Solvent Selection for Insoluble Ligands, a Challenge for Biological Assay Development: A TNF-α/SPD304 Study

Discovery of furopyridine-based compounds as novel inhibitors of Janus kinase 2: In silico and in vitro studies

Janus kinase 2 (JAK2), one of the JAK isoforms participating in a JAK/STAT signaling cascade, has been considered a potential clinical target owing to its critical role in physiological processes involved in cell growth, survival, development, and differentiation of various cell types, especially immune and hematopoietic cells. Substantial studies have proven that the inhibition of this target could disrupt the JAK/STAT pathway and provide therapeutic outcomes for cancer, immune disorders, inflammation, and COVID-19. Herein, we performed docking-based virtual screening of 63 in-house furopyridine-based compounds and verified the first-round screened compounds by in vitro enzyme- and cell-based assays. By shedding light on the integration of both in silico and in vitro methods, we could elucidate two promising compounds. PD19 showed cytotoxic effects on human erythroblast cell lines (TF-1 and HEL) with IC50 values of 57.27 and 27.28 μM, respectively, while PD12 exhibited a cytotoxic effect on TF-1 with an IC50 value of 83.47 μM by suppressing JAK2/STAT5 autophosphorylation. In addition, all screened compounds were predicted to meet drug-like criteria based on Lipinski's rule of five, and none of the extreme toxicity features were found. Molecular dynamic simulations revealed that PD12 and PD19 could form stable complexes with JAK2 in an aqueous environment, and the van der Waals interactions were the main force driving the complex formation. Besides, all compounds sufficiently interacted with surrounding amino acids in all crucial regions, including glycine, catalytic, and activation loops. Altogether, PD12 and PD19 identified here could potentially be developed as novel therapeutic inhibitors disrupting the JAK/STAT pathway.

Exploring the Solubility Limits of Edaravone in Neat Solvents and Binary Mixtures: Experimental and Machine Learning Study

This study explores the edaravone solubility space encompassing both neat and binary dissolution media. Efforts were made to reveal the inherent concentration limits of common pure and mixed solvents. For this purpose, the published solubility data of the title drug were scrupulously inspected and cured, which made the dataset consistent and coherent. However, the lack of some important types of solvents in the collection called for an extension of the available pool of edaravone solubility data. Hence, new measurements were performed to collect edaravone solubility values in polar non-protic and diprotic media. Such an extended set of data was used in the machine learning process for tuning the parameters of regressor models and formulating the ensemble for predicting new data. In both phases, namely the model training and ensemble formulation, close attention was paid not only to minimizing the deviation of computed values from the experimental ones but also to ensuring high predictive power and accurate solubility computations for new systems. Furthermore, the environmental friendliness characteristics determined based on the common green solvent selection criteria, were included in the analysis. Our applied protocol led to the conclusion that the solubility space defined by ordinary solvents is limited, and it is unlikely to find solvents that are better suited for edaravone dissolution than those described in this manuscript. The theoretical framework presented in this study provides a precise guideline for conducting experiments, as well as saving time and resources in the pursuit of new findings.

New contributions to the drug profile of TNFα inhibitor SPD304: Affinity, selectivity and ADMET considerations

Tumor necrosis factor alpha (TNFα) is a relevant clinical target for the treatment of chronic inflammatory diseases. Currently, only few small molecules are known as direct inhibitors of TNFα. To date, none of these molecules has shown both an efficient activity and a low toxicity to be considered for clinical trials. The SPD304 is considered as a reference of direct inhibitors of TNFα because of its well demonstrated mechanism (He et al., 2005). Herein, we provide new insights regarding the drug profile, selectivity and absorption, distribution, metabolism, excretion and toxicity (ADMET) considerations of SPD304 to evaluate its potential as a hit for the structure-based design of novel TNFα inhibitors. ELISA experiments confirmed the inhibition of TNFα/TNF receptor 1 binding (IC50 = 12 μM). Cellular-based assays highlighted the cytotoxicity of SPD304, as well as its ability to inhibit TNFα signaling pathways at non-cytotoxic concentrations. A surface acoustic wave (SAW) experiment highlighted only one binding site with a dissociation constant of 6.1 ± 4.7 nM. SPD304 inhibited the binding of the cytokines like interleukins (IL)-4 and IL-13 to their receptors and showed no direct inhibition on proteins involved in the TNFα pathway. Finally, the thermodynamic solubility and Caco-2 cells permeability of SPD304 were experimentally evaluated and ADMET in silico predictions are also discussed. The physicochemical, pharmacological and ADMET studies of SPD304 have shown that is not an ideal hit for a drug optimization program based on its chemical structure.

A Rational Insight into the Effect of Dimethyl Sulfoxide on TNF-α Activity

Direct inhibition of tumor necrosis factor-alpha (TNF-α) action is considered a promising way to prevent or treat TNF-α-associated diseases. The trimeric form of TNF-α binds to its receptor (TNFR) and activates the downstream signaling pathway. The interaction of TNF-α with molecular-grade dimethyl sulfoxide (DMSO) in an equal volumetric ratio renders TNF-α inert, in this state, TNF-α fails to activate TNFR. Here, we aimed to examine the inhibition of TNF-α function by various concentrations of DMSO. Its higher concentration led to stronger attenuation of TNF-α-induced cytokine secretion by fibroblasts, and of their death. We found that this inhibition was mediated by a perturbation in the formation of the functional TNF-α trimer. Molecular dynamics simulations revealed a transient interaction between DMSO molecules and the central hydrophobic cavity of the TNF-α homodimer, indicating that a brief interaction of DMSO with the TNF-α homodimer may disrupt the formation of the functional homotrimer. We also found that the sensitizing effect of actinomycin D on TNF-α-induced cell death depends upon the timing of these treatments and on the cell type. This study will help to select an appropriate concentration of DMSO as a working solvent for the screening of water-insoluble TNF-α inhibitors.

Discovery of Small-Molecule Inhibitors of Receptor Activator of Nuclear Factor-κB Ligand with a Superior Therapeutic Index

Receptor activator of nuclear factor-κB ligand (RANKL) constitutes the master mediator of osteoclastogenesis, while its pharmaceutical inhibition by a monoclonal antibody has been approved for the treatment of postmenopausal osteoporosis. To date, the pursuit of pharmacologically more favorable approaches using low-molecular-weight inhibitors has been hampered by low specificity and high toxicity issues. This study aimed to discover small-molecule inhibitors targeting RANKL trimer formation. Through a systematic screening of 39 analogues of SPD-304, a dual inhibitor of tumor necrosis factor (TNF) and RANKL trimerization, we identified four compounds (1b, 3b, 4a, and 4c) that selectively inhibited RANKL-induced osteoclastogenesis in a dose-dependent manner, without affecting TNF activity or osteoblast differentiation. Based on structure-activity observations extracted from the most potent and less toxic inhibitors of RANKL-induced osteoclastogenesis, we synthesized a focused set of compounds that revealed three potent inhibitors (19a, 19b, and 20a) with remarkably low cell-toxicity and improved therapeutic indexes as shown by the LC₅₀ to IC₅₀ ratio. These RANKL-selective inhibitors are an excellent starting point for the development of small-molecule therapeutics against osteolytic diseases.

Optimization of a Colorimetric Assay to Determine Lactate Dehydrogenase B Activity Using Design of Experiments

Lactate dehydrogenase B (LDH-B) is overexpressed in lung and breast cancer, and it has been considered as a potential target to treat these types of cancer. Herein, we propose a straightforward incomplete factorial (IF) design composed of 12 combinations of two reaction buffers, three pH values, three salt (NaCl) concentrations, and three incubation times, which we called IF-BPST (Buffer/pH/Salt/Time), for the optimization of a colorimetric LDH-B assay in a final volume of 100 µL using 96-well plates. The assay is based on the absorbance change at ~570 nm and the color change of the reaction mixture due to the release of NADH that reacts with nitroblue tetrazolium (NBT) and phenazine methosulfate (PMS), resulting in the formation of a blue-purple formazan. The results obtained using the IF-BPST were comparable with those obtained by response surface methodology. Our work revealed that the NBT/PMS assay with some modifications can be used to measure the activity of LDH-B and other dehydrogenases in a high-throughput screening format at the early stages of drug discovery. LDH-B containing lysates cannot be assayed directly, however, due to the sensitivity of the method toward detergents. Thus, we suggest precipitating the proteins in the lysates to remove the interfering detergents, and then to dissolve the protein pellet in a suitable buffer and carry out the assay.

Functionalizing nanoparticles with cancer-targeting antibodies: A comparison of strategies

Standard cancer therapies sometimes fail to deliver chemotherapeutic drugs to tumor cells in a safe and effective manner. Nanotechnology takes the lead in providing new therapeutic options for cancer due to major potential for selective targeting and controlled drug release. Antibodies and antibody fragments are attracting much attention as a source of targeting ligands to bind specific receptors that are overexpressed on cancer cells. Therefore, researchers are devoting time and effort to develop targeting strategies based on nanoparticles functionalized with antibodies, which hold great promise to enhance therapeutic efficacy and circumvent severe side effects. Several methods have been described to immobilize antibodies on the surface of nanoparticles. However, selecting the most appropriate for each application is challenging but also imperative to preserve antigen binding ability and yield stable antibody-conjugated nanoparticles. From this perspective, we aim to provide considerable knowledge on the most widely used methods of functionalization that can be helpful for decision-making and design of conjugation protocols as well. This review summarizes adsorption, covalent conjugation (carbodiimide, maleimide and "click" chemistries) and biotin-avidin interaction, while discussing the advantages, limitations and relevant therapeutic approaches currently under investigation.

Enhancement of saquinavir absorption and accumulation through the formation of solid drug nanoparticles

Background

Nanotechnology is now considered a promising drug delivery method for orally administered hydrophobic drugs to their sites of action. The effect of nanodispersion on cellular transport and accumulation of saquinavir (SQV) was investigated.

Methods

The transport of five solid drug nanoparticle (SDN) SQV formulations along Caco-2 cell monolayers (CCM) was compared to that of standard SQV. The SDNs were prepared using SQV mesylate (20%), Pluronic F127 (10%) plus five other excipients (HPMC, PVP, PVA, Lecithin S75 and Span 80) in different proportions. Cellular accumulation in CEM parental and CEMVBL (P-gp overexpressing) cells was conducted to ascertain the effect of nanodispersion on P-gp mediated efflux of SQV. All SDN formulations were dissolved in water, whereas SQV in DMSO to improve solubility. Quantification was via HPLC.

Results

From transport results, an SDN sample composed of SQV mesylate/Pluronic F127 plus HPMC (70%) and had a 24% increase in apparent absorption compared to standard SQV, largely driven by a 38% reduction in basolateral to apical permeation. Additionally, the formulation and two others (SQV mesylate/Pluronic F127 alone; and + HPMC (65%)/Lecithin [5%]) accumulated more significantly in CEM cells, suggesting enhanced delivery to these cells. Moreover, accumulation and transport of the three SDNs compared well to that of SQV despite being dissolved in water, suggestive of improved dissolution. The inclusion of PVA resulted in increased efflux.

Conclusion

The use of HPMC and Pluronic F127 produced SQV SDNs with improved permeation in Caco-2 cells and improved accumulation in CEM cells, but negative effects with PVA.

Deciphering Block Copolymers as Carriers of a Pyrazoline Derivative through Its Solvatochromic Behavior: A Spectroscopic and Theoretical Exploration

Many biologically active water-insoluble drug molecules have limited clinical application because of strong hydrophobicity. Recently triblock copolymers have attracted enormous interest as potential drug carriers. For the purpose of delivering the 5-(1-(bromohexa-1,3,5-triyn-1-yl)-3a,4,5,6,7,7a-hexahydro-1H-4,7-methanoindazol-3-yl)-3-methyl-1-phenyl-1H-pyrazole-4-carbonitrile (PYZ) molecule, triblock copolymers are used. In order to understand the delivery of this water-insoluble probe through triblock copolymers (TBP), the solvent-dependent fluorescence properties of this compound have been examined in different homogeneous solvents. Besides the experimental work, theoretical studies have also been conducted to explain actual orientation of atoms in PYZ through optimized structures to support the experimental findings. Moreover, the three TBP polymers P-123 (PEO₁₉ PPO₆₉ PEO₁₉ ), F-127 (PEO₁₀₀ PPO65PEO₁₀₀ ) and L-64 (PEO₁₃ PPO₃₀ PEO₁₃ ) have been treated here as potential carriers that encapsulate a pyrazoline derivative. The consequence of spatial captivity on the emission properties was systematically visualized by means of steady-state and time-resolved fluorescence spectroscopy. From DLS measurements the size variation with the polydispersity index of TBP in the presence and absence of PYZ in different triblock copolymers was also monitored. Furthermore these measurements have been supported by TEM imaging also.

Identification of Novel and Efficacious Chemical Compounds that Disturb Influenza A Virus Entry in vitro

Influenza A virus is a negative RNA stranded virus of the family Orthomyxoviridae, and represents a major public health threat, compounding existing disease conditions. Influenza A virus replicates rapidly within its host and the segmented nature of its genome facilitates re-assortment, whereby whole genes are exchanged between influenza virus subtypes during replication. Antiviral medications are important pharmacological tools in influenza virus prophylaxis and therapy. However, the use of currently available antiviral is impeded by sometimes high levels of resistance in circulating virus strains. Here, we identified novel anti-influenza compounds through screening of chemical compounds synthesized de novo on human lung epithelial cells. Computational and experimental screening of extensive and water soluble compounds identified novel influenza virus inhibitors that can reduce influenza virus infection without detectable toxic effects on host cells. Interestingly, the indicated active compounds inhibit viral replication most likely via interaction with cell receptors and disturb influenza virus entry into host cells. Collectively, screening of new synthesis chemical compounds on influenza A virus replication provides a novel and efficacious anti-influenza compounds that can inhibit viral replication via disturbing virus entry and indicates that these compounds are attractive candidates for evaluation as potential anti-influenza drugs.

Identification of an in vivo orally active dual-binding protein-protein interaction inhibitor targeting TNFα through combined in silico/in vitro/in vivo screening

TNFα is a homotrimeric pro-inflammatory cytokine, whose direct targeting by protein biotherapies has been an undeniable success for the treatment of chronic inflammatory diseases. Despite many efforts, no orally active drug targeting TNFα has been identified so far. In the present work, we identified through combined in silico/in vitro/in vivo approaches a TNFα direct inhibitor, compound 1, displaying nanomolar and micromolar range bindings to TNFα. Compound 1 inhibits the binding of TNFα with both its receptors TNFRI and TNFRII. Compound 1 inhibits the TNFα induced apoptosis on L929 cells and the TNFα induced NF-κB activation in HEK cells. In vivo, oral administration of compound 1 displays a significant protection in a murine TNFα-dependent hepatic shock model. This work illustrates the ability of low-cost combined in silico/in vitro/in vivo screening approaches to identify orally available small-molecules targeting challenging protein-protein interactions such as homotrimeric TNFα.

Aqueous Solubility Enhancement for Bioassays of Insoluble Inhibitors and QSPR Analysis: A TNF-α Study

The aim of this study is to improve the aqueous solubility of a group of compounds without interfering with their bioassay as well as to create a relevant prediction model. A series of 55 potential small-molecule inhibitors of tumor necrosis factor-alpha (TNF-α; SPD304 and 54 analogues), many of which cannot be bioassayed because of their poor solubility, was used for this purpose. The solubility of many of the compounds was sufficiently improved to allow measurement of their respective dissociation constants (K_d). Parameters such as dissolution time, initial state of the solute (solid/liquid), co-solvent addition (DMSO and PEG3350), and sample filtration were evaluated. Except for filtration, the remaining parameters affected aqueous solubility, and a solubilization protocol was established according to these. The aqueous solubility of the 55 compounds in 5% DMSO was measured with this protocol, and a predictive quantitative structure property relationship model was developed and fully validated based on these data. This classification model separates the insoluble from the soluble compounds and predicts the solubility of potential small-molecule inhibitors of TNF-α in aqueous solution (containing 5% DMSO as co-solvent) with an accuracy of 81.2%. The domain of applicability of the model indicates the type of compounds for which estimation of aqueous solubility can be confidently predicted.

Discovery of Novel Ligands for TNF-α and TNF Receptor-1 through Structure-Based Virtual Screening and Biological Assay

Tumor necrosis factor α (TNF-α) is overexpressed in various diseases, and it has been a validated therapeutic target for autoimmune diseases. All therapeutics currently used to target TNF-α are biomacromolecules, and limited numbers of TNF-α chemical inhibitors have been reported, which makes the identification of small-molecule alternatives an urgent need. Recent studies have mainly focused on identifying small molecules that directly bind to TNF-α or TNF receptor-1 (TNFR1), inhibit the interaction between TNF-α and TNFR1, and/or regulate related signaling pathways. In this study, we combined in silico methods with biophysical and cell-based assays to identify novel antagonists that bind to TNF-α or TNFR1. Pharmacophore model filtering and molecular docking were applied to identify potential TNF-α antagonists. In regard to TNFR1, we constructed a three-dimensional model of the TNF-α-TNFR1 complex and carried out molecular dynamics simulations to sample the conformations. The residues in TNF-α that have been reported to play important roles in the TNF-α-TNFR1 complex were removed to form a pocket for further virtual screening of TNFR1-binding ligands. We obtained 20 virtual hits and tested them using surface plasmon resonance-based assays, which resulted in one ligand that binds to TNFR1 and four ligands with different scaffolds that bind to TNF-α. T1 and R1, the two most active compounds with Kd values of 11 and 16 μM for TNF-α and TNFR1, respectively, showed activities similar to those of known antagonists. Further cell-based assays also demonstrated that T1 and R1 have similar activities compared to the known TNF-α antagonist C87. Our work has not only produced several TNF-α and TNFR1 antagonists with novel scaffolds for further structural optimization but also showcases the power of our in silico methods for TNF-α- and TNFR1-based drug discovery.

Cheminformatics-aided discovery of small-molecule Protein-Protein Interaction (PPI) dual inhibitors of Tumor Necrosis Factor (TNF) and Receptor Activator of NF-κB Ligand (RANKL)

We present an in silico drug discovery pipeline developed and applied for the identification and virtual screening of small-molecule Protein-Protein Interaction (PPI) compounds that act as dual inhibitors of TNF and RANKL through the trimerization interface. The cheminformatics part of the pipeline was developed by combining structure-based with ligand-based modeling using the largest available set of known TNF inhibitors in the literature (2481 small molecules). To facilitate virtual screening, the consensus predictive model was made freely available at: http://enalos.insilicotox.com/TNFPubChem/. We thus generated a priority list of nine small molecules as candidates for direct TNF function inhibition. In vitro evaluation of these compounds led to the selection of two small molecules that act as potent direct inhibitors of TNF function, with IC50 values comparable to those of a previously-described direct inhibitor (SPD304), but with significantly reduced toxicity. These molecules were also identified as RANKL inhibitors and validated in vitro with respect to this second functionality. Direct binding of the two compounds was confirmed both for TNF and RANKL, as well as their ability to inhibit the biologically-active trimer forms. Molecular dynamics calculations were also carried out for the two small molecules in each protein to offer additional insight into the interactions that govern TNF and RANKL complex formation. To our knowledge, these compounds, namely T8 and T23, constitute the second and third published examples of dual small-molecule direct function inhibitors of TNF and RANKL, and could serve as lead compounds for the development of novel treatments for inflammatory and autoimmune diseases.

Clinical Study on efficacy of allopurinol in patients with acute coronary syndrome and its functional mechanism

OBJECTIVE

To investigate the therapeutic effect of allopurinol treatment on acute coronary syndrome and to elucidate its possible mechanism.

METHODS

Patients with acute coronary syndrome (n = 100) were recruited as research subjects in our hospital. The patients were randomly divided into two groups, an allopurinol group (n = 50) and a control group (n = 50). These two groups were treated with conventional antiplatelet, anticoagulation and anti-ischemic therapy; allopurinol therapy was added to the allopurinol group based on conventional treatment indications. Biochemical markers such as serum creatinine, uric acid, BNP, blood glucose and blood lipid were compared between the two groups. Indicators of oxidative stress and inflammatory response (MDA, OX-LDL, NO, hs-CRP and TNF-α), as well as cardiovascular events during 2-years follow-up, were recorded.

RESULTS

On admission, there was no difference in serum creatinine, uric acid, BNP, blood glucose or lipid levels between the two groups (P > 0.05). However, after 1 month of treatment, these levels were improved in patients in the allopurinol group compared to the control group (P < 0.05). MDA, OX-LDL, hs-CRP and TNF-α decreased after treatment periods of 14 days and 1 month. They were also decreased at 3 month, 6 month, 1 year, and 2 year follow-up visits. However, data from the allopurinol group demonstrated significantly lower levels than in the control group (P < 0.05). Additionally, compared with the control group, allopurinol treatment significantly elevated the level of NO (P < 0.05). The total effective rates of the allopurinol group are much higher than in the control group for both angina pectoris (93.2% and 76%, respectively) and ECG (96% and 82%, respectively). Most patients in the allopurinol group (n = 40) and the control group (n = 41) received stent implantation with no significant difference shown between them. The incidence of cardiovascular events during 2 years of follow-up in the allopurinol group was 10%; it was 30% in the control group.

CONCLUSION

Allopurinol has a remarkable effect in the treatment of ACS and can improve the oxidative stress and inflammatory reaction indicators of patients. The protective mechanism of allopurinol might be achieved by suppressing the secretion and release of inflammatory mediators such as TNF-α, hs-CRP, OX-LDL and MDA while increasing levels of NO.

A metal-based tumour necrosis factor-alpha converting enzyme inhibitor

We report herein a novel iridium(III) complex 1 as an antitumour necrosis factor agent and the first metal-based inhibitor of TACE enzymatic activity. Complex 1 inhibited TNF-α secretion and p38 phosphorylation in human monocytic THP-1 cells.

Efficient soluble expression of active recombinant human cyclin A2 mediated by E. coli molecular chaperones

Bacterial expression of human proteins continues to present a critical challenge in protein crystallography and drug design. While human cyclin A constructs have been extensively characterized in complex with cyclin dependent kinase 2 (CDK2), efforts to express the monomeric human cyclin A2 in Escherichia coli in a stable form, without the kinase subunit, have been laden with technical difficulties, including solubility, yield and purity. Here, optimized conditions are described with the aim of generating for first time, sufficient quantities of human recombinant cyclin A2 in a soluble and active form for crystallization and ligand characterization purposes. The studies involve implementation of a His-tagged heterologous expression system under conditions of auto-induction and mediated by molecular chaperone-expressing plasmids. A high yield of human cyclin A2 was obtained in natively folded and soluble form, through co-expression with groups of molecular chaperones from E. coli in various combinations. A one-step affinity chromatography method was utilized to purify the fusion protein products to homogeneity, and the biological activity confirmed through ligand-binding affinity to inhibitory peptides, representing alternatives for the key determinants of the CDK2 substrate recruitment site on the cyclin regulatory subunit. As a whole, obtaining the active cyclin A without the CDK partner (referred to as monomeric in this work) in a straightforward and facile manner will obviate protein--production issues with the CDK2/cyclin A complex and enable drug discovery efforts for non-ATP competitive CDK inhibition through the cyclin groove.

Synthesis and biological evaluation of potential small moleculeinhibitors of tumor necrosis factor

A series of 39 novel SPD-304 analogs were designed synthesized and evaluated as inhibitors of TNF.

Quantification of the effects of ionic strength, viscosity, and hydrophobicity on protein-ligand binding affinity

In order to quantify the interactions between molecules of biological interest, the determination of the dissociation constant (K d) is essential. Estimation of the binding affinity in this way is routinely performed in "favorable" conditions for macromolecules. Crucial data for ligand-protein binding elucidation is mainly derived from techniques (e.g., macromolecular crystallography) that require the addition of high concentration of salts and/or other additives. In this study we have evaluated the effect of temperature, ionic strength, viscosity, and hydrophobicity on the K d of three previously characterized protein-ligand systems, based on variation in their binding sites, in order to provide insight into how these often overlooked unconventional circumstances impact binding affinity. Our conclusions are as follows: (1) increasing solvent viscosity in general is detrimental to ligand binding, (2) moderate increases in temperature have marginal effects on the dissociation constant, and (3) the degree of hydrophobicity of the ligand and the binding site determines the extent of the influence of cosolvents and salt concentration on ligand binding affinity.

A statistical approach for optimization of RANKL overexpression in Escherichia coli: purification and characterization of the protein

Receptor activator of nuclear factor-κB (RANK) and its cognate ligand (RANKL) is a member of the TNF superfamily of cytokines which is essential in osteobiology and its overexpression has been implicated in the pathogenesis of bone degenerative diseases such as osteoporosis. Therefore, RANKL is considered a major therapeutic target for the suppression of bone resorption in bone metabolic diseases such as rheumatoid arthritis and cancer metastasis. To evaluate the inhibitory effect of potential RANKL inhibitors a sufficient amount of protein is required. In this work RANKL was cloned for expression at high levels in Escherichia coli with the interaction of changing cultures conditions in order to produce the protein in a soluble form. In an initial step, the effect of expression host on soluble protein production was investigated and BL21(DE3) pLysS was the most efficient one found for the production of RANKL. Central composite design experiment in the following revealed that cell density before induction, IPTG concentration, post-induction temperature and time as well as their interactions had a significant influence on soluble RANKL production. An 80% increase of protein production was achieved after the determination of the optimum induction conditions: OD600nm before induction 0.55, an IPTG concentration of 0.3mM, a post-induction temperature of 25°C and a post-induction time of 6.5h. Following RANKL purification the thermal stability of the protein was studied. The interaction of RANKL with SPD304, a patented small-molecule inhibitor of TNF-α, was also studied in a fluorescence binding assay resulting in a Kd value of 14.1 ± 0.5 μM.