Preclinical toxicity of innovative molecules: In vitro, in vivo and metabolism prediction

GDNF and cAMP significantly enhance in vitro blood-brain barrier integrity in a humanized tricellular transwell model

Blood-brain barrier (BBB) is a crucial membrane safeguarding neural tissue by controlling the molecular exchange between blood and the brain. However, assessing BBB permeability presents challenges for central nervous system (CNS) drug development. In vitro studies of BBB-permeable agents before animal testing are essential to mitigate failures. Improved in vitro models are needed to mimic physiologically relevant BBB integrity. Here, we established an in vitro human-derived triculture BBB model, coculturing hCMEC/D3 with primary astrocytes and pericytes in a transwell format. This study found that the triculture BBB model exhibited significantly higher paracellular tightness (TEER 147.6 ± 6.5 Ω × cm2) than its monoculture counterpart (106.3 ± 1.0 Ω × cm2). Additionally, BBB permeability in the triculture model was significantly lower. While GDNF and cAMP have been shown to promote BBB integrity in monoculture models, their effect in our model was previously unreported. Our study demonstrates that both GDNF and cAMP increased TEER values (around 200 Ω × cm2 for each; 237.6 ± 17.7 Ω × cm2 for co-treatment) compared to untreated control, and decreased BBB permeability, mediated by increased claudin-5 expression. In summary, this humanized triculture BBB model, enhanced by GDNF and cAMP, offers an alternative for exploring in vitro drug penetration into the human brain.

Synthesis, design, and optimization of a potent and selective series of pyridylpiperazines as promising antimalarial agents

An optimization of the pyridylpiperazine series against Plasmodium falciparum has been performed, exploring a structure-activity relationship carried out on the toluyl fragment of hit 1, a compound with low micromolar activity against Plasmodium falciparum discovered by high-throughput screening. After confirming the crucial role played by this aryl fragment in the antiplasmodial activity, the replacement of the ortho-methyl substituent of 1 by halogenated ones led to an improvement for four analogs, either in terms of potency, expected pharmacokinetics profile, or both. Further introduction of endocyclic nitrogens in this fragment identified two more optimized compounds, 20 and 23, which are expected to be much more metabolically stable than 1. Additional assessment of the cytotoxicity, Ligand Lipophilic Efficiency, potency against the chloroquine-resistant Dd2 strain and in silico ADMET predictions revealed a satisfactory profile for most compounds, ultimately identifying the four optimized compounds 7, 9, 20 and 23 as promising compounds for further lead optimization of this series against Plasmodium falciparum.

Enhancing oral bioavailability of an antifungal thiazolylhydrazone derivative: Development and characterization of a self-emulsifying drug delivery system

RN104 (2-[2-(cyclohexylmethylene)hydrazinyl)]-4-phenylthiazole) is a thiazolylhydrazone derivative with prominent antifungal activity. This work aimed to develop a self-emulsifying drug delivery system (SEDDS) loaded with RN104 to improve its biopharmaceutical properties and enhance its oral bioavailability. Medium chain triglycerides, sorbitan monooleate, and polysorbate 80 were selected as components for the SEDDS formulation based on solubility determination and a pseudo-ternary phase diagram. The formulation was optimized using the central composite design in response surface methodology. The optimized condition consisted of medium chain triglycerides, sorbitan monooleate, and polysorbate 80 in a mass ratio of 65.5:23.0:11.5, achieving maximum drug loading (10 mg/mL) and minimum particle size (118.4 ± 0.7 nm). The developed RN104-SEDDS was fully characterized using dynamic light scattering, in vitro release studies, stability assessments, polarized light microscopy, and transmission electron microscopy. In vivo pharmacokinetic studies in mice demonstrated that RN104-SEDDS significantly improved oral bioavailability compared to free RN104 (the relative bioavailability was 2133 %). These results clearly indicated the successful application of SEDDS to improve the pharmacokinetic profile and to enhance the oral bioavailability of RN104, substantiating its potential as a promising antifungal drug candidate.

The Brazilian compound library (BraCoLi) database: a repository of chemical and biological information for drug design

The Brazilian Compound Library (BraCoLi) is a novel open access and manually curated electronic library of compounds developed by Brazilian research groups to support further computer-aided drug design works, available on https://www.farmacia.ufmg.br/qf/downloads/ . Herein, the first version of the database is described comprising 1176 compounds. Also, the chemical diversity and drug-like profiles of BraCoLi were defined to analyze its chemical space. A significant amount of the compounds fitted Lipinski and Veber's rules, alongside other drug-likeness properties. A comparison using principal component analysis showed that BraCoLi is similar to other databases (FDA-approved drugs and NuBBE_DB) regarding structural and physicochemical patterns. Furthermore, a scaffold analysis showed that BraCoLi presents several privileged chemical skeletons with great diversity. Despite the similar distribution in the structural and physicochemical spaces, Tanimoto coefficient values indicated that compounds present in the BraCoLi are generally different from the two other databases, where they showed different kernel distributions and low similarity. These facts show an interesting innovative aspect, which is a desirable feature for novel drug design purposes.

Recent Advances in the Prediction of Pharmacokinetics Properties in Drug Design Studies: A Review

This review presents the main aspects related to pharmacokinetic properties, which are essential for the efficacy and safety of drugs. This topic is very important because the analysis of pharmacokinetic aspects in the initial design stages of drug candidates can increase the chances of success for the entire process. In this scenario, experimental and in silico techniques have been widely used. Due to the difficulties encountered with the use of some experimental tests to determine pharmacokinetic properties, several in silico tools have been developed and have shown promising results. Therefore, in this review, we address the main free tools/servers that have been used in this area, as well as some cases of application. Finally, we present some studies that employ a multidisciplinary approach with synergy between in silico, in vitro, and in vivo techniques to assess ADME properties of bioactive substances, achieving successful results in drug discovery and design.

Antibacterial and antibiotic modifying activity, ADMET study and molecular docking of synthetic chalcone (E)-1-(2-hydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)prop-2-en-1-one in strains of Staphylococcus aureus carrying NorA and MepA efflux pumps

A large number of infections are caused by multi-resistant bacteria worldwide, adding up to a figure of around 700,000 deaths per year. Because of that many strategies are being developed in order to combat the resistance of microorganisms to drugs, in recent times, chalcones have been studied for this purpose. Chalcones are known as α, β-unsaturated ketones, characterized by having the presence of two aromatic rings that are joined by a three-carbon chain, they are a class of compounds considered an exceptional model due to chemical simplicity and a wide variety of biological activities, which include anticancer, anti-inflammatory, antioxidants, antimicrobials, anti-tuberculosis, anti-HIV, antimalarial, anti-allergic, antifungal, antibacterial, and antileishmanial. The objective of this work was evaluate the antibacterial and antibiotic modifying activity of chalcone (E)-1-(2-hydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)prop-2-en-1-one against the bacteria Staphylococcus aureus carrying a NorA and MepA efflux pump. The results showed that chalcone was able to synergistically modulate the action of Norfloxacin and Ethidium Bromide against the bacteria Staphylococcus aureus 1199B and K2068, respectively. The theoretical physicochemical and pharmacokinetic properties of chalcone showed that the chalcone did not present a severe risk of toxicity such as genetic mutation or cardiotoxicity, constituting a good pharmacological active ingredient.

Fungicidal Activity of a Safe 1,3,4-Oxadiazole Derivative Against Candida albicans

Candida albicans is the most common species isolated from nosocomial bloodstream infections. Due to limited therapeutic arsenal and increase of drug resistance, there is an urgent need for new antifungals. Therefore, the antifungal activity against C. albicans and in vivo toxicity of a 1,3,4-oxadiazole compound (LMM6) was evaluated. This compound was selected by in silico approach based on chemical similarity. LMM6 was highly effective against several clinical C. albicans isolates, with minimum inhibitory concentration values ranging from 8 to 32 µg/mL. This compound also showed synergic effect with amphotericin B and caspofungin. In addition, quantitative assay showed that LMM6 exhibited a fungicidal profile and a promising anti-biofilm activity, pointing to its therapeutic potential. The evaluation of acute toxicity indicated that LMM6 is safe for preclinical trials. No mortality and no alterations in the investigated parameters were observed. In addition, no substantial alteration was found in Hippocratic screening, biochemical or hematological analyzes. LMM6 (5 mg/kg twice a day) was able to reduce both spleen and kidneys fungal burden and further, promoted the suppresses of inflammatory cytokines, resulting in infection control. These preclinical findings support future application of LMM6 as potential antifungal in the treatment of invasive candidiasis.

Trypanocidal activity of new 1,6-diphenyl-1H-pyrazolo[3,4-b]pyridine derivatives: Synthesis, in vitro and in vivo studies

Despite the serious public health problems caused by Chagas disease in several countries, the available therapy remains with only two drugs that are poorly active during the chronic phase of the disease in addition to having severe side effects. In search of new trypanocidal agents, herein we describe the synthesis and biological evaluation of eleven new 1,6-diphenyl-1H-pyrazolo[3,4-b]pyridine compounds containing the carbohydrazide or the 2,3-dihydro-1,3,4-oxadiazole moieties. Two of them showed promising in vitro activity against amastigote forms of T. cruzi and were evaluated in vivo in male BALB/c mice infected with T. cruzi Y strain. Our results suggest that the substitution at the C-2 position of the phenyl group connected to the carbohydrazide or to the 2,3-dihydro-1,3,4-oxadiazole moieties plays an important role in the trypanocidal activity of this class of compounds. Moreover, the compound containing the 2,3-dihydro-1,3,4-oxadiazole moiety has demonstrated more favorable structural requirements for in vivo activity than its carbohydrazide analog.

Rapid and convenient biotransformation procedure for human drug metabolizing enzymes using permeabilized fission yeast cells

The development of convenient assays for the in vitro study of drug metabolizing enzymes (DMEs) such as cytochromes P450 (CYPs) and UDP-glucuronosyltransferases (UGTs) greatly facilitates metabolism studies of candidate drug compounds and other xenobiotics. We have developed and optimized an experimental approach that combines the advantages of recombinant expression in yeast with a microsomal-like biotransformation and thus allows for rapid and convenient enzymatic assays. Recombinant strains of the fission yeast Schizosaccharomyces pombe have previously been demonstrated to functionally express human CYPs and UGTs. Permeabilization of such cells with Triton X-100 results in the formation of enzyme bags, which can be used as biocatalysts. This protocol describes the preparation of such enzyme bags (3 h) and their application in enzyme activity assays (4 h) utilizing either pro-luminescent substrates and luminescence measurements or non-luminescent substrates and liquid chromatography coupled to mass spectrometry (LC-MS). Both applications provide practical tools for investigating CYP and UGT reactions in vitro without the need for additional sophisticated instrumentation or expertise.

Food additive "lauric acid" possess non-toxic profile on biochemical, haematological and histopathological studies in female Sprague Dawley (SD) rats

Background

Lauric acid (LA), a common constituent of coconut oil, is used as food additives and supplements in various formulations. Despite various potential pharmacological properties, no scientific evidence on its dose-related toxicity and safety is available till date.

Objective

The current study was conducted to evaluate acute oral toxicity of LA on normal rats.

Methods

The study was conducted in accordance with the Organization for Economic Co-operation and Development guidelines (OECD 423) with slight modifications. LA was administered orally to female Sprague Dawley (SD) rats (n = 6/group) at a single dose of 300 and 2,000 mg/kg body weight, respectively, while normal control received vehicle only. Animals from all the three groups were monitored for any behavioural and toxicological changes and mortality for two weeks. Food and fluid consumption, body weight was monitored on daily basis. At the end (on day 15th) of the experimental period, blood was collected for haematological and biochemical analysis. Further, all the animals were euthanized, and internal organs were harvested for histopathological investigation using four different stainings; haematoxylin and eosin, Masson trichrome, Periodic Acid Schiff and Picro Sirius Red for gross pathology through microscopical observation.

Results

The study results showed no LA treatment-related mortality and morbidity at two different dosages. Daily food and water consumption, body weight, relative organ weight, haematological, and biochemical analysis were observed to be normal with no severe alterations to the internal tissues.

Conclusion

The current finding suggests that single oral administration of LA, even up to 2,000 mg/kg body weight, did not exhibit any signs of toxicity in SD rats; thus, it was safe to be used on disease models in animals.

[Computer-aided drug design: from discovery of novel pharmaceutical agents to systems pharmacology]

New drug discovery is based on the analysis of public information about the mechanisms of the disease, molecular targets, and ligands, which interaction with the target could lead to the normalization of the pathological process. The available data on diseases, drugs, pharmacological effects, molecular targets, and drug-like substances, taking into account the combinatorics of the associative relations between them, correspond to the Big Data. To analyze such data, the application of computer-aided drug design methods is necessary. An overview of the studies in this area performed by the Laboratory for Structure-Function Based Drug Design of IBMC is presented. We have developed the approaches to identifying promising pharmacological targets, predicting several thousand types of biological activity based on the structural formula of the compound, analyzing protein-ligand interactions based on assessing local similarity of amino acid sequences, identifying likely molecular mechanisms of side effects of drugs, calculating the integral toxicity of drugs taking into account their metabolism, have been developed in the human body, predicting sustainable and sensitive options strains and evaluating the effectiveness of combinations of antiretroviral drugs in patients, taking into account the molecular genetic characteristics of the clinical isolates of HIV-1. Our computer programs are implemented as the web-services freely available on the Internet, which are used by thousands of researchers from many countries of the world to select the most promising substances for the synthesis and determine the priority areas for experimental testing of their biological activity.