Design and development of 1,3,5-triazine-thiadiazole hybrids as potent adenosine A2A receptor (A2AR) antagonist for benefit in Parkinson's disease

Eco-friendly green synthesis of N‑pyrazole amino chitosan using PEG-400 as an anticancer agent against gastric cancer cells via inhibiting EGFR

The present study was conducted to develop a green process that provides access to the development of Schiff base derivatives of chitosan with the heterocyclic moiety as a novel class of anti-gastric cancer agent. In the present study, we have synthesized these derivatives by reacting various pyrazoles with chitosan using CAN in PEG400. The compounds were synthesized in 20 min in excellent yield by using CAN at 5% in PEG400 at 80°C in the shortest reaction time of 20 min. The PEG400 could be efficiently recycled for the three consecutive runs. The developed compounds were tested for EGFR-TK inhibition using a Kinase-Glo Plus luminescence kinase assay kit where they exhibited significant activity revealing compound 2d as the most potent analog, while other compounds showed mild to moderate inhibitory activity. MTT assay was conducted to determine the effect of the three most potent EGFR inhibitors (2b, 2c, and 2d) on the proliferation of gastric cancer cells (SGC-7901). The results showed compound 2d as the most potent anticancer agent against SGC7901 cells. The effect of compound 2d was also quantified on the apoptosis and cell phase of SGC7901 cells using flow cytometry assay at various concentrations ranging from 0, 10, 20, and 30 µM. Results suggest that compound 2d showed significant inhibition of SGC-7901 by inducing apoptosis and arresting G0/G1 cell phase. The western blot analysis also revealed that compound 2d significantly inhibited the overexpression of EGFR in SGC-7901 cells. The study successfully demonstrated the development of N‑pyrazole amino chitosan as a novel class of agent against gastric cancer via inhibition of EGFR.

Hybrid PABA-glutamic acid conjugated 1,3,5-triazine derivatives: Design, synthesis, and antimalarial activity screening targeting Plasmodium falciparum dihydro folate reductase enzyme

Despite the successful reduction in the malaria health burden in recent years, it continues to remain a significant global health problem mainly because of the emerging resistance to first-line treatments. Also because of the disruption in malaria prevention services during the COVID-19 pandemic, there was an increase in malaria cases in 2021 compared to 2020. Hence, the present study outlined the in silico study, synthesis, and antimalarial evaluation of 1,3,5-triazine hybrids conjugated with PABA-glutamic acid. Docking study revealed higher binding energy compared to the originally bound ligand WR99210, predominant hydrogen bond interaction, and involvement of key amino acid residues, like Arg122, Ser120, and Arg59. Fourteen compounds were synthesized using traditional and microwave synthesis. The in vitro antimalarial evaluation against chloroquine-sensitive 3D7 and resistant Dd2 strain of Plasmodium falciparum showed a high to moderate activity range. Compounds C1 and B4 showed high efficacy against both strains and a further study revealed that compound C1 is non-cytotoxic against the HEK293 cell line with no acute oral toxicity. In vivo, study was performed for the most potent antimalarial compound C1 to optimize the research work and found to be effectively suppressing parasitemia of Plasmodium berghei strain in the Swiss albino mice model.

Recent biological applications of heterocyclic hybrids containing s-triazine scaffold

s-Triazine possesses an auspicious status in the field of drug discovery and development owing to its presence in many naturally occurring compounds as well as commercially available drugs like enasidenib, gedatolisib, bimiralisib, atrazine, indaziflam, and triaziflam. Easy, cost-effective, and efficient access to its derivatives in addition to their splendid biological activities such as anticancer, anti-inflammatory, antiviral, anticonvulsant, anti-tubercular, antidiabetic, antimicrobial, makes it an attractive heterocyclic nucleus in the field of medicinal chemistry. Other than the direct access of its derivatives from simple commercially available starting materials like amidine, the s-triazine derivatives have also been obtained starting from an inexpensive commercially available 2,4,6-trichloro-1,3,5-triazine (TCT) commonly known as cyanuric chloride. Owing to the high reactivity and the possibility of sequential substitution of TCT, a variety of biologically active heterocyclic scaffolds have been installed on this nucleus in order to have more potent compounds. These s-triazine-based heterocyclic hybrids have been reported to show enhanced biological activities in recent years. Therefore, it is important to summarize and highlight recent examples of these hybrids which is imperative to attract the attention of the drug development community.

Antitumor Activity of s-Triazine Derivatives: A Systematic Review

1,3,5-triazine derivatives, also called s-triazines, are a series of containing-nitrogen heterocyclic compounds that play an important role in anticancer drug design and development. To date, three s-triazine derivatives, including altretamine, gedatolisib, and enasidenib, have already been approved for refractory ovarian cancer, metastatic breast cancer, and leukemia therapy, respectively, demonstrating that the s-triazine core is a useful scaffold for the discovery of novel anticancer drugs. In this review, we mainly focus on s-triazines targeting topoisomerases, tyrosine kinases, phosphoinositide 3-kinases, NADP+-dependent isocitrate dehydrogenases, and cyclin-dependent kinases in diverse signaling pathways, which have been extensively studied. The medicinal chemistry of s-triazine derivatives as anticancer agents was summarized, including discovery, structure optimization, and biological applications. This review will provide a reference to inspire new and original discoveries.

Practical One-Pot Synthesis of 4,6-Bis(hetero)aryl- and 4-(Hetero) aryl-6-methyl-substituted 1,3,5-Triazin-2-amines

Two series of 4,6-disubstituted 1,3,5-triazin-2-amines were prepared by cesium carbonate-promoted cotrimerization of aromatic nitriles with guanidine and the reaction of (hetero)aryl nitriles with N-acetylguanidine. The first series of 4,6-bis(hetero)aryl-1,3,5-triazin-2-amines was synthesized in yields of 56–85% by adapting a traditional approach that starts from readily available substrates but requires strong and hard-to-handle bases as well as presents serious scope limitations. In this line, the method developed here used a mild base and overcame the scope limitation for p-substituted benzonitrile with electron-releasing group. The second series of 4-(hetero)aryl-6-methyl-1,3,5-triazin-2-amines comprises unsymmetrically substituted symmetrical triazines, which were synthesized in yields of 58–75%. In summary, this work highlighted a synthetic method, which tolerates broad range of substrates, including o- and p-substituted benzonitriles as well as heteroaromatic nitriles.

Design, Synthesis and Biological Evaluation of 1,3,5-Triazine Derivatives Targeting hA1 and hA3 Adenosine Receptor

Adenosine mediates various physiological activities in the body. Adenosine receptors (ARs) are widely expressed in tumors and the tumor microenvironment (TME), and they induce tumor proliferation and suppress immune cell function. There are four types of human adenosine receptor (hARs): hA₁, hA_2A, hA_2B, and hA₃. Both hA₁ and hA₃ AR play an important role in tumor proliferation. We designed and synthesized novel 1,3,5-triazine derivatives through amination and Suzuki coupling, and evaluated them for binding affinities to each hAR subtype. Compounds 9a and 11b showed good binding affinity to both hA₁ and hA₃ AR, while 9c showed the highest binding affinity to hA₁ AR. In this study, we discovered that 9c inhibits cell viability, leading to cell death in lung cancer cell lines. Flow cytometry analysis revealed that 9c caused an increase in intracellular reactive oxygen species (ROS) and a depolarization of the mitochondrial membrane potential. The binding mode of 1,3,5-triazine derivatives to hA₁ and hA₃ AR were predicted by a molecular docking study.

Skullcapflavone II protects neuronal damage in cerebral ischemic rats via inhibiting NF-ĸB and promoting angiogenesis

BACKGROUND

Cerebral ischemia (CI) is considered as a main cause of cerebral stroke (CS) and poses significant risk to the mankind across the world. In the present study, we intended to investigate the protective effect of Skullcapflavone II (SCP) a flavonoid isolated from S. baicalensis on cerebral ischemia/reperfusion (I/R) injury.

METHODS

The middle cerebral artery occlusion (MCAO) and reperfusion was used to create ischemic stroke rat model. The rats were treated with (5, 10, and 15 mg/kg) SCP and after the end of the experiment the rats were sacrificed and various biochemical parameters were assed to determine the pharmacological action of SCP.

RESULTS

SCP dramatically decreases cerebral edema, infarct volume, and improves neurological manifestation as confirmed by reduced neurological deficit. SCP also improves the survivability of neurons as evidenced by H and E and Nissl staining. The level of oxidative stress in the cerebral cortex of the rats was found reduced after treatment with SCP, as confirmed by increase in GSH and SOD activity with reduction in MDA content. In addition, SCP attenuated inflammation via reducing the level of TNF-α, IL-1β and IL-6 in brain tissues of rats. SCP increases the expression of Bcl2, cleaved caspase-3 and -9, while decreasing Bax, and NF-ĸB/TLR4. It causes induction of angiogenesis as suggested by increased expression of VEGF, Ang-1 and Tie-2 in cerebral cortex of rat.

CONCLUSIONS

Our data determined that SCP may provide protective effect on the I/R-induced cerebral ischemia.

Blockade of adenosine A2A receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is widely known for its multiple systems damage, especially neurocognitive deficits in children. Since their discovery, adenosine A_2A receptors (A_2ARs) have been considered as key elements in signaling pathways mediating neurodegenerative diseases such as Huntington's and Alzheimer's, as well as cognitive function regulation. Herein, we investigated A_2AR role in cognitive impairment induced by chronic intermittent hypoxia (CIH). Mice were exposed to CIH 7 h every day for 4 weeks, and intraperitoneally injected with A_2AR agonist CGS21680 or A_2AR antagonist SCH58261 half an hour before IH exposure daily. The 8-arm radial arm maze was utilized to assess spatial memory after CIH exposures.To validate findings using pharmacology, the impact of intermittent hypoxia was investigated in A_2AR knockout mice. CIH-induced memory dysfunction was manifested by increased error rates in the radial arm maze test. The behavioral changes were associated with hippocampal pathology, neuronal apoptosis, and synaptic plasticity impairment. The stimulation of adenosine A_2AR exacerbated memory impairment with more serious neuropathological damage, attenuated long-term potentiation (LTP), syntaxin down-regulation, and increased BDNF protein. Moreover, apoptosis-promoting protein cleaved caspase-3 was upregulated while anti-apoptotic protein Bcl-2 was downregulated. Consistent with these findings, A_2AR inhibition with SCH58261 and A_2AR deletion exhibited the opposite result. Overall, these findings suggest that A_2AR plays a critical role in CIH-induced impairment of learning and memory by accelerating hippocampal neuronal apoptosis and reducing synaptic plasticity. Blockade of adenosine A_2A receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice.

Adenosine receptor antagonists: Recent advances and therapeutic perspective

Adenosine is an endogenous purine-based nucleoside expressed nearly in all body tissues. It regulates various body functions by activating four G-protein coupled receptors, A₁, A_2A, A_2B, and A₃. These receptors are widely acknowledged as drug targets for treating different neurological, metabolic, and inflammatory diseases. Although numerous adenosine receptor inhibitors have been developed worldwide, achieving target selectivity is still a big hurdle in drug development. However, the identification of specific radioligands-based affinity assay, fluorescent ligands, and MS-based ligand assay have contributed to the development of selective and potent adenosine ligands. In recent years various small heterocyclic-based molecules have shown some promising results. Istradefylline has been approved for treating Parkinson's in Japan, while preladenant, tozadenant, CVT-6883, MRS-1523, and many more are under different phases of clinical development. The present review is focused on the quest to develop potent and selective adenosine inhibitors from 2013 to early 2021 by various research groups. The review also highlights their biological activity, selectivity, structure-activity relationship, molecular docking, and mechanistic studies. A special emphsesis on drug designing strategies has been also given the manuscript. The comprehensive compilation of research work carried out in the field will provide inevitable scope for designing and developing novel adenosine inhibitors with improved selectivity and efficacy.

Microwave-assisted synthesis of hybrid PABA-1,3,5-triazine derivatives as an antimalarial agent

The present manuscript deals with the development of novel p-aminobenzoic acid (PABA) associated 1,3,5-triazine derivatives as antimalarial agents. The molecules were developed via microwave-assisted synthesis and structures of compounds were ascertained via numerous analytical and spectroscopic techniques. The synthesized compounds were also subjected to ADMET analysis. In a docking analysis, the title compounds showed high and diverse binding affinities towards wild (-162.45 to -369.38 kcal/mol) and quadruple mutant (-165.36 to -209.47 kcal/mol) Pf-DHFR-TS via interacting with Phe58, Arg59, Ser111, Ile112, Phe116. The in vitro antimalarial activity suggested that compounds 4e, 4b, and 4h showed IC₅₀ ranging from 4.18 to 8.66 μg/ml against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum. Moreover, compounds 4g, 4b, 4e, and 4c showed IC₅₀ ranging from 8.12 to 12.09 μg/ml against chloroquine-resistant (Dd2) strain. In conclusion, our study demonstrated the development of hybrid PABA substituted 1,3,5-triazines as a novel class of Pf-DHFR inhibitor for antimalarial drug discovery.

Current Approaches and Tools Used in Drug Development against Parkinson's Disease

Parkinson's disease is a progressive neurodegenerative disorder characterized by the death of nerve cells in the substantia nigra of the brain. The treatment options for this disease are very limited as currently the treatment is mainly symptomatic, and the available drugs are not able to completely stop the progression of the disease but only to slow it down. There is still a need to search for new compounds with the most optimal pharmacological profile that would stop the rapidly progressing disease. An increasing understanding of Parkinson's pathogenesis and the discovery of new molecular targets pave the way to develop new therapeutic agents. The use and selection of appropriate cell and animal models that better reflect pathogenic changes in the brain is a key aspect of the research. In addition, computer-assisted drug design methods are a promising approach to developing effective compounds with potential therapeutic effects. In light of the above, in this review, we present current approaches for developing new drugs for Parkinson's disease.

1,3,5-Triazine: A versatile pharmacophore with diverse biological activities

1,3,5-Triazine and its derivatives have been the epicenter of chemotherapeutic molecules due to their effective biological activities, such as antibacterial, fungicidal, antimalarial, anticancer, antiviral, antimicrobial, anti-inflammatory, antiamoebic, and antitubercular activities. The present review represents a summarized report of the crucial biological activities possessed by substituted 1,3,5-triazine derivatives, with special attention to the most potent compounds.

Discovery of novel 1,3,5-triazine derivatives as potent inhibitor of cervical cancer via dual inhibition of PI3K/mTOR

This study describes the synthesis of novel 1,3,5-triazine derivatives as potent inhibitors of cervical cancer. The compounds were initially tested for inhibition of PI3K/mTOR, where they showed significant inhibitory activity. The top-ranking molecule (compound 6 h) was further tested against class I PI3K isoforms, such as PI3Kα, PI3Kβ, PI3Kγ and PI3Kδ, where it showed the most significant activity against PI3Kα. Compound 6 h was then tested for anti-cancer activity against triple-negative breast cancer cells (MDA-MB321), human breast cancer cells (MCF-7), human cervical cancer cells (HeLa) and human liver cancer cells (HepG2), and it showed the greatest potency against HeLa cells. The effects of compound 6 h were further evaluated against the HeLa cells, where it showed significant attenuation of cell viability by inducing cell cycle arrest in the G1 phase. Compound 6 h induced apoptosis and reduced migration and invasion of HeLa cells. Western blotting analysis showed that 6 h inhibited PI3K and mTOR with positive modulation of Bcl-2 and Bax levels in HeLa cells. The effects of compound 6 h were also investigated in a tumour xenograft mouse model, where it showed reduction of tumour volume and weight. It also inhibited the PI3K/Akt/mTOR signalling cascade in xenograft tumour tissues, as evidenced by western blotting analysis. The results of the present study suggest the possible utility of the designed 1,3,5-triazine derivative as a potent inhibitor of cervical cancer.

Discovery of novel 1,3,5-triazine as adenosine A2A receptor antagonist for benefit in Parkinson's disease

Parkinson's disease (PD) is a chronic neuro-degenerative ailment characterized by impairment in various motor and nonmotor functions of the body. In the past few years, adenosine A₂ A receptor (A₂ AR) antagonists have attracted much attention due to significant relief in PD. Therefore, in the current study, we intend to disclose the development of novel 1,3,5-triazines as A₂ AR antagonist. The radioligand binding and selectivity of analogs were tested in HEK293 (human embryonic kidney) and the cells were transfected with pcDNA 3.1(+) containing full-length human A₂ AR cDNA and pcDNA 3.1(+) containing full-length human A₁ R cDNA, where they exhibit selective affinity for A₂ AR. Molecular docking analysis was also conducted to rationalize the probable mode of action, binding affinity, and orientation of the most potent molecule (7c) at the active site of A₂ AR. It has been shown that compound 7c form numerous nonbonded interactions in the active site of A₂ AR by interacting with Ala59, Ala63, Ile80, Val84 Glu169, Phe168, Met270, and Ile274. The study revealed 1,3,5-triazines as a novel class of A₂ AR antagonists.