Determination Trial of Nondigestible Oligosaccharide in Processed Foods by Improved AOAC Method 2009.01 Using Porcine Small Intestinal Enzyme

Harnessing Prebiotics to Improve Type 2 Diabetes Outcomes

The gut microbiota, a complex ecosystem of microorganisms in the human gastrointestinal tract (GI), plays a crucial role in maintaining metabolic health and influencing disease susceptibility. Dysbiosis, or an imbalance in gut microbiota, has been linked to the development of type 2 diabetes mellitus (T2DM) through mechanisms such as reduced glucose tolerance and increased insulin resistance. A balanced gut microbiota, or eubiosis, is associated with improved glucose metabolism and insulin sensitivity, potentially reducing the risk of diabetes-related complications. Various strategies, including the use of prebiotics like inulin, fructooligosaccharides, galactooligosaccharides, resistant starch, pectic oligosaccharides, polyphenols, β-glucan, and Dendrobium officinale have been shown to improve gut microbial composition and support glycemic control in T2DM patients. These prebiotics can directly impact blood sugar levels while promoting the growth of beneficial bacteria, thus enhancing glycemic control. Studies have shown that T2DM patients often exhibit a decrease in beneficial butyrate-producing bacteria, like Roseburia and Faecalibacterium, and an increase in harmful bacteria, such as Escherichia and Prevotella. This review aims to explore the effects of different prebiotics on T2DM, their impact on gut microbiota composition, and the potential for personalized dietary interventions to optimize diabetes management and improve overall health outcomes.

Optimized extraction and large-scale proteomics of pig jejunum brush border membranes for use in in vitro digestion models

Despite the physiological importance of the hydrolases from the intestinal brush border membrane (BBM), a step simulating the intestinal digestion has not been included yet in the harmonized protocols of in vitro digestion, due to commercial unavailability of these enzymes and lack of consensus for the conditions of use. The proper utilize of BBM requires a detailed investigation of their enzymatic composition. BBM vesicles were purified from specimens of pig jejunum optimizing previously described methods and assayed for aminopeptidase N and dipeptidyl peptidase IV activity. Large-scale proteomics was carried out with a bottom-up shotgun approach, also performing a rough quantification with the iBAQ (intensity Based Absolute Quantification). Overall, 1428 proteins were identified and functionally classified by gene ontology enrichment analysis. The predominant enzyme fraction (220 gene products) was represented by hydrolases, including peptidases, glycosidases, and lipases. Aminopeptidase N and sucrase-isomaltase represented 52.9 % and 50.2 % of the peptidase and glycosidase abundance, respectively. In addition to expected transporters and cytoskeletal actin-binding proteins, purified BBM vesicles also contains a complex array of protease inhibitors, here described for the first time, that may modulate the activity of hydrolases. Considering the similarity with the human counterpart, intestinal porcine BBM are suited for simulating the human small intestinal digestion.

In vitro digestion of polysaccharides: InfoGest protocol and use of small intestinal extract from rat

Starch, dextran, pectin and modified citrus pectin were subjected to intestinal digestion following InfoGest protocol and a rat small intestine extract (RSIE) treatment. Gastric stage did not show any modification in the structure of the carbohydrates, except for modified pectin. Regarding intestinal phases, starch was hydrolyzed by different ways, resulting in a complementary behavior between InfoGest and RSIE. Contrarily, digestion of dextran was only observed using RSIE. Similar situation occurred in the case of pectins with RSIE, obtaining a partial hydrolysis, especially in the modified citrus pectin. However, citrus pectin was the less prone to hydrolysis by enzymes. The results demonstrated that InfoGest method underestimates the significance of the carbohydrates hydrolysis at the small intestine, thus indicating that RSIE is a very reliable and useful method for a more realistic study of polysaccharides digestion.

Hydrolysis and transglycosylation activities of glycosidases from small intestine brush-border membrane vesicles

In order to know the catalytic activities of the disaccharidases expressed in the mammalian small intestinal brush-border membrane vesicles (BBMV) high concentrated solutions of sucrose, maltose, isomaltulose, trehalose and the mixture sucrose:lactose were incubated with pig small intestine disaccharidases. The hydrolysis and transglycosylation reactions generated new di- and trisaccharides, characterized and quantified by GC-MS and NMR, except for trehalose where only hydrolysis was detected. In general, α-glucosyl-glucoses and α-glucosyl-fructoses were the most abundant structures, whereas no fructosyl-fructoses or fructosyl-glucoses were found. The in-depth structural characterization of the obtained carbohydrates represents a new alternative to understand the potential catalytic activities of pig small intestinal disaccharidases. The hypothesis that the oligosaccharides synthesized by glycoside hydrolases could be also hydrolysed by the same enzymes was confirmed. This information could be extremely useful in the design of new non-digestible or partially digestible oligosaccharides with potential prebiotic properties.

Bringing the digestibility of prebiotics into focus: update of carbohydrate digestion models

Oro-gastrointestinal digestion of dietary carbohydrates involves up to six different carbohydrases in a multistage process. Enzymes from the small intestinal brush border membrane play a major role in the digestibility of these substrates. However, to date, the inclusion of these small intestinal enzymes has been dismissed in most in vitro studies carried out, despite their importance in the degradation of carbohydrates. Several in vitro and in vivo studies have demonstrated the capability of brush border enzymes to degrade certain "non-digestible" carbohydrates to a different extent depending on their structural composition (monomeric composition, glycosidic linkage, etc.). In this sense, considering the available evidence, mucosal disaccharidases embedded in the small intestinal brush border membrane vesicles must be considered in addition to α-amylases; therefore, new approaches for the evaluation of the digestibility of carbohydrates have been recently reported. These new methods based on the utilization of the small intestinal enzymes present in the brush border membrane aim to fulfill the final and key step of the digestion of carbohydrates in the small intestine. Here, rat small intestinal extract enzymes as well as brush border membrane vesicles from pig have emerged as very reliable and useful tools to evaluate carbohydrate digestion. Thus, this review aims to go briefly through the most relevant digestion methods for carbohydrates that are currently available and to highlight the new improved methods, which include mammalian intestinal enzymes, and their current use in the evaluation of the digestibility of prebiotics.

Trial of Available Energy Evaluation of Highly Cross-linked Starch and Modified Cellulose Based on Breath H2 Excretion

Background:

The energy value of a substance is essential in nutritional labeling. However, the available energy of newly developed highly cross-linked phosphate starch (HCPS-N) and modified cellulose (MC) are unknown.

Objective:

To evaluate the available energy of HCPS-N and MC, an indirect and simple method which was applied as an indicator of the fermentability based on the breath hydrogen excretion, was used.

Methods:

HCPS-N was made from tapioca starch by polymerization in the presence of 0.5% phosphoric acid. MC was made from microcrystalline cellulose, maltodextrin, and karaya gum to attain a highly stable suspension. The present study was carried out using a within-subject, repeatedmeasures design. Blood was collected at 30 min intervals for 3 h after the ingestion of 30 g of a test substance. The end-respiratory gas was collected for 14 h after ingestion of 5 g of a test substance to evaluate the available energy.

Results and Discussion:

Plasma glucose and insulin levels did not elevate after the ingestion of HCPS-N, although they increased significantly after glucose ingestion. In the experiments to evaluate the available energy, breath hydrogen excretion after ingesting HCPS-N did not increase distinctly during the experiment. Breath hydrogen excretion after preceding HCPS-P (0 kcal) ingestion was also markedly smaller compared with the peak value at 4 h after FOS ingestion. For the ingestion of MC, breath hydrogen excretion increased scarcely, and the basal level remained until the end of the experiment.

Conclusion:

The available energies were evaluated to be 0 kcal/g for HCPS-N and 1 kcal/g for MC in healthy humans.

Highly Cross-linked Starch and Modified Cellulose as Dietary Fibers, and their Acclimation Effect on Hydrogen Excretion in Rats

Background:

Highly cross-linked phosphate starch (HCPS) and modified cellulose (MC) were newly developed and modified dietary fiber materials to prevent lifestyle-related diseases.

Objective:

We investigated the physiological property of HCPS and MC to be a dietary fiber.

Methods:

HCPS was made from tapioca starch by polymerization in the presence of 0.5% phosphoric acid, and MC was made from cellulose, maltodextrin and karaya gum by high-speed mixing. In the present study, rats were raised on a diet containing 10% or 15% HCPS, or 10% MC for four weeks, and physical effects such as growth, organ weights, blood biomedical parameters, fecal weight, and hydrogen excretion were recorded.

Results:

Growth was normal among all groups, and there was no significant difference in total body weight gain. Some organ weights including the adipose tissues differed slightly among groups, but no difference based on diet composition was observed. Blood biomedical parameters were normal and not significantly different among groups. Cecum tissue and content weights were significantly greater in the 15% HCPS, 10% MC, and 10% fructooligosaccharide (FOS) groups than in the control group, and fecal weight was significantly increased in the 10% and 15% HCPS, and 10% MC groups compared with the control group. Hydrogen excretion over 24 h was negligible when HCPS was administered orally to rats non-acclimatized to HCPS but increased significantly in rats acclimatized to 10% HCPS diet for one week.

Conclusion:

We conclude that both HCPS and MC could be suitable for use as low energy bulking materials.

Comparison of utilisation and fermentation of highly cross-linked phosphate starches produced from two different plant origins, potato and tapioca in rats and humans

The utilisation and fermentation of highly cross-linked phosphate starches made from two different origins, potato (HXL-P) and tapioca (HXL-T) were investigated in rats and humans. HXL-P and HXL-T were highly resistant to digestion by carbohydrate enzymes and were also resistant to fermentation by gut microbiota in rats. The postprandial blood glucose scarcely increased after administration of HXL-P or HXL-T in healthy humans. Incremental AUC of both HXL-P and HXL-T for 180 min was significantly lower than that of glucose (p < .05). Breath hydrogen excretion was very low after oral administration of HXL-P or HXL-T, and AUCs of breath hydrogen excretion for 13 h after administration were significantly lower than that of fructooligosaccharide as a reference of fermentation (p < .05). These results show that HXL-P and HXL-T were hardly digested and were highly resistant to fermentation. In conclusion, HXL-P and HXL-T could be good low-energy bulking ingredients to replace wheat flour.

Hydrolysis and transgalactosylation catalysed by β-galactosidase from brush border membrane vesicles isolated from pig small intestine: A study using lactulose and its mixtures with lactose or galactose as substrates

Enzymatic transgalactosylation, in different concentrated carbohydrate solutions, was investigated using brush border membrane vesicles (BBMV) from the pig small intestine. When lactulose was incubated with BBMV, the hydrolytic activity of the enzyme towards the disaccharide was observed to be very low compared to that towards the lactose, but the linkage specificity β-(1 → 3), previously observed in lactose solutions, was not significantly affected. As in the case of lactose, lactulose transgalactosylation by BBMV synthesizes the corresponding 3'-galactosyl derivative (β-Gal-(1 → 3)-β-Gal-(1 → 4)-β-Fru). Fructose released during lactulose hydrolysis was found to be good acceptor for the transgalactosylation reaction, giving rise to the synthesis of the disaccharide β-Gal-(1 → 5)-Fru. When incubating an 80/20 mixture of lactulose/galactose, the presence of galactose did not affect the qualitative composition of the transglycosylated substrate but enhanced the synthesis of β-Gal-(1 → 5)-Fru and decreased the synthesis of β-(1 → 3) glycosidic bonds. The marked tendency for synthesizing this linkage indicates that under hydrolytic conditions, β-Gal-(1 → 3)-Gal- and β-Gal-(1 → 5)-Fru glycosidic bonds would be preferentially digested.

In Vitro Digestibility of Galactooligosaccharides: Effect of the Structural Features on Their Intestinal Degradation

Small intestinal brush border membrane vesicles from pig were used to digest galactooligosaccharides from lactose (GOS) and from lactulose (OsLu). Dissimilar hydrolysis rates were detected after digestion. Predominant glycosidic linkages and monomeric composition affected the resistance to intestinal digestive enzymes. The β(1→3) GOS mixture was the most susceptible to hydrolysis (50.2%), followed by β(1→4) (34.9%), whereas β(1→6) linkages were highly resistant to digestion (27.1%). Monomeric composition provided a better resistance in β(1→6) OsLu (22.8%) compared to β(1→6) GOS (27.1%). This was also observed for β-galactosyl fructoses and β-galactosyl glucoses, where the presence of fructose provided higher resistance to digestion. Thus, the resistance to small intestinal digestive enzymes highly depends upon the structure and composition of prebiotics. Increasing knowledge in this regard could contribute to the future synthesis of new mixtures of carbohydrates, highly resistant to digestion and with potential to be tailored prebiotics with specific properties, targeting, for instance, specific probiotic species.

Trans-β-galactosidase activity of pig enzymes embedded in the small intestinal brush border membrane vesicles

This work highlights the utility of brush border membrane vesicles (BBMV) from the pig small intestine as a reliable model for gathering information about the reaction mechanisms involved in the human digestion of dietary carbohydrates. Concretely, the elucidation of the transgalactosylation mechanism of pig BBMV to synthesize prebiotic galacto-oligosaccharides (GOS) is provided, unravelling the catalytic activity of mammalian small intestinal β-galactosidase towards the hydrolysis of GOS. This study reveals that pig BBMV preferably synthesizes GOS linked by β-(1 → 3) bonds, since major tri- and disaccharide were produced by the transfer of a galactose unit to the C-3 of the non-reducing moiety of lactose and to the C-3 of glucose, respectively. Therefore, these results point out that dietary GOS having β-(1 → 3) as predominant glycosidic linkages could be more prone to hydrolysis by mammalian intestinal digestive enzymes as compared to those linked by β-(1 → 2), β-(1 → 4), β-(1 ↔ 1) or β-(1 → 6). Given that these data are the first evidence on the transglycosylation activity of mammalian small intestinal glycosidases, findings contained in this work could be crucial for future studies investigating the structure-small intestinal digestibility relationship of a great variety of available prebiotics, as well as for designing tailored fully non-digestible GOS.

Assessment of in Vitro Digestibility of Dietary Carbohydrates Using Rat Small Intestinal Extract

There are few studies on the assessment of digestibility of nondigestible carbohydrates, despite their increasingly important role in human health. In vitro digestibility of a range of dietary carbohydrates classified as digestible (maltose, sucrose, and lactose), well-recognized (lactulose, fructooligosaccharides (FOS), and two types of galactooligosaccharides (GOS) differing in the predominant glycosidic linkage), and potential (lactosucrose and GOS from lactulose, OsLu) prebiotics using a rat small intestinal extract (RSIE) under physiological conditions of temperature and pH is described. Recognized and potential prebiotics were highly resistant to RSIE digestion although partial hydrolysis at different extents was observed. FOS and lactulose were the most resistant to digestion, followed closely by OsLu and more distantly by both types of GOS and lactosucrose. In GOS, β(1 → 6) linkages were more resistant to digestion than β(1 → 4) bonds. The reported in vitro digestion model is a useful, simple, and cost-effective tool to evaluate the digestibility of dietary oligosaccharides.

Development of dietary soluble fibres by enzymatic synthesis and assessment of their digestibility in in vitro, animal and randomised clinical trial models

The aim was to develop novel fibres by enzymatic synthesis, to determine their total dietary fibre by AOAC method 2009.01 and to estimate their potential digestibility and assess their digestibility in vivo using glycaemic and insulinaemic responses as markers in mice and randomised clinical trial models. We found that fibre candidates to which α-(1,2) branching was added were resistant to digestion in the mouse model, depending on the amount of branching. These results show that in vivo models are needed to reliably assess the digestibility of α-glycosidic-linked oligomeric dietary fibre candidates, possibly due to absence of brush border α-glucosidase activity in the current in vitro assessment. α-(1,3)-linked and α-(1,6)-linked glucose oligomers were completely digested in humans and mice. In conclusion, it is possible to develop dietary soluble fibres by enzymatic synthesis. Adding α-(1,2) branching increases their resistance to digestion in vivo and can thus improve their suitability as potential fibre candidates. Clinical Trial Registry: ClinicalTrials.gov, NCT02701270.