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1.
Enzymatic glycosylation involving fluorinated carbohydrates.
Council, CE, Kilpin, KJ, Gusthart, JS, Allman, SA, Linclau, B, Lee, SS
Organic & biomolecular chemistry. 2020;(18):3423-3451
Abstract
Fluorinated carbohydrates, where one (or more) fluorine atom(s) have been introduced into a carbohydrate structure, typically through deoxyfluorination chemistry, have a wide range of applications in the glycosciences. Fluorinated derivatives of galactose, glucose, N-acetylgalactosamine, N-acetylglucosamine, talose, fucose and sialic acid have been employed as either donor or acceptor substrates in glycosylation reactions. Fluorinated donors can be synthesised by synthetic methods or produced enzymatically from chemically fluorinated sugars. The latter process is mediated by enzymes such as kinases, phosphorylases and nucleotidyltransferases. Fluorinated donors produced by either method can subsequently be used in glycosylation reactions mediated by glycosyltransferases, or phosphorylases yielding fluorinated oligosaccharide or glycoconjugate products. Fluorinated acceptor substrates are typically synthesised chemically. Glycosyltransferases are most commonly used in conjunction with natural donors to further elaborate fluorinated acceptor substrates. Glycoside hydrolases are used with either fluorinated donors or acceptors. The activity of enzymes towards fluorinated sugars is often lower than towards the natural sugar substrates irrespective of donor or acceptor. This may be in part attributed to elimination of the contribution of the hydroxyl group to the binding of the substrate to enzymes. However, in many cases, enzymes still maintain a significant activity, and reactions may be optimised where necessary, enabling enzymes to be used more successfully in the production of fluorinated carbohydrates. This review describes the current state of the art regarding chemoenzymatic production of fluorinated carbohydrates, focusing specifically on examples of the enzymatic production of activated fluorinated donors and enzymatic glycosylation involving fluorinated sugars as either glycosyl donors or acceptors.
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2.
Electrosynthesis of Biobased Chemicals Using Carbohydrates as a Feedstock.
Vedovato, V, Vanbroekhoven, K, Pant, D, Helsen, J
Molecules (Basel, Switzerland). 2020;(16)
Abstract
The current climate awareness coupled with increased focus on renewable energy and biobased chemicals have led to an increased demand for such biomass derived products. Electrosynthesis is a relatively new approach that allows a shift from conventional fossil-based chemistry towards a new model of a real sustainable chemistry that allows to use the excess renewable electricity to convert biobased feedstock into base and commodity chemicals. The electrosynthesis approach is expected to increase the production efficiency and minimize negative health for the workers and environmental impact all along the value chain. In this review, we discuss the various electrosynthesis approaches that have been applied on carbohydrate biomass specifically to produce valuable chemicals. The studies on the electro-oxidation of saccharides have mostly targeted the oxidation of the primary alcohol groups to form the corresponding uronic acids, with Au or TEMPO as the active electrocatalysts. The investigations on electroreduction of saccharides focused on the reduction of the aldehyde groups to the corresponding alcohols, using a variety of metal electrodes. Both oxidation and reduction pathways are elaborated here with most recent examples. Further recommendations have been made about the research needs, choice of electrocatalyst and electrolyte as well as upscaling the technology.
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3.
Carbohydrate and bioactive compounds composition of starchy tropical fruits and tubers, in relation to pre and postharvest conditions: A review.
Rinaldo, D
Journal of food science. 2020;(2):249-259
Abstract
In some tropical countries, people are suffering from both undernourishment and noncommunicable disorders, such as overweight/obesity. Starchy tropical fruits and tubers are of particular interest for their carbohydrate content and for the micronutrients they provide. The present study summarizes the content in carbohydrate, phenolics, carotenoids, and vitamin C, as well as the antioxidant activity of a wide range of tropical fruits and tubers. The energy content of fruits and tubers studied is in the range of 1,200 to 1,800 kJ/100 g of dry weight. They are thus important staple foods and, due to their diversity and seasonality, they can provide energy all year long by alternating the resources in the human diet. Starchy fruit and tuber crops have antiobesity properties as they are bulky, rich in moisture, and contain less than 2% of fat. Noncolored fruit and tubers provide total phenolics at about 20 to 140 mEq/100 g fresh weight. They thus have a high antioxidant capacity, as related to their total phenolic content but also to the presence of carotenoids, such as lutein, mostly in Dioscorea bulbifera and cocoyam. Yellow and orange-fleshed varieties contain more total phenolics and also more provitamin A carotenoids than noncolored fleshed ones. The contents in total phenolic and carotenoid greatly vary with the species and variety. The influence of pre and postharvest conditions on micronutrient content is discussed. Further studies on new processing methods are needed to maximize polyphenols and carotenoids retention in the foods and increase the bioaccessibility of these compounds. PRACTICAL APPLICATION This paper provides information on the nutritional quality of starchy tropical fruits and tubers. Nutritional quality is studied from the point of view of providing energy and bioactive compounds. The paper aims to promote the use of local resources in tropical areas, which could ultimately limit the adverse effects of food globalization on noncommunicable disorders. It could also lead to tropical countries being less dependent on food imports.
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4.
Anticancer potentiality and mode of action of low-carbohydrate proteins and peptides from mushrooms.
Rezvani, V, Pourianfar, HR, Mohammadnejad, S, Madjid Ansari, A, Farahmand, L
Applied microbiology and biotechnology. 2020;(16):6855-6871
Abstract
Severe side effects of chemotherapy as well as drug resistance highlight the ongoing need to discover novel natural bioactive compounds with anticancer potentiality. Mushroom-derived proteins are among the naturally occurring compounds that have been the subject of a body of research on their potentiality in cancer therapy. The greatest attention in relevant review articles has been paid to well-known mushroom-derived glycoproteins such as lectins and protein-bound polysaccharide complexes such as polysaccharide-K (PSK) or krestin and polysaccharopeptide (PSP), which contain substantial amounts of carbohydrates (50-90%). These complex compounds exert their anticancer activity mainly by binding to cell membranes leading to extrinsic (death receptor) apoptosis or intrinsic (mitochondrial) apoptotic pathways. However, several other research studies have reported pure, well-characterized, proteins or peptides from mushrooms, which are carbohydrate-free or have very low amounts of carbohydrate. These proteins may fall into four categories including fungal immunomodulatory proteins, ubiquitin-like proteins, enzymes, and unclassified proteins. Well-defined chemical structure, elucidated full amino acid or N-terminal sequences, purity, and having some distinct and specific pathways compared to glycoproteins have made these low-carbohydrate proteins attractive for cancer research. The aim of this review was therefore to improve the current understanding of mushroom-derived low-carbohydrate proteins and to consolidate the existing knowledge of the most promising mushroom species from which low-carbohydrate proteins have been derived, characterized, and examined for their anticancer activity. In addition, molecular targets and mechanisms of action of these proteins have been discussed. Key points • Mushroom-derived low-carbohydrate proteins lack or have low carbohydrate. • Low-carbohydrate proteins show potent anticancer activities in vitro and in vivo. • There are specific pathways for low-carbohydrate proteins to inhibit cancer cells.
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5.
Unexplained case of hypophosphataemic rickets.
Godden, B, Hilditch, C, Agrawal, R
Journal of paediatrics and child health. 2019;(7):851-853
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6.
All that a physician should know about FODMAPs.
Mehtab, W, Agarwal, A, Singh, N, Malhotra, A, Makharia, GK
Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology. 2019;(5):378-390
Abstract
A diet low in poorly absorbed, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is now considered as an effective strategy for symptoms control in patients with irritable bowel syndrome (IBS). The low FODMAP diet is administered in three phases, namely restriction of all dietary FODMAPs followed by rechallenge and then reintroduction of specific FODMAPs according to the tolerance of patients. A dietician should be involved in patients in whom a low FODMAP diet is planned. While restricting high FODMAPs, it is pertinent that patients are advised a well-balanced diet and suitable alternatives with low FODMAP contents in each food groups are prescribed. Strict adherence to a low FODMAP diet has been shown to improve symptoms, stool output, quality of life, and the overall well-being of patients with IBS. For those who do not respond to this dietary approach, a normal diet may be initiated and other treatment strategies (dietary or nondietary) should be considered. Interestingly, the low FODMAP diet has also been tried in other functional disorders, nonceliac gluten sensitivity, and even inflammatory bowel disease. Since the concept of FODMAP is relatively new, there is only limited data on the content of FODMAP in the Indian food items and there is a need to address this question. There is also a need for well-designed and adequately powered studies to explore the efficacy of low FODMAP diet in patients with IBS. In the present review article, we have compiled all the relevant information about FODMAPs with an objective to provide comprehensive information on FODMAPs to a physician.
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7.
Copolymers containing carbohydrates and other biomolecules: design, synthesis and applications.
Ma, Z, Zhu, XX
Journal of materials chemistry. B. 2019;(9):1361-1378
Abstract
Glycopolymers are synthetic polymers containing pendant carbohydrate groups. Other biological compounds can be incorporated into glycopolymers to prepare both random and block copolymers aimed at bio-related applications: boronic acid can be introduced as a functional group to obtain crosslinked hydrogels; cholesterol and bile acids can be introduced to render the polymers more hydrophobic for the formation of micelles. Sugar-containing block copolymers with biocompatible blocks such as polypeptides, poly(ethylene glycol), poly(lactic acid) and poly(ε-caprolactone) were also prepared for potential application in drug carriers. These glycopolymers interact with lectins or lectin-containing surfaces as natural carbohydrate mimics. This review highlights the recent progress in the synthesis of random or block glycopolymers. Examples of the applications of glycopolymers in the separation and removal of toxins and bacteria, tumor cell recognition and glucose-responsive insulin delivery are presented and discussed.
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8.
Nutritional hypophosphatemic rickets secondary to Neocate® use.
Akhtar Ali, S, Mathalikunnel, A, Bhardwaj, V, Braskett, M, Pitukcheewanont, P
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2019;(9):1887-1891
Abstract
Elemental formula is commonly used in children with feeding intolerance. We describe two, medically complex and feeding tube dependent, patients exclusively fed with Neocate® who subsequently developed hypophosphatemic rickets. Both patients had gross motor decline and pain with physical touch. They were found to have low serum phosphorus, normal calcium, and vitamin D studies, with elevated alkaline phosphatase suggestive of nutritional hypophosphatemia. Both courses were complicated by hypocalcemia following formula change and phosphorus supplementation, highlighting the need for careful management of phosphate repletion in affected individuals. Diligent serial electrolyte monitoring as well as attention to bone health is needed in conjunction with elemental nutrition. Formula change led to restoration of calcium and phosphorus homeostasis and radiographic improvement in these patients.
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9.
Metabolic engineering pathways for rare sugars biosynthesis, physiological functionalities, and applications-a review.
Bilal, M, Iqbal, HMN, Hu, H, Wang, W, Zhang, X
Critical reviews in food science and nutrition. 2018;(16):2768-2778
Abstract
Biomolecules like rare sugars and their derivatives are referred to as monosaccharides particularly uncommon in nature. Remarkably, many of them have various known physiological functions and biotechnological applications in cosmetics, nutrition, and pharmaceutical industries. Also, they can be exploited as starting materials for synthesizing fascinating natural bioproducts with significant biological activities. Regrettably, most of the rare sugars are quite expensive, and their synthetic chemical routes are both limited and economically unfeasible due to expensive raw materials. On the other hand, their production by enzymatic means often suffers from low space-time yields and high catalyst costs due to hasty enzyme denaturation/degradation. In this context, biosynthesis of rare sugars with industrial importance is receiving renowned scientific attention, across the globe. Moreover, the utilization of renewable resources as energy sources via microbial fermentation or microbial metabolic engineering has appeared a new tool. This article presents a comprehensive review of physiological functions and biotechnological applications of rare ketohexoses and aldohexoses, including D-psicose, D-tagatose, L-tagatose, D-sorbose, L-fructose, D-allose, L-glucose, D-gulose, L-talose, L-galactose, and L-fucose. Novel in-vivo recombination pathways based on aldolase and phosphatase for the biosynthesis of rare sugars, particularly D-psicose and D-sorbose using robust microbial strains are also deliberated.
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10.
Food-derived 1,2-dicarbonyl compounds and their role in diseases.
Hellwig, M, Gensberger-Reigl, S, Henle, T, Pischetsrieder, M
Seminars in cancer biology. 2018;:1-8
Abstract
Reactive 1,2-dicarbonyl compounds (DCs) are generated from carbohydrates during food processing and storage and under physiological conditions. In the recent decades, much knowledge has been gained concerning the chemical formation pathways and the role of DCs in food and physiological systems. DCs are formed mainly by dehydration and redox reactions and have a strong impact on the palatability of food, because they participate in aroma and color formation. However, they are precursors of advanced glycation end products (AGEs), and cytotoxic effects of several DCs have been reported. The most abundant DCs in food are 3-deoxyglucosone, 3-deoxygalactosone, and glucosone, predominating over methylglyoxal, glyoxal, and 3,4-dideoxyglucosone-3-ene. The availability for absorption of individual DCs is influenced by the release from the food matrix during digestion and by their reactivity towards constituents of intestinal fluids. Some recent works suggest formation of DCs from dietary sugars after their absorption, and others indicate that certain food constituents may scavenge endogenously formed DCs. First works on the interplay between dietary DCs and diseases reveal an ambiguous role of the compounds. Cancer-promoting but also anticancer effects were ascribed to methylglyoxal. Further work is still needed to elucidate the reactions of DCs during intestinal digestion and pathophysiological effects of dietary DCs at doses taken up with food and in "real" food matrices in disease states such as diabetes, uremia, and cancer.