Computational coevolution of antiviral drug resistance

Selective interaction of lansoprazole and astemizole with tau polymers: potential new clinical use in diagnosis of Alzheimer's disease

We describe the interactions of two benzimidazole derivatives, astemizole (AST) and lansoprazole (LNS), with anomalous aggregates of tau protein (neurofibrillary tangles). Interestingly, these compounds, with important medical applications in the treatment of allergies and gastrointestinal disorders respectively, specifically bind to aggregated variants of tau protein and to paired helical filaments isolated from brains of Alzheimer's disease (AD) patients. These ligands appear to be a powerful tool to tag brain-isolated tau-aggregates and heparin-induced polymers of recombinant tau. The interactions of AST and LNS with tau aggregates were assessed by classical radioligand assays, surface plasmon resonance, and bioinformatic approaches. The affinity of AST and LNS for tau aggregates was comparatively higher than that for amyloid-beta polymers according to our data. This is relevant since senile plaques are also abundant but are not pathognomonic in AD patients. Immunochemical studies on paired helical filaments from brains of AD patients and surface plasmon resonance studies confirm these findings. The capacity of these drugs to penetrate the blood-brain barrier was evaluated: i) in vitro by parallel artificial membrane permeability assay followed by experimental Log P determinations; and ii) in vivo by pharmacokinetic studies comparing distribution profiles in blood and brain of mice using HPLC/UV. Importantly, our studies indicate that the brain/blood concentration ratios for these compounds were suitable for their use as PET radiotracers. Since neurofibrillary tangles are positively correlated with cognitive impairment, we concluded that LNS and AST have a great potential in PET neuroimaing for in vivo early detection of AD and in reducing the formation of neurofibrillary tangles.

Symmetrical 1-pyrrolidineacetamide showing anti-HIV activity through a new binding site on HIV-1 integrase

AIM

To characterize the functional and pharmacological features of a symmetrical 1-pyrrolidineacetamide, N,N'-(methylene-di-4,1-phenylene) bis-1-pyrrolidineacetamide, as a new anti-HIV compound which could competitively inhibit HIV-1 integrase (IN) binding to viral DNA.

METHODS

A surface plasma resonance (SPR)-based competitive assay was employed to determine the compound's inhibitory activity, and the 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide cell assay was used to qualify the antiviral activity. The potential binding sites were predicted by molecular modeling and determined by site-directed mutagenesis and a SPR binding assay.

RESULTS

1-pyrrolidineacetamide, N,N'-(methylene-di-4,1-phenylene) bis-1-pyrrolidineacetamide could competitively inhibit IN binding to viral DNA with a 50% inhibitory concentration (IC(50)) value of 7.29+/-0.68 micromol/L as investigated by SPR-based investigation. Another antiretroviral activity assay showed that this compound exhibited inhibition against HIV-1(IIIB) replication with a 50% effective concentration (EC(50)) value of 40.54 micromol/L in C8166 cells, and cytotoxicity with a cytotoxic concentration value of 173.84 micromol/L in mock-infected C8166 cells. Molecular docking predicted 3 potential residues as 1-pyrrolidineacetamide, N,N'-(methylene-di-4,1-phenylene)bis-1- pyrrolidineacetamide binding sites. The importance of 3 key amino acid residues (Lys103, Lys173, and Thr174) involved in the binding was further identified by site-directed mutagenesis and a SPR binding assay.

CONCLUSION

This present work identified a new anti-HIV compound through a new IN-binding site which is expected to supply new potential drug-binding site information for HIV-1 integrase inhibitor discovery and development.