Immunomodulatory Effects of Enzymatic-Synthesized α-Galactooligosaccharides and Evaluation of the Structure-Activity Relationship

Distinguishing α/β-linkages and linkage positions of disaccharides in galactooligosaccharides through mass fragmentation and liquid retention behaviour

Galactooligosaccharides (GOS) are important prebiotics with function closely related to their structure. However, a comprehensive overview of the structure-function relationship is still limited due to the challenge in characterizing multiple isomers in GOS. This study presents a strategy of combining both hydrophilic interaction liquid chromatography (HILIC) retention time and tandem mass spectrometry (MS/MS) fragmentation pattern to distinguish α/β-linkages and linkage positions of disaccharide isomers in GOS through HILIC-MS/MS analysis. The results indicated that the ratio of m/z 203.0524 to m/z 365.1054 could distinguish α/β-linkages, while the ratios of m/z 347.0947 to m/z 365.1054, m/z 245.0642 to m/z 365.1054 and HILIC retention time could distinguish (1 → 2), (1 → 3), (1 → 4) and (1 → 6) linkages. The above rules enabled effective characterization of disaccharides in GOS-containing food samples, including milk powder, rice flour, drink, yogurt. This method can be used in the quality control of GOS and future research on the structure-specific health effects of GOS.

Chemical Profiling of Polar Lipids and the Polyphenolic Fraction of Commercial Italian Phaseolus Seeds by UHPLC-HRMS and Biological Evaluation

The common bean (Phaseolus vulgaris L.) is one of the oldest food crops in the world. In this study, the ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-MS/MS) technique was used to characterize the polar lipid composition and polyphenolic fraction of five bean varieties commonly consumed in Italy: Cannellino (PVCA), Controne (PVCO), Borlotti (PVBO), Stregoni (PVST), and Vellutina (PVVE). Lipid content represents a minor fraction of the whole metabolome in dry beans, and little is known about their polar lipids, which could be potentially bioactive components. Thirty-three compounds were detected through UHPLC-MS/MS, including oxylipins, phospholipids, N-acyl glycerolipids, and several fatty acids. The dichloromethane extracts were subjected to principal component analysis (PCA), with the results showing greater differentiation for the Borlotti variety. Moreover, 27 components belonging to different polyphenol classes, such as phenolic acids, flavonoids, catechins, anthocyanins and their glycosides, and some saponins, were identified in the hydroalcoholic seed extracts. In addition, the mineral content of the beans was determined. Considering the high number of compounds in the five apolar seed extracts, all samples were examined to determine their in vitro inhibitory activity against the enzyme cyclooxygenase-2 (COX-2), which is inducible in inflammatory cells and mediates inflammatory responses. Only PVCO showed the best inhibition of the COX-2 enzyme with an IC50 = 31.15 ± 2.16 µg/mL. In light of these results, the potential anti-inflammatory properties of PVCO were evaluated in the LPS-stimulated murine macrophage cell line J774A.1. Herein, we demonstrate, for the first time, that PVCO at 30 µg/mL can significantly reduce the release of TNF-α, with a less significant anti-inflammatory effect being observed in terms of IL-6 release.

Prebiotics for depression: how does the gut microbiota play a role?

Depression, a mood disorder characterized by persistent feelings of sadness and aversion to activity that can interfere with daily life, is a condition of great concern. Prebiotics, which are non-digestible substances selectively utilized by host microorganisms for health benefits, have gained attention for their potential to improve overall wellness and alleviate various disorders including depression. This study aims to review clinical trials utilizing carbohydrate-type prebiotics such as inulin-type fructans, galactooligosaccharides (GOS), human milk oligosaccharides, resistant starch, prebiotic phytochemicals including epigallocatechin gallate (EGCG), chlorogenic acids, resveratrol, and prebiotic lipids (n-3 polysaturated fatty acids) to determine their effects on depression. Our findings suggest that GOS at a daily dosage of 5 g and eicosapentaenoic acid at or less than 1 g can effectively mitigate depressive symptoms. While EGCG exhibits potential antidepressant properties, a higher dosage of 3 g/d may be necessary to elicit significant effects. The plausible mechanisms underlying the impact of prebiotics on depression include the synthesis of neurotransmitters, production of short-chain fatty acids, and regulation of inflammation.

Biological activity of galacto-oligosaccharides: A review

Galacto-oligosaccharides (GOS) are oligosaccharides formed by β-galactosidase transgalactosylation. GOS is an indigestible food component that can pass through the upper gastrointestinal tract relatively intact and ferment in the colon to produce short-chain fatty acids (SCFAs) that further regulate the body’s intestinal flora. GOS and other prebiotics are increasingly recognized as useful food tools for regulating the balance of colonic microbiota-human health. GOS performed well compared to other oligosaccharides in regulating gut microbiota, body immunity, and food function. This review summarizes the sources, classification, preparation methods, and biological activities of GOS, focusing on the introduction and summary of the effects of GOS on ulcerative colitis (UC), to gain a comprehensive understanding of the application of GOS.

Quantitative Disaccharide Profiling of Glycosaminoglycans from Two Different Preparations by PMP and Deuterated PMP Labeling

Glycosaminoglycan (GAG) fine structures from the same animal cells and tissues are controlled not only by the biosynthetic and metabolic enzymes but also by other environmental factors, such as chemicals, growth factors, nutritional factors, and isolation procedures. To facilitate direct quantitative comparison of disaccharide compositions from different GAG preparations, several stable isotope labeling strategies have been developed. In this report, 1-phenyl-3-methyl-5-pyrazolone (PMP) and deuterated d5-PMP are used for differential disaccharide labeling and profiling of chondroitin sulfate GAG by high performance liquid chromatography (HPLC) coupled with mass spectrometry (MS).

Preventive and Prebiotic Effect of α-Galacto-Oligosaccharide against Dextran Sodium Sulfate-Induced Colitis and Gut Microbiota Dysbiosis in Mice

β-Galacto-oligosaccharide (β-GOS) showed great potential in ulcerative colitis (UC) adjuvant therapy. Herein, the preventive and prebiotic effect of enzymatic-synthesized α-linked galacto-oligosaccharide (α-GOS) was investigated in dextran sodium sulfate-induced colitis and gut microbiota dysbiosis mice. Compared with β-GOS, the α-GOS supplement was more effective in improving preventive efficacy, promoting colonic epithelial barrier integrity, and alleviating inflammation cytokines. Moreover, the activation of the NOD-like receptor (NLR) family member NLRP3 inflammasome-mediated inflammation was significantly inhibited by both α-GOS and β-GOS. Gut microbiota analysis showed that α-GOS treatment reshaped the dysfunctional gut microbiota. The subsequent Spearman's correlation coefficient analysis indicated that these gut microbiota changes were significantly correlated with the inflammatory parameters. These results suggested that the enzymatic-synthesized α-GOS is a promising therapeutic agent in UC prevention and adjuvant treatment by maintaining intestinal homeostasis.

Carrier-Free Immobilization of α-Galactosidase as Nano-Biocatalysts for Synthesizing Prebiotic α-Galacto-Oligosaccharides

α-Galacto-oligosaccharides (α-GOSs) have great functions as prebiotics and therapeutics. This work established the method of batch synthesis of α-GOSs by immobilized α-galactosidase for the first time, laying a foundation for industrial applications in the future. The α-galactosidase from Aspergillus niger L63 was immobilized as cross-linked enzyme aggregates (CLEAs) nano-biocatalyst through enzyme precipitating and cross-linking steps without using carriers. Among the tested agents, the ammonium sulfate showed high precipitation efficacy and induced regular structures of α-galactosidase CLEAs (Aga-CLEAs) that had been analyzed by scanning electron microscopy and Fourier-transform infrared spectroscopy. Through optimization by response surface methodology, the ammonium sulfate-induced Aga-CLEAs achieved a high activity recovery of around 90% at 0.55 U/mL of enzymes and 36.43 mM glutaraldehyde with cross-linking for 1.71 h. Aga-CLEAs showed increased thermal stability and organic solvent tolerance. The storage ability was also improved since it maintained 74.5% activity after storing at 4 °C for three months, significantly higher than that of the free enzyme (21.6%). Moreover, Aga-CLEAs exhibited excellent reusability in the α-GOSs synthesis from galactose, retaining above 66% of enzyme activity after 10 batch reactions, with product yields all above 30%.

Enzymatically synthesized α-galactooligosaccharides attenuate metabolic syndrome in high-fat diet induced mice in association with the modulation of gut microbiota

The composition and structure of gut microbiota plays an important role in obesity induced by a high-fat diet (HFD) and related metabolic syndrome (MetS).

Phenolic Amides with Immunomodulatory Activity from the Nonpolysaccharide Fraction of Lycium barbarum Fruits

The fruits of Lycium barbarum have a long history as an edible and medicinal food in Asian regions and have multiple consumption methods; the polysaccharides (LBPs) are commonly considered as their major immunological constituents. The current study revealed that the total phenolic amide moieties from L. barbarum fruits showed greater potential immunomodulatory activity in vivo than did LBPs. Through subsequent investigation on the immunological bioactive phenolic amides, three new phenolic amides, lyciumamides L-N (1-3), as well as 12 analogues, were obtained from the total phenolic amide fraction. Extensive spectroscopic methods were used to elucidate the new structures. Compounds 4-6 and 15 significantly promoted LPS-stimulated B splenocyte, while compounds 4-6 displayed accelerative effects on the proliferation of Con A-stimulated T lymphocytes at a concentration of 20.0 μg/mL. These data indicated that extracts from L. barbarum fruits enriched with phenolic amides could be developed as a nutritional dietary supplement for immunocompromised individuals.

A comprehensive review on ethnomedicine, phytochemistry, pharmacology, and toxicity of Tephrosia purpurea (L.) Pers

Tephrosia purpurea (L.) Pers. is a well-known plant in Ayurveda and named "Sarwa wranvishapaka" for its property to heal wounds. Traditionally, it is practiced for impotency, asthma, dyspepsia, hemorrhoids, syphilis gonorrhea, rheumatism, enlargement of kidney and spleen. It is an important component of herbal preparations like Tephroli and Yakrifti used to cure liver disorders. Various phytocompounds including pongamol, purpurin, purpurenone, tephrosin, bulnesol, tephrostachin, β-sitosterol, and so on have been reported. Modern pharmacological studies have shown that the plant have wound healing, antileishmanial, anticarcinogenic, antimicrobial, antioxidant, hepatoprotective, antifertility, antispermatogenic, anti-diarrheal, diuretic, and insecticidal properties. Acetylcholinesterase inhibitory action reported from this plant aids its utilization for the development of drugs for Alzheimer's and dementia neurological disorders. Among the known active compounds of T. purpurea, tephrostachin is responsible for antiplasmodial activity, tephrosin, pongaglabol, and semiglabrin exerts antiulcer activity while quercetin, rutin, β-sitosterol, and lupeol are mainly responsible for its anti-inflammatory and anti-cancer properties. From different toxicological studies, concentrations up to 2,000 mg/kg were considered safe. The present review comprehensively summarizes the ethnomedicine, phytochemistry, pharmacology, and toxicology of T. purpurea. Further research on elucidation of the structure-function relationship among active compounds, understanding of multi-target network pharmacology and clinical applications will intensify its therapeutic potential.

Synthesis of potential prebiotic α-glucooligosaccharides using microbial glucansucrase and their in vitro fecal fermentation

Novel α-glucooligosaccharides were synthesized by the acceptor reaction of Leuconostoc citreum SK24.002 glucansucrase with maltose and sucrose. The impact of synthesis conditions, including the ratio of sucrose to maltose and the substrate concentration, on the formation of α-glucooligosaccharides was evaluated. Under the optimized experimental conditions, the yield of a mixture of α-glucooligosaccharides with DP 3-5 reached approximately 56.4% with a concentration of 170.7 mg mL-1. Each of these α-glucooligosaccharides was purified, and the structures were assigned as follows: α-D-Glcp-(1,6)-α-D-Glcp-(1,4)-D-Glcp (DP3), α-D-Glcp-(1,3)-α-D-Glcp-(1,6)-α-D-Glcp-(1,4)-D-Glcp (DP4), and α-D-Glcp-(1,6)-α-D-Glcp-(1,3)-α-D-Glcp-(1,6)-α-D-Glcp-(1,4)-D-Glcp (DP5), respectively. For these three structurally different oligosaccharides, the fermentation selectivity by fecal bacteria was determined in anaerobic batch culture. Fructooligosaccharide (FOS) was used as a positive prebiotic control. Similar to FOS, all three α-glucooligosaccharides selectively stimulated the proliferation of Bifidobacteria and Lactobacilli compared with the control. DP3 exhibited the strongest prebiotic ability to increase the Bifidobacterium and Lactobacillus population, whereas DP5 produced the most short-chain fatty acids. In addition, DP4 produced the highest butyrate concentration and resulted in the lowest acetate : propionate ratio. These results suggested that the enzymatically synthesized α-glucooligosaccharides were potential prebiotics, underlining correlations between the structural features of oligosaccharides and their impact on the metabolism of fecal microbiota.

Nondigestible Oligosaccharides with Anti-Obesity Effects

Obesity has an important influence on health conditions, causing a multitude of complications and comorbidities, and drug therapy is considered to be one of the treatment strategies. Nowadays, there is increasing interest in the study of intestinal microbiota regulation of obesity; also, an increasing number of agricultural and sideline products have been found to have anti-obesity potential. In the present review, we summarize an overview of current known and potential anti-obesity oligosaccharides and their molecular structures. We describe their anti-obesity potential activity and the molecular structure associated with this activity, the regulation of intestinal microbiota composition and its mechanism of action, including regulation of the short-chain fatty acid (SCFA) pathway and altering bile acid (BA) pathway. This review will provide new ideas for us to develop new anti-obesity functional foods.

Comparative metabolite fingerprinting of legumes using LC-MS-based untargeted metabolomics

Legumes are a well-known source of phytochemicals and are commonly believed to have similar composition between different genera. To date, there are no studies evaluating changes in legumes to discover those compounds that help to discriminate for food quality and authenticity. The aim of this work was to characterize and make a comparative analysis of the composition of bioactive compounds between Cicer arietinum L. (chickpea), Lens culinaris L. (lentil) and Phaseolus vulgaris L. (white bean) through an LC-MS-Orbitrap metabolomic approach to establish which compounds discriminate between the three studied legumes. Untargeted metabolomic analysis was carried out by LC-MS-Orbitrap from extracts of freeze-dried legumes prepared from pre-cooked canned legumes. The metabolomic data treatment and statistical analysis were realized by using MAIT R's package, and final identification and characterization was done using MSⁿ experiments. Fold-change evaluation was made through Metaboanalyst 4.0. Results showed 43 identified and characterized compounds displaying differences between the three legumes. Polyphenols, mainly flavonol and flavanol compounds, were the main group with 30 identified compounds, followed by α-galactosides (n = 5). Fatty acyls, prenol lipids, a nucleoside and organic compounds were also characterized. The fold-change analysis showed flavanols as the wider class of discriminative compounds of lentils compared to the other legumes; prenol lipids and eucomic acids were the most discriminative compounds of beans versus other legumes and several phenolic acids (such as primeveroside salycilic), kaempferol derivatives, coumesterol and α-galactosides were the most discriminative compounds of chickpeas. This study highlights the applicability of metabolomics for evaluating which are the characteristic compounds of the different legumes. In addition, it describes the future application of metabolomics as tool for the quality control of foods and authentication of different kinds of legumes.

Protective effects of α-galacto-oligosaccharides against a high-fat/western-style diet-induced metabolic abnormalities in mice

In this study, we investigated the effects of a newly synthesized α-galacto-oligosaccharide mixture (α-GOSg), 0.5% in drinking water, on high-fat/western-style diet (HFWD)-induced metabolic abnormality in mice in a study of 13 weeks. Raffinose family oligosaccharides (RFOs) were included as a comparison. Mice treated with α-GOSg had significantly lower body weight and body fat (p < 0.05), while RFOs were less effective. Both α-GOSg and RFOs significantly reduced serum levels of total cholesterol and low-density lipoprotein cholesterol, alanine aminotransferase and liver lipids. However, only α-GOSg significantly decreased the histopathological score for liver steatosis and downregulated hepatic fatty acid synthesis gene acetyl CoA carboxylase-α. α-GOSg also significantly reduced the content of bile acids in the small intestine and significantly increased the abundance of gut Bifidobacterium and decreased the abundance of Clostridium leptum. These actions are proposed to be key mechanisms contributing to the beneficial health effects of α-GOSg.

Bioconversion of Beet Molasses to Alpha-Galactosidase and Ethanol

Molasses are sub-products of the sugar industry, rich in sucrose and containing other sugars like raffinose, glucose, and fructose. Alpha-galactosidases (EC. 3.2.1.22) catalyze the hydrolysis of alpha-(1,6) bonds of galactose residues in galacto-oligosaccharides (melibiose, raffinose, and stachyose) and complex galactomannans. Alpha-galactosidases have important applications, mainly in the food industry but also in the pharmaceutical and bioenergy sectors. However, the cost of the enzyme limits the profitability of most of these applications. The use of cheap sub-products, such as molasses, as substrates for production of alpha-galactosidases, reduces the cost of the enzymes and contributes to the circular economy. Alpha-galactosidase is a specially indicated bioproduct since, at the same time, it allows to use the raffinose present in molasses. This work describes the development of a two-step system for the valuation of beet molasses, based on their use as substrate for alpha-galactosidase and bioethanol production by Saccharomyces cerevisiae. Since this yeast secretes high amounts of invertase, to avoid congest the secretory route and to facilitate alpha-galactosidase purification from the culture medium, a mutant in the SUC2 gene (encoding invertase) was constructed. After a statistical optimization of culture conditions, this mutant yielded a very high rate of molasses bioconversion to alpha-galactosidase. In the second step, the SUC2 wild type yeast strain fermented the remaining sucrose to ethanol. A procedure to recycle the yeast biomass, by using it as nitrogen source to supplement molasses, was also developed.