Latest Research on Glucan : Dec 2021

The effects of β-glucan on human immune and cancer cells

Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as β-glucans. β-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, β-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by β-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1→3 linear β-glycosidic chain of β-glucans cannot be digested. Most β-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small β-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, β-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate β-glucans is essential if we wish to investigate the effects of β-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified β-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of β-glucans or β-glucans containing compounds.[1]


Glucan-binding Proteins of the Oral Streptococci

The synthesis of extracellular glucan is an integral component of the sucrose-dependent colonization of tooth surfaces by species of the mutans streptococci. In investigators’ attempts to understand the mechanisms of plaque biofilm development, several glucan-binding proteins (GBPs) have been discovered. Some of these, the glucosyltransferases, catalyze the synthesis of glucan, whereas others, designated only as glucan-binding proteins, have affinities for different forms of glucan and contribute to aspects of the biology of their host organisms. The functions of these latter glucan-binding proteins include dextran-dependent aggregation, dextranase inhibition, plaque cohesion, and perhaps cell wall synthesis. In some instances, their glucan-binding domains share common features, whereas in others the mechanism for glucan binding remains unknown. Recent studies indicate that at least some of the glucan-binding proteins modulate virulence and some can act as protective immunogens within animal models. Overall, the multiplicity of GBPs and their aforementioned properties are testimonies to their importance. Future studies will greatly advance the understanding of the distribution, function, and regulation of the GBPs and place into perspective the facets of their contributions to the biology of the oral streptococci.[2]



Beta Glucan: A Valuable Functional Ingredient in Foods

β-Glucan is a valuable functional ingredient and various extraction techniques are available for its extraction. Choice of an appropriate extraction technique is important as it may affect the quality, structure, rheological properties, molecular weight, and other functional properties of the extracted β-glucan. These properties lead to the use of β-glucan into various food systems and have important implications in human health. This review focuses on the extraction, synthesis, structure, molecular weight, and rheology of β-glucan. Furthermore, health implications and utilization of β-glucan in food products is also discussed.[3]


β(1-3)(1-6)-D-glucans Modulate Immune Status and Blood Glucose Levels in Dogs

Aims: The objective of this study is to evaluate the effects of adding two different glucans coded as BGO1 and BGO2 into commercial feed of dogs.

Study Design: We measured changes in phagocytosis, levels of IL-2 in blood, antibody formation and level of blood sugar (normal homeostasis and experimentally-induced hyperglycaemie with streptozotocin).

Place and Duration of Study: Department of Pathology, University of Louisville, and Department of Research and Development, Biorigin, June 2012 and May 2013.

Methodology: The technique employing phagocytosis of synthetic polymeric microspheres was used for evaluation of phagocytic activity. IL-2 production was evaluated in serum by an ELISA kit. Formation of antibodies was tested using ovalbumin as an antigen, level of specific antibodies was measured by ELISA. Blood sugar evaluation was done both in normal animals and in animals with experimentally-induced hyperglycaemie. The level of glucose in serum was measured by Antech Diagnostics.

Results: In phagocytosis, both glucans significantly (P ≤0.05 level) increased the phagocytic activity of blood monocytes and neutrophils. Both glucans were active in IL-2 tests, but BG01 activity was 160% of that of BG02. Similar data were achieved in evaluation of effects on antibody response – BG01 reached OD of 0.717, whereas BG02 reached OD 0.411. Blood sugar evaluations showed no effect of glucan on normal dogs, but significant (P ≤0.05 level) reduction in dogs with hyperglycaemie (both glucans showed same activity). Conclusion: Our data showed that both glucans had significant immunomodulating effects in immune reactions in the dog model, strongly suggesting that supplementation of feed with these glucans results in improvement of biological and immunological conditions of dogs.[4]


Purification and Characterization of α-Glucan Phosphorylase Isoform Pho 2 from Spinach Leaves

α-Glucan phosphorylase is an important enzyme of carbohydrate metabolism. In spinach leaves, it has been reported in two multiple forms viz. Pho 2 (cytosolic) and Pho 1 (plastidial). Here, we extracted and purified Pho 2 form of α-glucan phosphorylase from spinach using salting out with ammonium sulfate, desalting using Sephadex G-25 chromatography, anion exchange chromatography using DEAE-Sepharose and gel filtration chromatography using Sepharose-4-B. The purified enzyme had a specific activity, 150 units/mg protein. There was 38% recovery and 652 fold purification after final Sepharose-4B chromatography. The purified enzyme showed a single protein band on SDS sodium dodecyl sulfate polyacrylamide gel electrophoresis having molecular weight 94,000±2000 daltons. The native molecular weight is found to be 188,000±3000 daltons as determined using gel filtration chromatography over Sephadex G-200. The Pho2 exhibited optimum pH at pH 6.0 with two half pH optima at pH 5.2 and pH 7.0. The optimum temperature of Pho2 is found to be 37ºC with two half temperature optima at 30ºC and 40ºC. The Km value of the enzyme for starch and glucose-1-phosphate is found to be 116 µg/mL and 0.55 mM, respectively.[5]


Reference

[1] Chan, G.C.F., Chan, W.K. and Sze, D.M.Y., 2009. The effects of β-glucan on human immune and cancer cells. Journal of hematology & oncology, 2(1), pp.1-11.

[2] Banas, J.A. and Vickerman, M.M., 2003. Glucan-binding proteins of the oral streptococci. Critical Reviews in Oral Biology & Medicine, 14(2), pp.89-99.

[3] Ahmad, A., Anjum, F.M., Zahoor, T., Nawaz, H. and Dilshad, S.M.R., 2012. Beta glucan: a valuable functional ingredient in foods. Critical reviews in food science and nutrition, 52(3), pp.201-212.

[4] Vetvicka, V. and Oliveira, C., 2014. β (1-3)(1-6)-D-glucans modulate immune status and blood glucose levels in dogs. Journal of Pharmaceutical Research International, pp.981-991.

[5] Jain, R. and Kumar, A., 2015. Purification and Characterization of α-Glucan Phosphorylase Isoform Pho 2 from Spinach Leaves. Biotechnology Journal International, pp.182-195.

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