmonary metastasis of colon cancer, while inulin combined with rifaximin significantly prolonged the survival time of mice, and inhibited pulmonary metastasis compared with model and inulin groups. Inulin treatment increased the abundance of harmful bacteria such as Proteobacteria and Actinobacteria, while combined treatment decreased their abundance and increased the abundance of beneficial bacteria containing Firmicutes and Eubacterium which belonged to the bile acid-related bacteria. The combination treatment decreased the content of primary bile acids and secondary bile acids in the feces of mice, especial for DCA and LCA which were the agonists of TGR5. Furthermore, the combination treatment reduced the mRNA expression of the TGR5, cyclin dependent kinase 4, cyclin 1 and CDK2, increased the mRNA expression of p21 in the lung, down-regulated the level of NF-κB p65, and up-regulated the level of TNF-α compared with the model group. The above may be the reason for the better use of the combination treatment.

Weight, habitual fibre intake, and microbiome composition predict tolerance to fructan supplementation.

Fructans are commonly used as dietary fibre supplements for their ability to promote the growth of beneficial gut microbes. However, fructan consumption has been associated with various dosage-dependent side effects. We characterised side effects in an exploratory analysis of a randomised trial in healthy adults (n = 40) who consumed 18 g/day inulin or placebo. We found that individuals weighing more or habitually consuming higher fibre exhibited the best tolerance. Furthermore, we identified associations between gut microbiome composition and host tolerance. Specifically, higher levels of Christensenellaceae R-7 group were associated with gastrointestinal discomfort, and a machine-learning-based approach successfully predicted high levels of flatulence, with [Ruminococcus] torques group and (Oscillospiraceae) UCG-002 sp. identified as key predictive taxa. These data reveal trends that can help guide personalised recommendations for initial inulin dosage. Our results support prior ecological findings indicating that fibre supplementation has the greatest impact on individuals whose baseline fibre intake is lowest.

Analysis of NADES and its water tailoring effects constructed from inulin and L-proline based on structure, physicochemical and antifreeze properties.

The structure, physicochemical and anti-freeze properties of natural deep eutectic solvent (NADES) composed of inulin and L-proline (molar ratio of 1:11) were investigated. Proton nuclear magnetic resonance (1H NMR), Fourier infrared spectroscopy (FTIR), and Raman spectroscopy revealed extensive hydrogen bonding in the pure NADES system, and the addition of water weakens the hydrogen bonding interactions between the components. The smaller transverse relaxation time (T2) represents the stronger hydrogen bond strength, and NADES+40 % H2O exhibited a large T2 (71.68 ms). When 10 % water was added, the viscosity decreased from 3620 mPa·s to 1777 mPa·s, but the conductivity increased to approximately twice the original value. Furthermore, adding 10 % water lowered the glass transition temperature (Tg) of NADES by 5.6 °C. NADES+10 % H2O exhibited favorable thermal stability and freezing resistance, as evidenced by the fact that approximately 82.61 % of the ice crystals area <200 µm2 after 30 min of crystallization. The changes in the structure, physicochemical, and anti-freezing properties of water-tailored NADES are expected to enable the design of novel antifreeze agents.