Influence of nano-fibrillated cellulose (NFC) on starch digestion and glucose absorption

Recent trends in nanocellulose: Metabolism-related, gastrointestinal effects, and applications in probiotic delivery

Nanocellulose, a versatile and sustainable nanomaterial derived from cellulose fibers, has attracted considerable attention in various fields due to its unique properties. Similar to dietary fibers, nanocellulose is difficult to digest in the human gastrointestinal tract. The indigestible nanocellulose is fermented by gut microbiota, producing metabolites and potentially exhibiting prebiotic activity in intestinal diseases. Additionally, nanocellulose can serve as a matrix material for probiotic protection and show promising prospects for probiotic delivery. In this review, we summarize the classification of nanocellulose, including cellulose nanocrystals (CNC), cellulose nanofibers (CNF), and bacterial nanocellulose (BNC), highlighting their distinct characteristics and applications. We discuss the metabolism-related characteristics of nanocellulose from oral ingestion to colon fermentation and introduce the prebiotic activity of nanocellulose in intestinal diseases. Furthermore, we provide an overview of commonly used nanocellulose-based encapsulation techniques, such as emulsification, extrusion, freeze drying, and spray drying, as well as the delivery systems employing nanocellulose matrix materials, including microcapsules, emulsions, and hydrogels. Finally, we discuss the challenges associated with nanocellulose metabolism, prebiotic functionality, encapsulation techniques, and delivery systems using nanocellulose matrix material for probiotics. This review will provide new insight into the application of nanocellulose in the treatment of intestinal diseases and probiotic delivery.

Organic acid treatments on citrus insoluble dietary fibers and the corresponding effects on starch in vitro digestion

Three environmentally friendly organic acids, acetic acid, citric acid and oxalic acid, were used to treat citrus insoluble dietary fiber (CIDF) in present study, aiming to explore the changes in structural properties as well as their inhibitory effects on starch digestion. The results showed that organic acid treatment significantly reduced the particle size of all three CIDFs, with rougher and folded surfaces, improved crystallinity and thermal stability. During in vitro digestion, it was found that organic acid treatment could increase the particle size and viscosity of digestion, and also effectively enhance the inhibitory ability of α-glucosidase activity, resulting in a further blockage of starch digestion. The starch digestion in oxalic acid-treated group (with 3 wt% addition) was significantly reduced by 18.72 % compared to blank group and 9.05 % compared to untreated. These findings provide evidence of the potential of organic acid-treated insoluble dietary fiber as a functional food.

Wet-type grinder-treated okara modulates gut microbiota composition and attenuates obesity in high-fat-fed mice

Wet-type grinder (WG) is a nanofiber technology used to atomize dietary fiber-rich materials. WG-treated okara (WGO) exhibits high dispersion and viscosity similar to those of viscous soluble dietary fibers. Here, we studied the effect of WGO supplementation on obesity and gut microbiota composition in high-fat diet (HFD)-fed mice. WGO intake suppressed body weight gain and fat accumulation, improved glucose tolerance, lowered cholesterol levels, and prevented HFD-induced decrease in muscle mass. WGO supplementation also led to cecum enlargement, lower pH, and higher butyrate production. The bacterial 16S ribosomal RNA genes (16S rDNA) were sequenced to determine the gut microbiota composition of the fecal samples. Sequencing of bacterial 16S rDNA revealed that WGO treatment increased the abundance of butyrate producer Ruminococcus and reduced the abundances of Rikenellaceae, Streptococcaceae, and Prevotellaceae, which are related to metabolic diseases. Metabolomics analysis of the plasma of WGO- and cellulose-treated mice were conducted using ultra-high-performance liquid chromatography-mass spectrometry. Metabolic pathway analysis revealed that the primary bile acid biosynthesis pathway was significantly positively regulated by WGO intake instead of cellulose. These results demonstrate that WG is useful for improving functional properties of okara to prevent metabolic syndromes, including obesity, diabetes, and dyslipidemia.

Comparison of Emulsion Stabilizers: Application for the Enhancement of the Bioactivity of Lemongrass Essential Oil

Recent focus on cellulose nanomaterials, particularly biodegradable and biocompatible cellulose nanocrystals (CNCs), has prompted their use as emulsion stabilizers. CNCs, when combined with salt, demonstrate enhanced emulsion stabilization. This study explored three emulsion stabilizers: Tween 80, soybean CNCs with salt (salted CNCs), and a combination of salted CNCs with Tween 80. Soybean CNCs, derived from soybean stover, were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Antifungal testing against Aspergillus flavus revealed increased bioactivity in all lemongrass essential oil (EO)-loaded emulsions compared to pure essential oil. In addition, all three emulsions exhibited a slight reduction in antifungal activity after 30 days of room temperature storage. The release experiment revealed that the EO-loaded nanoemulsion exhibited a slow-release profile. The nanoemulsion stabilized by salted CNCs and Tween 80 exhibited significantly lower release rates when compared to the nanoemulsion stabilized solely by Tween 80, attributed to the gel network formed by salted CNCs. The findings of this study highlight the efficacy of cellulose nanocrystals procured from soybean byproducts in conjunction with synthetic surfactants to create nanoencapsulated essential oils, resulting in improved antimicrobial efficacy and the achievement of sustained release properties.

Health and toxicological effects of nanocellulose when used as a food ingredient: A review

The use of nanocellulose (NC) has increased significantly in the food industry, as subtypes such as cellulose nanofibrils (CNF) or bacterial cellulose (BC) have been demonstrated to be a source of insoluble fiber with important benefits for human health. Despite these advantages, and due to its nanoscale size, NC must be assessed from a safety perspective that considers its exposure, fate, and biological effects in order to help more accurately estimate its potential hazards. The exposure routes of humans to NC include (i) ingestion during consumption of foods that contain cellulose as a food ingredient or (ii) contact of food with cellulose-containing materials, such as its packaging. That is why it is important to understand the potentially toxic effects that nanomaterials can have on human health, understanding that the different types of NC behave differently in terms of their ingestion, absorption, distribution, metabolism, and excretion. By analysing both in vitro and in vivo studies, the purpose of this paper is to present the most recent findings on the different types of NC and their safety when used in food. In addition, it provides an overview of relevant studies into NC and its health benefits when used as a food additive.

Modulating the glycemic response of starch-based foods using organic nanomaterials: strategies and opportunities

Traditionally, diverse natural bioactive compounds (polyphenols, proteins, fatty acids, dietary fibers) are used as inhibitors of starch digestive enzymes for lowering glycemic index (GI) and preventing type 2 diabetes mellitus (T2DM). In recent years, organic nanomaterials (ONMs) have drawn a great attention because of their ability to overcome the stability and solubility issues of bioactive. This review aimed to elucidate the implications of ONMs in lowering GI and as encapsulating agents of enzymes inhibitors. The major ONMs are presented. The mechanisms underlying the inhibition of enzymes, the stability within the gastrointestinal tract (GIT) and safety of ONMs are also provided. As a result of encapsulation of bioactive in ONMs, a more pronounced inhibition of enzymes was observed compared to un-encapsulated bioactive. More importantly, the lower the size of ONMs, the higher their inhibitory effects due to facile binding with enzymes. Additionally, in vivo studies exhibited the potentiality of ONMs for protection and sustained release of insulin for GI management. Overall, regulating the GI using ONMs could be a safe, robust and viable alternative compared to synthetic drugs (acarbose and voglibose) and un-encapsulated bioactive. Future researches should prioritize ONMs in real food products and evaluate their safety on a case-by-case basis.

Nanocellulose from Cocoa Shell in Pickering Emulsions of Cocoa Butter in Water: Effect of Isolation and Concentration on Its Stability and Rheological Properties

There is a growing interest in developing new strategies to completely or partially replace cocoa butter in food and cosmetic products due to its cost and health effects. One of these alternatives is to develop stable emulsions of cocoa butter in water. However, incorporating cocoa butter is challenging as it solidifies and forms crystals, destabilizing the emulsion through arrested coalescence. Prevention against this destabilization mechanism is significantly lower than against coalescence. In this research, the rheological properties of nanocellulose from cocoa shell, a by-product of the chocolate industry, were controlled through isolation treatments to produce nanocellulose with a higher degree of polymerization (DP) and a stronger three-dimensional network. This nanocellulose was used at concentrations of 0.7 and 1.0 wt %, to develop cocoa butter in-water Pickering emulsion using a high shear mixing technique. The emulsions remained stable for more than 15 days. Nanocellulose was characterized using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), hot water and organic extractives, atomic force microscopy (AFM), degree of polymerization (DP), and rheological analysis. Subsequently, the emulsions were characterized on days 1 and 15 after their preparation through photographs to assess their physical stability. Fluorescent and electronic microscopy, as well as rheological analysis, were used to understand the physical properties of emulsions.

Ultraprocessed plant-based foods: Designing the next generation of healthy and sustainable alternatives to animal-based foods

Numerous examples of next-generation plant-based foods, such as meat, seafood, egg, and dairy analogs, are commercially available. These products are usually designed to have physicochemical properties, sensory attributes, and functional behaviors that match those of the animal-sourced products they are designed to replace. However, there has been concern about the potential negative impacts of these foods on human nutrition and health. In particular, many of these products have been criticized for being ultraprocessed foods that contain numerous ingredients and are manufactured using harsh processing operations. In this article, the concept of ultraprocessed foods is introduced and its relevance to describe the properties of next-generation plant-based foods is discussed. Most commercial plant-based meat, seafood, egg, and dairy analogs currently available do fall into this category, and so can be classified as ultraprocessed plant-based (UPB) foods. The nutrient content, digestibility, bioavailability, and gut microbiome effects of UPB foods are compared to those of animal-based foods, and the potential consequences of any differences on human health are discussed. Some commercial UPB foods would not be considered healthy based on their nutrient profiles, especially those plant-based cheeses that contain low levels of protein and high levels of fat, starch, and salt. However, it is argued that UPB foods can be designed to have good nutritional profiles and beneficial health effects. Finally, areas where further research are still needed to create a more healthy and sustainable food supply are discussed.

Inhibition of α-amylase and amyloglucosidase by cellulose nanofibrils with different surface charge and spectroscopic analysis of their interaction mechanism

We investigated the inhibition effect of carboxymethylated cellulose nanofibrils with four different surface chargeon α-amylase and amyloglucosidase via enzyme activity inhibition assay, fluorescence spectra and secondary structure change analysis. These results revealed that cellulose nanofibril with lowest surface charge displayed the greatest inhibition effects against α-amylase (9.81 mg/mL) and amyloglucosidase (13.16 mg/mL). All cellulose nanofibrils in starch model significantly (p < 0.05) inhibited the starch digestion, where the inhibition effect was negatively correlated with the magnitude of particle surface charge. Cellulose nanofibrils could bind α-amylase or amyloglucosidase to form new complex in the manner of static quenching. The thermodynamic parameters demonstrated that the cellulose nanofibrils-starch hydrolase (α-amylase or amyloglucosidase) complexes were formed spontaneously via hydrophobic effects. Additionally, Fourier transform Infrared spectra exhibited the changes in the fraction of secondary structures of starch hydrolase after the interactions with carboxymethylated cellulose nanofibrils. These data provide a convenient and simple method tailor gastrointestinal digestion of starch by changing cellulose surface charge, to control postprandial serum glucose upsurge.

Six weeks effect of different nanocellulose on blood lipid level and small intestinal morphology in mice

AIMS

Cellulose nanofibrils (CNF, or NFC), cellulose nanocrystals (CNC, or NCC), and Tempo (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized CNF (Tempo-CNF) were compared for the short-term effect on mice fed with a high-fat and high-sugar (Western diet, WD) to investigate their effect when combined with a sub-optimal diet.

SCOPE

Thirty C57B/C female mice (10 weeks old; 5-6 mice/group) were given water, cellulose, or three types of nanocellulose once daily in a dose of 30 mg/kg body weight by oral gavage. After six weeks, weight changes, fecal output, glucose homeostasis, and gut permeability showed no significant among groups. Serum analysis including triglycerides, cholesterol and total bile acids and small intestinal morphology including villus length, villus width, crypt depth, goblet cell count and goblet cell density were no difference for all groups. Only CNC group had higher excretion of bile acids in the feces.

CONCLUSIONS

These results suggest that current treated dose using three types of nanocellulose had no detrimental effects on blood lipid level and small intestinal morphology.

Effects of electron beam irradiation treatment on the structural and functional properties of okara insoluble dietary fiber

BACKGROUND

Insoluble dietary fiber (IDF) has beneficial physiological effects, such as the promoting of intestinal peristalsis, the improving of intestinal flora, and the absorbing of some harmful substances. Okara, a byproduct of soybean processing, is a potential source of IDF. But the larger particle size and poor water solubility of okara IDF have adverse effects on sensory properties and functional characteristics. Therefore, we used an emerging type of physical method is electron beam irradiation (EBI) to modify okara, and investigated that the effects of EBI doses on the structure and functional properties of okara IDF.

RESULTS

It was found that the electron beam treatment damaged the crystalline structure of IDF. Observation of the surface of EBI-treated IDF revealed a loose and porous morphology rather than the typical smooth structure. At a dose of 6 kGy, a smallest particle size and largest specific surface area of IDF was obtained, and these factors increased the apparent viscosity of an IDF dispersion. The water holding capacity, swelling capacity and the oil holding capacity upon irradiation at 6 kGy increased 74.13%, 84.76% and 41.62%, respectively. In addition, the capacity for adsorption of cholesterol, sodium cholate, glucose and nitrite ion were improved after electron beam treatment.

CONCLUSION

The modified okara IDF showed improved particle sizes and hydration properties, and these changes correlated with an improvement to the rough taste of IDF and improvements to the texture and storage period upon supplementation into food. © 2022 Society of Chemical Industry.

The effect of ball milling on the structure, physicochemical and functional properties of insoluble dietary fiber from three grain bran

The effects of ball milling processing on the structure, physicochemical, and functional properties of insoluble dietary fiber (IDF) in bran from prosomillet, wheat and rice were investigated. Meanwhile, the effect of IDF on glucose tolerance and blood lipid levels in mice was evaluated as well. With findings, for all three grains, the particle sizes of IDF were significantly reduced after ball milling treatment (p < 0.05). Scanning electron microscopy revealed fragmented fiber with numerous pores and cracks. The reactive groups of three IDF samples were found to be similar by fourier transform infrared spectroscopy. And consistent with X-ray diffraction and thermal analysis, for all three grains, ball milling reduced the crystallinity of IDF and helped to increase the release of free phenol by 23.4 %, 8.9 %, and 12.2 %, respectively. Furthermore, the water holding capacity, glucose delay capacity, glucose, sodium cholate, and cholesterol adsorption capacity, and in vitro digestibility of starch and fat were all improved to varying degrees. Animal experiments showed that ball milling treatment effectively slowed the postprandial rise in blood sugar (especially IDF of rice bran) and blood lipids (especially IDF of prosomillet bran). As a result, ball milling treatment is a potential method for dietary fiber modification in the food industry.

Toxicological Assessment of Cellulose Nanomaterials: Oral Exposure

Cellulose nanomaterials (CNMs) have emerged recently as an important group of sustainable bio-based nanomaterials (NMs) with potential applications in multiple sectors, including the food, food packaging, and biomedical fields. The widening of these applications leads to increased human oral exposure to these NMs and, potentially, to adverse health outcomes. Presently, the potential hazards regarding oral exposure to CNMs are insufficiently characterised. There is a need to understand and manage the potential adverse effects that might result from the ingestion of CNMs before products using CNMs reach commercialisation. This work reviews the potential applications of CNMs in the food and biomedical sectors along with the existing toxicological in vitro and in vivo studies, while also identifying current knowledge gaps. Relevant considerations when performing toxicological studies following oral exposure to CNMs are highlighted. An increasing number of studies have been published in the last years, overall showing that ingested CNMs are not toxic to the gastrointestinal tract (GIT), suggestive of the biocompatibility of the majority of the tested CNMs. However, in vitro and in vivo genotoxicity studies, as well as long-term carcinogenic or reproductive toxicity studies, are not yet available. These studies are needed to support a wider use of CNMs in applications that can lead to human oral ingestion, thereby promoting a safe and sustainable-by-design approach.

Incineration-Generated Polyethylene Micro-Nanoplastics Increase Triglyceride Lipolysis and Absorption in an In Vitro Small Intestinal Epithelium Model

Despite mounting evidence of micro-nanoplastics (MNPs) in food and drinking water, little is known of the potential health risks of ingested MNPs, and nothing is known of their potential impact on nutrient digestion and absorption. We assessed the effects of environmentally relevant secondary MNPs generated by incineration of polyethylene (PE-I), on digestion and absorption of fat in a high fat food model using a 3-phase in vitro simulated digestion coupled with a tri-culture small intestinal epithelium model. The presence of 400 μg/mL PE-I increased fat digestion by 33% and increased fat absorption by 147 and 145% 1 and 2 h after exposure. Analysis of the PE-I lipid corona during digestion revealed predominantly triacylglycerols with enrichment of fatty acids in the small intestinal phase. Protein corona analysis showed enrichment of triacylglycerol lipase and depletion of β-casein in the small intestinal phase. These findings suggest digestion of triacylglycerol by lipase on the surface of lipid-coated MNPs as a potential mechanism. Further studies are needed to investigate the mechanisms underlying the greater observed increase in fat absorption, to verify these results in an animal model, and to determine the MNP properties governing their effects on lipid digestion and absorption.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Effects of non-covalent binding of lignans with rice starch driven by high-pressure homogenization on the starch structure and in vitro nutritional characteristics

As a type of phytoestrogen, lignans have attracted attention in recent years for their nutritional functions. To investigate the effects of lignans on the structural and nutritional functions of starch, honokiol (HK) and arctiin (AC) were complexed with rice starch respectively under high-pressure homogenization (UHPH) (UHPHRS/HK and UHPHRS/AC). The results showed that both HK and AC could form inclusive complexes with rice starch via non-covalent bonding (hydrophobic interaction and hydrogen bonds), and these complexes could further form V-type crystals and aggregates, which reduced the starch digestibility as well as endowing them with the ability to retard glucose release and bind sodium cholate. Interestingly, due to its smaller molecular size, HK could induce starch to form a more compact structure than AC, leading to better nutritional functions. When the addition of HK/AC reached 8%, the resistant starch content could reach 26% and 19.8%, respectively. Meanwhile, the glucose dialysis retardation index could increase to 17.2% and 14.8%, respectively, and the sodium cholate-binding capacity could increase to 33.1 mg g^-1 and 21.8 mg g^-1, respectively. These results demonstrated that UHPH with lignans' molecular interaction could be beneficial for controlling the nutritional functions of starch products with the desired digestibility.

Influence of native cellulose, microcrystalline cellulose and soluble cellodextrin on inhibition of starch digestibility

Cellulose is a major component of dietary fiber and it is proved to influence starch digestibility. The effects of native cellulose (NC), microcrystalline cellulose (MC), soluble cellodextrin (SC) on starch digestion have not been clearly elucidated. In this study, three types of cellulose with representative molecular weights (NC, 422500 Da; MC, 27750 Da; SC, 2202 Da) were prepared and their effects on starch digestion, glucose diffusion, α-amylase and amyloglucosidase activity were compared. The results suggested SC inhibited starch digestibility to a greater degree than those of NC and MC. When addition of SC reached 3 %, rapidly digestible starch proportion decreased from 31.2 % to 11.3 % and resistant starch proportion increased from 15.0 % to 58.0 %. Notably, hindrance effects of SC on glucose diffusion were higher than those of NC and MC. Moreover, SC reduced activity of α-amylase and amyloglucosidase to a larger extent than those of MC and NC. With the effect of starch digestion inhibition, NC, MC and SC could be utilized as functional food ingredients. Especially, the soluble property and the highest starch digestion inhibition ability of SC favors its application in food industry.

Palm-based cellulose nanofiber isolated from mechano-chemical processing as sustainable rheological modifier in reduced fat mayonnaise

Abstract

Reducing fat intake from our daily diet serves to be an effective way to combat the rising obesity issue worldwide. Hence, reducing fat content in mayonnaise, a high fat food product, is one of the primary trends in the food industry. To date, research on the use of nanocellulose, a new and emerging form of fat mimetic, in mayonnaise formulation remains limited. This study sets out to formulate reduced fat 5%, 15%, and 30% mayonnaise using varying concentration of nanocellulose synthesized from palm pressed fiber followed by a 20‐day stability study. Nanocellulose was synthesized with particle size of 106.0 ± 18.7 nm and zeta potential of −72.5 ± 2.26 mV. It was used as fat mimetic in mayonnaise. Rheological analysis conducted showed that incorporation of nanocellulose into reduced fat mayonnaise formulation was able to counteract the loss of viscosity in mayonnaise caused by fat content reduction. This finding was further supported by the smaller oil droplets that are closely packed in reduced fat mayonnaise formulation when viewed under light microscope. Nonetheless, significant oil droplet coalescence was found in reduced fat mayonnaise formulations during storage period which could lead to loss of viscosity. Taken together, these findings suggest that CNF was able to act as fat mimetic upon formulation of mayonnaise but the same cannot be said during long term storage of mayonnaise.

Practical Application

We successfully isolated nanocellulose from palm biomass (palm pressed fiber) using green approach and used it as a fat replacer for preparation of 5%, 15%, and 30% reduced fat mayonnaise. A computation study revealed a strong binding affinity of the nanocellulose on the lipase active site essential to inhibit the digestion of fats and oils. Therefore, nanocellulose demonstrated a huge potential to be used as not only as fat replacer but also rheological modifier for the development of reduced fat or vegan foods.

Effects of ingested nanocellulose and nanochitosan materials on carbohydrate digestion and absorption in an in vitro small intestinal epithelium model

Nanoscale materials derived from natural biopolymers like cellulose and chitosan have many potentially useful agri-food and oral drug delivery applications. Because of their large and potentially bioactive surface areas and other unique physico-chemical properties, it is essential when evaluating their toxicological impact to assess potential effects on the digestion and absorption of co-ingested nutrients. Here, the effects of cellulose nanofibers (CNF), cellulose nanocrystals (CNC), and chitosan nanoparticles (Chnp) on the digestion and absorption of carbohydrates were studied. Starch digestion was assessed by measuring maltose released during simulated digestion of starch solutions. Glucose absorption was assessed by measuring translocation from the resulting digestas across an in vitro transwell tri-culture model of the small intestinal epithelium and calculating the area under the curve increase in absorbed glucose, analogous to the glycemic index. At 1% w/w, CNF and Chnp had small but significant effects (11% decrease and 14% increase, respectively) and CNC had no effect on starch hydrolysis during simulated digestion of a 1% w/w rice starch solution. In addition, at 2% w/w CNC had no effect on amylolysis in 1% solutions of either rice, corn, or wheat starch. Similarly, absorption of glucose from digestas of starch solutions (i.e., from maltose), was unaffected by 1% w/w CNF or CNC, but was slightly increased (10%, p<0.05) by 1% Chnp, possibly due to the slightly higher maltose concentration in the Chnp-containing digestas. In contrast, all of the test materials caused sharp increases (~1.2, 1.5, and 1.6 fold for CNC, CNF, and Chnp, respectively) in absorption of glucose from starch-free digestas spiked with free glucose at a concentration corresponding to complete hydrolysis of 1% w/w starch. The potential for ingested cellulose and chitosan nanomaterials to increase glucose absorption could have important health implications. Further studies are needed to elucidate the mechanisms underlying the observed increases and to evaluate the potential glycemic effects in an intact in vivo system.

Dietary fibers fractionated from gardenia (Gardenia jasminoides Ellis) husk: structure and in vitro hypoglycemic effect

BACKGROUND

Gardenia (Gardenia jasminoides Ellis) husk rich in dietary fiber is a byproduct of fructus processing, and commonly discarded as waste. The husk was fractionated by sequential extraction into four fractions: water-soluble fiber (W-SF), acid-soluble fiber (Ac-SF), alkali-soluble fiber (Al-SF) and insoluble residue fiber (IRF). The aim of this study was to investigate the differences in structure and in vitro hypoglycemic effect of these fibers.

RESULTS

Monosaccharide composition and Fourier transform infrared spectra showed that the major component might be pectin for W-SF and Ac-SF, xylan as well as pectin for Al-SF and cellulose for IRF. These fibers offered excellent water-holding capacity and swelling capacity, except that IRF was only slightly swellable in water. W-SF exhibited significantly higher capacities to adsorb glucose (2.408 mmol g^-1 at a glucose concentration of 200 mmol L^-1 ) and inhibit α-amylase activity (29.48-49.45% inhibition rate at a concentration of 4-8 mg mL^-1 ), probably caused by the higher viscosity and hydration properties; while Ac-SF, Al-SF and IRF (especially Al-SF) were more effective in retarding the glucose diffusion across a dialysis membrane (34.97-41.67% at 20-30 min), which might be attributed to particle size and specific surface area. All the fibers could quench the intrinsic fluorescence of α-amylase to some degree.

CONCLUSIONS

Dietary fiber from gardenia husk, especially W-SF, can be used as a potential hypoglycemic ingredient in diabetic functional foods. © 2020 Society of Chemical Industry.

In vitro antidiabetic, antioxidant activities and GC-MS analysis of Rhynchostylis Retusa and Euphorbia Neriifolia leaf extracts

This study aimed to assess the antidiabetic, and antioxidant potential of Rhynchostylis retusa and Euphorbia neriifolia, well known for traditional ethnomedicinal uses in North-east India. Leaf extracts prepared in water, methanol and petroleum ether were evaluated for in vitro antidiabetic and antioxidant assay using α-amylase inhibition, glucose diffusion method and DPPH radical scavenging activity. The α-amylase inhibition with E. neriifolia methanolic extract at 400 μg/ml (66.67%) and R. retusa aqueous extract at 300 μg/ml (58.15%) were stronger than in equivalent concentrations of acarbose, i.e., 62.17, and 51.52%, respectively. Aqueous extract R. retusa showed a maximum 67.65% inhibition of glucose diffusion at 180 min in comparison to control without leaf extract. The DPPH radical scavenging activity of E. neriifolia extract in methanol was significantly better than equivalent aqueous or ether extract. However, the solvent choice had little impact on antioxidant activity in R. retusa. GC-MS analysis revealed the presence of a large number of phytochemicals in methanol fraction of E. neriifolia aqueous extracts in comparison to R. retusa. Though the in vitro α-amylase inhibition or glucose diffusion retardation implied potential medicinal use of endangered orchid R. retusa and E. neriifolia, further investigation may be warranted for identification of relevant bio-active compounds and in vivo validation of their pharmacological properties.

Review of gut nanotoxicology in mammals: Exposure, transformation, distribution and toxicity

Nanomaterials are increasingly used in food processing, daily necessities and other fields due to their excellent properties, and increase the environmental contamination. Human beings will inevitably come into contact with these nanomaterials through multiple exposure routes especially oral exposure. The intestine is an important organ for nutrient absorption and physiologic barrier, which may be the main target of nanoparticles (NPs) exposure. However, for a long time, research on the toxicity of NPs has mainly focused on organs such as liver, kidney and brain. There are few assessment data over the intestinal safety. Recently, as reported, NPs can be translocated to the intestinal part in mammals and would be distributed in different substructures of intestines, thus causing damage to the structure and function of the intestine, in which the gut microbiota and its metabolites play important roles. In addition, due to the special physiological environment of gut, nanomaterials will undergo complex transformations that may cause different biological effects from their original form. Therefore, this review aims to assess the potential adverse effects of NPs on intestine and its possible mechanisms through the results of in vivo mammalian experiments. In addition, the exposure pathway, biodistribution and biotransformation of NPs in the intestine are also considered. We hope this review will arouse people's attention to the intestinal nanotoxicology and provide basic information for further related studies.

Inhibitory effects of chondroitin sulfate on alpha-amylase activity: A potential hypoglycemic agent

Inhibiting the activity of the intestinal enzyme α-amylase that catalyzes the degradation of starch into glucose can control blood glucose and provide an essential way for the treatment of Type-II diabetes mellitus (T2DM). Here, we compared the structural information of chondroitin sulfate (CS) from different origins and the effects on activity of α-amylase and blood glucose have been investigated. The inhibitory effects of shark and porcine CSs against α-amylase activity is obvious with IC₅₀ values of 11.97 and 14.42 mg/ml, respectively, but the bovine CS almost no effect. From the data of fluorescence spectroscopic analyses, CSs from shark and pig quench Try fluorescence intensity of the enzyme, whereas bovine CS induces an increase. In vivo, oral administration of shark and porcine CSs efficiently suppresses postprandial blood glucose levels in normal and diabetic mice. Our study found that CSs from different sources showed different biological functions even if both molecular weight and disaccharide subunit composition are almost the same, and demonstrated that the CSs from shark and pig as α-amylase inhibitors could be regarded as a novel functional food ingredient in T2DM management.

Effect of Physicochemical Properties of Carboxymethyl Cellulose on Diffusion of Glucose

Soluble dietary fibers (SDF) are known to reduce the post-prandial plasma glucose levels. However, the detailed mechanisms of this reduced glucose release in the human gut still remain unclear. The aim of our study was to systematically investigate the effect of different types of SDF on glucose release in an in vitro model as a prerequisite for the selection of fibers suitable for application in humans. Three types of carboxymethyl cellulose (CMC) were used to investigate the correlations between fiber concentration, molecular weight (M_W), and viscosity on diffusion of glucose using a side-by-side system. CMC solutions below the coil overlap (c*) influenced the glucose diffusivity only marginally, whereas at concentrations above c* the diffusion of glucose was significantly decreased. Solutions of lower M_W exhibited a lower viscosity with lower glucose diffusion compared to solutions with higher M_W CMC, attributed to the higher density of the solutions. All CMC solutions showed a systematic positive deviation from Stokes-Einstein behavior indicating a greater rise in viscosity than reduction in diffusion. Therefore, our results pave the way for a new approach for assessing glucose diffusion in solutions comprising dietary fibers and may contribute to further elucidating the mechanisms of post-prandial plasma glucose level reduction.

Structure characterization and in vitro hypoglycemic effect of partially degraded alginate

Alginate is a low-cost polysaccharide found abundantly in seaweeds which consists of mannuronate and guluronate, and it is considered a sustainable gum source for dietary fiber. To solve the high viscosity-related problems while retaining its physiological properties, four partially degraded alginate products (PDA1-4) with molecular weight of 1.05-0.40 × 10⁵ g mol^-1 and intrinsic viscosity of 170.9-38.9 mL g^-1 were enzymatically prepared and characterized. ¹H Nuclear magnetic resonance analysis showed the used alginate lyase had a preference to degrade guluronate-blocks. PDA1 and PDA2 presented random coil conformation, whereas PDA3 and PDA4 displayed compact spherical-coil conformation over random coil conformation in solution. In vitro assays suggested a glucose-adsorption capacity order of PDA1 < PDA2 < alginate < PDA3 < PDA4 and a glucose-diffusion retardation capacity order of PDA3 < PDA1 ≤ alginate < PDA2 < PDA4, indicating that partially degraded alginate reinforced the hypoglycemic effect, especially mannuronate-rich PDA4. Overall, the study may have important implications for development of PDA as dietary fiber with potential hypoglycemic activity.

Influence of cellulose nanocrystals (CNC) on permeation through intestinal monolayer and mucus model in vitro

Cellulose nanocrystals (CNC) as a novel ingredient in foods and pharmaceuticals still lacks the safety and functionality information. We aimed to assess the absorption of CNC in small intestine and the effect on cell viability. In the second part, the impact of CNC on substance permeation through mucus layer, including the potential functionality in improving high blood cholesterol, was tested. No noticeable amount of CNC was found to penetrate through differentiated Caco-2 monolayer and in vitro mucus layer, and CNC had low toxicity on Caco-2 cell viability up to 10 mg/mL. CNC at 2 % (w/w) may affect the permeability of the mucus layer and larger molecules are more easily influenced. CNC may also alleviate hypercholesteremia by increasing viscosity of digesta, adsorbing cholesterol, and decreasing bile acids permeation. The results suggest CNC may not penetrate the small intestinal lining and may be used as a functional supplement.

Cellulose and cellulose derivatives: Different colloidal states and food-related applications

Development of new sources and isolation processes has recently enhanced the production of cellulose in many different colloidal states. Even though cellulose is widely used as a functional ingredient in the food industry, the relationship between the colloidal states of cellulose and its applications is mostly unknown. This review covers the recent progress on illustrating various colloidal states of cellulose and the influencing factors with special emphasis on the correlation between the colloidal states of cellulose and its applications in food industry. The associated unique colloidal states of cellulose like high aspect ratio, crystalline structure, surface charge, and wettability not only promote the stability of colloidal systems, but also help improve the nutritional aspects of cellulose by facilitating its interactions with digestive system. Further studies are required for the rational control and improvement of the colloidal states of cellulose and producing food systems with enhanced functional and nutritional properties.

Preparation, characterization and in vitro hypoglycemic activity of banana condensed tannin-inulin conjugate

To enhance the hypoglycemic effects of inulin, banana condensed tannins (BCT) were grafted onto inulin via a free radical method to synthesize the novel BCT grafted inulin (BCT-g-inulin) complex. Spectroscopic methods, XRD, TGA, 1H NMR, GPC and morphology analyses were utilized to characterize the structural properties of the BCT-g-inulin complex, and our results confirmed the conjugation of BCT and inulin. The conjugation possibly occurred between the hydroxyl group attached at the C6 position of inulin and the C6/C8 position of flavon-3-ol units of BCT. The grafting ratio and grafting efficiency of the BCT-g-inulin complex were 357.54 ± 2.98 g kg-1 complex and 74.57 ± 1.44%, respectively. The data of the antioxidant assays indicated that the BCT-g-inulin complex showed a significantly higher antioxidant activity than native inulin. Also, the grafting reaction remarkably improved the in vitro anti-diabetic activity of inulin. The glucose adsorption capacity and glucose dialysis retardation index of the BCT-g-inulin complex were remarkably higher than those of inulin, while the BCT-g-inulin complex showed much stronger inhibitory effects against α-amylase and α-glucosidase compared with inulin. Notably, the inhibition of both α-amylase and α-glucosidase by the BCT-g-inulin complex occurred through mixed-competitive mode. On the basis of fluorescence spectroscopy, the fluorescence of α-amylase and α-glucosidase could be quenched by the BCT-g-inulin complex through a static quenching mechanism. Hence, the BCT-g-inulin complex might have the potential to be developed as an effective anti-diabetic agent.

In Vitro Biological Impact of Nanocellulose Fibers on Human Gut Bacteria and Gastrointestinal Cells

Wood-derived nanofibrillated cellulose (NFC) has long been recognized as a valuable nanomaterial for food-related applications. However, the safety of NFC cannot be predicted just from the chemical nature of cellulose, and there is a need to establish the effect of the nanofibers on the gastrointestinal tract, to reassure the safe use of NFC in food-related products. The present work selected the intestinal cells Caco-2 and the gut bacteria Escherichia coli and Lactobacillus reuteri to evaluate the in vitro biological response to NFC. NFC materials with different surface modifications (carboxymethylation, hydroxypropyltrimethylammonium substitution, phosphorylation and sulfoethylation) and unmodified NFC were investigated. The materials were characterized in terms of surface functional group content, fiber morphology, zeta potential and degree of crystallinity. The Caco-2 cell response to the materials was evaluated by assessing metabolic activity and cell membrane integrity. The effects of the NFC materials on the model bacteria were evaluated by measuring bacterial growth (optical density at 600 nm) and by determining colony forming units counts after NFC exposure. Results showed no sign of cytotoxicity in Caco-2 cells exposed to the NFC materials, and NFC surface functionalization did not impact the cell response. Interestingly, a bacteriostatic effect on E. coli was observed while the materials did not affect the growth of L. reuteri. The present findings are foreseen to contribute to increase the knowledge about the potential oral toxicity of NFC and, in turn, add to the development of safe NFC-based food products.

Pectin-microfibrillated cellulose microgel: Effects on survival of lactic acid bacteria in a simulated gastrointestinal tract

Using high pressure microfluidization, we prepared micro-fibrillated soybean cellulose (MFSC) and analyzed its morphology and structure. MFSC was then incorporated into low-methoxyl pectin (PC) to coat lactic acid bacteria (LAB) by ionotropic gelation, and the effects of PC-MFSC microgel on LAB survival in a simulated gastrointestinal tract were investigated. Particle size analysis showed that the MFSC particle size decreased significantly with increasing jet pressure. Transmission electron microscopy analysis indicated that many cellulosic microfibers appeared at 150 MPa. Infrared spectroscopy and X-ray diffraction analysis revealed that the crystal structure changed from β-cellulose I type to II type with increasing jet pressure, but excessive pressure (200 MPa) damaged the crystalline structure of MFSC. Scanning microscopy indicated that cellulosic microfibers not only promoted a compact pectin gel morphology but also adhered to and coated the LAB in the pectin gel. MFSC-150 stabilized the pectin gel network, preventing the weakening of the gel under low pH conditions. Compared with other PC-MFSCs, PC-MFSC-150 microgel significantly decreased LAB susceptibility to gastrointestinal juice and increased the viability of LAB.

Analysis of kinetic parameters and mechanisms of nanocrystalline cellulose inhibition of α-amylase and α-glucosidase in simulated digestion of starch

This study evaluated the in vitro inhibitory influence of particle size of nanocrystalline cellulose (NCC) fractions against α-amylase and α-glucosidase using cooked potato starch-protein food model system. The kinetics of the resulting inhibitions in the presence of NCC of the two tested enzymes were examined and characterised. Both the size and dose of NCC significantly (p < 0.05) inhibited α-amylase and α-glucosidase by modulating the rate of hydrolysis of starch in the food model system lower than that of the control (no added fibre). At equal concentrations of each NCC fraction, the smallest particle size (≤125 nm) exhibited the highest potency as an inhibitor (median inhibitory concentration (IC₅₀) = 2.98 mg mL^-1 and 4.57 mg mL^-1 for α-amylase and α-glucosidase, respectively). Increasing concentrations of each NCC fraction caused an apparent significant decrease in V_max values (p < 0.05) with insignificant change in the K_m values for both the tested enzymes. Furthermore, binding assays demonstrated that NCC particles may bind to the two tested enzymes in a non-specific manner. Analysis of the kinetics of the enzymes suggested that the mechanism of inhibition showed that the two tested enzymes mainly exhibited non-competitive mode of inhibition. The observed inhibition of the two tested enzymes suggests that reducing the cellulose size ≤125 nm may enhance its inhibition potency and potentially attenuate starch hydrolysis when added to diet.

Enhancing the prebiotic effect of cellulose biopolymer in the gut by physical structuring via particle size manipulation

Cellulose is generally recognised as dietary fibre with no limit of permissible quantity in food, and its consumption may modulate digesta content and impact positively on the gastrointestinal physiology and gut microflora. However, cellulose in its native form possessed inherent undesirable physical properties, making it unattractive for food applications. Here, we postulate that by changing cellulose size to nanometric scale, its prebiotic effect would be altered and fermented differently in contrast with micro size cellulose by the gut microbiome and promote the yield of metabolites such as short chain fatty acids (SCFAs). Using faecal matter from three healthy human donors as microbial source, in vitro fermentation of variable size fractions of cellulose from the same were fermented under anaerobic conditions, and SCFAs as well Bifidobacterium selectively isolated and analysed. The increase in production of acetate (194%), butyrate (224%) and propionate (211%) after 24 h of fermentation was significantly promoted by the size reduction and revealed size-dependent relationship as exemplified R² values >0.83. Consequently, gavaging rats with nanometric size cellulose (125 nm) significantly (p < 0.05) increased these SCFAs yields as well Bifidobacterium counts in contrast with both control and the micro scale size cellulose. Therefore, engineered nanocellulose might have beneficial physiological impact on the gut with improved prebiotic effect.

Subchronic exposure to cellulose nanofibrils induces nutritional risk by non-specifically reducing the intestinal absorption

Previous studies of cellulose nanofibrils (CNF) in decreasing fat absorption and glucose release suggested their potential application as food additives or supplements in diets containing high contents of fat and sugars. However, the long-term effects of CNF uptake remained unknown. The purpose of this study was to determine the effects of subchronic oral CNF consumption on various health aspects of Western diets (WD)-fed mice. The results demonstrated that CNF decreased fat absorption in the jejunum and attenuated WD-induced fatty liver, but slightly decreased lean body mass and affected glucose homeostasis. Additional in vivo studies showed that CNF decreased the intestinal absorption. The in vitro studies suggested that CNF did not decrease the viability of any cells used; however, they prevented epithelial and T cells, but not macrophages, from accessing the viability dye. Taken together, CNF decreased the intestinal absorption non-specifically, which might lead to nutritional risks after long-term exposure.

Structural Features and Digestive Behavior of Fucosylated Chondroitin Sulfate from Sea Cucumbers Stichopus japonicus

Fucosylated chondroitin sulfate from sea cucumber Stichopus japonicus (FCS_SJ) has been demonstrated with various biological activities; however, its precise structure is still controversial, and digestive behavior remains poorly understood. FCS_SJ was purified, and its detailed structure was elucidated mainly based on the NMR spectroscopic methods. Its main chain was characterized as →4)-β-d-GlcA-(1 → 3)-β-d-GalNAc-(1→ with GalNAc4S6S:GalNAc4S in a ratio of 1.5:1, and three types of sulfated fucosyl branches attaching C-3 of GlcA, namely, Fucp2S4S, Fucp3S4S, and Fucp4S, were found in a ratio of 2:1.5:1. The digestibility of FCS_SJ was investigated in vitro, and the unchanged molecular weight and reducing sugar content indicated that FCS_SJ was not broken down under salivary and gastrointestinal digestion. Furthermore, FCS_SJ showed a significant inhibitory impact on pancreatic lipase dose-dependently but not on α-amylase, indicating that the inhibition of pancreatic lipase by FCS_SJ might be a pathway for its hypolipidemic effect. These findings propose a fucosylated chondroitin sulfate and provide insight into the mechanism of its physiological effects in the digestion system.

Nanomaterials for the theranostics of obesity

As a chronic and lifelong disease, obesity not only significant impairs health but also dramatically shortens life span (at least 10 years). Obesity requires a life-long effort for the successful treatment because a number of abnormalities would appear in the development of obesity. Nanomaterials possess large specific surface area, strong absorptivity, and high bioavailability, especially the good targeting properties and adjustable release rate, which would benefit the diagnosis and treatment of obesity and obesity-related metabolic diseases. Herein, we discussed the therapy and diagnosis of obesity and obesity-related metabolic diseases by using nanomaterials. Therapies of obesity with nanomaterials include improving intestinal health and reducing energy intake, targeting and treating functional cell abnormalities, regulating redox homeostasis, and removing free lipoprotein in blood. Diagnosis of obesity-related metabolic diseases would benefit the therapy of these diseases. The development of nanomaterials will promote the diagnosis and therapy of obesity and obesity-related metabolic diseases.

In vitro investigation of the influence of nano-fibrillated cellulose on lipid digestion and absorption

Nanocellulose, including nano-fibrillated cellulose (NFC), has been a topic of significant interest and a number of studies have focused on using it for the fabrication of stable oil-in-water emulsions. However, limited studies have been performed to understand the potential influence of NFC on lipid digestion and absorption. In this study, a simulated digestion model, consisting of salivary, gastric and intestinal digestion phases, was used to investigate the effects of NFC on lipid digestion and absorption. To better understand the mechanisms behind, the effects of NFC on lipase activity, micellar solubility of cholesterol and bile acid diffusion were studied in addition to the cholesterol adsorption capacity of NFC, with conventional cellulose as a comparison. Results showed that NFC slightly reduced lipase activity, but NFC or cellulose at concentrations up to 1.1% (w/w) did not significantly influence lipid digestion under simulated intestinal conditions. Moreover, NFC showed greater bile acid retardation effect than cellulose, and slightly higher cholesterol adsorption capacity probably due to its larger specific surface area. Nonetheless, NFC did not significantly affect micellar solubility of cholesterol. These results suggest that NFC, when added into fat-rich foods, may have health benefits via its viscosity effect and retardation effect on bile acid absorption.