Tomaž Trobec

Platelets play pivotal roles in thromboembolic diseases, such as myocardial infarction and ischemic stroke. In patients envenomed by the snake Vipera a. ammodytes (Vaa), pronounced and transient thrombocytopenia without bleeding is observed. We previously showed that Vaa-snaclec-3/2, the snake venom C-type lectin-like protein, mediates this effect ex vivo. Here, we extended our study of the antithrombotic potential of this protein in vivo using a mouse model of ferric chloride (FeCl₃)-induced carotid artery thrombosis. Prior to inducing thrombus formation, the mice received 1, 5, 10, 20, or 50 μg/kg Vaa-snaclec-3/2 intravenously. Afterward, the arterial blood flow was monitored with a perivascular Doppler probe. Additionally, the platelet count in the peripheral venous blood; tail bleeding time; and liver, lung, kidney, spleen, and heart histology were evaluated. The lowest dose of Vaa-snaclec-3/2 that we showed to cause severe thrombocytopenia and completely inhibit FeCl₃-induced thrombus formation was 20 µg/kg. This dose prolonged the median tail bleeding time from 86.5 to 153.5 s but did not induce acute spontaneous hemorrhage, as demonstrated by histological analysis. Histology revealed no signs of apoptosis, necrosis or other degenerative changes in the inspected organs of mice exposed to 20 μg/kg Vaa-snaclec-3/2. Platelet clusters were observed only in the lungs, which appear to be the primary site of platelet sequestration and the cause of thrombocytopenia. Taken together, our findings highlight the high potential of Vaa-snaclec-3/2 as a safe and effective antithrombotic agent for the transient prevention of thrombosis in acute clinical settings.

The growing demand for agricultural products has led to the misuse of pesticides, resulting in the use of higher concentrations of these substances. This has led to an increase in toxicity imposed on other beneficial organisms and to the bioaccumulation of toxic pesticide concentrations in the bodies of both pests and non-target organisms, as well as in their end users, including humans. In this study, the neurotoxic potential of the commonly used pesticides abamectin (an insecticide) and boscalid (a fungicide) was evaluated. Both in vitro and in silico studies showed that human butyrylcholinesterase is not a target for abamectins B1A and B1B. Boscalid showed a modest Glide score (−28.8 kJ/mol) and a considerably higher IC₅₀ (308.8 µM) against human butyrylcholinesterase than the approved inhibitor (2-((1-(benzenesulfonyl)-1H-indol-4-yl)oxy)ethyl)(benzyl)amine (IC₅₀ = 0.473 µM). However, due to its non-mutagenicity and low toxicity, structural analogues of boscalid might be considered as candidates for the symptomatic treatment of Alzheimer’s disease. Molecular dynamics simulations over 100 ns confirmed the stability of boscalid within the active site of butyrylcholinesterase, where it maintained key interactions with catalytic residues such as Trp82 and His438. These findings highlight its potential as a starting point for structure-based drug design strategies aimed at optimizing cholinesterase inhibitors with improved pharmacokinetic properties. According to absorption, distribution, metabolism, elimination, and toxicity studies, boscalid is orally active, which cannot be attributed to abamectins B1A and B1B.

In this study, Antarctic Latrunculia sponge-derived discorhabdin G was considered a hit for developing potential lead compounds acting as cholinesterase inhibitors. The hypothesis on the pharmacophore moiety suggested through molecular docking allowed us to simplify the structure of the metabolite. ADME prediction and drug-likeness consideration provided valuable support in selecting 5-methyl-2H-benzo[h]imidazo[1,5,4-de]quinoxalin-7(3H)-one as a candidate molecule. It was synthesized in a four-step sequence starting from 2,3-dichloronaphthalene-1,4-dione and evaluated as an inhibitor of electric eel acetylcholinesterase (eeAChE), human recombinant AChE (hAChE), and horse serum butyrylcholinesterase (BChE), together with other analogs obtained by the same synthesis. The candidate molecule showed a slightly lower inhibitory potential against eeAChE but better inhibitory activity against hAChE than discorhabdin G, with a higher selectivity for AChEs than for BChE. It acted as a reversible competitive inhibitor, as previously observed for the natural alkaloid. The findings from the in vitro assay were relatively consistent with the data available from the AutoDock Vina and Protein-Ligand ANTSystem (PLANTS) calculations.

Organoruthenium pyrithione (1-hydroxypyridine-2-thione) complexes have been shown in our recent studies to be a promising family of compounds for development of new anticancer drugs. The complex [(η⁶-p-cymene)Ru(pyrithionato)(pta)]PF₆ contains phosphine ligand pta (1,3,5-triaza-7-phosphaadamantane) as a functionality that improves the stability of the complex and its aqueous solubility. Here, we report our efforts to find pta alternatives and discover new structural elements to improve the biological properties of ruthenium anticancer drugs. The pta ligand was replaced by a selection of phosphine, phosphite, and arsine ligands to identify new functionalities, leading to improvement in inhibitory potency towards enzyme glutathione S-transferase. In addition, cytotoxicity in breast, bone, and colon cancers was investigated.

Enzyme butyrylcholinesterase (BChE) shows increased activity in some brain regions after progression of Alzheimer’s disease and is therefore one of the therapeutic targets for symptomatic treatment of this neurodegenerative disorder. The organoruthenium(II) complex [(η⁶-p-cymene)Ru(II)(1-hydroxy-3-methoxypyridine-2(1H)-thionato)pta]PF₆ (C1) was designed based on the results of our previous structure–activity studies. Inhibitory activity toward cholinesterase enzymes shows that this complex selectively, competitively, and reversibly inhibits horse serum BChE (hsBChE) with an IC₅₀ value of 2.88 µM. When tested at supra-pharmacological concentrations (30, 60, 90, and 120 µM), C1 had no significant effect on the maximal amplitude of nerve-evoked and directly elicited single-twitch and tetanic contractions. At the highest tested concentration (120 µM), C1 had no effect on resting membrane potential, but significantly decreased the amplitude of miniature end-plate potentials (MEPP) without reducing their frequency. The same concentration of C1 had no effect on the amplitude of end-plate potentials (EPP), however it shortened the half-decay time of MEPPs and EPPs. The decrease in the amplitude of MEPPs and shortening of the half-decay time of MEPPs and EPPs suggest a possible weak inhibitory effect on muscle-type nicotinic acetylcholine receptors (nAChR). These combined results show that, when applied at supra-pharmacological concentrations up to 120 µM, C1 does not importantly affect the physiology of neuromuscular transmission and skeletal muscle contraction.

The management of neurological disorders such as dementia associated with Alzheimer's or Parkinson's disease includes the use of cholinesterase inhibitors. These compounds can slow down the progression of these diseases and can also be used in the treatment of glaucoma and myasthenia gravis. The majority of the cholinesterase inhibitors used in the clinic are derived from natural products and our current paper describes the use of a small marine pharmacophore to develop potent and selective cholinesterase inhibitors. Fourteen small inhibitors were designed based on recent discoveries about the inhibitory potential of a range of related marine secondary metabolites. The compounds were evaluated, in kinetic enzymatic assays, for their ability to inhibit three different cholinesterase enzymes and it was shown that compounds with a high inhibitory activity towards electric eel and human recombinant acetylcholinesterase (IC₅₀ between 20–70 μM) could be prepared. It was also shown that this compound class was particularly active against horse serum butyrylcholinesterase, with IC₅₀ values between 0.8–16 μM, which is an order of magnitude more potent than the clinically used positive control neostigmine. The compounds were further tested for off-target toxicity against both human umbilical vein endothelial cells and bovine and human erythrocytes and were shown to display a low mammalian cellular toxicity. Overall, the study illustrates how the brominated dipeptide marine pharmacophore can be used as a versatile natural scaffold for the design of potent, and selective cholinesterase inhibitors.

Cholinesterases (ChEs) show increased activities in patients with Alzheimer’s disease, and remain one of the main therapeutic targets for treatment of this neurodegenerative disorder. A library of organoruthenium(II) complexes was prepared to investigate the influence of their structural elements on inhibition of ChEs, and on another pharmacologically important group of enzymes, glutathione S-transferases (GSTs). Two groups of organoruthenium(II) compounds were considered: (i) organoruthenium(II) complexes with p-cymene as an arene ligand, and (ii) organoruthenium(II) carbonyl complexes as CO-releasing molecules. Eight organoruthenium complexes were screened for inhibitory activities against ChEs and GSTs of human and animal origins. Some compounds inhibited all of these enzymes at low micromolar concentrations, while others selectively inhibited either ChEs or GSTs. This study demonstrates the importance of the different structural elements of organoruthenium complexes for their inhibitory activities against ChEs and GSTs, and also proposes some interesting compounds for further preclinical testing as ChE or GST inhibitory drugs.

Aegerolysin proteins ostreolysin A6 (OlyA6), pleurotolysin A2 (PlyA2) and erylysin A (EryA) produced by the mushroom genus Pleurotus bind strongly to an invertebrate-specific membrane sphingolipid, and together with a protein partner pleurotolysin B (PlyB), form transmembrane pore complexes. This pore formation is the basis for the selective insecticidal activity of aegerolysin/PlyB complexes against two economically important coleopteran pests: the Colorado potato beetle and the western corn rootworm. In this study, we evaluated the toxicities of these aegerolysin/PlyB complexes using feeding tests with two ecologically important non-target arthropod species: the woodlouse and the honey bee. The mammalian toxicity of the EryA/PlyB complex was also evaluated after intravenous administration to mice. None of the aegerolysin/PlyB complexes were toxic against woodlice, but OlyA6/PlyB and PlyA2/PlyB were toxic to honeybees, with 48 h mean lethal concentrations (LC₅₀) of 0.22 and 0.39 mg/mL, respectively, in their food. EryA/PlyB was also tested intravenously in mice up to 3 mg/kg body mass, without showing toxicity. With no toxicity seen for EryA/PlyB for environmentally beneficial arthropods and mammals at the tested concentrations, these EryA/PlyB complexes are of particular interest for development of new bioinsecticides for control of selected coleopteran pests.