Synthesis, biological evaluation, and docking studies of novel pyrrolo[2,3-b]pyridine derivatives as both ectonucleotide pyrophosphatase/phosphodiesterase inhibitors and antiproliferative agents

Ectonucleotidase inhibitors: targeting signaling pathways for therapeutic advancement-an in-depth review

Ectonucleotidase inhibitors are a family of pharmacological drugs that, by selectively targeting ectonucleotidases, are essential in altering purinergic signaling pathways. The hydrolysis of extracellular nucleotides and nucleosides is carried out by these enzymes, which include ectonucleoside triphosphate diphosphohydrolases (NTPDases) and ecto-5'-nucleotidase (CD73). Ectonucleotidase inhibitors can prevent the conversion of ATP and ADP into adenosine by blocking these enzymes and reduce extracellular adenosine. These molecules are essential for purinergic signaling, which is associated with a variability of physiological and pathological processes. By modifying extracellular nucleotide metabolism and improving purinergic signaling regulation, ectonucleotide pyrophosphatase/phosphodiesterase (ENPP) inhibitors have the potential to improve cancer treatment, inflammatory management, and immune response modulation. Purinergic signaling is affected by CD73 inhibitors because they prevent AMP from being converted to adenosine. These inhibitors are useful in cancer therapy and immunotherapy because they may improve chemotherapy effectiveness and alter immune responses. Purinergic signaling is controlled by NTPDase inhibitors, which specifically target enzymes involved in extracellular nucleotide breakdown. These inhibitors show promise in reducing immunological responses, thrombosis, and inflammation, perhaps assisting in the treatment of cardiovascular and autoimmune illnesses. Alkaline phosphatase (ALP) inhibitors alter the function of enzymes involved in dephosphorylation reactions, which has an impact on a variety of biological processes. By altering the body's phosphate levels, these inhibitors may be used to treat diseases including hyperphosphatemia and certain bone problems. This article provides a guide for researchers and clinicians looking to leverage the remedial capability of ectonucleotidase inhibitors in a variety of illness scenarios by illuminating their processes, advantages, and difficulties.

Synthesis of 2,4-dihydroxyacetophenone derivatives as potent PDE-1 and -3 inhibitors: in vitro and in silico insights

Aim: Synthesis of novel bis-Schiff bases having potent inhibitory activity against phosphodiesterase (PDE-1 and -3) enzymes, potentially offering therapeutic implications for various conditions. Methods: Bis-Schiff bases were synthesized by refluxing 2,4-dihydroxyacetophenone with hydrazine hydrate, followed by treatment of substituted aldehydes with the resulting hydrazone to obtain the product compounds. After structural confirmation, the compounds were screened for their in vitro PDE-1 and -3 inhibitory activities. Results: The prepared compounds exhibited noteworthy inhibitory efficacy against PDE-1 and -3 enzymes by comparing with suramin standard. To clarify the binding interactions between the drugs, PDE-1 and -3 active sites, molecular docking studies were carried out. Conclusion: The potent compounds discovered in this study may be good candidates for drug development.

Synthesis, in vitro, and in silico studies of morpholine-based thiosemicarbazones as ectonucleotide pyrophosphatase/phosphodiesterase-1 and -3 inhibitors

An extensive range of new biologically active morpholine based thiosemicarbazones derivatives 3a-r were synthesized, characterized by spectral techniques and evaluated as inhibitors of ENPP isozymes. Most of the novel thiosemicarbazones exhibit potent inhibition towards NPP1 and NPP3 isozymes. Compound 3 h was potent inhibitor of NPP1 with IC50 value of 0.55 ± 0.02. However, the most powerful inhibitor of NPP3 was 3e with an IC50 value of 0.24 ± 0.02. Furthermore, Lineweaver-Burk plot for compound 3 h against NPP1 and for compound 3e against NPP3 was devised through enzymes kinetics studies. Molecular docking and in silico studies was also done for analysis of interaction pattern of all newly synthesized compounds. The results were further validated by molecular dynamic (MD) simulation where the stability of conformational transformation of the best protein-ligand complex (3e) were justified on the basis of RMSD and RMSF analysis.

Insight into small-molecule inhibitors targeting extracellular nucleotide pyrophosphatase/phosphodiesterase1 for potential multiple human diseases

Extracellular nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) has been identified as a type II transmembrane glycoprotein. It plays a crucial role in various biological processes, such as bone mineralization, cancer cell proliferation, and immune regulation. Consequently, ENPP1 has garnered attention as a promising target for pharmacological interventions. Despite its potential, the development of clinical-stage ENPP1 inhibitors for solid tumors, diabetes, and silent rickets remains limited. However, there are encouraging findings from preclinical trials involving small molecules exhibiting favorable therapeutic effects and safety profiles. This perspective aims to shed light on the structural properties, biological functions and the relationship between ENPP1 and diseases. Additionally, it focuses on the structure-activity relationship of ENPP1 inhibitors, with the intention of guiding the future development of new and effective ENPP1 inhibitors.

Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 inhibitors: Research progress and prospects

The cancer immunotherapies involved in cGAS-STING pathway have been made great progress in recent years. STING agonists exhibit broad-spectrum anti-tumor effects with strong immune response. As a negative regulator of the cGAS-STING pathway, ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) can hydrolyze extracellular 2', 3'-cGAMP and reduce extracellular 2', 3'-cGAMP concentration. ENPP1 has been validated to play important roles in diabetes, cancers, and cardiovascular disease and now become a promising target for tumor immunotherapy. Several ENPP1 inhibitors under development have shown good anti-tumor effects alone or in combination with other agents in clinical and preclinical researches. In this review, the biological profiles of ENPP1 were described, and the structures and the structure-activity relationships (SAR) of the known ENPP1 inhibitors were summarized. This review also provided the prospects and challenges in the development of ENPP1 inhibitors.

Discovery of Orally Bioavailable Phthalazinone Analogues as an ENPP1 Inhibitor for STING-Mediated Cancer Immunotherapy

A lack of the T cell-inflamed tumor microenvironment limits the efficacy of immune checkpoint inhibitors (ICIs). Activation of stimulator of interferon genes (STING)-mediated innate immunity has emerged as a novel therapeutic approach in cancer therapy. 2',3'-Cyclic GMP-AMP (cGAMP) is a natural STING agonist; however, cGAMP is subjected to endogenous degradation by ecto-nucleotide pyrophosphatase phosphodiesterase 1 (ENPP1). To improve the ICI response rate, we developed 29f, a novel ENPP1 inhibitor with phthalazin-1(2H)-one as the core scaffold. 29f inhibited the cGAMP hydrolysis by ENPP1 in vitro (IC50 = 68 nM) and enhanced the STING-mediated type I interferon response in both immune and tumor cells. 29f demonstrated excellent metabolic stability and bioavailability (F = 65%). Orally administered 29f promoted tumor growth inhibition in a CT26 syngeneic model and increased the anti-PD-L1 response. Furthermore, 29f-induced immunological memory prevented the tumor relapse against tumor rechallenge, suggesting the promising therapeutic potential of 29f.

Synthesis of new class of indole acetic acid sulfonate derivatives as ectonucleotidases inhibitors

Ectonucleotidases inhibitors (ENPPs, e5'NT (CD73) and h-TNAP) are potential therapeutic candidates for the treatment of cancer. Adenosine, the cancer-developing, and growth moiety is the resultant product of these enzymes. The synthesis of small molecules that can increase the acidic and ionizable structure of adenosine 5-monophosphate (AMP) has been used in traditional attempts to inhibit ENPPs, ecto-5'-nucleotidase and h-TNAP. In this article, we present a short and interesting method for developing substituted indole acetic acid sulfonate derivatives (5a-5o), which are non-nucleotide based small molecules, and investigated their inhibitory potential against recombinant h-ENPP1, h-ENPP3, h-TNAP, h-e5'NT and r-e5'NT. Their overexpression in the tumor environment leads to high adenosine level that results in tumor development as well as immune evasion. Therefore, selective, and potent inhibitors of these enzymes would be expected to decrease adenosine levels and manage tumor development and progression. Our intended outcome led to the discovery of new potent inhibitors like' 5e (IC50 against h-ENPP1 = 0.32 ± 0.01 μM, 58 folds increased with respect to suramin), 5j (IC50 against h-ENPP3 = 0.62 ± 0.003 μM, 21 folds increase with respect to suramin), 5c (IC50 against h-e5'NT = 0.37 ± 0.03 μM, 115 folds increase with respect to sulfamic acid), 5i (IC50 against r-e5'NT = 0.81 ± 0.05 μM, 95 folds increase with respect to sulfamic acid), and 5g (IC50 against h-TNAP = 0.59 ± 0.08 μM, 36 folds increase with respect to Levamisole). Molecular docking studies revealed that inhibitors of these selected target enzymes induced favorable interactions with the key amino acids of the active site, including Lys255, Lys278, Asn277, Gly533, Lys528, Tyr451, Phe257, Tyr340, Gln465, Gln434, Lys437, Glu830, Cys818, Asn499, Arg40, Phe417, Phe500, Asn503, Asn599, Tyr281, Arg397, Asp526, Phe419 and Tyr502. Enzyme kinetic studies revealed that potent compounds such as 5j and 5e blocked these ectonucleotidases competitively while compounds 5e and 5c presented an un-competitive binding mode. 5g revealed a non-competitive mode of inhibition.

Quantum chemical, spectroscopic and molecular docking investigations of potential pulmonary fibrosis drug methyl 2-chloro 4-iodonicotinate

In this work, the methyl 2-chloro 4-iodonicotinate (MCIN) was investigated to study the structural, spectroscopic and electronic properties using density functional theory (DFT) quantum chemical calculations. The most stable structure of MCIN was optimized by DFT/B3LYP method with a LanLD2Z basis set. The optimized parameters and vibrational wavenumbers were determined. The vibrational task of the molecule was done by potential energy distribution calculations. The ¹³ C NMR spectrum of the MCIN molecule was simulated by the Gauge-Invariant-Atomic Orbital method using a dimethyl sulfoxide solution and the isotropic chemical shift values of the molecule were calculated and observed. Ultraviolet-visible spectra were simulated and observed. The pharmaceutical activity was predicted using frontier molecular orbital and natural bond orbital analysis. The reactive sites of the MCIN molecule were determined using Mulliken atomic charge distribution, molecular electrostatic potential surface and the local reactivity analysis. The molecular docking analysis confirms that the title molecule can be used in drug design for the treatment of pulmonary fibrosis.

Synthesis and Biological Evaluation of Arylamide Sulphonate Derivatives as Ectonucleotide Pyrophosphatase/Phosphodiesterase-1 and -3 Inhibitors

Aberrant level of ectonucleotide pyrophosphatase/phosphodiesterase-1 and -3 is linked with numerous disorders, for instance, diabetes, cancer, osteoarthritis, chondrocalcinosis, and allergic reactions. These disorders may be cured or minimized by blocking the activity of ENPP1 and ENPP3 isozymes. In this study, arylamide sulphonates were synthesized, characterized, and evaluated for their capability to affect the activity of isozymes ENPP1 and ENPP3. Among the selective inhibitors of ENPP1, compounds 4f and 4q exhibited sub-micromolar IC₅₀ values of 0.28 ± 0.08 and 0.37 ± 0.03 μM, respectively, followed by 7a, with IC₅₀ equal to 0.81 ± 0.05 μM, whereas out of the selective inhibitors of isozyme ENPP3, 4t and 7d preferably lessened the activity to half of the maximal inhibitory concentration of 0.15 ± 0.04 and 0.16 ± 0.01 μM alternatively. In addition, many structures including 4c, 4g, 4k, 4l, 4n, 4o, 4r, 4s, 7b, 7c, and 7e inhibited the activity of both isozymes to a significant level. Enzyme kinetic study of compound 4j revealed an uncompetitive mode of inhibition of ENPP1 isozyme, while 7e competitively blocked the activity of ENPP3. Cell viability analysis revealed the compound 4o as a cytotoxic agent against MCF7 (human breast cancer cell line) with a percentage inhibition of 63.2 ± 2.51%, whereas compounds 4c, 4d, 4n, and 7d decreased the HeLa cell viability (human cervical cancer cell line) to more than 50%. The tested compounds were non-cytotoxic against HEK293 (a human embryonic kidney cell line). Molecular docking analysis of selected inhibitors of both isozymes produced optimistic interactions with the influential amino acids, such as Leu290, Lys295, Tyr340, Asp376, His380, and Pro323 of ENPP1, whereas residues Asn226, His329, Leu239, Tyr289, Pro272, Tyr320, and Ala205 of ENPP3 crystallographic structure formed interactions with the potent inhibitors.

Pyridine Scaffolds, Phenols and Derivatives of Azo Moiety: Current Therapeutic Perspectives

Synthetic heterocyclic compounds have incredible potential against different diseases; pyridines, phenolic compounds and the derivatives of azo moiety have shown excellent antimicrobial, antiviral, antidiabetic, anti-melanogenic, anti-ulcer, anticancer, anti-mycobacterial, anti-inflammatory, DNA binding and chemosensing activities. In the present review, the above-mentioned activities of the nitrogen-containing heterocyclic compounds (pyridines), hydroxyl (phenols) and azo derivatives are discussed with reference to the minimum inhibitory concentration and structure–activity relationship, which clearly indicate that the presence of nitrogen in the phenyl ring; in addition, the hydroxyl substituent and the incorporation of a diazo group is crucial for the improved efficacies of the compounds in probing different diseases. The comparison was made with the reported drugs and new synthetic derivatives that showed recent therapeutic perspectives made in the last five years.