Synthesis and pharmacological evaluation of novel thienopyrimidine and triazolothienopyrimidine derivatives

Novel tricyclic thienopyrimidines (2, 3, 5, 8) and triazole-fused tetracyclic thienopyrimidines (6a–c and 9a–c) were synthesized from the precursor 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile (1). The structures of newly synthesized compounds were established by spectral and analytical data. The title compounds were screened for analgesic, anti-inflammatory, ulcerogenicity index, and antibacterial activities. Test compounds exhibited significant activity, the compounds (6a–c) and (9a–c) showed more potent analgesic activity, and the compounds (6c) and (9c) showed more potent anti-inflammatory activity than the reference standard Diclofenac Sodium. All the synthesized compounds exhibited remarkable antibacterial activity.     

Synthesis and antitumor screening of new series of pyrimido-[4,5-b]quinolines and [1,2,4]triazolo[2′,3′:3,4]pyrimido[6,5-b]quinolines

New series of pyrimido[4,5-b]quinolines and [1,2,4]triazolo[2′,3′:3,4]pyrimido[6,5-b]quinolines have been synthesized. Compounds 4a, 4e, 4f, 4h, 5b, 5d, 6a, 6d, 6e, 8c, 8d, 10c–e, 10h, 11a, 11b, and 12a were tested for in vitro antitumor activity against human breast carcinoma (MCF-7) cell line, where compound 8d was found to be the most active member with IC₅₀ value of 3.62 μM. The DNA-binding affinity for the same compounds showed that compounds 8d and 10d exhibited the highest affinity to DNA. The detailed synthesis, spectroscopic, and biological data are reported.     

Synthesis, antitumor activity, and structure–activity relationship of some 4H-pyrano[3,2-h]quinoline and 7H-pyrimido[4′,5′:6,5]pyrano[3,2-h]quinoline derivatives

Several 4H-pyrano[3,2-h]quinoline (3a–d, 4a, 7a,b, 9a–c, 10a,b, 11a,b, and 13a–c) and 7H-pyrimido[4′,5′:6,5]pyrano[3,2-h]quinoline derivatives (8a–c) were obtained by treatment of 8-hydroxyquinoline (1a) and 8-hydroxy-2-methylquinoline (1b) with α-cyano-p-chloro/bromocinnamonitrile (2a,b) or 4H-pyrano[3,2-h]quinoline derivatives (3a,c,d) with different electrophilic reagents followed by nucleophilic reagents. Structures of these compounds were established on the basis of spectral data. The antitumor activity of the synthesized compounds was investigated in comparison with Vinblastine. Among them, compounds 3c,d, 4a, 8b, 9b,c, 11a,b, and 13a,c inhibited the growth of cancer cells compared to Vinblastine. The structure–activity relationships were discussed.     

Synthesis, antimicrobial, and antioxidant activities of some new indole analogues containing pyrimidine and fused pyrimidine systems

To examine new leads with potential antimicrobial and antioxidant activities, a new series of tetrahydropyrimidines (2a–c, 3a–c and 4a–c), pyrazolo[3,4-d]pyrimidines (5a–c), and ditetrazolo[1,5-a;1′,5′-c]pyrimidines (6a–c) were synthesized in this study using appropriate synthetic routes. The newly synthesized compounds have been tested for their antimicrobial and antioxidant activities against DPPH stable free radical. In the case of antibacterial activity, compounds 2a, 6a, and 6c exhibited the maximum zone of inhibition against Staphylococcus aureus; compound 6c exhibited maximum zone of inhibition against Pseudomonas aeruginosa; and compound 2a showed maximum inhibitory growth against Klebsiella pneumonia. While in the case of antifungal activities, compound 5a showed good zone of inhibition against Aspergillus oryzae, compounds 2b and 6a exhibited maximum zone of inhibition against Aspergillus niger. In case of antioxidant activities, compound 2a showed the highest DPPH radical scavenging activity.     

Synthesis, biological evaluation, and molecular modeling studies of novel heterocyclic compounds as anti-proliferative agents

Two novel series of heterocyclic compounds have been synthesized. In first series, isatin was allowed to react with substituted aromatic/cyclic carbonyl compounds to get desired mannich bases (2a–e). In second series, 4,5-disubstituted oxazoles (6a–p) were synthesized. Eight compounds (2c, 6a, 6e, 6f, 6i, 6j, 6m, and 6n) were screened for anticancer activity in 60 cell lines. Compound 2c, 1-[(4,7,7-trimethyl-3-oxobicyclo[2.2.1]heptan-2-yl)methyl]indoline-2,3-dione, showed maximum activity and thus, selected for further evaluation at five dose level screening. Furthermore, molecular docking studies of compounds 2c into the colchicine-binding site of tubulin, revealed possible mode of inhibition by the compound.     

Synthesis and cytotoxicity of novel 4-(4-(substituted)-1H-1,2,3-triazol-1-yl)-N-phenethylbenzenesulfonamides

A new series of 4-(4-(substituted)-1H-1,2,3-triazol-1-yl)-N-phenethylbenzenesulfonamide derivatives 5 were synthesized through the Click approach and evaluated for their cytotoxic activity against four cancer cell lines (HuCCA-1, HepG2, A549, and MOLT-3). Most of the synthesized triazoles 5 displayed cytotoxicity against MOLT-3 cell line, except for analogs 5a–c and 5e. Significantly, 4-phenyltriazoles (5a and 5n), 4-(naphthalen-2-yloxy)methyltriazole 5d, as well as 4-((2-oxo-2H-chromen-7-yl)oxy)methyltriazole 5l showed higher cytotoxic activity against HepG2 cells than the reference drug, etoposide. Interestingly, the 4-phenyltriazole 5a was the most potent and promising compound with IC₅₀ value of 9.07 μM against HepG2 cell line. The analog 5a also exerted the highest cytotoxic activity against HuCCA-1 cells. This finding provides the novel lead molecules for further development.     

New aminoadamantane derivatives with antiproliferative activity

1-Benzyl-2-aminoadamantanes 2a–c, conformationally constrained aminoadamantanes 3a, b and 4 and diaminoadamantanes derivatives 5a–c, 6a–c were synthesized and tested as antiproliferative agents. The in vitro biological evaluation showed a significant difference in activity between 1-phenyl and 1-benzyl derivatives.     

Synthesis and evaluation of anti-proliferative activity of 1,4-disubstituted phthalazines

A series of new phthalazine derivatives 3a–i and 4a–c were synthesized via the reaction of 1-chlorophthalazine derivative 2 with either N-substituted-piperazines, primary or their secondary amines. The structure of the synthesized, new compounds were characterized by spectral data. The anti-proliferative activity on human breast cancer cell line MCF-7 of the synthesized compounds was determined. The results showed that six of the test compounds (3a, 3g, 3i, and 4a–c) displayed potent cytotoxic activity ranging from 1.4 to 2.3?μmol.     

Synthesis of azabicyclo[4.2.0]octa-1,3,5-trien-8-one analogues of 1H-imidazo[4,5-c]quinoline and evaluation of their antimicrobial and anticancer activities

In search of new and efficient antimicrobial and anticancer agents based on the imidazoquinoline structural framework, a series of novel 7-(1-isobutyl-1H-imidazo[4,5-c]quinolin-4-yl)-7-azabicyclo[4.2.0]octa-1,3,5-trien-8-ones (8a–f) were synthesized from the corresponding 2,4-dihydroxoquinoline derivative through multistep reactions. The structures of these compounds were established by IR, ¹H NMR, ¹³C NMR and mass spectral studies. The 7-(1-isobutyl-1H-imidazo[4,5-c]quinolin-4-yl)-7-azabicyclo[4.2.0]octa-1,3,5-trien-8-one (8a–f) analogues were evaluated for their in vitro antimicrobial activity by serial dilution method minimum inhibitory concentration (MIC). The derivatives 8c, 8e and 8f exhibited excellent antibacterial activity comparable to the parent drug ampicillin with MIC value. Compounds 7a–f and 8a–f were also assessed for their cytotoxic activity (IC₅₀) against HeLa cells using the Trypan blue exclusion assay method. The compounds 7c and 8b displayed potential anticancer activity. In a molecular docking study, these compounds showed minimum binding energy and good affinity towards the active pocket. They are believed to be good inhibitors of β-tubulin. The results of these studies provided evidence that 7-(1-isobutyl-1H-imidazo[4,5-c]quinolin-4-yl)-7-azabicyclo[4.2.0]octa-1,3,5-trien-8-one (8a–f) derivatives are a promising class of antibacterial and anticancer agents.     

Design, synthesis, and anticonvulsant screening of some substituted piperazine and aniline derivatives of 5-phenyl-oxazolidin-2,4-diones and 5,5-diphenylimidazolidin-2,4 diones

Substituted piperazine and aniline derivatives of oxazolidin-2,4-diones and imidazolidin-2,4-diones were synthesized by N3 alkylation and screened for their anticonvulsant activity by the maximal electroshock (MES) test, and their neurotoxicity was evaluated by the rotarod test. Among all the synthesized derivatives, compounds 4b, 6c, 6d, 10b, 11a, 11b, and 11d were found to exhibit maximum seizure protection in MES test and were devoid of any neurotoxic effects. Furthermore, the functional activity of these compounds were evaluated in vivo for 5-HT_1A receptor affinity by using rectal body temperature and lower lip retraction in rats, while head twitch response in mice was performed for the determination of probable affinity toward 5-HT_2A receptor. The results of these tests demonstrated that compounds 4b, 6c, 6d, 10b, 11a, 11b, and 11d exhibited 5-HT_1A (pre- and postsynaptic) agonist/antagonist features whereas compounds 11a and 11b exhibited antagonist action for 5-HT_2A receptor. From the in vivo studies it was observed that a majority of aniline derivatives (6c, 6d, 11a, 11b, 11d) were found to be more active as compared to their bulky piperazine congeners (4b, 10b). Thus, the overall reduction in the bulkiness of the derivatives without compromising the lipophilicity is well appreciated for providing insights into the structural requirements necessary for development of new effective molecules having anticonvulsant effect.     

Synthesis of some new indolo[2,3-c]isoquinolinyl pyrazoles, -1,3,4-oxadiazoles and their biological activities

A new series of novel compounds [10-substituted 6H, 7H-indolo[2,3-c]isoquinolin-5-one-6-yl]carbohydrazides (3a–c), 1-[10-substituted 6H, 7H-indolo[2,3-c]isoquinolin-5-one-6-yl]fomyl-, -3′,5′-dimethylpyrazoles (4a–c), -3′,5′-diphenylpyrazoles (5a–c), -3′-methylpyrazol-5′-ones (6a–c) and -1′,3′,4′-oxidiazole-2′-thiones (7a–c) linked to indoloisoquinoline at position-6 through formyl bridge was prepared. The structures of these newly synthesized compounds were confirmed by their spectral studies and elemental analysis. These compounds have been screened for their antimicrobial and antioxidant activities. Compounds 4a, 4b, 5a, 5b, 5c, 6b, 7a, and 7c exhibited the maximum zone of inhibition against A. niger, A. flavus, and A. fumigatus. Compounds 4a, 5a, 5c, 6b, 6c, 7a, and 7b showed good antibacterial activity. Compounds 4b, 4c, 5b, 5c, 6a, 6b, 7a, 7b, and 7c showed good radical scavenging activity compared with standards.     

Synthesis, molecular docking study, and anticancer activity of triaryl-1,2,4-oxadiazole

This study describes synthesis of a new group of triaryl-1,2,4-oxadiazole derivatives and their anticancer activities. The target compounds were prepared from reaction of different imines and 4-substituted benzohydroxyiminoyl chlorides. All the synthesized compounds were screened for antiproliferative activities against MCF7 and K562 cell lines using MTT assay at 50-μM concentration. Four compounds that showed more than 50 % cytotoxicity were selected for determination of IC₅₀. Out of these, 6c-1y showed remarkable inhibitory cytotoxicity activity against MCF7 and K562 cell lines with IC₅₀ 6.50 and 21.66 μM, respectively. A molecular modeling study where 6c-1y was docked in the binding site of COX-2 showed a 2.3-Å hydrogen bond forming via hydroxyl group of Ser516 residue and oxygen of central oxadiazole ring and triaryl moiety of 6c-1y oriented toward the hydrophobic pockets of COX-2. Our data indicate that these derivatives may present promising chemotherapeutic agents, possibly targeting COX-2 pathway.     

Synthesis, antimicrobial, analgesic activity, and molecular docking studies of novel 1-(5,7-dichloro-1,3-benzoxazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde derivatives

Condensation of 5,7-dichloro-2-hydrazino-1,3-benzoxazole 3 with different aromatic acetophenones in methanol using catalytic amount of glacial acetic acid afforded the corresponding 1-phenylethanone(5,7-dichloro-1,3-benzoxazol-2-yl)hydrazones 5a–e in good yield. The compounds 5a–e, when subjected to Vilsmeier–Haack reaction with POCl₃ in DMF yielded (5,7-dichloro-1,3-benzoxazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde derivatives 6a–e. The structural assignments of the compounds 6a–e are based on their spectral data and elemental analysis. The obtained compounds were tested for antimicrobial and analgesic activities, and subjected to molecular docking studies with respect to antimicrobial activity. The compound 6b showed pronounced antimicrobial and analgesic activity and exhibited an interesting binding profile with very high receptor affinity.     

Microwave-assisted synthesis of triazolothiadiazole analogs as anticancer agents

A series of S-alkyl derivatives of 3-(substituted-(1,1′-biphenyl)-3-yl)[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole-6-thiol (4a–j) were synthesized by conventional and microwave irradiation methods. Microwave method proved to be a rapid and better yield compare to that of conventional method. The synthesized compounds were characterized by ¹H NMR, ¹³C NMR, ¹⁹F NMR, IR, LCMS, and elemental spectroscopic analysis. These compounds were screened for their in vitro anticancer activity by MTT assay. Among the tested compounds, the compound 4c was the most promising anticancer agent with IC₅₀ value 12 μM in HT29 cell line.     

Synthesis and biological evaluation of novel 4,5-dihydropyrazole derivatives as potent anticancer and antimicrobial agents

A focused library of 4,5-dihydropyrazole dervivatives (4, 5, 6, 7a–h, 8, 9a–g, and 10a–g) were synthesized from novel 5-(2,6-difluorophenyl)-3-phenyl-4,5-dihydropyrazole-1-carbothioamide 4. The synthesized compounds were characterized using elemental analysis and spectral data (IR, mass spectra, ¹H and ¹³C NMR) and evaluated for antimicrobial activity by broth dilution method and in vitro anticancer activity. Among the synthesized compounds 7a, 9c, 9g, and 10d exhibit broad spectrum antimicrobial activity against tested microbial strains. The in vitro cancer results ascertain 7a, 9c, and 10d are most potent molecules in comparison to reference standard cisplatin.     

Design, synthesis, antimicrobial, anti-inflammatory, and analgesic activity of novel dihydrobenzo furo[3,2-e]isoxazolo[4,5-b]azepin-5(5aH)-ones

Novel series of dihydro benzofuro[3,2-e]isoxazolo[4,5-b]azepin-5(5aH)-ones 6 have been synthesized from 3,5-dimethyl-4-nitroisoxazole 1. Compound 1 on treatment with salicyl aldehydes afforded the corresponding nitrostyrylisoxazoles 3, which upon reaction with ethyl bromo acetate followed by cyclization with triethylamine furnished ethyl 2,3-dihydro-3-[(3-methyl-4-nitro-5-isoxazolyl)methyl]benzofuran-2-carboxylates 5. Reductive cyclization of compounds 5 was effected with SnCl₂–MeOH to give the title compounds 6. Compounds 4–6 were characterized by IR, ¹H NMR, ¹³C NMR and Mass spectral data. The title compounds 6a–g were evaluated for their antimicrobial, anti-inflammatory, LOX-5 inhibitory, and analgesic activity. Compounds 6b and 6c exhibited significant antimicrobial activity, potent anti-inflammatory and analgesic activities as that of standard drugs.     

[1,2,4]Triazolo[4,3-a]quinoxaline: synthesis, antiviral, and antimicrobial activities

A series of novel [1,2,4]triazolo[4,3-a]quinoxaline derivatives and their isosteres, pyrimido-quinoxaline, were synthesized as potential antiviral and antimicrobial agents. The new compounds were synthesized via aromatic nucleophilic substitution of 4-chloro-8-methyl[1,2,4]triazolo[4,3-a]quinoxaline-1-amine with different amines and triazole-2-thiol. Some of the synthesized compounds were subjected to antiviral and cytotoxicity screening using plaque-reduction assay. Most of the tested compounds exhibited cytotoxicity at concentration 160?μg/ml and compound 8b showed promising antiviral activity. In vitro antimicrobial screening against different pathogenic organisms using agar diffusion method demonstrated that compounds 4d, 6c, 7b, and 8a exhibit antibacterial and/or antifungal activities.     

Synthesis and anticancer activity of some novel fused pyridine ring system

New series of pyrido[3??,2??:4,5]thieno[3,2-d]pyrimidines (7a,b) and thieno[2,3-b:4,5-b??] dipyridine (11a?Cc) were synthesized from 4-aryl-6-(4-chlorophenyl)-2-thioxo-1,2-dihydro pyridine-3-carbonitriles 4a,b via application of Thorpe-Zielger reaction. The novel target compounds were evaluated in vitro for their anticancer activity against human breast adenocarcinoma MCF-7 and colon carcinoma cell line (HCT 116). Most of the tested compounds exploited potent to moderate growth inhibitory activity, in particular compound 11d, which exhibited superior potency to the reference drug Doxorubicin (IC₅₀ = 5.95, 6.09 and 8.48, 8.15 ??M, respectively). The structures of the compounds obtained were determined by spectroscopic data.     

Synthesis and in vitro antitumor activity of new quinoline, pyrimido[4,5-b]quinoline, [1,2,3]triazino[4,5-b]quinoline, and [1,2,4]triazolo[2′,3′:3,4]pyrimido[6,5-b]quinoline analogs

New series of quinoline, pyrimido[4,5-b]quinoline, [1,2,3]triazino[4,5-b]quinoline, and [1,2,4]triazolo[2′,3′:3,4]pyrimido[6,5-b]quinoline analogs have been synthesized and characterized by analytical and spectrometrical methods (IR, ¹H NMR, ¹³C NMR, MS). Fifteen of the newly synthesized compounds; namely, 3a, b, 4b, 6a, b, 10a–f, and 14a–d were evaluated for their in vitro antitumor activity at the National Cancer Institute (NCI) 60 cell lines panel assay. Compounds 4b and 10f are the most active members in this study, demonstrating significant broad spectrum antitumor activity against most of the tested sub-panel tumor cell lines. The detailed synthesis, spectroscopic, and biological data are described.     

Synthesis and antiprotozoal activity of 1,2,3,4-tetrahydro-2-thioxopyrimidine analogs of combretastatin A-4

Eighteen 1,2,3,4-tetrahydro-2-thioxopyrimidine analogs (5a?Cj, 6a?Ce, and 7a?Cc) of combretastatin A-4 were synthesized with the objective of discovering compounds capable of controlling the growth of Trypanosoma?lewisii, Leishmania?tarantole, Plasmodium?falciparum, and Giardia?lamblia. Even though the target compounds demonstrated differential cytotoxicity against mammalian cancer cells, with IC₅₀ values ranging from 0.5 to >100???M, the range of activity against Trypanosoma, Leishmania, and Plasmodium, and to a good extent for Giardia, was narrow. The IC₅₀ values of ??active?? compounds against the parasites ranged from about 10???? to slightly greater than 50???M. Specifically, compounds 5a, 5g, 5h, 6c, 7a, and 7c were not cytotoxic against mammalian cancer cells (IC₅₀?>?100???M) but showed good activity against the parasites, except Giardia (e.g., compounds 6c and 7a), suggesting that these compounds may act in a similar mechanism in parasites. Compounds 5f and 6b were previously shown to promote microtubule depolymerization in mammalian cells.