Characterization of Aurintricarboxylic Acid (ATA) Interactions with Plasma Transporter Protein and SARS-CoV-2 Viral Targets: Correlation of Functional Activity and Binding Energetics

Abstract

In an effort to identify functional-energetic correlations leading to the development of efficient anti-SARS-CoV-2 therapeutic agents, we have designed synthetic analogs of aurintricarboxylic acid (ATA), a heterogeneous polymeric mixture of structurally related linear homologs known to exhibit a host of biological properties, including antiviral activity. These derivatives are evaluated for their ability to interact with a plasma transporter protein (human serum albumin), eukaryotic (yeast) ribosomes, and a SARS-CoV-2 target, the RNA-dependent RNA polymerase (RdRp). The resultant data are critical for characterizing drug distribution, bioavailability, and effective inhibition of host and viral targets. Promising lead compounds are selected on the basis of their binding energetics which have been characterized and correlated with functional activities as assessed by inhibition of RNA replication and protein synthesis. Our results reveal that the activity of heterogeneous ATA is mimicked by linear compounds of defined molecular weight, with a dichlorohexamer salicylic-acid derivative exhibiting the highest potency. These findings are instrumental for optimizing the design of structurally defined ATA analogs that fulfill the requirements of an antiviral drug with respect to bioavailability, homogeneity, and potency, thereby expanding the arsenal of therapeutic regimens that are currently available to address the urgent need for effective SARS-CoV-2 treatment strategies.

Magnesium enhances aurintricarboxylic acid’s inhibitory action on the plasma membrane Ca2+-ATPase

“…3b). These results agree with those previously described for aqueous solutions of ATA at pH 7.4 7 and suggest that the molecule is a monomer at the evaluated concentrations. Figure 3c shows the fluorescence at 306 nm of 10 µM ATA as a function of the Mg 2+ concentrations.…”

Mechanisms of antiviral action and toxicities of ipecac alkaloids: Emetine and dehydroemetine exhibit anti-coronaviral activities at non-cardiotoxic concentrations

“…Another activity of emetine and its analogs that may account for antiviral activity is inhibition of protein synthesis. We tested the potential of these compounds to inhibit translation in rabbit reticulocyte lysate (RRL) using mRNA coding for firefly luciferase ( Minetti et al., 2022 ). Emetine and DHE4, which share the 1R, 11bS configuration, are similar in protein synthesis inhibition, with IC 50 values of 1.2 and 1.3 μM, respectively ( Fig.…”

“…To monitor effects on protein synthesis we exposed cells to ipecac alkaloids for 1 h followed by 10 min of pulse labeling with puromycin. Puromycin is incorporated into the nascent protein chains and blocks further translation, thereby producing puromycilated peptides ( Minetti et al., 2022 ; Dadehbeigi and Dickson, 2013 ). These peptides can be detected using standard immunoblotting techniques, employing anti-puromycin antibodies.…”

Forces Driving a Magic Bullet to Its Target: Revisiting the Role of Thermodynamics in Drug Design, Development, and Optimization

“…While establishing the foundation required for understanding the energetic basis of complex biological systems, the Breslauer research group has focused on gene transcription regulation, repair, and replication [29,30,39,45,46]. Professor Breslauer's impressive academic career spanning five decades is chronicled in a recent retrospective [23] as his research group continues to pursue effective therapeutic interventions for combating and treating infectious diseases such as the SAR-CoV-2 pandemic [47]. In summary, the indelible impact of Professor Breslauer's pioneering contributions to the field of biothermodynamics and their consequential impact on advancing drug discovery strategies is gratefully acknowledged and recognized by a legion of peers.…”

“…Employing a combination of biochemical and biophysical approaches, investigators are currently evaluating a number of repurposed compounds against RdRp. Inspired by studies conducted on protein synthesis inhibitors over five decades ago [161], these lead compounds have demonstrated the ability to interact with SARS-CoV-2 RdRp and inhibit ribosomal protein synthesis [47]. The screening and characterization of prospective SARS-CoV-2 therapeutics have been documented including a HTS using the nsp10-nsp16 complex.…”