Complex Carbohydrates and Glycoconjugates: Structure, Functions and Applications

The study of carbohydrates has a long history: for two centuries, the researches performed the way from “sweet matter” to glycomics [...]

Role of Age and Sex on Simple and Complex Carbohydrates Rich Foods Consumption and Thyroid Cancer Risk: Hospital Based Case - Control Study

Background: The risk of thyroid cancer has already been related to diet/carbohydrates rich foods, but the association has not been investigated in terms of age and sex implications. Objective: We studied the relationship between thyroid cancer and the consumption of simply and complex carbohydrates rich foods, mainly investigating the possible predictive role of age and sex. Methods: We analyzed data from a hospital case-control study conducted in Italy from 2015 to 2018, including 106 cases of thyroid cancer and 121 controls. The consumption of simple and complex carbohydrates rich foods was investigated through the validated Lifestyles Questionnaire using a 4-level scale (never, 1 time per week, 2–3 times a week, 6 times a week). Statistical data analysis was conducted using the IBM SPSS Statistics 21.0 program. Results: We found a moderate negative correlation between simple carbohydrates rich foods consumption and age (rho= -0.364, p:0.00), particularly in females (females: rho= -0.374, p:0.00; males: rho=-0.266, p=0.036). A weak positive correlation was found between age and complex carbohydrates-rich foods only in males (rho= 0.244, p=0.054). The Two-Way Analysis of Variance confirmed that, overall, simple carbohydrates rich foods consumption decreased with age categories (Case: F=2.59, p=0.032; Control: F=3.14, p=0.011), although it remains higher for female than male cases at all age categories (≤38, 39-52, 53+years). Conversely the complex carbohydrates rich foods intake had interaction with age categories only in controls group (Control: F=1.95, p=0.09; Case: F=0.744, p=0.592), where based on sex, it remains higher for female than male at ≤38 and 39-52 age categories. It should be emphasized that in category ≤38 we had only one male cases. Conclusion: Our study adds new and relevant information to support the hypothesis that age and sex could impact the thyroid cancer risk by their involvement in simple carbohydrates rich foods consumption. Therefore, future interventions are needed for an understanding of the pathophysiological associations between only carbohydrates rich foods intake and thyroid cancer, mainly for older and female populations, and also for the improvement of preventive public health policies and “Gender Medicine”.

Gums—Characteristics and Applications in the Food Industry

Gums, or polysaccharides, are complex carbohydrates, soluble in water, which can form gels and mucilages. They have high molar mass and can be formed by galactose, arabinose, rhamnose, xylose, galacturonic acid, among others. They have gelling characteristics, thickening, moisture retention, emulsification and stabilization. Polysaccharides are widely used in the formulation of food products, due to their wide versatility. Its diversity of applications is closely linked to its chemical structures. The characterization of structural molecules allows the knowledge of the properties of polysaccharides or glycoconjugates. In this sense, this chapter addresses knowledge about chemical, molecular, rheological, thermodynamic characteristics that are extremely important to identify the use and applications of polysaccharides in the context of elaboration and innovation in the food industry.

Short chain fatty acid butyrate, a breast milk metabolite, enhances immature intestinal barrier function genes in response to inflammation in vitro and in vivo

Infants born under 1500 grams have an increased incidence of necrotizing enterocolitis in the ileum and the colon which is a life-threatening intestinal necrosis. This is in part due to excessive inflammation in the immature intestine to colonizing bacteria because of an immature innate immune response. Breastmilk complex carbohydrates create metabolites of colonizing bacteria in the form of short-chain fatty acids (SCFAs). We studied the effect of breastmilk metabolites, SCFAs, on immature intestine with regard to anti-inflammatory effects. This showed that acetate, propionate and butyrate were all anti-inflammatory to an IL-1β inflammatory stimulus. In this study, to further define the mechanism of anti-inflammation, we created transcription profiles of RNA from immature human enterocytes after exposure to butyrate with and without an IL-1β inflammatory stimulus. We demonstrated that butyrate stimulates an increase in tight-junction and mucus genes and if we inhibit these genes the anti-inflammatory effect is partially lost. SCFAs, products of microbial metabolism of complex carbohydrates of breastmilk oligosaccharides, have been found with this study to induce an anti-IL-1β response that is associated with an upregulation of tight junctions and mucus genes in epithelial cells (H4 cells). These studies suggest that breastmilk in conjunction with probiotics can reduce excessive inflammation with metabolites that are anti-inflammatory and stimulate an increase in the mucosal barrier.

How and why plants and human N-glycans are different: Insight from molecular dynamics into the “glycoblocks” architecture of complex carbohydrates

The N-glycosylation is one of the most abundant and diverse post-translational modifications of proteins, implicated in protein folding and structural stability, and mediating interactions with receptors and with the environment. All N-glycans share a common core from which linear or branched arms stem from, with functionalization specific to different species and to the cells’ health and disease state. This diversity generates a rich collection of structures, all diversely able to trigger molecular cascades and to activate pathways, which also include adverse immunogenic responses. These events are inherently linked to the N-glycans’ 3D architecture and dynamics, which remain for the large part unresolved and undetected because of their intrinsic structural disorder. In this work we use molecular dynamics (MD) simulations to provide insight into N-glycans’ 3D structure by analysing the effects of a set of very specific modifications found in plants and invertebrate N-glycans, which are immunogenic in humans. We also compare these structural motifs and combine them with mammalian N-glycan motifs to devise strategies for the control of the N-glycan 3D structure through sequence. Our results suggest that the N-glycans’ architecture can be described in terms of the local spatial environment of groups of monosaccharides. We define these “glycoblocks” as self-contained 3D units, uniquely identified by the nature of the residues they comprise, their linkages and structural/dynamic features. This alternative description of glycans’ 3D architecture can potentially lead to an easier prediction of sequence-to-structure relationships in complex carbohydrates, with important implications in glycoengineering design.

Structurally complex carbohydrates maintain diversity in gut-derived microbial consortia under high dilution pressure

ABSTRACT Dietary fibers are major substrates for maintaining and shaping gut microbiota, but the structural specificity of these fibers for the diversity, structure and function of gut microbiota are poorly understood. Here, we employed an in vitro sequential batch fecal culture approach to address two ecological questions: (i) whether the chemical complexity of a carbohydrate influences its ability to maintain microbial diversity against high dilution pressure (ii) whether substrate structuring or obligate microbe-microbe metabolic interactions (e.g. exchange of amino acids or vitamins) exert more influence on maintained diversity. Sorghum arabinoxylan (SAX, a complex polysaccharide), inulin (a low-complexity oligosaccharide) and their corresponding monosaccharide controls were selected as model carbohydrates. Our results demonstrate that complex carbohydrates stably sustain diverse microbial consortia. Furthermore, other metabolic interactions were less influential in structuring microbial consortia consuming SAX than inulin. Finally, very similar final consortia were enriched on SAX from the same individual's fecal microbiota one month later, suggesting that polysaccharide structure is more influential than stochastic alterations in microbiome composition in governing the outcomes of sequential batch cultivation experiments. These data suggest that carbohydrate structural complexity affords independent niches that structure fermenting microbial consortia, whereas other metabolic interactions govern the composition of communities fermenting simpler carbohydrates.

Starch and Glycogen Analyses: Methods and Techniques

For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included.