Quantum Biochemical Investigation of Lys49-PLA2 from Bothrops moojeni

Deciphering Interactions between Potential Inhibitors and the Plasmodium falciparum DHODH Enzyme: A Computational Perspective

Malaria is a parasitic disease that, in its most severe form, can even lead to death. Insect-resistant vectors, insufficiently effective vaccines, and drugs that cannot stop parasitic infestations are making the fight against the disease increasingly difficult. It is known that the enzyme dihydroorotate dehydrogenase (DHODH) is of paramount importance for the synthesis of pyrimidine from the Plasmodium precursor, that is, for its growth and reproduction. Therefore, its blockade can lead to disruption of the parasite's life cycle in the vertebrate host. In this scenario, PfDHODH inhibitors have been considered candidates for a new therapy to stop the parasitic energy source. Given what is known, in this work, we applied molecular fractionation with conjugated caps (MFCC) in the framework of the quantum formalism of density functional theory (DFT) to evaluate the energies of the interactions between the enzyme and the different triazolopyrimidines (DSM483, DMS557, and DSM1), including a complex carrying the mutation C276F. From these results, it was possible to identify the main features of each system, focusing on the wild-type and mutant PfDHODH and examining the major amino acid residues that are part of the four complexes. Our analysis provides new information that can be used to develop new drugs that could prove to be more effective alternatives to present antimalarial drugs.

Oral and IV Varespladib Rescue Experiments in Juvenile Pigs with Weakness Induced by Australian and Papuan Oxyuranus scutellatus Venoms

Antivenom is currently the standard-of-care treatment for snakebite envenoming, but its efficacy is limited by treatment delays, availability, and in many cases, species specificity. Many of the rapidly lethal effects of envenoming are caused by venom-derived toxins, such as phospholipase A2 (sPLA2); therefore, small molecule direct toxin inhibitors targeting these toxins may have utility as initial and adjunct therapies after envenoming. Varespladib (intravenous, IV) and varespladib-methyl (oral) have been shown to potently inhibit sPLA2s from snake venoms in murine and porcine models, thus supporting their further study as potential treatments for snakebite envenoming. In this pilot study, we tested the ability of these compounds to reverse neurotoxic effects of venom from the Australian and Papuan taipan (Oxyuranus scutellatus) subspecies in juvenile pigs (Sus domesticus). The mean survival time for control animals receiving Australian taipan venom (0.03 mg/kg, n = 3) was 331 min ± 15 min; for those receiving Papuan taipan venom (0.15 mg/kg, n = 3) it was 178 ± 31 min. Thirteen pigs received Australian taipan venom and treatment with either IV or oral varespladib (or with IV to oral transition) and all 13 survived the duration of the study (≥96 h). Eight pigs received Papuan taipan venom followed by treatment: Briefly: Two animals received antivenom immediately and survived to the end of the study. Two animals received antivenom treatment delayed 45 min from envenoming and died within 4 h. Two animals received similarly delayed antivenom treatment and were rescued by varespladib. Two animals were treated with varespladib alone after a 45-min delay. Treatment with varespladib only was effective but required repeat dosing over the course of the study. Findings highlight both the importance of early treatment and, as well, a half-life for the investigational inhibitors now in Phase II clinical trials for snakebite. Varespladib rapidly reversed weakness even when administered many hours post-envenoming and, overall, our results suggest that varespladib and varespladib-methyl could be efficacious tools in the treatment of sPLA2-induced weakness from Oxyuranus envenoming. Further clinical study as initial therapy and as potential method of rescue from some types of antivenom-resistant envenomings are supported by these data.

Quantum biochemistry description of PI3Kα enzyme bound to selective inhibitors

The PI3K class I is composed of four PI3K isoforms that serve as regulatory enzymes governing cellular metabolism, proliferation, and survival. The hyperactivation of PI3Kα is observed in various types of cancer and is linked to poor prognosis. Unfortunately, the development inhibitors selectively targeting one of the isoforms remains challenging, with only few agents in clinical use. The main difficulty arises from the high conservation among residues at the ATP-binding pocket across isoforms, which also serves as target pocket for inhibitors. In this work, molecular dynamics and quantum calculations were performed to investigate the molecular features guiding the binding of selective inhibitors, alpelisib and GDC-0326, into the ATP-binding pocket of PI3Kα. While molecular dynamics allowed crystallographic coordinates to relax, the interaction eergy between each amino acid residues and inhibitors was obtained by combining the Molecular Fractionation with Conjugated Caps scheme with Density Functional Theory calculations. In addition, the atomic charge of ligands in the bound and unbound (free) was calculated. Results indicated that the most relevant residues for the binding of alpelisib are Ile932, Glu859, Val851, Val850, Tyr836, Met922, Ile800, and Ile848, while the most important residues for the binding of GDC-0326 are Ile848, Ile800, Ile932, Gln859, Glu849, and Met922. In addition, residues Trp780, Ile800, Tyr836, Ile848, Gln859 Val850, Val851, Ile932 and Met922 are common hotspots for both inhibitors. Overall, the results from this work contribute to improving the understanding of the molecular mechanisms controlling selectivity and highlight important interactions to be considered during the rational design of new agents.Communicated by Ramaswamy H. Sarma.

Varespladib in the Treatment of Snakebite Envenoming: Development History and Preclinical Evidence Supporting Advancement to Clinical Trials in Patients Bitten by Venomous Snakes

The availability of effective, reliably accessible, and affordable treatments for snakebite envenoming is a critical and long unmet medical need. Recently, small, synthetic toxin-specific inhibitors with oral bioavailability used in conjunction with antivenom have been identified as having the potential to greatly improve outcomes after snakebite. Varespladib, a small, synthetic molecule that broadly and potently inhibits secreted phospholipase A2 (sPLA2s) venom toxins has renewed interest in this class of inhibitors due to its potential utility in the treatment of snakebite envenoming. The development of varespladib and its oral dosage form, varespladib-methyl, has been accelerated by previous clinical development campaigns to treat non-envenoming conditions related to ulcerative colitis, rheumatoid arthritis, asthma, sepsis, and acute coronary syndrome. To date, twenty-nine clinical studies evaluating the safety, pharmacokinetics (PK), and efficacy of varespladib for non-snakebite envenoming conditions have been completed in more than 4600 human subjects, and the drugs were generally well-tolerated and considered safe for use in humans. Since 2016, more than 30 publications describing the structure, function, and efficacy of varespladib have directly addressed its potential for the treatment of snakebite. This review summarizes preclinical findings and outlines the scientific support, the potential limitations, and the next steps in the development of varespladib's use as a snakebite treatment, which is now in Phase 2 human clinical trials in the United States and India.

In silico analysis of energy interactions between nociceptin/orfanin FQ receptor and two antagonists with potential antidepressive action

This study addresses the binding energies of NOPR-ligand complexes and presents the main amino acid residues involved in the interaction between these complexes.