Anti-HIV Activities of Precisely Defined, Semirigid, Carboxylated Alternating Copolymers

Progress in Treatment and Diagnostics of Infectious Disease with Polymers

In this era of advanced technology and innovation, infectious diseases still cause significant morbidity and mortality, which need to be addressed. Despite overwhelming success in the development of vaccines, transmittable diseases such as tuberculosis and AIDS remain unprotected, and the treatment is challenging due to frequent mutations of the pathogens. Formulations of new or existing drugs with polymeric materials have been explored as a promising new approach. Variations in shape, size, surface charge, internal morphology, and functionalization position polymer particles as a revolutionary material in healthcare. Here, an overview is provided of major diseases along with statistics on infection and death rates, focusing on polymer-based treatments and modes of action. Key issues are discussed in this review pertaining to current challenges and future perspectives.

Antiviral activity of natural humic substances and shilajit materials against HIV-1: Relation to structure

Natural products, such as humic substances (HS) and shilajit, are known to possess antiviral activity. Humic-like components are often called as carriers of biological activity of shilajit. The goal of this study was to evaluate anti-HIV activity of well characterized HS isolated from coal, peat, and peloids, and compare it to that of water-soluble organic matter (OM) isolated from different samples of Shilajit. The set of humic materials included 16 samples of different fractional composition: humic acid (HA), hymatomelanic acid (HMA), fulvic acid (FA). The set of shilajit OM included 19 samples of different geographic origin and level of alteration. The HIV-1 p24 antigen assay and cell viability test were used for assessment of antiviral activity. The HIV-1 Bru strain was used to infect CEM-SS cells. The obtained EC50 values varied from 0.37 to 1.4 mg L^-1 for the humic materials, and from 14 to 142 mg L^-1 for the shilajit OM. Hence, all humic materials used in this study outcompeted largely the shilajit materials with respect to anti-HIV activity: For the humic materials, the structure-activity relationships revealed strong correlation between the EC50 values and the content of aromatic carbon indicating the most important role of aromatic structures. For shilajit OM, the reverse relationship was obtained indicating the different mechanism of shilajit activity. The FTICRMS molecular assignments were used for ChEMBL data mining in search of the active humic molecules. As potential carriers of antiviral activity were identified aromatic structures with alkyl substituents, terpenoids, N-containing analogs of typical flavonoids, and aza-podophyllotoxins. The conclusion was made that the typical humic materials and Shilajit differ greatly in molecular composition, and the humic materials have substantial preferences as a natural source of antiviral agents as compared to shilajit.

Homogeneous nanodiscs of native membranes formed by stilbene-maleic-acid copolymers

Methylstilbene-alt-maleic acid copolymers spontaneously convert biological membranes into bilayer discs with ∼20 nm diameters. This readily functionalizable class of copolymers has the compositional homogeneity, hydrophobicity, dynamics, and charge that may help to achieve optimal structural resolution, membrane dissolution, stability, and broad utility.

Computational study of HIV gp120 as a target for polyanionic entry inhibitors: Exploiting the V3 loop region

Multiple approaches are being utilized to develop therapeutics to treat HIV infection. One approach is designed to inhibit entry of HIV into host cells, with a target being the viral envelope glycoprotein, gp120. Polyanionic compounds have been shown to be effective in inhibiting HIV entry, with a mechanism involving electrostatic interactions with the V3 loop of gp120 being proposed. In this study, we applied computational methods to elucidate molecular interactions between the repeat unit of the precisely alternating polyanion, Poly(4,4′-stilbenedicarboxylate-alt–maleic acid) (DCSti-alt-MA) and the V3 loop of gp120 from strains of HIV against which these polyanions were previously tested (IIIb, BaL, 92UG037, JR-CSF) as well as two strains for which gp120 crystal structures are available (YU2, 2B4C). Homology modeling was used to create models of the gp120 proteins. Using monomers of the gp120 protein, we applied extensive molecular dynamics simulations to obtain dominant morphologies that represent a variety of open-closed states of the V3 loop to examine the interaction of 112 ligands of the repeating units of DCSti-alt-MA docked to the V3 loop and surrounding residues. Using the distance between the V1/V2 and V3 loops of gp120 as a metric, we revealed through MD simulations that gp120 from the lab-adapted strains (BaL and IIIb), which are more susceptible to inhibition by DCSti-alt-MA, clearly transitioned to the closed state in one replicate of each simulation set, whereas none of the replicates from the Tier II strains (92UG037 and JR-CSF) did so. Docking repeat unit microspecies to the gp120 protein before and after MD simulation enabled identification of residues that were key for binding. Notably, only a few residues were found to be important for docking both before and after MD simulation as a result of the conformational heterogeneity provided by the simulations. Consideration of the residues that were consistently involved in interactions with the ligand revealed the importance of both hydrophilic and hydrophobic moieties of the ligand for effective binding. The results also suggest that polymers of DCSti-alt-MA with repeating units of different configurations may have advantages for therapeutic efficacy.

Supramolecular combinations of humic polyanions as potent microbicides with polymodal anti-HIV-activities

Anti-HIV potency of humic PAs is governed by scaffolds diversity.