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Antimalarials. 3. 1,2,4-Triazines.

The syntheses of a number of substituted 1,2,4-triazines as potential antimalarials are described. The structural requirements for antimalarial activity are discussed with reference to the substituents of a phenyl group in the 6 position and amino groups at the 3 and 5 positions. Of the compounds tested, 2,5, and 7 produced cures in mice infected with plasmodium berghei. Compounds 2(3,5-diamino-6-(4-trifluoromethylphenyl)-1,2,4-triazine),3,5,8,12,and 37 produced cures in chicks infected with Plasmodium gallinaceum.

Animals↗

Crystallography, quantitative structure-activity relationships, and molecular graphics in a comparative analysis of the inhibition of dihydrofolate reductase from chicken liver and Lactobacillus casei by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s.

The inhibition of dihydrofolate reductase from chicken liver and from Lactobacillus casei has been studied with 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines. It was found that for the chicken enzyme, inhibitor potency for 101 triazines was correlated by the following equation: log 1/Kiapp = 0.85 sigma tau' - 1.04 log (beta X 10 sigma tau' + 1) + 0.57 sigma + 6.36. The parameter tau' indicates that for certain substituents, tau = 0. In the case of the L. casei DHFR results, meta and para derivatives could not be included in the same equation. For 38 meta-substituted compounds, it was found that log 1/Kiapp = 0.38 tau'3-0.91 log (beta X 10 tau'3 + 1) + 0.71I + 4.60 and for 32 para-substituted phenyltriazines log 1/Kiapp = 0.44 tau'4-0.65 log (beta tau'4 + 1') - 0.90 upsilon + 0.69I + 4.67. In the L. casei equation, I is an indicator variable for substituents of the type CH2ZC6H4-Y and ZCH2C6H4-Y, where Z = O, NH, S, or Se. The parameter upsilon is Charton's steric parameter, which is similar to Taft's Es. The mathematical models obtained from correlation analysis are compared with stereo color graphics models.

Animals↗

Inhibition of human dihydrofolate reductase by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s. A quantitative structure-activity relationship analysis.

The inhibitory activity of 101 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines against purified dihydrofolate reductase from human lymphoblastoid cell (WIL 2) has been studied. From the obtained Kiapp values, quantitative structure-activity relationships (QSAR) have been derived. The QSAR from human dihydrofolate reductase are compared with QSAR for triazines inhibiting bovine and murine tumor DHFR, as well with QSAR for their inhibitory action on murine tumor cell culture.

Animals↗

Pyrido[3',2':4,5]thieno[3,2-d]-N-triazines: a new series of orally active antiallergic agents.

A new series of orally active mediator release inhibitors, pyrido[3',2':4,5]thieno[3,2-d]-N-triazines, was synthesized and evaluated for antiallergic activity. Several products showed high activity as inhibitors or wheal information in the rat passive cutaneous anaphylaxis screen and as inhibitors of histamine release from passively sensitized rat mast cells. Many compounds were orally active in the PCA test. The most potent compound, 7-phenylpyrido-[3',2':4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)- one (10) with an I50 value of 0.05 microM, was 60 times more potent than disodium cromoglycate (DSCG) in the RMC assay.

Administration, Oral↗

Design, synthesis and biological evaluation of novel N-alkyl- and N-acyl-(7-substituted-2-phenylimidazo[1,2-a][1,3,5]triazin-4-yl)amines (ITAs) as novel A(1) adenosine receptor antagonists.

Prompted by pharmacophore and docking based models, we have synthesized and tested a number of N-alkyl and N-acyl-(7-substituted-2-phenylimidazo[1,2-a][1,3,5]triazin-4-yl)amines (ITAs, 7) designed as a new class of A(1) adenosine receptor (A(1)AR) antagonists. Binding affinities at the A(1)AR, A(2A)AR, and A(3)AR were determined using bovine cerebral membranes. Most of the compounds displayed K(i) values at the A(1)AR in the submicromolar or even in the low nanomolar range, thus confirming the rationale leading to their synthesis. All or most of the ligands turned out to be selective for the A(1)AR over the A(2A)AR and A(3)AR subtypes, respectively. Structure-affinity relationships at the A(1)AR were rationalized by docking simulations in terms of putative ligand/receptor interactions. Among the ITAs investigated, 1-[(7-methyl-2-phenylimidazo[1,2-a][1,3,5]triazin-4-yl)amino]acetone (7j) exhibited the best combination of affinity at the A(1)AR (K(i) = 12 nM) and selectivity over the A(2A)AR and A(3)AR subtypes (K(i)s > 10000 nM).

Animals↗

Synthesis and identification of [1,3,5]triazine-pyridine biheteroaryl as a novel series of potent cyclin-dependent kinase inhibitors.

On the basis of previous studies, we identified pyrazine-pyridine A as a potent vascular endothelial growth factor inhibitor and pyrimidine-pyridine B as a moderately potent cyclin dependent kinase (CDK) inhibitor. A proposed combination of CGP-60474 and compound B led to the discovery of [1,3,5]triazine-pyridine as a new series of potent CDK inhibitors. Palladium-catalyzed C-C bond formation reactions, particularly the Negishi coupling reaction, were used to assemble various triazine-heteroaryl analogues effectively. Among them, compound 20 displayed high inhibitory potency at CDK1 (IC(50) = 0.021 microM), CDK2, and CDK5 and submicromolar potency at CDK4, CDK6, and CDK7. Compound 20 also displayed high potency at GSK-3beta. It demonstrated potent antiproliferative activity on various tumor cell lines, including HeLa, HCT-116, U937, and A375. When 20 was administered intraperitoneally at 150 and 125 mg/kg to nude mice bearing human A375 xenografts, the compound produced a significant survival increase. Molecular docking studies were conducted in an attempt to enhance the understanding of the observed structure-activity relationship.

Aminopyridines↗

2-Hydroxy-4,6-diamino-[1,3,5]triazines: a novel class of VEGF-R2 (KDR) tyrosine kinase inhibitors.

2-Hydroxy-4,6-diamino-[1,3,5]triazines are described which are a novel class of potent inhibitors of the VEGF-R2 (flk-1/KDR) tyrosine kinase. 4-(Benzothiazol-6-ylamino)-6-(benzyl-isopropyl-amino)-[1,3,5]triazin-2-ol (14d) exhibited low nanomolar potency in the in vitro enzyme inhibition assay (IC(50) = 18 nM) and submicromolar inhibitory activity in a KDR-induced MAP kinase autophosphorylation assay in HUVEC cells (IC(50) = 280 nM), and also demonstrated good in vitro selectivity against a panel of growth factor receptor tyrosine kinases. Further, 14d showed antiangiogenic activity in an aortic ring explant assay by blocking endothelial outgrowths in rat aortas with an IC(50) of 1 microM.

Angiogenesis Inhibitors↗

Novel diamino derivatives of [1,2,4]triazolo[1,5-a][1,3,5]triazine as potent and selective adenosine A2a receptor antagonists.

Piperazine derivatives of 2-furanyl[1,2,4]triazolo[1,5-a][1,3,5]triazine have recently been demonstrated to be potent and selective adenosine A(2a) receptor antagonists with oral activity in rodent models of Parkinson's disease. We have replaced the piperazinyl group with a variety of linear, monocyclic, and bicyclic diamines. Of these diamines, (R)-2-(aminomethyl)pyrrolidine is a particularly potent and selective replacement for the piperazinyl group. With this diamine component, we have been able to prepare numerous analogues with low nanomolar affinity toward the A(2a) receptor and good selectivity with respect to the A(1) receptor (>200-fold in some cases). Selected analogues from this series of [1,2,4]triazolo[1,5-a][1,3,5]triazine have now been shown to be orally active in the mouse catalepsy model.

Adenosine A2 Receptor Antagonists↗

Synthesis and in vivo validation of [O-methyl-11C]2-{4-[4-(7-methoxynaphthalen-1-yl)piperazin- 1-yl]butyl}-4-methyl-2H-[1,2,4]triazine-3,5-dione: a novel 5-HT1A receptor agonist positron emission tomography ligand.

Antagonist 5-HT(1A) PET ligands are available, but an agonist ligand would give more information about signal transduction capacity. Synthesis and in vivo evaluation of [O-methyl-(11)C]2-{4-[4-(7-methoxynaphthalen-1-yl)piperazin-1-yl]butyl}-4-methyl-2H-[1,2,4]triazine-3,5-dione (10), a potential high affinity (K(i) = 1.36 nM) 5-HT(1A) agonist PET tracer is described. Piperazine 10 is a 5-HT(1A) agonist with an EC(50) comparable to serotonin, based on cAMP formation and GTP(gamma)S binding assays. Radiosynthesis of [(11)C]10 has been achieved by reacting 2-{4-[4-(7-hydroxynaphthalen-1-yl)piperazin-1-yl]butyl}-4-methyl-2H-[1,2,4]triazine-3,5-dione (9) and [(11)C]CH(3)OTf in 25 +/- 5% (n = 15) yield at the end of synthesis (EOS). The chemical and radiochemical purities of [(11)C]10 were >99% with a specific activity 1500 +/- 300 Ci/mmol (n =15). PET studies in anesthetized baboon demonstrate [(11)C]10 specific binding in brain regions rich in 5-HT(1A) receptors. Binding of [(11)C]10 was blocked by WAY100635 and 8-OH-DPAT. The regional brain volumes of distribution (V(T)) of [(11)C]10 in baboon correlate with [(11)C]WAY100635 V(T) in baboons. These data provide evidence that [(11)C]10 is the first promising agonist PET tracer for the 5-HT(1A) receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

Discovery and preclinical studies of (R)-1-(4-(4-fluoro-2-methyl-1H-indol-5-yloxy)-5- methylpyrrolo[2,1-f][1,2,4]triazin-6-yloxy)propan- 2-ol (BMS-540215), an in vivo active potent VEGFR-2 inhibitor.

A series of substituted 4-(4-fluoro-1H-indol-5-yloxy)pyrrolo[2,1-f][1,2,4]triazine-based inhibitors of vascular endothelial growth factor receptor-2 kinase is reported. Structure-activity relationship studies revealed that a methyl group at the 5-position and a substituted alkoxy group at the 6-position of the pyrrolo[2,1-f][1,2,4]triazine core gave potent compounds. Biochemical potency, kinase selectivity, and pharmacokinetics of the series were optimized and in vitro safety liabilities were minimized to afford BMS-540215 (12), which demonstrated robust preclinical in vivo activity in human tumor xenograft models. The l-alanine prodrug of 12, BMS-582664 (21), is currently under evaluation in clinical trials for the treatment of solid tumors.

Alanine↗

5-Lipoxygenase inhibitors: synthesis and structure-activity relationships of a series of 1-aryl-2H,4H-tetrahydro-1,2,4-triazin-3-ones.

Synthetic routes were developed to access a variety of novel 1-aryl-2H,4H-tetrahydro-1,2,4-triazin-3-one analogs which were evaluated as 5-lipoxygenase (5-LO) inhibitors. The parent structure, 1-phenylperhydro-1,2,4-triazin-3-one (4), was found to be a selective inhibitor of 5-LO in broken cell, intact cell, and human blood assays with IC50 values of 5-21 microM. In a rat anaphylaxis model, 4 blocked leukotriene formation with an ED50 = 7 mg/kg when administered orally. Compound 4 exhibited selectivity for inhibition of 5-LO with little activity against related enzymes: 12-LO from human platelets, 15-LO from soybean, and cyclooxygenase (COX) from sheep seminal vesicle. In pilot subacute toxicity testing, 4 did not produce methemoglobinemia in rats (400 mg/kg po daily for 9 days) or in dogs (200 mg/kg po daily for 28 days). These results indicated that the triazinone structure provided a 5-LO inhibitor template devoid of the toxicity problems observed in the related phenidone (1) and pyridazinone (3) classes of 5-LO inhibitors. The parent compound 4 is a selective, orally bioavailable 5-LO inhibitor which can serve as a useful reference standard for in vivo pharmacological studies involving leukotriene-mediated phenonmena.

Animals↗

Intramolecular inverse-electron-demand Diels-Alder reactions of imidazoles with 1,2,4-triazines: a new route to 1,2,3,4-tetrahydro-1,5-naphthyridines and related heterocycles.

The intramolecular inverse-electron-demand Diels-Alder reaction between imidazoles and 1,2,4-triazines linked by a trimethylene tether from the imidazole N1 position to the triazine C3 proceed in excellent yields to produce 1,2,3,4-tetrahydro-1,5-naphthyridines. The reaction proceeds by a cycloaddition with subsequent loss of nitrogen, followed by a presumed stepwise loss of a nitrile. The analogous intramolecular cycloadditions employing a tetramethylene tether also proceeded to give 2,3,4,5-tetrahydro-1H-pyrido[3,2-b]azepines in acceptable yields. The reaction to produce the tetrahydro-1,5-naphthyridines can also be promoted with microwave irradiation.

Cyclization↗

Novel orthogonal strategy toward solid-phase synthesis of 1,3,5-substituted triazines.

[reaction: see text] To improve upon the previous orthogonal method for synthesis of a triazine library, an alternative strategy has been developed via oxidation-activation of the thioether to the sulfone. Through a comparison between these two methods, the sulfone strategy was demonstrated as an enhanced method in the generation of highly pure triazine library compounds.

Combinatorial Chemistry Techniques↗

1,3,5-triazine-based mass spectral tagging of one-bead one-compound libraries.

A triazine-based mass encoding strategy that accommodates cleavable linker, isotopic labeling, and diversity receptor moieties is reported. The resulting triazine-based tags, which are coupled to bifunctionalized TentaGel resin in a one-pot transformation, enable the construction of a 1-oxa-2,8-diazaspiro[4.5]dec-2-ene-7-carboxamide library and facilitate decoding by equalizing the ionization potential of the liberated tags in single bead MALDI-TOF experiments as well as balancing the reactivity of the starting tags in the resin coupling step. [reaction: see text].

Aza Compounds↗

An unprecedented nitrogen elimination reaction: mechanistic studies using 15N-labeled 4-amino-7-benzylpyrrolo[2,3-d][1,2,3]triazine-5-carbonitrile.

[formula: see text] In the course of our work on novel pyrrolo[2,3-d][1,2,3]triazines we have discovered that 1 undergoes an elimination of nitrogen at 250 degrees C to give 2. We have conducted 15N labeling studies that establish that the loss of N-2 and N-3 from 1 had occurred rather than N-1 and N-2, presumably via a retro Diels-Alder reaction of the imino tautomer 7. This study provides an alternative to the commonly accepted mechanism which involves the loss of N-1 and N-2 via the transient formation of a diazonium compound generated from 4-amino- or 4-oxo-substituted 1,2,3-triazines condensed with carbocycles or heterocycles.

Isotope Labeling↗

Determination of triazine herbicides in foods with liquid chromatography mass spectrometry.

Eight residual triazine herbicides and three metribuzin metabolites in foods were determined by liquid chromatography mass spectrometry (LC-MS) with an atmospheric pressure chemical ionization (APCI) interface, under both positive and negative ion modes. Herbicides were extracted with acetonitrile, and no cleanup procedure was adopted in this method. Four foods were spiked with eight herbicides and three metabolites at 0.05 ppm. The average recoveries of these herbicides usually ranged from 82 to 99% and the relative standard deviations were usually around 10%. These results suggest that LC-MS with APCI can be used to determine residues of triazine herbicides in foods.

Chromatography, Liquid↗

Selective sensing of triazine herbicides in imprinted membranes using ion-sensitive field-effect transistors and microgravimetric quartz crystal microbalance measurements.

A series of triazine herbicides consisting of the chlorotriazine atranex (atrazine), (1), prozinex, (2), tyllanex, (3), simanex, (4) and the methylthiolated triazines ametrex, (5), prometrex, (6) and terbutex, (7), were imprinted in an acrylamide-methacrylate copolymer. The polymer was deposited on the gate surface of ion-sensitive field-effect transistors (ISFETs) and piezoelectric Au-quartz crystals. Selective sensing of the imprinted substrates was accomplished by the imprinted polymer membrane associated with the ISFETs and Au-quartz crystals. Binding of the substrates onto the imprinted polymer associated with the gate of the ISFET alters the electrical charge and potential of the gate interface, thus allowing the potentiometric transduction of the binding events. The association of the substrates with the imprinted membrane linked to the Au-quartz crystal results in the membrane swelling, thus enabling the microgravimetric quartz crystal microbalance assay of the substrate binding events. The specificity of the imprinted recognition sites is attributed to complementary H-bond and electrostatic interactions between the substrates and the acrylamide-methacrylic acid copolymer.

Electrochemistry↗

The use of various immobilized-triazine affinity dyes for the purification of 6-phosphogluconate dehydrogenase from Bacillus stearothermophilus.

1. 6-Phosphogluconate dehydrogenase from Bacillus stearothermophilus was purified approximately 260-fold on triazine-immobilized dye columns to a final specific activity of 54 mumol of NADP+ reduced/min per mg of protein and an overall yield of 62%. 2. An investigation of the capacities of different triazine dyes that inhibit 6-phosphogluconate dehydrogenase was carried out. Cibacron Blue F3G-A and Procion Red HE-3B strongly inhibited the enzyme in free solution and were therefore chosen as the ligands in the purification scheme. 3. KCl was found to be the most suitable agent for eluting 6-phosphogluconate dehydrogenase from Procion Red HE-3B-Sepharose 6B. NADP+ could specifically elute 6-phosphogluconate dehydrogenase from Cibacron Blue F3G-A-Sepharose 6B. 4. A study of the effect of temperature on the binding of pure 6-phosphogluconate dehydrogenase to both Cibacron Blue-Sepharose and Procion Red-Sepharose showed that the binding increased with an increase in temperature.

Affinity Labels↗