Unified Methodology for the Primary Preclinical In Vivo Screening of New Anticoagulant Pharmaceutical Agents from Hematophagous Organisms

The development of novel anticoagulants requires a comprehensive investigational approach that is capable of characterizing different aspects of antithrombotic activity. The necessary experiments include both in vitro assays and studies on animal models. The required in vivo approaches include the assessment of pharmacokinetic and pharmacodynamic profiles and studies of hemorrhagic and antithrombotic effects. Comparison of anticoagulants with different mechanisms of action and administration types requires unification of the experiment scheme and its adaptation to existing laboratory conditions. The rodent thrombosis models in combination with the assessment of hemostasis parameters and hematological analysis are the classic methods for conducting preclinical studies. We report an approach for the comparative study of the activity of different anticoagulants in vivo, including the investigation of pharmacodynamics and the assessment of hemorrhagic effects (tail-cut bleeding model) and pathological thrombus formation (inferior vena cava stenosis model of venous thrombosis). The reproducibility and uniformity of our set of experiments were illustrated on unfractionated heparin and dabigatran etexilate (the most common pharmaceuticals in antithrombic therapy) as comparator drugs and an experimental drug variegin from the tick Amblyomma variegatum. Variegin is notorious since it is a potential analogue of bivalirudin (Angiomax, Novartis AG, Basel, Switzerland), which is now being actively introduced into antithrombotic therapy.

Improving the Stability and Effectiveness of Immunotropic Squalene Nanoemulsion by Adding Turpentine Oil

Turpentine oil, owing to the presence of 7-50 terpenes, has analgesic, anti-inflammatory, immunomodulatory, antibacterial, anticoagulant, antioxidant, and antitumor properties, which are important for medical emulsion preparation. The addition of turpentine oil to squalene emulsions can increase their effectiveness, thereby reducing the concentration of expensive and possibly deficient squalene, and increasing its stability and shelf life. In this study, squalene emulsions were obtained by adding various concentrations of turpentine oil via high-pressure homogenization, and the safety and effectiveness of the obtained emulsions were studied in vitro and in vivo. All emulsions showed high safety profiles, regardless of the concentration of turpentine oil used. However, these emulsions exhibited dose-dependent effects in terms of both efficiency and storage stability, and the squalene emulsion with 1.0% turpentine oil had the most pronounced adjuvant and cytokine-stimulating activity as well as the most pronounced stability indicators when stored at room temperature. Thus, it can be concluded that the squalene emulsion with 1% turpentine oil is a stable, monomodal, and reliably safe ultradispersed emulsion and may have pleiotropic effects with pronounced immunopotentiating properties.

Peptide Blocker of Ion Channel TRPV1 Exhibits a Long Analgesic Effect in the Heat Stimulation Model

The ion channel TRPV1, which is one of the most important integrators of pain and inflammatory stimuli, is considered a promising therapeutic target in the treatment of pain conditions. In this work, we performed a comparative study of the analgesic effect in the "hot plate" test of recombinant analogues of Kunitz-type peptides from the sea anemone Heteractis crispa venom: APHC1-modulator of TRPV1 and HCRG21-a full blocker of TRPV1. As a result of biological tests, it was shown that the full blocker HCRG21, despite the higher value of 50% effective concentration of TRPV1 inhibition, had an equal analgesic ability with the APHC1 upon intramuscular administration and retained it for 13 h of observation. The analgesic effect of APHC1 at a dose of 0.1 mg/kg when administered intramuscularly developed very quickly in 5 min but lasted 3 h. The differences in the pharmacodynamic profile of the peptides are in good agreement with different mechanisms of binding to TRPV1.

A novel view of the problem of Osteoarthritis in experimental rat model

Introduction: The article presents the results of the functional tests to improve the assessment of MIA-induced osteoarthritis development and the effectiveness of NSAID therapy.

Materials and methods: In the study, 26 male SD rats were used. MIA-induced osteoarthritis was simulated in the right knee joint. After an intra-articular injection of MIA, the animals were treated with ibuprofen and meloxicam. Pain assessment was studied in the following functional tests: incapacitance (hind limb weight bearing) test, von Frey test (mechanical allodynia), grip strength test, and knee diameter measurement. At the end of the study, a histological analysis of the knee joint was performed.

Results and discussion: An intra-articular MIA injection reduced 1.5 times the paw withdrawal threshold. In the rats that suffered MIA-induced osteoarthritis, the difference between the diameters of the intact and injected joints was 1.05 mm, compared to 0.03 mm difference in the control group. Hind limb weight bearing asymmetry was 89.5% when simulating MIA-induced osteoarthritis. The muscular hind limb grip strength in rats with MIA-induced osteoarthritis was significantly reduced on 3rd and 7th days after simulating osteoarthritis. Ibuprofen and meloxicam showed significant efficacy in all the above tests, although ibuprofen effectiveness was more pronounced than that of meloxicam.

Conclusion: The following functional tests were identified as the most significant and sufficient to assess the development of MIA-induced osteoarthritis and analgesic efficacy of NSAIDs: incapacitance test, allodynia test (von Frey filaments), measurement of hind limb grip strength and measurement of the diameter of the inflamed knee joint. The histological analysis made it possible to confirm the correspondence of the physiological response and pathological changes in the knee joint.

Study of protective properties of butyrylcholinesterase in acute anticholinesterase poisoning on BChE-KO and BALB/c mice

Introduction: The article presents the results of studying the protective properties of recombinant human butyrylcholinesterase (rhBChE) in a model of acute anticholinesterase poisoning in mice knocked out for the BChE gene. Balb/c inbred mice were also used to demonstrate the important role of BChE.

Materials and methods: In the study, BChE-ko and Balb/c mice were used. An organophosphorus compound (OPC) paraoxon was used as a toxic agent causing acute anticholinesterase poisoning. rhBChE was used as an antidote for OPC poisoning. To obtain rhBChE, an expression system based on CHO cell lines was chosen. In order to suppress BChE in Balb/c mice, a carboxyl esterase blocker cresylbenzodioxaphosphorin oxide (CBDP) was used. Two parameters were used to study the recovery after toxicity modeling: the end time of the animal tremor and the distance covered in open-field for 3 minutes.

Results and discussion: The acute poisoning model using the CBDP blocker showed that the sensitivity of Balb/c mice increased significantly. The use of rhBChE against the background of CBDP allowed achieving 100% survival of animals with the minimum lethal dose of paraoxon. Knockout mice are expected to be more sensitive to the toxin, and the use of a biological trap in the form of rhBChE made it possible for 70% of the animals to survive with the minimum lethal dose of paraoxon. Besides, the use of rhBChE facilitated reducing the recovery time after OPC poisoning.

Conclusion: The results of the study showed that the use of rhBChE as a protective agent in acute OPC poisoning significantly increased the survival of the animals and reduced the clinical manifestations of poisoning.

Maximum tolerant dose and analgesic activity of PT1 peptide

Introduction: The article presents the results of the study of the maximum tolerant dose (MTD) and the analgesic activity of peptide PT1 isolated from Alopecosa marikovskyi spider venom. PT1 is the first compound of polypeptide nature, capable of exerting a selective modulating effect on purinergic P2X3 receptors.

Materials and methods: The study was conducted on 174 ICR mice. The analgesic activity of the peptide was evaluated in a thermal hypersensitivity test triggered by CFA and in a model of chemical irritation.

Results and discussion: The determined MTD for the peptide PT1 when administered intravenously provides evidence to attribute it to low-toxic compounds. The maximum analgesic activity of PT1 using the biomodel of hypersensitivity induced by CFA when tested 15 minutes after the administration was recorded at doses of 0.1 and 0.5 mg/kg. In the visceral pain test, the maximum analgesic activity 15 minutes after the administration of the chemical stimulus was observed at a dose of 0.01 mg/kg.

Conclusions: According to the results of testing peptide PT1, it is shown that it belongs to low-toxic compounds, has a pronounced analgesic activity in a wide range of doses of 0.0001–10 mg/kg.