Synthesis, characterization and pharmacological evaluation of (E)-N′-(substituted-benzylidene)isonicotinohydrazide derivatives as potent anticonvulsant agents

A series of (E)-N′-(substituted-benzylidene)isonicotinohydrazide derivatives were synthesized by coupling it with different substituted aldehydes, acetophenone, and benzophenones in presence of absolute ethanol along with catalytic amount of glacial acetic acid. All the synthesized compound were confirmed and characterized by using various spectral technique like IR, ¹H NMR, ¹³C NMR, and mass spectroscopy studies. Anticonvulsant evaluations of all the synthesized compounds were done using various seizures models like maximal electroshock-induced seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) at a dose of 30, 100, and 300?mg/kg body weight and anticonvulsant activity was noted at 0.5?h and 4?h time intervals after the drug administration. Compound 1a (E)-N′-2-benzylidene isonicotinohydrazide, 1g (E)-N′-2-ethoxybenzylidene isonicotinohydrazide, 1k (E)-N′-3-flourobenzylidene isonicotinohydrazide and 3a (E)-N′-diphenylmethylene isonicotinohydrazide showed protection in MES model, which indicates that these compounds have the ability to prevent the spread of seizure at 300?mg/kg dose and showed protection at 0.5?h duration. Compound 3a was also found to be active in scPTZ screen at a dose of 300?mg/kg. In neurotoxicity screen, all the synthesized compounds were found non-toxic except compounds 1n, 2a, and 3b. Further compounds 1a, 1g, 1k, and 3a were also evaluated in the minimal clonic seizure model and exhibited potent anticonvulsant activity with lower neurotoxicity. Among all synthesized derivatives, analogue 3a was found to exhibit protection in MES and scPTZ seizure models. This study proved that isonicotinoyl hydrazides synthesized by condensing isoniazid with various aldehydes and ketones displayed moderate to potent anticonvulsant activity.     

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, 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 activity of benzofuran barbitone and benzofuran thiobarbitone derivatives

The synthesis of novel series of benzofuran derivatives, containing barbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl) methylidene]pyrimidin-2,4,6(1H,3H,5H)-trione (4a–i) and thiobarbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl)methylidene]-2-thioxodihydropyrimidin-4,6(1H, 5H)-dione (5a–i) have been reported. The target compounds (4a–i) and (5a–i) were synthesized by the Knoevenagel condensation of (5-substituted-1-benzofuran-2-yl)(2/4-substitutedphenyl) methanone (3a–i) with barbituric acid and thiobarbituric acid, respectively, in acid medium. These compounds were screened for the antimicrobial and antioxidant activities. From antimicrobial activity results it was found that compounds 4a, 5a, 4c, and 5c displayed good antibacterial and antifungal activity against all tested strains. Further, the synthesized compounds were studied for docking on the enzyme, Glucosamine-6-phosphate synthase and the compounds 4c and 5c have emerged has an active antimicrobial agent with least binding energy (?5.27 and ?4.85 kJ mol^?1). Compounds 4e, 4f, 5e, and 5f showed promising free radical scavenging activity and compounds 5a and 5b showed good chelating ability with Fe²⁺ ions.     

Synthesis of β-amino carbonyl derivatives of coumarin and benzofuran and evaluation of their biological activity

A series of β-amino carbonyl compounds containing coumarin (4a–h) and benzofuran (6a–i) moieties was synthesized by a three component Mannich reaction of 3-acetyl-2H-chromen-2-one (1) or 1-(1-benzofuran-2-yl) ethanone (5) with p-substituted aromatic aldehydes (2a–g) and aromatic amines (3a–b) in the presence of cerric ammonium nitrate as a catalyst. The newly synthesized compounds were screened for antimicrobial and antioxidant activities. Compounds 4b, 4e, 4f, 6f, 6g, and 6i showed microbial inhibition with minimal inhibition concentration ranging between 0.040 and 0.500 mg/mL, compounds 4b, 4c, 6c, 6e, and 6i showed promising free radical scavenging activity and compounds 4b, 4f, 6c, 6d, and 6h showed good chelating ability with Fe²⁺ ions. The synthesized compounds were studied for docking on the enzyme, glucosamine-6-phosphate synthase to predict the binding affinity and orientation at the active site of the receptor.     

Synthesis and evaluation of analgesic, anti-inflammatory, and anticancer activities of new pyrazole-3(5)-carboxylic acid derivatives

In this article, we synthesized a series of novel 1-benzyl-5(3)-p-tolyl-1H-pyrazole-3(5)-carboxylic acid derivatives and characterized by IR, ¹H NMR, and mass spectroscopy. Compounds were evaluated for their in vivo analgesic and anti-inflammatory activity using the p-benzoquinone-induced writhing test and the carrageenan-induced paw edema model, respectively. Out of 14 compounds tested, 7a, 7c, 7e, 7f, 7i, 8a–b, and 8f–g exhibited potent analgesic and/or anti-inflammatory activity as compared to reference drugs aspirin and indomethacin. Anticancer activity of these compounds was assessed against five cancer cell lines with the MTT assay (HL-60, human promyelocytic leukemia cells; HeLa, human cervical cancer cells; Raji, human B lymphocyte cell line; MCF7, human breast adenocarcinoma cell line; MDA-MB-231, estrogen-independent human breast cancer cell line). Compounds 7a, 8a, and 8b with high anti-inflammatory activity, and also 7d and 7j with mild anti-inflammatory activity exhibited promising anticancer activity against some selected cell lines.     

Synthesis and characterization of flurbiprofen hydrazide derivatives as potential anti-HCV, anticancer and antimicrobial agents

A novel series of new flurbiprofen hydrazide derivatives 2-(2-fluorobiphenyl-4-yl)-N′-[(substituted phenyl/5-nitro-2-furyl)methylene]propanehydrazide (3a–k), 2-(2-fluorobiphenyl-4-yl)-N-(2-substituted-4-oxo-1,3-thiazolidine-3-yl)propanamide (4a–b, 4d–k), 2-[2-(2-fluorobiphenyl-4-yl) propanoyl]-N-substituted hydrazinecarbothioamide (5a–h) and 2-(2-fluorobiphenyl-4-yl)-N′-[(3-methyl-4-oxo-1,3-thiazolidin-2-ylidene]propanehydrazide (6a–b, 6e and 6g) has been synthesized in this study. All synthesized compounds were screened for antimicrobial activity against various bacterial and fungal strains. Additionally, compounds were evaluated for the ability to inhibit Hepatitis C virus NS5B polymerase. The most active 4-thiazolidinone compound was 4k (SGK119) with 67.0 % and thiosemicarbazide compound was 5d (SGK123) with 69.50 % inhibition at 200 μM against hepatitis C virus NS5B RNA polymerase. Anticancer activity of the selected compounds (3i, 3j, 3h, 4d, 4i and 6b) was determined at a single dose towards the full panel of 60 human cancer cell lines by the National Cancer Institute (NCI). 2-(2-Fluoro-4-biphenylyl)-N-[2-[4-(trifluoromethyl)phenyl]-4-oxo-1,3-thiazolidine-3-yl]propanamide 4d, containing thiazolidinone ring, demonstrated the most marked effect with 20.80 % growth percent on leukaemia cancer cell line SR at 10^?5 M. The results demonstrated that none of the compounds tested have anticandidal and antifungal activities, but two of them (4a and 4i) showed antibacterial inhibition against Micrococcus luteus, and Staphylococcus cohnii and Staphylococcus aureus, respectively.     

Synthesis, antitumor activity of 2-amino-4H-benzo[h]chromene derivatives, and structure–activity relationships of the 3- and 4-positions

Several 2-amino-4H-benzo[h]chromenes (3a–i) and (5a–h) were obtained by reaction of 4-chloro-1-naphthol (1) with α-cyanocinnamonitrile (2a–i) or ethyl α-cyanocinnamate derivatives (4a–h), respectively. 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, Colchicine, and Doxorubicin well-known anticancer drugs, using MTT colorimetric assay. Among them, the compounds 5e, 3c, 5f, b, d, 3d, 5c, a were the most active against MCF-7, 5a against HCT-116 and 5a, 3e, a against HepG-2 as compared with the standard drug Vinblastine, while the compounds 5e, 3c, 5f, b, d, 3d, 5c, a, h, 3i, g, a, e were the most active against MCF-7, 5a, c, e, f, b, 3e, c, g, b, 5d, h, 3d, i, 5g against HCT-116, 5a, 3e, a, 5e, 3c, 5d, c, f, 3b, 5g, 3g, 5h against HepG-2 as compared with the standard drug Colchicine. The structure–activity relationships of the 3- and 4-positions were discussed.     

New 6-bromoimidazo[1,2-a]pyridine-2-carbohydrazide derivatives: synthesis and anticonvulsant studies

In the present work, we report the facile synthesis and anticonvulsant study of new imidazo[1,2-a]pyridines carrying biologically active hydrazone functionality (3a–3e) and suitably substituted 1,2,4-triazole moieties (4, 5a–5d, 6, and 7a–7d). The newly synthesized intermediates and final compounds were characterized by various spectral techniques such as FTIR, ¹H NMR, ¹³C NMR, and mass spectral and elemental analysis studies. The in vivo anticonvulsant study of the target compounds were carried out following maximal electroshock seizure and subcutaneous pentylene tetrazole methods, while their toxicity study was performed following rotarod method by taking 20, 40, and 100 mg/kg dose levels. Most of the new compounds displayed remarkable anticonvulsant properties at these doses. Particularly, compounds 3b and 4 carrying hydrogen bond donor groups, viz. hydroxyl and amine moieties respectively, exhibited complete protection against seizure and their results are comparable to that of standard drug diazepam. Further, the motor impairment study revealed that all the compounds are nontoxic upto 100 mg/kg.     

Synthesis and anticonvulsant activity of novel quinazolin-4(3H)-one derived pyrazole analogs

Eighteen novel 6,8-(dibromo/unsubstituted)-2-(methyl/phenyl)-3-(4-(5-(substitutedphenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carbonyl)phenyl)-quinazolin-4(3H)-ones 4a–4r were designed and synthesized in good yield. Antiepileptic screening of the title compounds was performed using MES and scPTZ seizures tests while the neurotoxicity was determined by rotorod test. In the preliminary screening, compounds 4d, 4e, 4p, 4q, and 4r were found active in MES model, while 4a, 4d, 4f, 4m, and 4p showed significant antiepileptic activity in scPTZ model. Further, all these eight compounds were administered to rats and compounds 4e, 4p, and 4q showed better activity than Phenytoin in oral route. Among these compounds 4p revealed protection in MES after i.p. administration at a dose of 30 mg/kg (0.5 h) and 100 mg/kg (4 h). The compound 4p also provided protection in the scPTZ at a dose of 100 mg/kg (0.5 h) and 300 mg/kg (4 h).     

Synthesis,characterization, and antibacterial activities of some novel N,N′-disubstituted thiourea, 2-amino thiazole,and imidazole-2-thione derivatives

In the search of bioactive molecules, a series of novel N-substituted thiourea derivatives 3(a–d) are prepared by reaction of the α-amino pyridyl ketone hydrochloride (2a) with the corresponding aryl isothiocyanates. The synthesis of some new 2-amino thiazoles 4(a–d) and imidazole-2-thiones 6(a–d) were attempted by intramolecular cyclization reaction of the N,N′-disubstituted thioureas 3(a–d) and their intermediate ketals 5(a–d) in diluted aqueous acidic and strong acidic mediums. The structure of all newly synthesized compounds was established by analytical and spectral data. The antibacterial studies to all of the synthesized compounds against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis bacteria with Gram-positive and negative strains, as MIC values are reported. Some of these compounds such as 3a,b,d and 4b,d exhibited a good to significant antibacterial activity. Also, all of new synthesized compounds 3,4,6(a–d) were active against Gram-positive S. aureus bacterium. Thus, some of these compounds can emerge as a promising tool for further research work.     

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 and anticonvulsant activity of some new series of pyrrole derivatives

A new series of compounds 3a–f were synthesized from condensation method. Newly synthesized compounds were established by IR, ¹H NMR, ¹³C NMR, mass spectral and elemental analysis. Synthesized compounds 3a–f were screened for anticonvulsant activity. The compound 2,2′-({3-methyl-5-[2-phenylethenyl]-1H-pyrrole-2,4-diyl}dicarbonyl)dihydrazinecarbothioamide 3a showed significant activity compared with other compounds 3b–f against pentamethylene tetrazole-induced seizures.     

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.     

Antimicrobial and antiquorum-sensing studies. Part 2: synthesis, antimicrobial, antiquorum-sensing and cytotoxic activities of new series of fused [1,3,4]thiadiazole and [1,3]benzothiazole derivatives

New series of [1,3,4]thiadiazolo[3,2-a]pyrimidines, [1,3,4]thiadiazolo[2,3-b]quinazolines, and pyrimido[2,1-b][1,3]benzothiazoles have been synthesized and characterized by analytical and spectrometrical methods (IR, MS, ¹H, and ¹³C NMR). Sixteen of the synthesized compounds; namely, 3a, b, 5a–f, 8a, b, 10, 11a–c, and 13a, b were screened for antibacterial activity against Escherichia coli, Staphylococcus aureus, and Bacillus cereus. They were found to be either moderately active, slightly active or inactive against the selected microorganisms. The antifungal activity of these compounds were also tested against Candida albicans, Aspergillus fumigatus 293, and Aspergillus flavus 3375. Compound 11a showed potent antifungal activity against the three selected fungi; the rest of the tested compounds displayed either weaker activity or were completely inactive. The same compounds were examined for antiquorum-sensing activity against Chromobacterium violaceum ATCC 12472, where compounds 3a, 10, 11a, and 13a, b exhibited promising activity. The in vitro cytotoxic activity of these compounds was also studied by brine shrimp lethality bioassay, and results indicated that compounds 3a, 11a, and 13a have the highest cytotoxic activity.     

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.     

New route for synthesis,spectroscopy, and X-ray studies of 2-[aryl-(6′-hydroxy-4′,4′-dimethyl-2′-oxocyclohex-6′-enyl)methyl]-3-hydroxy-5,5-dimethylcyclohex-2-enone and 1,8-dioxo-octahydroxanthenes and antitumor evaluation

Treatment of 1-(benzothiazol-2-yl-thio)-acetonitrile 1 with 5,5-dimethyl-1,3-cyclohexanedione-(dimedone) 2 and aromatic aldehyde 3a, b in refluxing ethanol containing a catalytic amount of piperidine lead to bisdimedone derivatives 5a and b in short periods of times with excellent yields and not 4H-chromen-5(6H)-one derivatives 8. The compound 5a was then cyclized to 1,8-dioxo-octahydroxanthene derivative 6. The structures of the synthesized compounds were elucidated by elemental analysis ¹H NMR and ¹³C NMR spectra, COSY, HSQC, HMBC, MS, and X-ray crystallographic investigations. The cytotoxicity of the synthesized compounds 5a, b, and 6 were studied and evaluated. Three human tumor and three normal cell lines, namely as breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268), human fibroblast (WI-38), normal prostate epithelial cells, and normal colon mucosal, NCM 460 cells, respectively. The tested compounds were found to exhibit higher inhibitory effects toward the tumor and normal cell lines than the reference drug, doxorubicin.     

Synthesis of some new thiazolopyrane and thiazolopyranopyrimidine derivatives bearing a sulfonamide moiety for evaluation as anticancer and radiosensitizing agents

A new series of thiazolopyrane 5a–d, 11–13 and thiazolopyranopyrimidine 6–10, 7b, 8b, and 14 derivatives bearing a sulfonamide moiety were designed and synthesized. The molecular design was performed using molecular operating environment software to predict the binding mode of the proposed compounds on hCAII. All the newly synthesized compounds were evaluated for their in vitro anticancer activity against human liver cancer cell line in which hCAII is overexpressed. Compounds 8b and 14 showed higher activities compared with doxorubicin as a positive control. The radiosensitizing ability of the promising compounds 3, 7a, 8b, 12, and 14 was studied which showed an increase in the cell killing effect of γ-radiation after combination with them.