Letters in Drug Design & Discovery - Volume 21, Issue 5, 2024

Background: Genetic studies support a key role for RORγ and RORα in the differentiation of proinflammatory Th17 cells, and a growing body of evidence suggests a pathogenic role for Th17 in several autoimmune diseases, including MS, rheumatoid arthritis, inflammatory bowel disease, type I diabetes, and psoriasis. RORγ antagonists have been shown to suppress Th17 differentiation and delay the onset of disease in an experimental autoimmune encephalomyelitis mouse model of MS. Objective: Given the high therapeutic interest of RORγ antagonists and the promising activity of currently known ligands, small molecules with higher potency and receptor selectivity (in particular within the ROR family) are highly desirable. We used our small molecule compound library to discover, characterize, and optimize novel RORγ antagonists for the treatment of autoimmune diseases from Mixture-based Combinatorial Chemical Libraries. Methods: We screened the FIU collection of small molecule libraries (>30 million compounds) composed of 75 molecular scaffolds systematically arranged in positional scanning and scaffold ranking formats. We identified scaffolds that selectively inhibit the binding of RORγ, RORγ, and RORβ but not RORα, and others that function as antagonists of all three receptors. Results: The deconvolution of selected PS-SCL mixtures led to the identification of novel chemical entities, trisubstituted piperazine and diketopiperazine that function as RORγ antagonists. Conclusion: The screening of a large complex library led to the rapid identification of novel trisubstituted piperazine and diketopiperazine antagonists of the nuclear retinoic acid receptor-related orphan receptor gamma (RORγ).

Anticancer drug development is complex and multi-factorial, demanding robust drug evaluative architecture in experimental and preclinical studies. To increase the number of drug licensing, biochemical, pharmacological, technical and economic changes (balance and integration) in evaluative systems should be focused in labs throughout the world. Despite great progress, treatment breakthroughs and drug industry need new ideas and more competitive technology (new generation of in vitro test systems). Overall, drug evaluative systems comprise anticancer drug development (medicinal chemistry and pharmacology) from initial screening to clinical validity. Its advances greatly impact the outcomes of drug production (rates of final drug licensing and efficacy of therapeutics in the clinic). In this regard, creative ideas and new techniques will change the norm and convention of drug screening and mechanic exploration in the future. This article provides multi-disciplinary approaches for experimental and preclinical anticancer drug evaluations, selections and combinations (chemistry and biomedicine). Future trends for drug evaluative systems are especially highlighted in in-depth, multilateral and multidisciplinary approaches.

Cancers remain the leading cause of death worldwide, despite significant advances in their diagnosis and treatment. The inadequacy and ineffectiveness of standard treatments (chemotherapy, radiotherapy, and surgery), their severe side effects, and the resistance of tumor cells to chemotherapeutics have forced researchers to investigate alternative therapeutic strategies. Magnetic nanoparticles (MNPs) have been evaluated as one of the promising strategies in treating cancers, a major public health problem. Due to their intrinsic magnetic properties, MNPs are tools that can be designed to be multifunctional in medicine, including cancer therapy. Multifunctionality can be achieved with various drug/agent loadings, such as chemotherapeutic drugs, radionuclides, nucleic acids, and antibodies. This provides a multimodal theranostics platform for cancer diagnosis, monitoring, and therapy. These substances can then be delivered to the tumor tissue using an external magnetic field (EMF). Magnetic or photothermal applications kill cancer cells at the tumor site by inducing local hyperthermia, whereas photodynamic therapy kills them by producing reactive oxygen species. MNP applications also prevent drug resistance. In addition, alone or with different combination options, MNP applications provide synergistic effects and reduce side effects. Functionalized MNPs can be used to remove unwanted cells from blood, including circulating tumor cells (CTCs), which are key factors in the metastatic process and leukemia cells. Despite numerous successful studies, there are some unpredictable obstacles to be discovered in routine usage. This review focuses mainly on the application of MNPs in cancer treatment, covering future perspectives and challenges.

Background: Nowadays, infectious diseases caused by bacteria are one of the major risks for the human population worldwide. Antimicrobial resistance determined the necessity to develop both, new drugs and therapeutic approaches as alternatives to antibiotics and novel methods to detect bacteria. Aptamers have revealed their potential in combating antimicrobial infections. Aptamers are small singlestranded DNA or RNA oligonucleotides obtained through an in vitro process able to bind several targets with high affinity and specificity. Objective: The aim of this review is to provide an overview of the state of the art of aptamer-based antimicrobial therapeutic strategies, new methods of detection of bacteria, and their potential use as delivery systems. Conclusion: Recent applications on research about aptamers suggest their important potential in discovering novel pharmacological tools for the treatment of microbial infections.

Introduction: The Epidermal growth factor receptor is a transmembrane glycoprotein that belongs to the ErbB family of tyrosine kinase receptors, which includes four EGFR members ErbB1 (HER1/ErbB1), ErbB2 (HER2/neu), ErbB3 (HER3), and ErbB4 (HER4). Methods: Amplification of EGFR corresponds to tyrosine kinase autophosphorylation that activates a downstream signalling pathway involved in regulating tumorigenesis, differentiation, and preservation. Results: In cancer treatment, inhibition of EGFR is essential; therefore, potential EGFR inhibitors are required. Previously approved tyrosine kinase inhibitors such as erlotinib, lapatinib, and gefitinib and heterocyclic compounds such as pyrimidine, quinazolines, isoquinoline, purine, pyrazole, benzothiazole, imidazole, have received a lot of attention in cancer treatment due to their EGFR inhibition activity. Conclusion: This review focuses on the diverse categories of synthetic entities compounds that were reported as potential EGFR and EGFR/ErbB-2 dual inhibitors. Furthermore, it will provide inexorable scope for investigators to design and synthesize potent EGFR inhibitors.

Background: It has been shown that drugs used parenterally cause errors in immunosuppressant concentrations measured by LC-MS / MS method. It is yet unknown whether this measurement error is due to drug-drug interaction or analytical interference. Objective: The aim of this study is to investigate the possible interaction and inhibition concentrations of broad-spectrum antibiotics (ertapenem, meropenem, imipenem) with 4 different immunosuppressants (tacrolimus, sirolimus, everolimus, cyclosporine A) by molecular docking. Methods: The docking results of ertapenem, meropenem, and imipenem-cilastatin drugs, which are frequently used in intensive care units and wards, were analyzed with the Autodock 4.2 program. Binding energy levels and inhibition concentrations were recorded. Results: The highest binding energies of the most stable conformations, providing the best compatibility among the active ingredients, belong to cilastatin. The interaction energy of cilastatin with sirolimus in 320 conformations was calculated as -4.08 kcal/mol. Sirolimus interacted with ertapenem at -3.43, imipenem at -2.53, and meropenem at -3.84 kcal/mol. According to these values, the receptor, which is the most compatible host with all ligand molecules, is sirolimus. The least interaction energy value was calculated between cyclosporine and imipenem (-1.12 kcal / mol). Conclusion: Concerning the most stable conformations of models docked with Autodock tools, it has been determined that carbapenems interact with immunosuppressants. Since the detected inhibition concentration levels can be seen in blood samples taken immediately after carbapenem injection, immunosuppressant measurement is recommended before the use of carbapenem in immunosuppressant monitoring of transplant patients.

Background: Silymarin is a flavonoid utilised in liver dysfunction for years; new studies have emphasised its potential utility as a therapy for nanoparticulate targeting in many other disorders. In order to establish the product quality of such compounds, researchers have been trying to develop a robust method of analysis, but the methods developed till now are too expensive and time-consuming. Here we proposed quality by design-assisted development and validation of the UV spectroscopic method using Design-Expert® software in the estimation of Silymarin for fabrication of nanoparticulate formulations, which is simple, accurate, cost-effective and non-tedious. Aims: The proposed method is a simple, new, robust, accurate, and precise UV visible spectroscopic technique for estimating silymarin produced in nano-formulations utilising an analytical quality by design (AQbD) approach. Methods: A UV spectrophotometric technique was established, as maximum absorption (287.7) was measured using a Shimadzu UV-1800 double-beam UV visible spectrophotometer. The characterization of silymarin was done by melting point, DSC and FTIR techniques. The two critical method variables chosen were scanning speed and sample interval to be analysed by the design of experiment methodology utilizing the central composite design principle, which shows robustness and optimized technique involved in this work. Results: The spectroscopy technique was developed and validated as per International Conference of Harmonization recommendations. The Beer's-Lambert rule was followed in a series of 2-12 μg/ml dilution increments, with a correlation value of R² = 0.999. The method's linearity was shown to be excellent across the concentration range. The percent recovery of the current method approach was determined to be within the confidential limitations, i.e., less than 2% expressed as % RSD, and the methodology was proved to be precise at inter and intraday variations (% RSD). The LOD and LOQ were found to be 0.264 μg/ml and 0.801 μg/ml which were also determined correctly. During specificity testing, no interfering peaks were found. Conclusion: This UV approach has been used successfully to determine the quantity of silymarin present in the nanoparticulate formulation, which can be used for testing its other pharmaceutical dosage forms.

Background: Asthma is a common chronic respiratory disorder characterized by inflammation and remodeling of the airways. Aims: This study aimed to identify the inhibitory effects of Huatan Tongluo decoction (HTTLD) on airway inflammation and associated remodeling mechanisms. Methods: Mice were immunized with ovalbumin (OVA) for 8 weeks to generate chronic asthma mouse models (CAS), which were randomly divided into 4 groups administrated with pachyman, dexamethasone (DEX), HTTLD, and without anything (CAS model), while mice who administrated saline were assigned as the control group. Hematoxylin-eosin (H) and Masson trichrome were used to determine inflammatory infiltration and airway remodeling (fiber deposition). Inflammatory cytokines, including VEGF, PDGF, and TGF-β1, were analyzed using ELISA. The gene transcriptions and expressions of MMP-9, TIMP-1, VEGF, HIF-1α, NF-kB, and β-actin were evaluated using RT-PCR and Western blot, while the expression of p-Smad2/3 was determined by Western blot. Results: HTTLD inhibited inflammatory infiltration and airway remodeling (reducing airway wall thickness and decreasing fiber deposition) of lung tissues in the CAS mouse model. HTTLD markedly attenuated levels of TGF-β1, VEGF, and PDGF compared to those of mice in the CAS model group (p < 0.05). HTTLD significantly reduced the secretion of matrix metalloproteinases (MMP-9 and TIMP-1) and the expression of NF-kB/HIF-1α compared to mice in the CAS model group (p < 0.05). HTTLD prominently downregulated phosphorylated levels of the Smad2/3 molecule (ratio of p-Smad3/2/Smad2/3) compared to mice in the CAS group (p < 0.05). Conclusion: HTTLD inhibited inflammatory infiltration and airway remodeling in an OVA-induced chronic asthma mouse model by attenuating the TGF-β1/Smad2/3 signaling pathway and suppressing the oxidative stress-mediated NF-kB/HIF-1α/MMPs signaling pathway.

Background: Cancer is a serious concern in developing countries. Due to various worldwide impacts, it has surpassed coronary disorders becoming the leading cause of mortality. In cancer progression, the involvement of RORs (retinoic acid receptor-related orphan receptors) has gained attention in the search for versatile agents. Thiazole has the potential to be used as a scaffold in the development of anticancer drugs. Objective: This work’s major goal was to design and synthesize promising anticancer candidates. Methods: Docking investigations concerning the RORγt receptor were utilized in the design of the compounds. A series of novel thiazole derivatives was synthesized employing Hantsch synthesis. Melting points, TLC development, and spectral analyses were considered for the synthesized compounds' characterization. Corresponding spectra were analyzed and determined to be consistent with the assigned structure. On 60 human cancer cell lines, selected compounds were investigated in vitro by NCI (National Cancer Institute), USA, for anticancer action. Results: Varying ratios of anticancer potential were presented by the compounds in in vitro studies. Compound 3c was determined to be the most active compound in the series, with a -15.03 mean growth percent. In silico study revealed that the synthesized compounds could have anticancer possibilities. In the targeted pdb id (6q7a) binding site, compound 3c demonstrated excellent docking scores in molecular docking analyses, supporting its ability to be utilized as a lead compound in rational drug design. Conclusion: Compounds with satisfactory docking scores within the binding pocket of chosen pdb id (6q7a) validated their suitability for usage as lead compounds in rational drug design. Outcomes of in silico investigations were in agreement with the findings of the cytotoxicity experiments. Leukemia, renal, breast, and lung cancer cell lines were most sensitive to the substance-treated tumor cells. Electronwithdrawing groups were essential for antiproliferative action, according to the findings.

Background: The deficiency of vitamin D is a global concern affecting individuals of all age groups. Insufficient exposure to sunlight and disease conditions can lead to cholecalciferol (vitamin D3) deficiency. Objective: Cholecalciferol is a lipophilic crystalline molecule, and it is highly susceptible to degradation under environmental conditions, including light, temperature, and oxygen, and its degradation rate is high in the low pH range. Therefore, an enteric solid dispersion-based formulation was developed in the present study for the oral delivery of cholecalciferol. Methods: Enteric polymer hydroxypropylmethylcellulose acetate succinate (HPMCAS)-based solid dispersion was developed and characterized by Fourier transform-infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and X-ray diffraction analysis. The effect of various concentrations of cholecalciferol formulations on the viability of Caco-2 cells was determined using an MTT assay. A dissolution and stability study of the product was also performed. Results: An amorphous form of cholecalciferol in the solid dispersion was reported. The drug content of solid dispersions was in the order of 90%. The viability assay indicated that the surfactant used in the developed solid dispersion of cholecalciferol had no cytotoxic effect on Caco-2 cells. A dissolution study on enteric solid dispersion in two-stage dissolution under a biomimetic medium indicated the pHdependent release of cholecalciferol from the HPMCAS-based solid dispersion. Moreover, the stability study showed no significant changes in the cholecalciferol content in the developed formulation under storage at experimental conditions. Conclusion: The enteric solid dispersion of cholecalciferol was developed, which exhibited compatibility with Caco-2 cells, improved dissolution, and acceptable stability profile, and represented a potential option for efficient delivery of cholecalciferol.

Background: In this article, a series of novel oxazolidinone derivatives containing dithiocarbamate moieties have been designed and synthesized. Materials and Methods: Their antibacterial activities were measured against Staphylococcus aureus, vancomycin-resistant Enterococcus faecium (VREF), linezolid-resistant Enterococcus faecalis (LREF) and Streptococcus agalactiae (GBS) by minimal inhibitory concentration (MIC) assays. Results: Dithiocarbamates were found conducive to the maintenance of antibacterial activity. Most of them exhibited potent activity against Gram-positive pathogens comparable to linezolid. The most promising compound A8 showed remarkable antibacterial activity against S.aureus, VREF, LREF, and GBS pathogens with MIC values between 0.25 and 1 μg/mL, which might be a promising drug candidate for further investigation. Conclusion: A series of novel oxazolidinone derivatives containing dithiocarbamate moieties might be promising drug candidates for further investigation.

Introduction: Marine microbes are known to produce novel bioactive compounds. In this work, the bacterium Actinoalloteichus cyanogriseus, AU-RM-4, isolated from marine soil sediment, capable of producing high amounts of black extracellular melanin pigment when grown on anaerobic actinomycetes agar is reported. The maximum melanin production was approximately 2.5 mg/mL. Methods: The melanin pigment was recovered using acid treatment and the characteristic melanin absorption peaks at 253 nm and 291 nm were observed in the UV range. The antibacterial activity of the melanin pigment against a range of clinically infectious bacteria was assayed in vitro by disc diffusion and serial dilution methods. Results: The A. cyanogriseus melanin showed antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae (MIC value -500 μg/mL). The effects of the AU-RM-4 melanin on the morphology of pathogenic bacteria were observed under scanning (SEM) and transmission electron microscopy (TEM). It is concluded that A. cyanogriseus isolate AU-RM-4 is a promising melanin-producing marine bacterium, whose melanin pigment has antibacterial activity against certain pathogenic bacteria (S. aureus and K. pneumoniae). Conclusion: Melanin produced by A. cyanogriseus AU-RM-4 could have commercial potential in the pharmaceutical and cosmetic industries for the production of pharmaceutical formulations, and also in the food industries as a colouring and antibacterial agent.

Background: Glioblastoma is one of the most aggressive types of tumors, which occurs in the central nervous system, and has a high fatality rate. Among the cellular changes observed in glioblastoma is the overexpression of certain anti-apoptotic proteins, such as Bcl-xL. Recently, the alkaloid sanguinarine (SAN) was identified as a potent inhibitor of this class of proteins. Objective: In this work, the antitumor activity of ten aryl-isoquinolines that were synthesized based on molecular simplification of SAN was investigated. Methods: The SAN derivatives were prepared by Suzuki reaction and bimolecular nucleophilic substitution. The compounds were tested against glioblastoma (U87MG) and melanoma (A375) tumor lines in the MTT and SRB assay. The cell death mechanism was evaluated by flow cytometry. The molecular modeling study was used to evaluate the interactions between the prepared compounds and the Bcl-xL protein. Results: Analogues presented IC50 values against glioblastoma lower than temozolomide. Evaluation against astrocytes and fibroblasts indicated that the analogues were significantly superior to SAN regarding selectivity. The most active compound, 2e, induced phosphatidylserine externalization and mitochondrial membrane depolarization, indicating apoptotic death by the intrinsic pathway. In addition, 2e provides cell cycle arrest at the G2/M phase. Molecular dynamics suggested that 2e interacts with Bcl-xL mainly by hydrophobic interactions. Conclusion: In our study, aryl-isoquinoline represents a relevant scaffold to be explored by medicinal chemists to develop potential anti-glioblastoma agents.

Background: Multiple myeloma (MM) is a hematological malignancy of plasma cells that produce a monoclonal immunoglobulin protein. Despite significant advances in the treatment of MM, currently available therapies are associated with toxicity and resistance. As a result, there is an increasing demand for novel, effective therapeutics. Inhibition of histone deacetylases (HDACs) is emerging as a potential method for treating cancer. HDAC6 is one of 18 different HDAC isoforms that regulate tubulin lysine 40 and function in the microtubule network. HDAC6 participates in tumorigenesis and metastasis through protein ubiquitination, tubulin, and Hsp90. Several studies have found that inhibiting HDAC6 causes AKT and ERK dephosphorylation, which leads to decreased cell proliferation and promotes cancer cell death via the PI3K/AKT and MAPK/ERK signaling pathways. Objective: The objective of this study is to target HDAC6 and identify potent inhibitors for the treatment of multiple myeloma by employing computer-aided drug design. Materials and Methods: A total of 199,611,439 molecules from five different chemical databases, such as CHEMBL25, ChemSpace, Mcule, MolPort, and ZINC, have been screened against HDAC6 by structure- based virtual screening, followed by filtering for various drug-likeness, ADME, toxicity, consensus molecular docking, and 100 ns MD simulation. Results: Our research work resulted in three molecules that have shown strong binding affinity (CHEMBL2425964 -9.99 kcal/mol, CHEMBL2425966 -9.89 kcal/mol, and CSC067477144 -9.86 kcal/mol) at the active site HDAC6, along with effective ADME properties, low toxicity, and high stability. Inhibiting HDAC6 with these identified molecules will induce AKT and ERK dephosphorylation linked to reduced cell proliferation and promote cancer cell death. Conclusion: CHEMBL2425964, CHEMBL2425966, and CSC067477144 could be effective against multiple myeloma.

Background: Polo-like kinase 1 (PLK1) is an important target for anti-cancer drugs. A series of novel 2,4-diarylaminopyrimidine derivatives (DAPDs) as PLK1 inhibitors (PLKIs) with remarkable activities have been reported recently. Methods: A systemically computational study was performed on these DAPDs, including threedimensional quantitative structure-activity relationship (3D-QSAR) modeling, molecular docking, and molecular dynamics (MD) simulation. Results: The constructed 3D-QSAR models exhibited reliable predictability with satisfactory validation parameters. The dockings revealed the binding modes of DAPDs in PLK1 protein, and two key residue, Cys133 and Phe183, could interact with DAPDs by hydrogen bonds and π-π stacking, which might be significant for the activity of these PLKIs. Eight compounds with higher predicted activity than the most active DAPD-compound (16) were designed based on the 3D-QSAR models. These newly designed compounds also exhibited higher docking scores than compound 16 in the binding pocket of PLK1. The ADME predictions and MD simulations further indicated that two hit compounds with reasonable pharmacokinetics properties could stably bind with PLK1 and have the potential to become novel PLKIs. Conclusion: Two newly designed compounds might have the potential to be novel PLKIs. These results might provide important information for the design and development of novel PLKIs.