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Ameliorating Insulin Signalling Pathway by Phytotherapy
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Ethnopharmacology of Wild Plants, 2021
To be proven potential anti-hyperglycemic agents of T. cordifolia leaves against alpha amylase enzyme. Shareef et al. (2014) had extracted leaves in petroleum ether, chloroform, ethyl acetate and methanol solvents. The percentage inhibition of α-amylase by the extracts was studied in a concentration range of 10–640 μg/mL. Of the four extracts, ethyl acetate and methanol were comparatively effective than in petroleum ether and chloroform in inhibiting α-amylase. The IC50of petroleum ether and chloroform extract was 100 and 120 μg/mL, respectively, and methanol extracts were 20 μg/mL. The ethylacetate and methanol exhibited a maximum inhibition of 98% at 50 μg/mL concentration. Dinesh Kumar et al. (2010) had performed in vitro assay by taking ethanolic extract against α-amylase at concentrations 10–100 μg/mL, which exhibited minimum alpha-amylase inhibitory effects from 12.32 ± 0.79 to 36.41 ± 0.39 μg/mL with an IC50 value 138.80 ± 0.16 μg/mL. Dichloromethane (DCM) extract demonstrated 100% inhibition of the α-glucosidase (Chougale et al. 2009), but in the case of, salivary amylase and pancreatic amylase were 75% and 83%, respectively. Introducing maltose load of 2 mg/g along with 0.3 mg/g b. w. of the DCM stem extract to the normal and diabetic rats, the hypoglycemic activity was raised by 50 and 58%, respectively, as compared to the controls. The extract happened to inhibit α-glycosidase in a non-competitive way.
Section Pretreatment, Epitope Demasking, and Methods for Dealing with Unwanted Staining
Published in Lars-Inge Larsson, Immunocytochemistry: Theory and Practice, 2020
Apart from proteases, some other enzymes have been used for treating sections before immunocytochemistry. These include mixed glycosidases, which Andrews et al.1 reported to reduce unwanted staining of frozen sections. The tissue material used was from mice. Attempts to stain it with mouse monoclonal antibodies were complicated since the second antimouse IgG reagent, as expected, also reacted with endogenous mouse immunoglobulins, present in the interstitial fluid. The authors found that the mixed glycosidase treatment eluted endogenous mouse immunoglobulins and provided for a better background.1 The method would probably not work on tissues fixed in cross-linking fixatives. An alternative approach, applicable to tissues fixed in cross-linking fixatives, and thereby to extractable antigens, would be to use directly labeled (e.g., with fluorochromes, colloidal gold, or biotin) monoclonal antibodies. Much immunoglobulin does occur in interstitial tissues. These can be removed by prolonged washes in saline prior to fixation, but such washing has, of course, applicability only to firmly bound antigens.5
Biochemical Adaptations to Early Extrauterine Life
Published in Emilio Herrera, Robert H. Knopp, Perinatal Biochemistry, 2020
José M. Medina, Carlos Vicario, María C. Juanes, Emilio Fernández
Immediately after delivery, the fall in the insulin/glucagon ratio triggers liver glycogenolysis in order to supply neonatal tissues with glucose for both general and specific purposes (see Section II). Activation of glycogenolysis is achieved by phosphorylation of glycogen phosphorylase through the phosphorylation cascade that is switched on by the increase in cAMP levels (Figure 3). It is very intriguing, however, that the synthesis of glucose 6-phosphatase, a compulsory enzyme for the output of glucose from liver glycogen, is delayed in the rat, being fully active at the middle of the suckling period.12 Since glycogenolysis is very active 2 h after delivery (Figure 4) other enzymes would be responsible for early postnatal glycogenolysis. This may be the case of lysosomal α-glycosidase which has been claimed to be involved in neonatal glycogenolysis.6
Targeting glyco-immune checkpoints for cancer therapy
Published in Expert Opinion on Biological Therapy, 2021
Another important challenge for the development of drugs targeting glyco-immune checkpoints is the possibility of new types of toxicities. Siglecs mAb tested in early clinical trials have not shown excess or new types of toxicities [91]. However, treatment with sialic acid mimetics to inhibit sialic acid biosynthesis is already quite toxic in mouse models and applications were only possible by direct injection of the mimetic into tumors [35,102]. Inhibitors of sialic acid biosynthesis such as chemical inhibitors of the N-acetyl-glucosamine-epimerase (GNE) are efficient in vitro but too toxic for in vivo applications [111]. The treatment with tumor-targeted glycosidases such as sialidase linked to trastuzumab can be used systemically in mouse models [37]. However, it remains unclear how much systemic desialylation will be seen in longer cancer treatment regimens in patients. For example, it is likely that blood cells, the kidney and the liver will experience some degree of desialylation. In kidneys, the negatively charged sialic acid is responsible for keeping positively charged blood proteins within glomerular capillaries and the glomerular desialylation could lead to significant protein loss including nephrotic syndrome. Early clinical trials with glycosidases will rapidly show if these new molecules can be safely used.
Synthesis of novel tris-chalcones and determination of their inhibition profiles against some metabolic enzymes
Published in Archives of Physiology and Biochemistry, 2021
Serdar Burmaoglu, Ali Osman Yilmaz, M. Fatih Polat, Rüya Kaya, İlhami Gulcin, Oztekin Algul
The α-glycosidase (α-Gly) enzyme (E.C. 3.2.1.20) catalyses the hydrolysis of glycosidic bonds of oligo and polysaccharides to liberate monosaccharides, including glucose monomers. It is released from the intestine cells and is very widely distributed in all organisms (Gulcin and Taslimi 2018, Gulcin et al.2018, Taslimi and Gulcin 2018, Taslimi et al.2018). In humans, α-glycosidase inhibitors (α-GIs) have crucial importance for the controlling of some disorders including hyperglycaemia and type 2 diabetes mellitus (T2DM) (Daryadel et al.2018, Gondolova et al.2018). α-GIs can reduce the uptake of dietary carbohydrates and repress postprandial hyperglycaemia and T2DM. Thus, these α-GIs are endowed with sugar molecules such as moieties competing with the oligosaccharides for binding to the active site of the enzyme (Scozzafava et al.2015, Demir et al.2018, Maharramova et al.2018).
MICROBIOTA INSIGHTS IN CLOSTRIDIUM DIFFICILE INFECTION AND INFLAMMATORY BOWEL DISEASE
Published in Gut Microbes, 2020
C. Rodríguez, E. Romero, L. Garrido-Sanchez, G. Alcaín-Martínez, RJ. Andrade, B. Taminiau, G. Daube, E. García-Fuentes
The impairment of intestinal barrier function or disruption of mucosal T cells by inflammatory mediators favor C. difficile colonization and toxin production. Some phospholipids, such as phosphatidylcholine and phosphatidylethanolamine, are released during this disruption. Phosphatidylcholine is converted into ethanolamine and glycerol by bacterial phosphodiesterases. C. difficile benefits from the breakdown of ethanolamine and utilizes it as a source of nitrogen and carbon.95,96 On the other hand, a higher glycosidase activity has been reported in IBD patients than in healthy subjects. Indeed, disruption of intestinal barrier function and the intestinal microbiota also entails the liberation of monosaccharides, which promote the multiplication and colonization of C. difficile.96 A previous study described in depth how C. difficile catabolises microbiota-liberated mucosal carbohydrates and how pathogen expansion is even aided by microbiota-induced elevation of sialic acid levels in vivo.97