Synthesis, alkaline phosphatase inhibition studies and molecular docking of novel derivatives of 4-quinolones

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.

Photoinduced radical tandem annulation of 1,7-diynes: an approach for divergent assembly of functionalized quinolin-2(1H)-ones

The first photocatalytic trichloromethyl radical-triggered annulative reactions of amide-linked 1,7-diynes with polyhalomethanes were established for the flexible assembly of functionalized quinolin-2(1H)-ones with generally acceptable yields. With the installation of the aryl group (R1) into the alkynyl moiety, C-center radical-initiated Kharasch-type addition/nucleophilic substitution/elimination cascade to produce quinolin-2(1H)-ones-incorporating gem-dihaloalkene, whereas three examples of polyhalogenated quinolin-2(1H)-ones were afforded when amide-linked 1,7-diynes bearing two terminal alkyne units were subjected to BrCX3 by exploiting dry acetonitrile as a solvent.

Current status of N-, O-, S-heterocycles as potential alkaline phosphatase inhibitors: a medicinal chemistry overview

Heterocycles are a class of compounds that have been found to be potent inhibitors of alkaline phosphatase (AP), an enzyme that plays a critical role in various physiological processes such as bone metabolism, cell growth and differentiation, and has been linked to several diseases such as cancer and osteoporosis. AP is a widely distributed enzyme, and its inhibition has been considered as a therapeutic strategy for the treatment of these diseases. Heterocyclic compounds have been found to inhibit AP by binding to the active site of the enzyme, thereby inhibiting its activity. Heterocyclic compounds such as imidazoles, pyrazoles, and pyridines have been found to be potent AP inhibitors and have been studied as potential therapeutics for the treatment of cancer, osteoporosis, and other diseases. However, the development of more potent and selective inhibitors that can be used as therapeutics for the treatment of various diseases is an ongoing area of research. Additionally, the study of the mechanism of action of heterocyclic AP inhibitors is an ongoing area of research, which could lead to the identification of new targets and new therapeutic strategies. The enzyme known as AP has various physiological functions and is present in multiple tissues and organs throughout the body. This article presents an overview of the different types of AP isoforms, their distribution, and physiological roles. It also discusses the structure and mechanism of AP, including the hydrolysis of phosphate groups. Furthermore, the importance of AP as a clinical marker for liver disease, bone disorders, and cancer is emphasized, as well as its use in the diagnosis of rare inherited disorders such as hypophosphatasia. The potential therapeutic applications of AP inhibitors for different diseases are also explored. The objective of this literature review is to examine the function of alkaline phosphatase in various physiological conditions and diseases, as well as analyze the structure-activity relationships of recently reported inhibitors. The present review summarizes the structure-activity relationship (SAR) of various heterocyclic compounds as AP inhibitors. The SAR studies of these compounds have revealed that the presence of a heterocyclic ring, particularly a pyridine, pyrimidine, or pyrazole ring, in the molecule is essential for inhibitory activity. Additionally, the substitution pattern and stereochemistry of the heterocyclic ring also play a crucial role in determining the potency of the inhibitor.

Synthesis of Nitrogen Heterocycles by Domino C–N Coupling/Hydroamination Reactions

The present article presents a personalized Account on the synthesis of nitrogen heterocycles by domino C–N coupling/hydroamination reactions and related processes. The starting materials, 2-alkynyl-1-halohetarenes, are regioselectively available by Sonogashira reactions of various 1,2-dihalogenated heterocycles, such as thiophenes, benzothiophenes, furans and benzofurans, pyridines, quinolines, pyrimidines, and other ring systems. More complex products are formed by domino C–N coupling/hydroamination/C–H arylation reactions of 2-alkynyl-1-halohetarenes with 2-bromoanilines. In these reactions, not only two, but three bonds are formed in one step. In many cases, the products constitute new heterocyclic core structures and show interesting pharmacological or fluorescence properties.

1 Introduction

2 Domino C–N Coupling/Hydroamination Reactions

3 Domino C–N Coupling/Hydroamination/C–H Arylation Reactions

4 Conclusions

TNAP as a therapeutic target for cardiovascular calcification: a discussion of its pleiotropic functions in the body

Cardiovascular calcification (CVC) is associated with increased morbidity and mortality. It develops in several diseases and locations, such as in the tunica intima in atherosclerosis plaques, in the tunica media in type 2 diabetes and chronic kidney disease, and in aortic valves. In spite of the wide occurrence of CVC and its detrimental effects on cardiovascular diseases (CVD), no treatment is yet available. Most of CVC involve mechanisms similar to those occurring during endochondral and/or intramembranous ossification. Logically, since tissue-nonspecific alkaline phosphatase (TNAP) is the key-enzyme responsible for skeletal/dental mineralization, it is a promising target to limit CVC. Tools have recently been developed to inhibit its activity and preclinical studies conducted in animal models of vascular calcification already provided promising results. Nevertheless, as its name indicates, TNAP is ubiquitous and recent data indicate that it dephosphorylates different substrates in vivo to participate in other important physiological functions besides mineralization. For instance, TNAP is involved in the metabolism of pyridoxal phosphate and the production of neurotransmitters. TNAP has also been described as an anti-inflammatory enzyme able to dephosphorylate adenosine nucleotides and lipopolysaccharide. A better understanding of the full spectrum of TNAP's functions is needed to better characterize the effects of TNAP inhibition in diseases associated with CVC. In this review, after a brief description of the different types of CVC, we describe the newly uncovered additional functions of TNAP and discuss the expected consequences of its systemic inhibition in vivo.

Photoredox Cyclization of N-Arylacrylamides for Synthesis of Dihydroquinolinones

Metal- and additive-free photoredox cyclization of N-arylacrylamides is herein reported that provides a concise access to the formation of dihydroquinolinones. In this protocol, sustainable visible light was used as the energy source, and the organic light-emitting molecule 4CzIPN served as the efficient photocatalyst. This reaction system features exclusive 6-endo-trig cyclization selectivity with a generally good yield of a range of functionalized dihydroquinolinones and dihydrobenzoquinolinones. Mechanistical studies reveal the feasibility of both 1,3-H shift and intersystem crossing of the diradical intermediate.

Hypervalent Iodine(III)-Promoted C3-H Regioselective Halogenation of 4-Quinolones under Mild Conditions

A simple and practical protocol for the C3-H regioselective halogenation of 4-quinolones by the action of potassium halide salt and PIFA/PIDA in good to excellent yields was developed. The current approach provides feasible access to the diversity of C3-halgenated 4-quinolones at room temperature with high regioselectivity and good functional group tolerance, from which bioactive compounds can be easily constructed. Moreover, the current method featured eco-friendly, operational convenience and is suitable for halogenation in a gram scale of 4-quinolones in water without sacrificing yields.

2-Benzylidenebenzofuran-3(2H)-ones as a new class of alkaline phosphatase inhibitors: synthesis, SAR analysis, enzyme inhibitory kinetics and computational studies

The excelling role of organic chemistry in the medicinal field continues to be one of the main leads in the drug development process. Particularly, this industry requires organic chemists to discover small molecular structures with powerful pharmacological potential. Herein, a diverse range of chalcone (1–11) and aurone (12–22) derivatives was designed and synthesized and for the first time, and both motifs were evaluated as potent inhibitors of alkaline phosphatases (APs). Structural identification of the target compounds (1–22) was accomplished using common spectroscopic techniques. The effect of the nature and position of the substituent was interestingly observed and justified based on the detailed structure–activity relationship (SAR) of the target compounds against AP. It was concluded from the obtained results that all the newly synthesized compounds exhibit high inhibitory potential against the AP enzyme. Among them, compounds 12 (IC₅₀ = 2.163 ± 0.048 μM), 15 (IC₅₀ = 2.146 ± 0.056 μM), 16 (IC₅₀ = 2.132 ± 0.034 μM), 18 (IC₅₀ = 1.154 ± 0.043 μM), 20 (IC₅₀ = 1.055 ± 0.029 μM) and 21 (IC₅₀ = 2.326 ± 0.059 μM) exhibited excellent inhibitory activity against AP, and even better/more active than KH₂PO₄ (standard) (IC₅₀ = 2.80 ± 0.065 μM). Remarkably, compound 20 (IC₅₀ = 1.055 ± 0.029 μM) may serve as a lead structure to design more potent inhibitors of alkaline phosphatase. To the best of our knowledge, these synthetic compounds are the most potent AP inhibitors with minimum IC₅₀ values reported to date. Furthermore, a molecular modeling study was performed against the AP enzyme (1EW2) to check the binding interaction of the synthesized compounds 1–22 against the target protein. The Lineweaver–Burk plots demonstrated that most potential derivative 20 inhibited h-IAP via a non-competitive pathway. Finally, molecular dynamic (MD) simulations were performed to evaluate the dynamic behavior, stability of the protein–ligand complex, and binding affinity of the compounds, resulting in the identification of compound 20 as a potential inhibitor of AP. Accordingly, excellent correlation was observed between the experimental and theoretical results. The pharmacological studies revealed that the synthesized analogs 1–22 obey Lipinski's rule. The assessment of the ADMET parameters showed that these compounds possess considerable lead-like characteristics with low toxicity and can serve as templates in drug design.

Aurones are the plant secondary metabolites belonging to the flavonoid’s family. The bioactivities of aurones are very promising, thus these heterocyclic compounds can be considered as an alluring scaffold for drug design and development.

Emodin Inhibits the Proliferation of MCF-7 Human Breast Cancer Cells Through Activation of Aryl Hydrocarbon Receptor (AhR)

Natural products have proved to be a promising source for the development of potential anticancer drugs. Emodin, a natural compound from Rheum palmatum, is used to treat several types of cancers, including lung, liver, and pancreatic. However, there are few reports regarding its use in the treatment of breast cancer. Thus, the therapeutic effect and mechanism of emodin on MCF-7 human breast cancer cells were investigated in this study. Morphological observations and cell viability were evaluated to determine the anti-proliferation activity of emodin. Network pharmacology and molecular docking were performed to screen the potential targets. Western blot analysis was used to explore a potential antitumor mechanism. The results showed that emodin (50–100 μmol/L) could significantly inhibit the proliferation of MCF-7 cells in a time and dose-dependent manner. Furthermore, virtual screening studies indicated that emodin was a potent aryl hydrocarbon receptor (AhR) agonist in chemotherapy for breast cancer. Finally, when MCF-7 cells were treated with emodin (100 μmol/L) for 24 h, the AhR and cytochrome P450 1A1 (CYP1A1) protein expression levels were significantly upregulated compared with the control group. Our study indicated that emodin exhibited promising antitumor activity in MCF-7 cells, likely through activation of the AhR-CYP1A1 signaling pathway. These findings lay a foundation for the application of emodin in breast cancer treatment.

A Cascade Reaction of Michael Addition and Truce-Smiles Rearrangement to Synthesize Trisubstituted 4-Quinolone Derivatives

A novel transition-metal-free cascade reaction to synthesize 4-quinolone derivatives has been demonstrated. Michael addition and Truce-Smiles rearrangement are included in this protocol, providing a broad scope of 4-quinolones in moderate-to-excellent yields. This work serves as an example of the use of sulfonamides through Truce-Smiles rearrangement to build heterocyclic compounds under mild conditions.

In silico exploration of binding of selected bisphosphonate derivatives to placental alkaline phosphatase via docking and molecular dynamics

Bisphosphonates constitute a group of pyrophosphate analogues therapeutically active against bone diseases. Numerous studies confirm their anticancer and antimetastatic potential as well as ability to relieve pathological pain. Although this is a known class of compounds, many aspects of their action remain unexplained and their new interaction partners are still being discovered. Due to the structural similarity to pyrophosphate, their interaction with pyrophosphate-recognizing enzymes seems to be feasible. In current work, the placental alkaline phosphatase (PLAP) is considered as a potential target for these class of compounds. PLAP is one of the enzymes responsible for degradation of pyrophosphate with high clinical significance. An elevation of PLAP level are considered as a potential cancer marker. An in silico study of complexes formed between selected phosphate derivatives and PLAP was performed. It indicates that all tested compounds: alendronic acid, clodronic acid, etidronic acid, zoledronic acid, imidodiphosphoric acid, pyrophosphoric acid, medronic acid, chloromethylenediphosphonic acid and hypophosphoric acid form a complexes with PLAP, stabilized by hydrogen bonds, hydrophobic and van der Waals interactions. Zoledronic acid, drug used in prevention of bone complications during cancer treatment was found to have the lowest estimated energy of binding (-6.6 kcal/mol). In silico study yielded very low energy of binding also for hypophosphate, equal -6.4 kcal/mol, despite having no identified hydrogen bonds. Subsequent molecular dynamic simulations, followed by molecular mechanics generalized-born surface area with pairwise decomposition calculations confirmed the stability of protein-ligand complexes. The results indicate that selected phosphate derivatives may potentially interact with the enzyme, changing its function, what should be investigated during in vitro studies.

Synthesis and computational studies of highly selective inhibitors of human recombinant tissue non-specific alkaline phosphatase (h-TNAP): A therapeutic target against vascular calcification

In this study, we have discovered small druglike molecules as selective inhibitors of human tissue-nonspecific alkaline phosphatase (h-TNAP), an enzyme critical for the regulation of extracellular matrix calcification. The upregulation of h-TNAP is associated with various pathologies particularly the vascular calcification (VC). Selective inhibition of h-TNAP over h-NPP1 may serve as a useful therapeutic strategy against vascular calcification. A series of novel triazolyl pyrazole derivatives (10a-y) in which thiol bearing triazole moiety as the zinc binding functional group was introduced to a pyrazole based pharmacophore was synthesized and evaluated as potent and selective inhibitors of h-TNAP over h-NPP1. The biological screening against h-TNAP, h-IAP, h-NPP1 and h-NPP3 showed that many of the synthesized compounds are selective inhibitors of TNAP. Particularly, the compounds 10a-h, 10j, 10m-q, 10u, 10w and 10x displayed high potency and complete selectivity towards h-TNAP over h-NPP1. Compound 10q emerged as a highly potent inhibitor (IC₅₀ = 0.16 µM or 160 nM) against h-TNAP with 127-fold increased inhibition compared to levamisole. On the other hand, compound 10e was found to be most selective inhibitor against the tested APs and NPPs (IC₅₀ = 1.59 ± 0.36 µM). Binding sites architecture analysis, molecular-docking and molecular dynamics simulations (MDS), revealed the basis for h-TNAP and h-IAP ligand selectivity as well as selectivity towards h-TNAP over h-NPP1. These newly discovered inhibitors are believed to represent valuable lead structures to further streamline the generation of candidate compounds to target VC.

Recent advances in intestinal alkaline phosphatase, inflammation, and nutrition

In recent years, much new data on intestinal alkaline phosphatase (IAP) have been published, and major breakthroughs have been disclosed. The aim of the present review is to critically analyze the publications released over the last 5 years. These breakthroughs include, for example, the direct implication of IAP in intestinal tight junction integrity and barrier function maintenance; chronic intestinal challenge with low concentrations of Salmonella generating long-lasting depletion of IAP and increased susceptibility to inflammation; the suggestion that genetic mutations in the IAP gene in humans contribute to some forms of chronic inflammatory diseases and loss of functional IAP along the gut and in stools; stool IAP as an early biomarker of incipient diabetes in humans; and omega-3 fatty acids as direct inducers of IAP in intestinal tissue. Many recent papers have also explored the prophylactic and therapeutic potential of IAP and other alkaline phosphatase (AP) isoforms in various experimental settings and diseases. Remarkably, nearly all data confirm the potent anti-inflammatory properties of (I)AP and the negative consequences of its inhibition on health. A simplified model of the body AP system integrating the IAP compartment is provided. Finally, the list of nutrients and food components stimulating IAP has continued to grow, thus emphasizing nutrition as a potent lever for limiting inflammation.

Electroreductive Intermolecular Coupling of 4-Quinolones with Benzophenones: Synthesis of 2-Substituted 4-Quinolones

The electroreductive coupling of 1-alkoxycarbonyl-4-quinolones with benzophenones in the presence of trimethylsilyl chloride gave adducts reacted at the 2-position of 4-quinolones as trimethylsilyl ethers. The adducts were transformed to 2-(diarylhydroxymethyl)-4-quinolones. The electroreduction of 1,3-diethoxycarbonyl-4-quinolones and polyhalogenated 3-alkoxycarbonyl-1-alkyl-4-quinolones with benzophenones also gave adducts reacted at the 2-position of 4-quinolones. On the contrary, the electroreductive coupling of 1,3-diethooxycarbonyl-8-methoxy-4-quinolones occurred at the 4-position of 4-quinolones to give 4-substituted quinolines.

Exploration of quinolone and quinoline derivatives as potential anticancer agents

BACKGROUND

Among the different types of cancers, breast cancer, bone cancer and cervical cancer are the most common gender specific cancer types that are affecting the women worldwide. Currently, many enzymatic and cellular pathways are known as drug targets for the treatment of cancer. Even though many improvements have been made in the therapy of various types of cancer, but the major disadvantage of available anti-cancer drugs is their non-selective behavior towards cancer cells as well as normal cells.

OBJECTIVES

In the light of this fact, the searching of new compounds with selective behavior only towards cancer cells is critically important. Previously, we have identified several series of compounds as the potential inhibitors of these families.

METHODS

Herein, we investigate quinolones and quinolines for their anti-cancer activity against breast cancer cells (MCF-7), bone marrow cancer cells (K-562) and cervical cancer cells (HeLa) by MTT assay. The most effective derivatives were further subjected to flow cytometry analysis followed by fluorescence microscopic analysis by using 4´,6-diamidine-2´-phenylindole (DAPI) and propidium staining (PI) staining.

RESULTS

All the tested compounds were found selective only towards cancer cells. The identified compounds also induced either G2 or S-phase cell cycle arrest within the respective cancer cell line, chromatin condensation and the nuclear fragmentation, as well as maximum interaction with DNA.

CONCLUSIONS

These results provide evidence that the characteristic chemical features of attached groups are the key factors for their anticancer effects and play a useful role in revealing the mechanisms of action in relation to the known compounds in future research programs. Graphical abstract Flow cytometric analysis of cell cycle using propidium iodide staining. Cell apoptosis observed under fluorescence microscope using DAPI and PI staining.

Synthesis and docking studies of N-(5-(alkylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamide analogues as potential alkaline phosphatase inhibitors

A series of N-(5-(alkylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamides 6a-i were synthesized as alkaline phosphatase inhibitors. The intermediate 5-substituted 1,3,4-oxadiazole-2-thione 4 was synthesized starting with hippuric acid. Hippuric acid in the first step was converted into corresponding methyl ester 2 which upon reaction with hydrazine hydrate furnished the formation of hydrazide 3. The hippuric acid hydrazide was then cyclized into 5-substituted 1,3,4-oxadiazole-2-thione 4. The intermediate 4 was then reacted with alkyl or aryl halides 5a-5i to afford the title compounds N-(5-(methylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamides 6a-i. The bioassay results showed that compounds 6a-i exhibited good to excellent alkaline phosphatase inhibitory activity. The most potent activity was exhibited by the compound 6i having IC₅₀ value 0.420 μM, whereas IC₅₀ value of standard (KH₂ PO₄ ) was 2.80 μM. Molecular docking studies was performed against alkaline phosphatase enzyme (PDBID 1EW2) to check binding affinity of the synthesized compounds 6a-i against target protein. The docking results showed that three compounds 6c, 6e, and 6i have maximum binding interactions with binding energy values of -8 kcal/mol. The compound 6i displayed the interactions of oxadiazole ring nitrogen with amino acid His265 having a binding distance 2.13 Ǻ. It was concluded from our results that synthesized compounds, especially compound 6i may serve as lead structure to design more potent inhibitors of human alkaline phosphatase.

Synthesis of sulfadiazinyl acyl/aryl thiourea derivatives as calf intestinal alkaline phosphatase inhibitors, pharmacokinetic properties, lead optimization, Lineweaver-Burk plot evaluation and binding analysis

To seek the new medicinal potential of sulfadiazine drug, the free amino group of sulfadiazine was exploited to obtain acyl/aryl thioureas using simple and straightforward protocol. Acyl/aryl thioureas are well recognized bioactive pharmacophore containing moieties. A new series (4a-4j) of sulfadiazine derived acyl/aryl thioureas was synthesized and characterized through spectroscopic and elemental analysis. The synthesized derivatives 4a-4j were subjected to calf intestinal alkaline phosphatase (CIAP) activity. The derivative 4a-4j showed better inhibition potential compared to standard monopotassium phosphate (MKP). The compound 4c exhibited higher potential in the series with IC₅₀ 0.251 ± 0.012 µM (standard KH₂PO₄ 4.317 ± 0.201 µM). Lineweaver-Burk plots revealed that most potent derivative 4c inhibition CIAP via mixed type pathway. Pharmacological investigations showed that synthesized compounds 4a-4j obey Lipinsk's rule. ADMET parameters evaluation predicted that these molecule show significant lead like properties with minimum possible toxicity and can serve as templates in drug designing. The synthetic compounds show none mutagenic and irritant behavior. Molecular docking analysis showed that compound 4c interacts with Asp273, His317 and Arg166 amino acid residues.