ABSTRACT
The self-assembly thermodynamics of pH-sensitive di-block and tri-block gradient copolymers of acrylic acid and styrene was studied for the first time using isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) performed at varying pH. We were able to monitor each step of micellization as a function of decreasing pH. The growth of micelles is a multi-stage process that is pH dependent with several exothermic and endothermic components. The first step of protonation of the acrylic acid monomer units was accompanied mainly by conformational changes and the beginning of self-assembly. In the second stage of self-assembly, the micelles become larger and the number of micelles becomes smaller. While solution acidity increases, the isothermal calorimetry data show a broad deep minimum corresponding to an exothermic process attributed to an increase in the size of hydrophobic domains and an increase in the structure's hydrophobicity. The minor change in heat capacity (ΔCp) confirms the structural changes during this exothermic process. The exothermic process terminates deionization of acrylic acid. The pH-dependence of the ζ-potential of the block gradient copolymer micelles exhibits a plateau in the regime corresponding to the pH-controlled variation of the micellar dimensions. The onset of micelle formation and the solubility of the gradient copolymers were found to be dependent on the length of the gradient block.
ABSTRACT
OBJECTIVES: Development of a novel drug candidate with improved potency against influenza virus neuraminidase compared with currently available therapeutics, and high activity against oseltamivir-resistant viruses. METHODS: A number of synthetic compounds were evaluated for antiviral properties in vitro and in vivo. Three-dimensional molecular docking, assisted by a pharmacophore model, was applied to classify compounds within the series by their inhibitory potency. Compound stability in blood and in animal models was determined. Pharmacokinetic studies in dogs and rats after oral or intravenous administration were performed. RESULTS: A novel highly potent drug candidate [(3R,4R,5S)-5-[(diaminomethylene)amino]-3-(1-ethylpropoxy)-4-[(fluoroacetyl)amino]cyclohex-1-ene-1-carboxylic acid; AV5080] was synthesized and tested. AV5080 exhibited high activity against influenza virus neuraminidase in vitro, with IC(50) values of 0.03 nM and 0.07 nM against the neuraminidase of A/Duck/Minnesota/1525/1981/H5N1 and A/Perth/265/2009/H1N1 (wild-type), respectively. Notably, AV5080 was highly active against oseltamivir-resistant influenza viruses. CONCLUSIONS: Based on the results presented in this study, AV5080 is a promising novel oral drug candidate for the treatment of influenza, including oseltamivir-resistant types. Further pre-clinical development of AV5080 is warranted.
Subject(s)
Antiviral Agents/isolation & purification , Enzyme Inhibitors/isolation & purification , Neuraminidase/antagonists & inhibitors , Viral Proteins/antagonists & inhibitors , Administration, Oral , Animals , Antiviral Agents/administration & dosage , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Dogs , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/pharmacokinetics , Enzyme Inhibitors/pharmacology , Female , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H1N1 Subtype/enzymology , Influenza A Virus, H5N1 Subtype/drug effects , Influenza A Virus, H5N1 Subtype/enzymology , Inhibitory Concentration 50 , Molecular Docking Simulation , RatsABSTRACT
This article reexamines some opinions concerning pH requirements for optimal immobilization of monoclonal antibodies (mAbs) by passive adsorption in antigen capture ELISA. It was discovered that substitution of "classical" sodium phosphate (pH 7.5) and carbonate (pH 9.5) coating solutions by acid (pH 2.8) buffers maximized antigen capture 4 out of 10 different tested anti-HBsAg mAbs, resulting in a 1.5-2.5 increase of binding curve coefficients. By measuring both mAbs amounts and functionality, the enhancement effect was attributed to the better preservation of solid phase antibodies activity.
Subject(s)
Antibodies, Monoclonal/immunology , Antigens/isolation & purification , Enzyme-Linked Immunosorbent Assay/methods , Hepatitis B Surface Antigens/immunology , Adsorption , Animals , Antibodies, Monoclonal/analysis , Antigen-Antibody Reactions , Buffers , Enzyme-Linked Immunosorbent Assay/instrumentation , Humans , Hydrogen-Ion Concentration , Immunoassay/methods , RabbitsABSTRACT
A medium-sized focused library of novel Oseltamivir structural analogues with promising antiviral activity was successfully synthesized using a combinatorial approach. The synthesized compounds were then thoroughly evaluated in neuraminidase- and cell-based assays. As a result, (3R,4R,5S)-4-(2,2-difluoroacetylamino)-5-amino-3-(1-ethyl-propoxy)-cyclohex-1-enecarboxylic acid (AV5027) was identified as novel Hit-compound with picomolar potency. QSAR analysis was carried out based on the obtained biological data. Computational modeling was performed using a 3D-molecular docking approach and classical regression analysis. The developed integral model demonstrated a sufficient prediction accuracy and tolerance to evaluate compounds based on their potential activity against neuraminidase (NA) at least within the scaffold. Several compounds from the series can be reasonably regarded as promising anti-influenza drug-candidates.