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The synthesis, the antitumor activity, the SAR and, whenever described, the possible mode of action of 1,2,4-triazine derivatives, their N-oxides, N,N'-dioxides as well as the benzo- and hetero-fused systems are reported. Herein are treated derivatives disclosed to literature from the beginning of this century up to 2016. Among the three possible triazine isomers, 1,2,4-triazines are the most studied ones and many derivatives having remarkable antitumor activity have been reported in the literature and also patented reaching advanced phases of clinical trials., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

4-Benzyl-1,2,4-triazin-3,5(2 H ,4 H )-dione (3-benzyl-6-azauracil, 2 ), and 2,4-dibenzyl-1,2,4-triazin-3,5(2 H ,4 H )-dione (1,3-dibenzyl-6-azauracil, 3 ) were synthesized by the reaction of 1,2,4-triazin-3,5(2 H ,4 H )-dione (6-azauracil, 1 ) with benzyl bromide and potassium carbonate in dry acetone via the 18-crown-6-ether catalysis. In these reaction methods, we developed more convenient and efficient methodologies to afford compounds 2 and 3 in good yields. These compounds were characterized by ¹H- and 13 C-NMR, MS spectrum, IR spectroscopy and elemental analysis. The structure of 2 was verified by 2D-NMR measurements, including gHSQC and gHMBC measurements. A single-crystal X-ray diffraction experiment indicated that compound 3 , with the molecular formula C 17 H 15 N₃O₂, crystallized from a CH₃OH/CH₂Cl₂ diffusion solvent system in a monoclinic space group P 2₁/ c with a = 13.7844(13), b = 8.5691(8), c = 13.0527(12) Å, β = 105.961(2)°, V = 1482.3(2) ų, Z = 4, resulting in a density D calc of 1.314 g/cm³. The crystal structure of compound 3 is tightly stabilized by contact with five other molecules from the six short contacts formed by intermolecular C-O···H-C ar , C-H···C ar , and weakly π···π stacking interactions. The dihedral angle 31.90° is formed by the mean planes of the benzene rings of the N-2 and N-4 benzyl groups., Competing Interests: The authors declare no conflict of interest.

A novel series of 2-((5,6-diphenyl-1,2,4-triazin-3-yl)thio)-N-arylacetamides 5a-5q have been synthesized and evaluated for their α-glucosidase inhibitory activity. All newly synthesized compounds exhibited potent α-glucosidase inhibitory activity in the range of IC 50 =12.46±0.13-72.68±0.20μM, when compared to the standard drug acarbose (IC 50 =817.38±6.27μM). Among the series, compound 5j (12.46±0.13μM) with strong electron-withdrawing nitro group on the arylacetamide moiety was identified as the most potent inhibitor of α-glucosidase. Molecular docking study was carried out to explore the binding interactions of these compounds with α-glucosidase. Our study identifies a novel series of potent α-glucosidase inhibitors for further investigation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A novel series of triazine-triazole derivatives 7a-7m were synthesized, characterized by 1 H NMR and evaluated for their α-glucosidase inhibitory activity. All the synthesized compounds displayed potent α-glucosidase inhibitory activity with IC 50 range of 11.63 ± 0.15 to 37.44 ± 0.35 μM, when compared to the standard drug acarbose (IC 50  = 817.38 ± 6.27 μM). Among the series, compound 7i (IC 50  = 11.63 ± 0.15 μM) bearing 2,5-dichloro substitution at phenyl ring, represented the most potent α-glucosidase inhibitory activity. Molecular docking studies of the most active compounds with the homology modelled α-glucosidase were also performed to explore the possible inhibitory mechanism. Our studies shown that these triazine-triazole derivatives are a new class of α-glucosidase inhibitors., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

A set of 1,2,4-triazine derivatives were designed as cyclooxygenase-2 (COX-2) inhibitors. These compounds were synthesized and screened for inhibition of cyclooxygenases (COX-1 and COX-2) based on a cellular assay using human whole blood (HWB) and lipoxygenase (LOX-15) that are key enzymes in inflammation. The results showed that 3-(2-(benzo[d][1,3]dioxol-5-ylmethylene)hydrazinyl)-5,6-bis(4-methoxyphenyl)-1,2,4-triazine (G11) was identified as the most potent COX-2 inhibitor (78%) relative to COX-1 (50%). Ferric reducing anti-oxidant power (FRAP) assay revealed that compound G10 possesses the highest anti-oxidant activity. The compound G3 with IC50 value of 124 μM was the most potent compound in LOX inhibitory assay. Molecular docking was performed and a good agreement was observed between computational and experimental results.

A series of novel hybrids comprising of 1,3,4-oxadiazole/thiadiazole and 1,2,4-triazole tethered to 5,6-diphenyl-1,2,4-triazin-3(2H)-one were designed, synthesised and evaluated as COX-2 inhibitors for the treatment of inflammation. The synthesised hybrids were characterised using FT-IR, 1H NMR, 13C NMR, elemental (C,H,N) analyses and assessed for their anti-inflammatory potential by in vitro albumin denaturation assay. Compounds exhibiting activity comparable to indomethacin and celecoxib were further evaluated for in vivo anti-inflammatory activity. Oral administration of promising compounds 3c-3e and 4c-4e did not evoke significant gastric, hepatic and renal toxicity in rats. These potential compounds exhibited reduced malondialdehyde (MDA) content on the gastric mucosa suggesting their protective effects by inhibition of lipid peroxidation. Based on the outcome of in vitro COX assay, compounds 3c-3e and 4c-4e (IC 50 0.60-1.11μM) elicited an interesting profile as competitive selective COX-2 inhibitors. Further, selected compounds 3e and 4c were found devoid of cardiotoxicity post evaluation on myocardial infarcted rats. The in silico binding mode of the potential compounds into the COX-2 active site through docking and molecular dynamics exemplified their consensual interaction and subsequent COX-2 inhibition with significant implications for structure-based drug design., (Copyright © 2016 Elsevier Inc. All rights reserved.)

A new series of 1,2,4-triazine derivatives bearing carbazole moiety 7a-7p were designed, synthesized, and evaluated for their α-glucosidase inhibitory activity. The majority of the screened compounds displayed potent α-glucosidase inhibitory activity, with IC50 values in the range of 4.27±0.07-47.75±0.25μM as compared to the standard drug acarbose. Among the series, compound 7k represented the most potent α-glucosidase inhibitory activity with IC50 values of 4.27±0.07μM. Kinetic analysis revealed that compound 7k is a non-competitive inhibitor with a Ki of 4.43μM. Furthermore, the binding interactions of compound 7k with α-glucosidase was confirmed through molecular docking. This study showed these 1,2,4-triazine derivatives bearing carbazole moiety as a new class of α-glucosidase inhibitors., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

As per structural requirement essential for anticonvulsant activity, a series of new 6-(2-amino-substituted phenyl)-4-(substituted phenyl)-1,2,4-triazine-3,5-dione derivatives were designed and synthesized. All the synthesized title derivatives were assessed for in vivo anticonvulsant screening by the two most employed standard animal seizure models, maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ)-induced seizures, along with minimal motor impairment screening by rotarod test. Among all the synthesized compounds, the compound 4r showed excellent anticonvulsant activity with neither signs of neurotoxicity in the minimal motor impairment test nor signs of hepatotoxicity in the serum enzyme activity assay. The in silico studies of these title compounds were carried out for estimation of a pharmacophore pattern and the prediction of pharmacokinetic properties. To know the exact mechanism of our title compounds, a molecular docking study was carried out on the homology model of sodium ion (Na(+) ) channel and GABAA receptors. The results of the docking study as well as the in vitro study on both the receptors showed that our target compounds best act through the GABAA receptor rather than the Na(+) channel receptors. Additionally, GABA enzyme estimation was performed for further confirmation of the mechanism involved in its anticonvulsant activity. Conclusively, the compound 4r presents a novel scaffold in the search for safer and efficient anticonvulsants having neuroprotective as well as GABAergic effects., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels-Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels-Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route.

Intramolecular inverse electron demand cycloadditions of isatin-derived 1,2,4-triazines with acetylenic dienophiles tethered by amidations or transesterifications proceed in excellent yields to produce lactam- or lactone-fused α-carbolines. Beginning with various isatins and alkynyl dienophiles, a pilot-scale library of eighty-eight α-carbolines was prepared by using this robust methodology for biological evaluation.