Straightforward synthesis of 2,4,6-trisubstituted 1,3,5-triazine compounds targeting cysteine cathepsins K and S

Synthesis and Biological Evaluation of Novel Piperidine-3-Carboxamide Derivatives as Anti-Osteoporosis Agents Targeting Cathepsin K

A series of novel piperidamide-3-carboxamide derivatives were synthesized and evaluated for their inhibitory activities against cathepsin K. Among these derivatives, compound H-9 exhibited the most potent inhibition, with an IC50 value of 0.08 µM. Molecular docking studies revealed that H-9 formed several hydrogen bonds and hydrophobic interactions with key active-site residues of cathepsin K. In vitro, H-9 demonstrated anti-bone resorption effects that were comparable to those of MIV-711, a cathepsin K inhibitor currently in phase 2a clinical trials for the treatment of bone metabolic disease. Western blot analysis confirmed that H-9 effectively downregulated cathepsin K expression in RANKL-reduced RAW264.7 cells. Moreover, in vivo experiments showed that H-9 increased the bone mineral density of OVX-induced osteoporosis mice. These results suggest that H-9 is a potent anti-bone resorption agent targeting cathepsin K and warrants further investigation for its potential anti-osteoporosis values.

1,3,5-Triazine Nitrogen Mustards with Different Peptide Group as Innovative Candidates for AChE and BACE1 Inhibitors

A series of new analogs of nitrogen mustards (4a–4h) containing the 1,3,5-triazine ring substituted with dipeptide residue were synthesized and evaluated for the inhibition of both acetylcholinesterase (AChE) and β-secretase (BACE1) enzymes. The AChE inhibitory activity studies were carried out using Ellman’s colorimetric method, and the BACE1 inhibitory activity studies were carried out using fluorescence resonance energy transfer (FRET). All compounds displayed considerable AChE and BACE1 inhibition. The most active against both AChE and BACE1 enzymes were compounds A and 4a, with an inhibitory concentration of AChE IC₅₀ = 0.051 µM; 0.055 µM and BACE1 IC₅₀ = 9.00 µM; 11.09 µM, respectively.

Highly Selective Sub-Nanomolar Cathepsin S Inhibitors by Merging Fragment Binders with Nitrile Inhibitors

Pharmacological inhibition of cathepsin S (CatS) allows for a specific modulation of the adaptive immune system and many major diseases. Here, we used NMR fragment screening and crystal structure-aided merging to synthesize novel, highly selective CatS inhibitors with picomolar enzymatic Ki values and nanomolar functional activity in human Raji cells. Noncovalent fragment hits revealed binding hotspots, while the covalent inhibitor structure-activity relationship enabled efficient potency optimization.

Novel chalcone derivatives containing a 1,2,4-triazine moiety: design, synthesis, antibacterial and antiviral activities

A series of novel chalcone derivatives containing the 1,2,4-triazine moiety were synthesized and their structures were confirmed by 1H NMR, 13C NMR and elemental analyses. Antiviral bioassays revealed that most of the compounds exhibited good antiviral activity against tobacco mosaic virus (TMV) at a concentration of 500 μg mL-1. The designated compound 4l was 50% effective in terms of curative and protective activities against TMV with 50% effective concentrations (EC50) of 10.9 and 79.4 μg mL-1, which were better than those of ningnanmycin (81.4 and 82.2 μg mL-1). Microscale thermophoresis (MST) also showed that the binding of compound 4l to coat protein (TMV-CP) yielded a K d value of 0.275 ± 0.160 μmol L-1, which was better than that of ningnanmycin (0.523 ± 0.250 μmol L-1). At the same time, molecular docking studies for 4l with TMV-CP (PDB code:1EI7) showed that the compound was embedded well in the pocket between the two subunits of TMV-CP. Meanwhile, compound 4a demonstrated excellent antibacterial activities against Ralstonia solanacearum (R. solanacearum), with an EC50 value of 0.1 μg mL-1, which was better than that of thiodiazole-copper (36.1 μg mL-1) and bismerthiazol (49.5 μg mL-1). The compounds act by causing folding and deformation of the bacterial cell membrane as observed using scanning electron microscopy (SEM). The chalcone derivatives thus synthesized could become potential alternative templates for novel antiviral and antibacterial agents.

Discovery of 2-(aminopyrimidin-5-yl)-4-(morpholin-4-yl)-6- substituted triazine as PI3K and BRAF dual inhibitor

AIM

The discovery and development of novel agents simultaneously targeting PI3K/AKT/mammalian target of rapamycin and Ras/RAF/MEK, two signaling pathways, are urgent to improve the curative effect of kinase inhibitors and overcome acquired resistance.

METHODS/RESULTS

In the present study, 2-(2-aminopyrimidin-5-yl)-4-(morpholin-4-yl)-6-(N-cyclopropyl-N- (1-benzoylpiperidin-4-yl))triazines/pyrimidines were designed as PI3K and BRAF dual inhibitors. The synthesized 20 compounds exhibited potent antiproliferative effects in vitro against HCT116, A375, MCF-7, Colo205, A549 and LOVO cancer cell lines. The tested compounds A6, A7, A9 and A11 remarkably displayed inhibitory activities toward both PI3Kα and BRAF^V600E.

CONCLUSION

These results indicated that our design compounds can serve as potent PI3Kα and BRAF^V600E dual inhibitors and effective antiproliferative agents, which can be further optimized to discover more potent PI3Kα and BRAF^V600E dual inhibitors.

Selective inhibition of human cathepsin S by 2,4,6-trisubstituted 1,3,5-triazine analogs

We report herein the synthesis and biological evaluation of a new series of 2,4,6-trisubstituted 1,3,5-triazines as reversible inhibitors of human cysteine cathepsins. The desired products bearing morpholine and N-Boc piperidine, respectively, were obtained in three to four steps from commercially available trichlorotriazine. Seventeen hitherto unknown compounds were evaluated in vitro against various cathepsins for their inhibitory properties. Among them, compound 7c (4-(morpholin-4-yl)-6-[4-(trifluoromethoxy)anilino]-1,3,5-triazine-2-carbonitrile) was identified as the most potent and selective inhibitor of cathepsin S (Ki  =  2  ±  0.3 nM). Also 7c impaired the autocatalytic maturation of procathepsin S. Molecular docking studies support that 7c bound within the active site of cathepsin S, by interacting with Gly23, Cys25 and Trp26 (S1 subsite), with Asn67, Gly69 and Phe70 (S2 subsite) and with Gln19 (S1' pocket).

Synthesis and PI3 Kinase Inhibition Activity of Some Novel Trisubstituted Morpholinopyrimidines

A number of new substituted morpholinopyrimidines were prepared utilizing sequential nucleophilic aromatic substitution and cross-coupling reactions. One of the disubstituted pyrimidines was converted into two trisubstituted compounds which were screened as PI3K inhibitors relative to the well-characterized PI3K inhibitor ZSTK474, and were found to be 1.5⁻3-times more potent. A leucine linker was attached to the most active inhibitor since it would remain on any peptide-containing prodrug after cleavage by prostate-specific antigen, and it did not prevent inhibition of AKT phosphorylation and hence the inhibition of PI3K by the modified inhibitor.

Synthesis and PI 3-Kinase Inhibition Activity of Some Novel 2,4,6-Trisubstituted 1,3,5-Triazines

A number of new trisubstituted triazine phosphatidylinositol 3-kinase (PI3K) inhibitors were prepared via a three-step procedure utilizing sequential nucleophilic aromatic substitution and cross-coupling reactions. All were screened as PI3K inhibitors relative to the well-characterized PI3K inhibitor, ZSTK474. The most active inhibitors prepared here were 2–4 times more potent than ZSTK474. A leucine linker was attached to the most active inhibitor since it would remain on any peptide-containing prodrug after cleavage by a prostate-specific antigen, and it did not prevent inhibition of protein kinase B (Akt) phosphorylation, and hence, the inhibition of PI3K by the modified inhibitor.

Most rotavirus strains require the cation-independent mannose-6-phosphate receptor, sortilin-1, and cathepsins to enter cells

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Rotaviruses require the TGN to LE transporter CI-M6PR for cell entry.

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Sortilin-1 was identified as a cell factor involved in rotavirus replication.

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Rotaviruses require cathepsins also to enter Caco-2 cells.

Cathepsins, endosomal acid proteases, are transported from the trans-Golgi network to late endosomes by the mannose-6-phosphate receptor (M6PR). We have previously demonstrated that some rotavirus strains, like UK, Wa, WI61, DS-1, and YM, require the cation-dependent (CD-) M6PR and cathepsins to enter from late endosomes to the cytoplasm in MA104 cells, while other strains, like the simian strain RRV, which enter cells from maturing endosomes, do not. However, the role of other trans-Golgi network-late endosome transporters, such as the cation-independent (CI-) M6PR and sortillin-1, has not been evaluated. In this work, we found that several rotavirus strains that require the CD-M6PR for cell entry are also dependent on CI-M6PR and sortilin-1. Furthermore, we showed that the infectivity of all these rotavirus strains also requires cathepsins to enter not only MA104 cells, but also human intestinal Caco-2 cells. This study identifies sortilin-1 as a novel cell factor necessary for the infectivity of a virus; in addition, our results strongly suggest that cathepsins could be common cell factors needed for the infectivity of most rotavirus strains.

Discovery of 5,6-diaryl-1,2,4-triazines hybrids as potential apoptosis inducers

A series of 5,6-diaryl-1,2,4-triazines hybrids bearing a 1,2,3-triazole linker were synthesized by molecular hybridization strategy and evaluated for antiproliferative activity against three selected cancer cell lines (MGC-803, EC-109 and PC-3). The first structure-activity relationship (SAR) for these 5,6-diaryl-1,2,4-triazines is explored in this report with evaluation of 15 variants of the structural class. Among these chemical derivatives, 3-(((1-(4-fluorobenzyl)-1H-1,2,3-triazol-4-yl)methyl)thio)-5,6-diphenyl-1,2,4-triazine (11E) showed the more potent inhibitory effect against three cell lines than 5-Fu. Cellular mechanism studies in MGC-803 cells elucidated 11E inhibited colony formation and arrested cell cycle at G2/M phase. Furthermore, compound 11E caused morphological changes, decreased mitochondrial membrane potential, and induced apoptosis through the apoptosis-related proteins in MGC-803 cells. It was the first time, to our knowledge, that 5,6-diaryl-1,2,4-triazines bearing a 1,2,3-triazole linker were used as potential apoptosis inducers.

Rational design, synthesis and biological screening of triazine-triazolopyrimidine hybrids as multitarget anti-Alzheimer agents

In our endeavor towards the development of potent multitarget ligands for the treatment of Alzheimer's disease, a series of triazine-triazolopyrimidine hybrids were designed, synthesized and characterized by various spectral techniques. Docking and scoring techniques were used to design the inhibitors and to display their interaction with key residues of active site. Organic synthesis relied upon convergent synthetic routes were mono and di-substituted triazines were connected with triazolopyrimidine using piperazine as a linker. In total, seventeen compounds were synthesized in which the di-substituted triazine-triazolopyrimidine derivatives 9a-d showed better acetylcholinesterase (AChE) inhibitory activity than the corresponding tri-substituted triazine-triazolopyrimidine derivatives 10a-f. Out of the disubstituted triazine-triazolopyrimidine based compounds, 9a and 9b showed encouraging inhibitory activity on AChE with IC₅₀ values 0.065 and 0.092 μM, respectively. Interestingly, 9a and 9b also demonstrated good inhibition selectivity towards AChE over BuChE by ∼28 folds. Furthermore, kinetic analysis and molecular modeling studies showed that 9a and 9b target both catalytic active site as well as peripheral anionic site of AChE. In addition, these derivatives effectively modulated Aβ self-aggregation as investigated through CD spectroscopy, ThT fluorescence assay and electron microscopy. Besides, these compounds exhibited potential antioxidants (2.15 and 2.91 trolox equivalent by ORAC assay) and metal chelating properties. In silico ADMET profiling highlighted that, these novel triazine derivatives have appropriate drug like properties and possess very low toxic effects in the primarily pharmacokinetic study. Overall, the multitarget profile exerted by these novel triazine molecules qualified them as potential anti-Alzheimer drug candidates in AD therapy.

Nanomolar-Potency Aminophenyl-1,3,5-triazine Activators of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Chloride Channel for Prosecretory Therapy of Dry Eye Diseases

Dry eye disorders are a significant health problem for which limited therapeutic options are available. CFTR is a major prosecretory chloride channel at the ocular surface. We previously identified, by high-throughput screening, aminophenyl-1,3,5-triazine CFTR_act-K089 (1) that activated CFTR with EC₅₀ ≈ 250 nM, which when delivered topically increased tear fluid secretion in mice and showed efficacy in an experimental dry eye model. Here, functional analysis of aminophenyl-1,3,5-triazine analogs elucidated structure-activity relationships for CFTR activation and identified substantially more potent analogs than 1. The most potent compound, 12, fully activated CFTR chloride conductance with EC₅₀ ≈ 30 nM, without causing cAMP or calcium elevation. 12 was rapidly metabolized by hepatic microsomes, which supports its topical use. Single topical administration of 25 pmol of 12 increased tear volume in wild-type mice with sustained action for 8 h and was without effect in CFTR-deficient mice. Topically delivered 12 may be efficacious in human dry eye diseases.