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A Short Overview on Anti-Diabetic Natural Products: Reviewing the Herbotherapeutic Potentials
Published in Debarshi Kar Mahapatra, Cristóbal Noé Aguilar, A. K. Haghi, Natural Products Pharmacology and Phytochemicals for Health Care, 2021
Mojabir Hussen Ansari, Debarshi Kar Mahapatra
Gymnema, in India, is widely called “gurmar” which means ‘sugar destroying.’ The hypoglycemic activity of Gymnema can be tested along with insulin and results are encouraging. Research suggests that leaf extract of G. sylvestre containing gymnemic acid that suppresses the elevated blood sugar concentration by blocking glucose utilization in the intestine. The extract of the plant acts to work by increasing endogenous insulin production by increasing serum C-peptide levels. It is a chain of amino acid that is formed by cleaving of proinsulin molecules produces from the pancreas to form insulin. Moreover, Gymnema also decreases the level of cholesterol, triglyceride, and LDL-C, whereas it increases the level of HDL-C [12–14]. The gymnemic acid possesses hypoglycemic activity due to delay the glucose absorption in the blood. As gymnemic acid molecules fill the receptor location in the absorptive external layer of the intestine, therefore, absorption of sugar molecules inhibited, which result in low blood sugar level.
Biocatalyzed Synthesis of Antidiabetic Drugs
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
After this pioneering work, some other strategies were developed using recombinant microorganisms that produce intact proinsulin instead of the A or B chains separately. Proinsulin is the pro-hormone precursor to insulin made in the β cells of the islets of Langerhans, consisting in 81 aminoacidic residues arranged in three chains, namely, the above mentioned A and B chains, connected each other by a C chain (Steiner and Oyer, 1967) between the C terminal end of chain B and the N terminal end of the A chain, as shown in Fig. 11.2. For instance, Novo used engineered Saccharomyces cerevisiae cells to secrete proinsulin; subsequently, two enzymatic cleavages, the first one catalyzed by trypsin leading to the removal of most of the C chain, and the second one catalyzed by caboxypeptidase to delete two Arg residues from ThrB30, yield the human insulin (Thim et al., 1986; Ladisch and Kohlmann, 1992). Preparation of human insulin from proinsulin.
Enzyme Nanocapsules for Glucose Sensing and Insulin Delivery
Published in Grunwald Peter, Biocatalysis and Nanotechnology, 2017
Insulin is synthesized by pancreatic beta cells, which are known to cluster as the islets of Langerhans in pancreas (Ashby et al., 1975). Although the islets account for only 1–2% of the total mass of pancreas, they are the only tissues responsible for insulin secretion in the entire body throughout the whole life. Insulin is a small protein that is constituted by two short polypeptide chains, the A- and B-chains, linked together by disulfide bonds (Katsoyannis, 1964). During the production of insulin, it is, however, first synthesized as an inactive, single chain polypeptide called preproinsulin. Preproinsulin contains a 24-residue signal peptide which directs the translocation of the nascent protein to the endoplasmic reticulum (ER) for posttranslational processing. Upon entering the ER, the signal peptide is proteolytically removed to form proinsulin, which then folds into the correct conformation and forms three vital disulfide bonds in the ER lumen. Proinsulin undergoes maturation into active insulin through digestion by specific peptidases in the secretary vesicles (Yoi et al., 1979). Finally, the resulting mature insulin is packaged and stored in secretary granules waiting for secretion (Lindall et al., 1963).
New approaches towards the discovery and evaluation of bioactive peptides from natural resources
Published in Critical Reviews in Environmental Science and Technology, 2020
Nam Joo Kang, Hyeon-Su Jin, Sung-Eun Lee, Hyun Jung Kim, Hong Koh, Dong-Woo Lee
Bioactive peptides (BPs) are specific protein fragments with positive impacts on body functions or conditions, and thus have the potential to improve human health. The human body contains multiple BPs, consisting of up to a few dozen amino acids linked by peptide bonds, that are involved in inflammation, hemostasis, neurotransmission, immune response, cell proliferation, hormone responses, and oxidative stress (Korhonen & Pihlanto, 2006). Such peptides, many of which are generated by proteolysis, act as molecular mediators of many cellular processes. For example, cleavage of fibrinogen by thrombin is required to generate fibrin monomers for blood clotting (Crawley, Zanardelli, Chion, & Lane, 2007). In addition, the C-peptide cleaved from proinsulin plays a key role in Ca2+-dependent intracellular signaling pathways, resulting in the synthesis of insulin itself (Wahren, Kallas, & Sima, 2012).