Interactions of insulin with tragacanthic acid biopolymer: Experimental and computational study

Design, synthesis, spectroscopic characterizations, antidiabetic, in silico and kinetic evaluation of novel curcumin-fused aldohexoses

Curcumin (bis-α,β-unsaturated β-diketone) plays an important role in the prevention of numerous diseases, including diabetes. Curcumin, as an enzyme inhibitor, has ideal structural properties including hydrophobic nature, flexible backbone, and several available hydrogen bond (H-bond) donors and acceptors. In this study, curcumin-fused aldohexose derivatives 3(a-c) were synthesized and used as influential agents in the treatment of diabetes with inhibitory properties against two carbohydrate-hydrolyzing enzymes α-glucosidase (α-Gls) and α-amylase (α-Amy) which are known to be significant therapeutic targets for the reduction of postprandial hyperglycemia. These compounds were isolated, purified, and then spectrally characterized via FT-IR, Mass, ¹H, and ¹³C NMR, which strongly confirmed the targeted product's formation. Also, their inhibitory properties against α-Gls and α-Amy were evaluated spectroscopically. The Results indicated that all compounds strongly inhibited α-Amy and α-Gls by mixed and competitive mechanisms, respectively. The intrinsic fluorescence of α-Amy was quenched by the interaction with compounds 1 and 3b through a dynamic quenching mechanism, and the 1 and 3b/α-Amy complexes were spontaneously formed, mainly driven by the hydrophobic interaction and hydrogen bonding. Fourier transform infrared spectra (FT-IR) comprehensively verified that the binding of compounds 1 and 3b to α-Amy would change the conformation and microenvironment of α-Amy, thereby inhibiting the enzyme activity. Docking and molecular dynamics (MD) simulations showed that all compounds interacted with amino acid residues located in the active pocket site of the proteins. In vivo studies confirmed the plasma glucose diminution after the administration of compound 3b to Wistar rats. Accordingly, the results of the current work may prompt the scientific communities to investigate the possibility of compound 3b application in the clinic.

Insulin Complexation with Cyclodextrins-A Molecular Modeling Approach

Around 5% of the population of the world is affected with the disease called diabetes mellitus. The main medication of the diabetes is the insulin; the active form is the insulin monomer, which is an instable molecule, because the long storage time, or the high temperature, can cause the monomer insulin to adapt an alternative fold, rich in β-sheets, which is pharmaceutically inactive. The aim of this study is to form different insulin complexes with all the cyclodextrin used for pharmaceutical excipients (native cyclodextrin, methyl, hydroxyethyl, hydroxypropyl and sulfobutylether substituted β-cyclodextrin), in silico condition, with the AutoDock molecular modeling program, to determine the best type of cyclodextrin or cyclodextrin derivate to form a complex with an insulin monomer, to predict the molar ratio, the conformation of the complex, and the intermolecular hydrogen bonds formed between the cyclodextrin and the insulin. From the results calculated by the AutoDock program it can be predicted that insulin can make a stable complex with 5–7 molecules of hydroxypropyl-β-cyclodextrin or sulfobutylether-β-cyclodextrin, and by forming a complex potentially can prevent or delay the amyloid fibrillation of the insulin and increase the stability of the molecule.

Rational design of a new variant of Reteplase with optimized physicochemical profile and large-scale production in Escherichia coli

Structural engineering of the recombinant thrombolytic drug, Reteplase, and its cost-effective production are important goals in the pharmaceutical industry. In this study, a single-point mutant of the protein was rationally designed and evaluated in terms of physicochemical characteristics, enzymatic activity, as well as large-scale production settings. An accurate homology model of Reteplase was used as the input to appropriate tools to identify the aggregation-prone sites, while considering the structural stability. Selected variants underwent extensive molecular dynamic simulations (total 540 ns) to assess their solvation profile and their thermal stability. The Reteplase-fibrin interaction was investigated by docking. The best variant was expressed in E. coli, and Box-Behnken design was used through response surface methodology to optimize its expression conditions. M72R mutant demonstrated appropriate stability, enhanced enzymatic activity (p < 0.05), and strengthened binding to fibrin, compared to the wild type. The optimal conditions for the variant's production in a bioreactor was shown to be 37 ºC, induction with 0.5 mM IPTG, for 2 h of incubation. Under these conditions, the final amount of the produced enzyme was increased by about 23 mg/L compared to the wild type, with an increase in the enzymatic activity by about 2 IU/mL. This study thus offered a new Reteplase variant with nearly all favorable properties, except solubility. The impact of temperature and incubation time on its large-scale production were underlined as well.