Synthesis of some new azole, pyrimidine, pyran, and benzo/naphtho[b]furan derivatives incorporating thiazolo[3,2-a]benzimidazole moiety

New benzimidazothiazole derivatives as anti-inflammatory, antitumor active agents: Synthesis, in-vitro and in-vivo screening and molecular modeling studies

A new series of benzimidazothiazole derivatives has been synthesized. The structure of the products was confirmed by spectroscopic techniques such as IR, NMR and mass spectroscopy. The tested compounds were evaluated for their anti-inflammatory activity either in vitro through the COX enzyme inhibition assay, or in vivo through carrageenan paw edema technique. Results revealed that compound 25 and 29 represented the most active ones among the entire series with % inhibition 72.19, 72.07 for COX-1, and 87.46, 87.38 for COX-2, respectively. Interestingly, all synthesized compounds exhibited IC₅₀ values less than both reference drugs celecoxib and naproxen, indicating their superior potency. For compound 25, it showed about 340 and 198 times more potent than celecoxib and naproxen respectively as COX-1 inhibitor (IC₅₀ value 0.044 vs. 15.000 and 8.700 µM), and 10 and 115 times more potent than the same drugs as COX-2 inhibitor (IC₅₀ value 4.52 vs. 40.00 and 520.00 nM). The antitumor activity of the products was also evaluated and the results obtained are consistent with those obtained by the anti-inflammatory screening where compounds 25 and 29 proved to be the most active ones among the other compounds with %GI ranging from 31.5 to 62.5% and they exhibited the lowest IC₅₀ values as well. The ADMET analysis of the tested compounds was also performed in addition to the molecular modeling studies that included flexible alignment, surface and electrostatic maps in addition to the Lipinisk's rule of five.

Tyrosine kinase inhibition effects of novel Pyrazolo[1,5-a]pyrimidines and Pyrido[2,3-d]pyrimidines ligand: Synthesis, biological screening and molecular modeling studies

Tyrosine kinases are one of the most critical mediators in the signaling path way. Late studies have proved the part of tyrosine kinases in the pathophysiology of cancer diseases. This current research paper has focused on investigating the novel Pyrazolo[1,5-a]pyrimidines and Pyrido[2,3-d]pyrimidines as a small molecules that can inhibit tyrosine kinase in cancer cells. NCI protocol was applied to test the antitumor activity of such compounds. Leukemia and renal cancer cell lines proved to be sensitive to some derivatives such as 6b-d, 9a and 11 with GI% values ranging from 30.4 to 41.3%. In addition, compound 11 proved to be the most active against MCF-7 with GI% 62.5. The synthesized compounds were also evaluated for their inhibitory effects against EGFR kinase enzyme. Compound 9b proved to be the most active one among the synthesized series with inhibition % value of 81.72 at 25 nM concentration and IC₅₀ 8.4 nM which is very close to the reference drug Sorafenib. In vitro cytotoxicity test was also performed using the MCF-7 breast cell line. Computer modeling using the active site of tyrosine kinase as a template and the most active tyrosine kinase inhibitors were calculated. Docking studies of the synthesized compounds into the active site of EGFR kinase domain showed good agreement with the obtained biological results.

Induction of intrinsic apoptosis pathway in colon cancer HCT-116 cells by novel 2-substituted-5,6,7,8-tetrahydronaphthalene derivatives

2-Acetyl tetralin (1) reacted with N,N-dimethylformamide dimethylacetal (DMF-DMA) to afford the enaminone 3. The reaction of 3 with piperidine and morpholine afforded the trans enaminone 5a,b, respectively. Compound 3 was treated with primary aromatic amines to give secondary enaminones 6a-e. The enaminone 3 reacted with acetylglycine and hippuric acid to yield pyranones 10a, b, respectively. The reaction of enaminone 3 with 1,4-benzoquinone and 1,4-naphthoquinone gave benzofuranyl tetralin derivatives 14a,b, respectively. Also, when 3 reacted with 5-amino-3-phenyl-1H-pyrazole 15a and 5-amino-1,2,3-triazole 15b, it afforded the new pyrazolo[1,5-a]pyrimidine 17a and 1,2,3-triazolo[1,5-a]pyrimidine 17b, respectively. While the reaction of 3 with pyrimidines 18a, b resulted in the formation of pyrido[2,3-d]pyrimidine derivatives 20a, b, respectively. Investigations of the cytotoxic effect of those compounds against different human cell lines indicated that some compounds showed high selective cytotoxicity against colon cancer HCT-116 cells. Some of these compounds led to DNA damaging and fragmentation that was associated with the induction of apoptosis via mitochondrial pathway. This pathway is initiated by the impairment of mitochondrial transmembrane potential (Δψm) and in response to that the mitochondria released cytochrome c increased, that in turn activated caspase-9 and caspase-3 and induced apoptosis. Compounds 17b and 20b were promising anti-cancer agents that induced intrinsic apoptosis pathway in colon cancer cells.

Multistage fragmentation of ion trap mass spectrometry system and pseudo-MS3 of triple quadrupole mass spectrometry characterize certain (E)-3-(dimethylamino)-1-arylprop-2-en-1-ones: a comparative study

A new approach was recently introduced to improve the structure elucidation power of tandem mass spectrometry simulating the MS³ of ion trap mass spectrometry system overcoming the different drawbacks of the latter. The fact that collision induced dissociation in the triple quadrupole mass spectrometer system provides richer fragment ions compared to those achieved in the ion trap mass spectrometer system utilizing resonance excitation. Moreover, extracting comprehensive spectra in the ion trap needs multistage fragmentation, whereas similar fragment ions may be acquired from one stage product ion scan using the triple quadrupole mass spectrometer. The new strategy was proven to enhance the qualitative performance of tandem mass spectrometry for structural elucidation of different chemical entities. In the current study we are endeavoring to prove our hypothesis of the efficiency of the new pseudo-MS³ technique via its comparison with the MS³ mode of ion trap mass spectrometry system. Ten pharmacologically and synthetically important (E)-3-(dimethylamino)-1-arylprop-2-en-1-ones (enaminones 4a–j) were chosen as model compounds for this study. This strategy permitted rigorous identification of all fragment ions using triple quadrupole mass spectrometer with sufficient specificity. It can be used to elucidate structures of different unknown components. The data presented in this paper provide clear evidence that our new pseudo-MS³ may simulate the MS³ of ion trap spectrometry system.

Design, diversity-oriented synthesis and structure activity relationship studies of quinolinyl heterocycles as antimycobacterial agents

The current study reports design and diversity oriented synthesis of novel bis heterocycles with a common 2-methyl, C-4 unsubstituted quinoline moiety as the central key heterocycle. Employing reagent based skeletal diversity approach; a facile synthesis of bis heterocycles with different heterocyclic rings at C-3 position of the quinoline moiety has been accomplished. A broad range of heterocyclic frameworks thus obtained were evaluated for their antimycobacterial activity. The active scaffolds were further explored by a parallel library generation in order to establish SAR. Further, low cytotoxicity against A549 cell line enhances the potential of the synthesized molecules as promising antimycobacterial agents.

A Facile Synthesis of Pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine and Pyrido[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazine Bearing a Thiophene Moiety

Pyridinone derivative8was synthesized and transformed into the respective chloropyridine9, which was allowed to react with hydrazine hydrate to afford pyrazolo[3,4-b]pyridin-3-amine derivative11. Compound11was used as a key intermediate for a facile synthesis of the title compounds14,15,17,21a,b, and24a–cwhere the reaction of11with some 1,3-dielecrophiles resulted in the formation of pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidines14,15, and17, whereas diazotization of compound11gave the respective diazonium salt18which was coupled with some active methylene-containing compounds to give the corresponding hydrazones19a,band22a–c. Cyclization of the latter hydrazones yielded the pyrido[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazines21a,band24a–c, respectively.

3-(3-Methoxyphenyl)benzo[d]thiazolo[3,2-a]imidazol-9-ium hydrogen sulfate

In the title mol­ecular salt, C₁₆H₁₃N₂OS⁺·HSO₄⁻, the thia­zolo[3,2-a]benzimidazolium ring system is roughly planar [maximum deviation = 0.046 (3) Å] and makes a dihedral angle of 58.22 (11)° with the benzene ring. The meth­oxy group is almost coplanar with its attached benzene ring [C_meth­yl—O—C—C = −1.6 (5)°]. In the crystal, the cation is linked to the anion by a bifurcated N—H⋯(O,O) hydrogen bond, generating an R₁²(4) ring motif. The ion pairs are then connected by a C—H⋯O hydrogen bond into inversion dimers and these dimers are further linked by O—H⋯O hydrogen bonds into an infinite tape along [100]. A π–π stacking inter­action [centroid-to-centroid distance = 3.5738 (18) Å] and a short inter­molecular contact [S⋯O = 2.830 (3) Å] are also observed.

(Z)-2-(4-Chloro-benzyl-idene)benzo[d]thia-zolo[3,2-a]imidazol-3(2H)-one

The mol-ecule of the title compound, C(16)H(9)ClN(2)OS, is approximately planar, the dihedral angle between the thia-zolo[3,2-a]benzimidazole ring system and the 4-chloro-phenyl ring being 2.10 (5)°. An intra-molecular C-H⋯S inter-action generates an S(6) ring motif. In the crystal, mol-ecules are stacked into columns along the b axis by π-π inter-actions with centroid-centroid distances of 3.6495 (7)-3.9546 (8) Å.