Adenosine kinase inhibitors: polar 7-substitutent of pyridopyrimidine derivatives improving their locomotor selectivity

Synthesis, anticancer activity and molecular docking of new quinolines, quinazolines and 1,2,4-triazoles with pyrido[2,3-d] pyrimidines

Recently, heterocyclic compounds such as pyrido [2,3-d] pyrimidinones, 1,2,4-triazolopyrimidines, pyrimidoquinazolines, and quinoline derivatives have gained attention from researchers due to their pharmacological and biological activities. To synthesize new compounds, quinoline-2-thioxopyrido [2,3-d] pyrimidinone (1) and methylthioquinoline-pyrido [2,3-d] pyrimidinones (2) were used as starting materials. The new compounds synthesized were quinoline-pyrido [2,3-d] (DeGoey et al., 2013; Gouda et al., 2020; Dangolani et al., 2018) [1, 2,4]triazolopyrimidinones (5a-d), 2-methylsulfonyl-quinoline-pyrido [2,3-d]pyrimidinone (6), pyrido [2,3-d]pyrimidine derivatives, pyridopyrimido (Gouda et al., 2020; DeGoey et al., 2013) 2,12,1-b] quinazoline (9), pyrido [(Khajouei et al., 2021; Gouda et al., 2020) 3,23,2-e]bis (1,2,4-triazole)pyrimidine (12a,b) and pyridopyrimido-diquinazoline-dione (16) derivatives. These compounds were synthesized with high efficiency, producing yields ranging from 69% to 90%, under moderate conditions, through treating (2) or (10) with various reagents such as anthranilic acid, phosphorus oxychloride, hydrazine hydrate, formic acid, glacial acetic acid, arylamine (aniline, 4-chloroaniline, or 4-methoxyaniline), and sec-amine (piperazine or morpholine). The new structures of the synthesized compounds were verified using various spectroscopic procedures, such as IR, NMR, and mass spectra. Molecular docking studies were carried out to investigate and discuss how the prepared compounds bind to amino acids such as Estrogen Receptor alpha, EGFR, and NADPH oxidase protein. Also, the synthesized products were tested for their anticancer and antioxidant activities against the (MCF-7) breast carcinoma cell line and human normal Retina pigmented epithelium cells (RPE-1). The study on the structure-activity relationship (SAR) established a correlation between the chemical structure of the newly synthesized compounds and their anticancer activity. The findings suggest that compounds 5a-d, 9,12a-b, and 16 exhibited promising anticancer activity and antioxidant effects as measured by DPPH inhibition.

Synthesis, design, and antimicrobial activity of pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidinones based on quinoline derivatives

The pyrido[2,3‐d]pyrimidine moieties are one of the most biologically widespread heterocyclic compounds as antimicrobial, antioxidant, antitubercular, antiviral and anti‐inflammatory. Hence, we synthesized an efficient new series of 2‐thioxo‐pyrido[2,3‐d]pyrimidinone, 2‐hydrazinyl‐(quinolin‐2‐yl)pyrido[2,3‐d]pyrimidinone,N′‐(quinolin‐2‐yl)‐pyrido[2,3‐d]pyrimidine‐(formo/aceto)‐hydrazide and substituted‐(quinolin‐2‐yl)pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidinone derivatives. The characterization of new compounds was corresponded by using spectroscopic techniques, IR, NMR and Mass spectra. In vitro, all compounds were evaluated as antimicrobial activity compared with cefotaxime sodium and nystatin as the standard drug. This work deals with the exploration of the new heterocyclic compounds and medicinal diversity of quinoline‐pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidine derivatives that might pave the way for long in the discovery of therapeutic medicine for future drug design.

Novel Pyrimidine Derivatives as Antioxidant and Anticancer Agents: Design, Synthesis and Molecular Modeling Studies

The heterocyclic ring system of pyrido [2,3-d]pyrimidines is a privileged scaffold in medicinal chemistry, possessing several biological activities. The synthesis of the pyrimidine derivatives was performed via the condensation of a suitable α,β-unsaturated ketone with 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate in glacial acetic acid. Chalcones were synthesized, as starting materials, via the Claisen-Schmidt condensation of an appropriately substituted ketone and an appropriately substituted aldehyde in the presence of aqueous KOH 40% w/v in ethanol. All the synthesized compounds were characterized using IR, ¹H-NMR, ¹³C-NMR, LC-MS and elemental analysis. The synthesized compounds were evaluated for their antioxidant (DPPH assay), anti-lipid peroxidation (AAPH), anti-LOX activities and ability to interact with glutathione. The compounds do not interact significantly with DPPH but strongly inhibit lipid peroxidation. Pyrimidine derivatives 2a (IC₅₀ = 42 μΜ), 2f (IC₅₀ = 47.5 μΜ) and chalcone 1g (IC₅₀ = 17 μM) were the most potent lipoxygenase inhibitors. All the tested compounds were found to interact with glutathione, apart from 1h. Cell viability and cytotoxicity assays were performed with the HaCaT and A549 cell lines, respectively. In the MTT assay towards the HaCaT cell line, none of the compounds presented viability at 100 μM. On the contrary, in the MTT assay towards the A549 cell line, the tested compounds showed strong cytotoxicity at 100 μM, with derivative 2d presenting the strongest cytotoxic effects at the concentration of 50 μΜ.

Synthesis and Antimicrobial, Anticancer and Anti-Oxidant Activities of Novel 2,3-Dihydropyrido[2,3-d]pyrimidine-4-one and Pyrrolo[2,1-b][1,3]benzothiazole Derivatives via Microwave-Assisted Synthesis

In our attempt towards the synthesis and development of effective antimicrobial, anticancer and antioxidant agents, a novel series of 2,3-dihydropyrido[2,3-d]pyrimidin-4-one 7a–e and pyrrolo[2,1-b][1,3]benzothiazoles 9a–e were synthesized. The synthesis of 2-(1,3-benzo thiazol-2-yl)-3-(aryl)prop-2-enenitrile (5a–e) as the key intermediate was accomplished by a microwave efficient method. Via a new variety oriented synthetic microwave pathway, these highly functionalized building blocks allowed access to numerous fused heteroaromatic such as 7-amino-6-(1,3-benzo thiazol-2-yl)-5-(aryl)-2-thioxo-2,3dihydropyrido [2,3-d]pyrimidin-4(1H)-one 7a–e and 1-amino-2-(aryl)pyrrolo[2,1-b][1,3]benzothiazole-3-carbonitrile derivatives 9a–e in order to study their antimicrobial and anticancer activity. The present investigation offers effective and rapid new procedures for the synthesis of the newly polycondensed heterocyclic ring systems. All the newly synthesized compounds were evaluated for antimicrobial, anticancer and antioxidant activity. Compounds 7a,d, and 9a,d showed higher antimicrobial activity than cefotaxime and fluconazole while the remaining compounds exhibited good to moderate activity against bacteria and fungi. An anticancer evaluation of the newly synthesized compounds against the three tumor cell lines (lung cell NCI-H460, liver cancer HepG2 and colon cancer HCT-116) exhibited that compounds 7a, d, and 9a,d have higher cytotoxicity against the three human cell lines compared to doxorubicin as a reference drug. These compounds also exhibited higher antioxidant activity and a great ability to protect DNA from damage induced by bleomycin.

Pyrrole and Fused Pyrrole Compounds with Bioactivity against Inflammatory Mediators

A new series of pyrrolopyridines and pyrrolopyridopyrimidines have been synthesized from aminocyanopyrroles. The synthesized compounds have been characterized by FTIR, ¹H-NMR and mass spectroscopy. The final compounds have been screened for in vitro pro-inflammatory cytokine inhibitory and in vivo anti-inflammatory activity. The biological results revealed that among all tested compounds some fused pyrroles, namely the pyrrolopyridines 3i and 3l, show promising activity. A docking study of the active synthesized molecules confirmed the biological results and revealed a new binding pose in the COX-2 binding site.

Adenosine kinase: exploitation for therapeutic gain

Adenosine kinase (ADK; EC 2.7.1.20) is an evolutionarily conserved phosphotransferase that converts the purine ribonucleoside adenosine into 5'-adenosine-monophosphate. This enzymatic reaction plays a fundamental role in determining the tone of adenosine, which fulfills essential functions as a homeostatic and metabolic regulator in all living systems. Adenosine not only activates specific signaling pathways by activation of four types of adenosine receptors but it is also a primordial metabolite and regulator of biochemical enzyme reactions that couple to bioenergetic and epigenetic functions. By regulating adenosine, ADK can thus be identified as an upstream regulator of complex homeostatic and metabolic networks. Not surprisingly, ADK dysfunction is involved in several pathologies, including diabetes, epilepsy, and cancer. Consequently, ADK emerges as a rational therapeutic target, and adenosine-regulating drugs have been tested extensively. In recent attempts to improve specificity of treatment, localized therapies have been developed to augment adenosine signaling at sites of injury or pathology; those approaches include transplantation of stem cells with deletions of ADK or the use of gene therapy vectors to downregulate ADK expression. More recently, the first human mutations in ADK have been described, and novel findings suggest an unexpected role of ADK in a wider range of pathologies. ADK-regulating strategies thus represent innovative therapeutic opportunities to reconstruct network homeostasis in a multitude of conditions. This review will provide a comprehensive overview of the genetics, biochemistry, and pharmacology of ADK and will then focus on pathologies and therapeutic interventions. Challenges to translate ADK-based therapies into clinical use will be discussed critically.

Synthesis and antibacterial activity of a new series of 2,3,5,7-substituted-pyrido[2,3-d]pyrimidin-4(3h)-one derivatives

A new series of 2,3,5,7-substituted-pyrido[2,3-d]pyrimidin-4(3H)-one derivatives were prepared from 2-amino-N,6-substituted phenyl-4-(trifluoromethyl or methyl)nicotinamides. The key intermediate 2-amino-N,6-substituted phenyl-4-(trifluoromethyl or methyl)nicotinamides were synthesized from 2-bromo-N,6-disubstituted phenyl-4-(trifluoromethyl or methyl)nicotinamides as well as from ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) coupling of 2-amino-4,6-substituted nicotinic acid and substituted arylamines. All the synthesized compounds were screened for antibacterial activity against Gram +ve and Gram -ve bacteria. Compound 7c showed better antibacterial activity against Gram +ve and Gram -ve bacteria.

4-amino-5-aryl-6-arylethynylpyrimidines: structure-activity relationships of non-nucleoside adenosine kinase inhibitors

A series of non-nucleoside adenosine kinase (AK) inhibitors is reported. These inhibitors originated from the modification of 5-(3-bromophenyl)-7-(6-morpholin-4-ylpyridin-3-yl)pyrido[2,3-d]pyrimidin-4-ylamine (ABT-702). The identification of a linker that would approximate the spatial arrangement found between the pyrimidine ring and the aryl group at C(7) in ABT-702 was a key element in this modification. A search of potential linkers led to the discovery of an acetylene moiety as a suitable scaffold. It was hypothesized that the aryl acetylenes, ABT-702, and adenosine bound to the active site of AK (closed form) in a similar manner with respect to the orientation of the heterocyclic base. Although potent acetylene analogs were discovered based on this assumption, an X-ray crystal structure of 5-(4-dimethylaminophenyl)-6-(6-morpholin-4-ylpyridin-3-ylethynyl)pyrimidin-4-ylamine (16a) revealed a binding orientation contrary to adenosine. In addition, this compound bound tightly to a unique open conformation of AK. The structure-activity relationships and unique ligand orientation and protein conformation are discussed.

5-(3-Bromophenyl)-7-(6-morpholin-4-ylpyridin-3-yl)pyrido[2,3-d]pyrimidin-4-ylamine: structure-activity relationships of 7-substituted heteroaryl analogs as non-nucleoside adenosine kinase inhibitors

4-Amino-5,7-disubstituted pyridopyrimidines are potent, non-nucleoside inhibitors of adenosine kinase (AK). We recently identified a potent, orally efficacious analog, 4 containing a 7-pyridylmorpholine substituted ring system as the key structural element of this template. In this report, we disclose the pharmacologic effects of five- and six-membered heterocyclic ring replacements for the pyridine ring in 4. These replacements were found to have interesting effects on in vivo efficacy and genotoxicity as well as in vitro potency. We discovered that the nitrogen in the heterocyclic ring at C(7) is important for the modulation of mutagenic side effects (Ames assay).

Synthesis and biological evaluation of 6,7-disubstituted 4-aminopyrido[2,3-d]pyrimidines as adenosine kinase inhibitors

The synthesis and structure-activity relationship of a series of 6,7-disubstituted 4-aminopyrido[2,3-d]pyrimidines as novel non-nucleoside adenosine kinase inhibitors is described. A variety of substituents, primarily aryl, at the C6 and C7 positions of the pyridopyrimidine core were found to yield analogues that are potent inhibitors of adenosine kinase. In contrast to the 5,7-disubstituted and 5,6,7-trisubstituted pyridopyrimidine series, these analogues exhibited only modest potency to inhibit AK in intact cells.

Synthesis and biological evaluation of pteridine and pyrazolopyrimidine based adenosine kinase inhibitors

Three new approaches have been tested to modify existing pyridopyrimidine and alkynylpyrimidine classes of nonnucleoside adenosine kinase inhibitors 2 and 3. 4-Amino-substituted pteridines 8a-e were generally less active than corresponding 5- and 6-substituted pyridopyrimidines 2. Pyrazolopyrimidine 13c with IC(50)=7.5 nM was superior to its open chain alkynylpyrimidine analog 13g (IC(50)=22 nM) while pyrrolopyrimidines such as 17a were inactive.