Synthesis of 4H-chromene, coumarin, 12H-chromeno[2,3-d]pyrimidine derivatives and some of their antimicrobial and cytotoxicity activities

Condensation of 3-N,N-diethylaminophenol (1) with α-cyanocinnamonitriles (2a-c) and ethyl α-cyanocinnamates (2d-f) provided compounds 3a-f and 4a-c. 12H-Chromeno[2,3-d]pyrimidine derivatives 6, 11-13 and 16 were obtained by treatment of 4H-chromene compounds (3) with different electrophiles followed by nucleophilic reagents. Structures of these compounds were established on the basis of IR, UV, ¹H NMR, ¹³C NMR and MS data. Some of the new compounds were evaluated for antimicrobial and cytotoxicity activities.     

Synthesis and antimicrobial properties of some new thiazolyl coumarin derivatives

Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully characterized by IR, ¹H NMR, ¹³C NMR, elemental analysis and mass spectral data. The structures of some compounds were further confirmed by X-ray crystallography. All of these derivatives, 10a-d and 15a-h, were screened in vitro for antimicrobial activity against various bacteria species including Mycobacterium tuberculosis and Candida albicans. The compounds 10c, 10d and 15e exhibited very good activities against all of the tested microbial strains.     

Synthesis and identification of β-aryloxyquinolines and their pyrano[3,2-c]chromene derivatives as a new class of antimicrobial and antituberculosis agents

A new class of β-aryloxyquinolines 3a-i and their pyrano[3,2-c]chromene derivatives 6a-r incorporating a validated molecular target has been synthesized via a nucleophilic displacement and a one-pot multicomponent reaction respectively. In vitro antimicrobial activity of the synthesized compounds were investigated against a representative panel of pathogenic strains specifically Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Escherichia coli, Salmonella typhi, Vibrio cholera, Aspergillus fumigatus and Candida albicans. Compounds 3c, 3e, 3g, 6f, 6l and 6q exhibited excellent antibacterial activity while compound 6p exhibited more potent antifungal activity than that of first line standard drugs. In vitro antituberculosis activity was evaluated against Mycobacterium tuberculosis H37Rv and compound 6f is emerged as the promising antimicrobial member with better antitubercular activity. Majority of the compounds appears to be better antimicrobials but poor antituberculars.     

Synthesis, antitumor and antimicrobial activities of 4-(4-chlorophenyl)-3-cyano-2-(β-O-glycosyloxy)-6-(thien-2-yl)-nicotinonitrile

4-(4-Chlorophenyl)-3-cyano-6-(thien-2-yl)-1H-pyridin-2-one (2) was obtained by reaction of 2-acetyl thiophene with 4-chlorobenzaldehyde and ethyl cyanoacetate in presence of ammonium acetate or by the reaction of α,β-unsaturated compound 1 with ethyl cyanoacetate in the presence of ammonium acetate. 4-(4-Chlorophenyl)-2-(2′,3′,4′,6′-tetra-O-acetyl-β-d-gluco/galactopyranosyloxy)-6-(thien-2-yl)nicotinonitrile (5a and 5b), riboside 11, xyloside 12 and lactoside 16 were prepared by the reaction of 2 with glycosyl/galactosyl/xylosyl/lactosyl bromide and peracetylated xylose/ribose under the conventional and microwave irradiation methods. The reaction has regioselectively gave the O-glycosides and not the N-glycosides. The glycosides 5a,b, riboside 11, xyloside 12 and lactoside 16 were deacetylated in the presence of Et₃N/MeOH and few drops of water to give 7a,b, 13, 14 and 17. The structure of the new synthesized compounds was confirmed by using IR, ¹H, ¹³C NMR spectra and microanalysis. Selected members of these compounds were screened for antitumor and antibacterial activity.     

Synthesis and antitumor activity of new sulfonamide derivatives of thiadiazolo[3,2-a]pyrimidines

New series of sulfonamide derivatives of [1,3,4]thiadiazolo[3,2-a]pyrimidine were synthesized and investigated as antitumor agents. Some of the newly prepared compounds were tested for their in vitro and in vivo antitumor activities. Preliminary biological studies revealed that compounds 4c, 4f, and 4j exhibited the highest affinity to DNA, while compounds 4h,i, 6a-c, 8 and 12-14 exhibited moderate activity. Also, compounds 4j, 4f and 4c showed the highest percentage increase in lifespan of mice inoculated with Ehrlich ascites cells over 5-flurouracil (positive control). The detailed synthesis, spectroscopic and biological data are reported.     

Synthesis, in vitro antioxidant, anthelmintic and molecular docking studies of novel dichloro substituted benzoxazole-triazolo-thione derivatives

A novel 6,8-dichloro [1,2,4]triazolo [3,4-b] [1,3]benzoxazole-3(2H)-thione 4 and its derivatives 5a and 5b are synthesized from 5,7-dichloro-2-hydrazinyl-1,3-benzoxazole 3, obtained by reaction of hydrazine hydrate with ethyl [(5,7-dichloro-1,3-benzoxazol-2-yl)sulfanyl]acetate 2. The newly synthesized compounds are characterized by analytical ¹H NMR, ¹³C NMR, LC-MS mass spectrometry and elemental analysis. All synthesized compounds are screened for in vitro antioxidant and anthelmintic activities. In correlation to anthelmintic activity, compounds are subjected to molecular docking studies for the binding to β-Tubulin, target protein elite to the parasites.Compounds 3, 4 and 5a exhibited potential radical scavenging capacity with good anthelmintic activity. In molecular docking study also, compounds showed minimum binding energy and have good affinity toward the active pocket thus, they may be considered as good inhibitor of β-Tubulin.     

Synthesis, in vitro antimicrobial and in vivo antitumor evaluation of novel pyrimidoquinolines and its nucleoside derivatives

Seven series of pyrimidoquinoline derivatives have been synthesized, tetrazolo[4′,3′:-1,2]pyrimido[4,5-b]quinoline (3), 2-aminopyrimido[4,5-b]quinoline (4), triazolo[4′,3′:1,2]-pyrimidoquinoline (5a,b, 10), imidazolo[3′,2′:1,2]pyrimido[4,5-b]-quinoline (8a,b), 6-chloro-2-methylthiopyrimido[4,5-b]quinoline (12), acetylated nucleosides (16, 17a,b) and deacetylated nucleosides (18, 19a,b). Some of the novel pyrimidoquinoline derivatives possess highly activity toward the bacteria and fungi species. The new quinolines derivatives were evaluated for their anticancer activity toward human cancer cell lines by the National Cancer Institute (NCI). Most of them had excellent growth inhibition activity, having LD₅₀ values in the low micromolar to nanomolar concentration range.     

A regioselective synthesis of some new pyrazol-1'-ylpyrazolo[1,5-a]pyrimidines in aqueous medium and their evaluation as antimicrobial agents

An efficient and environmental benign regioselective synthesis of some new pyrazol-1′-ylpyrazolo[1,5-a]pyrimidines (7b-h) has been accomplished via treatment of 3(5)-amino-5(3)-hydrazinopyrazole dihydrochloride (5) with several unsymmetrical 1,3-diketones (6b-h) using water as a solvent without any catalysts or additives. The structure of 7b-h was established on the basis of rigorous analysis of ¹H, ¹³C NMR, IR spectral data and MS. Eight compounds (7a-h) were screened for their antibacterial activity against two gram-positive and two gram-negative bacteria and compounds (7a, b, d and e) for antifungal activity against four phytopathogenic fungi. Compounds 7c and 7e manifest rather broad antibacterial activity than standard antibiotics. One lead compound, 7a (10 mg/ml and 200 mg/ml) exhibited equipotent or more potent antifungal activity against all tested microorganisms than standard drug.     

Novel C-4' modified azithromycin analogs with remarkably enhanced activity against erythromycin-resistant Streptococcus pneumoniae: the synthesis and antimicrobial evaluation

Three novel structural series of C-4″ modified azithromycin analogs with two amide groups, which were connected by different alkyl linkage, were designed, prepared and evaluated for their in vitro antibacterial activity against seven phenotypes of respiratory pathogens. Among them, 7d, 8j and 9j, as representatives of corresponding series, exhibited remarkably improved activity against erythromycin-resistant Streptococcus pneumoniae expressing the erm gene, the mef gene, and the erm and mef genes. In addition, 7a-c, 7f-h, 7j, 8d, 8g, 8i, 9a-b and 9i displayed favorable efficacy against erythromycin-resistant S. pneumoniaeA22072 expressing the mef gene.     

Design, synthesis, and antiproliferative activity of new 1H-pyrrolo[3,2-c]pyridine derivatives against melanoma cell lines

Synthesis of a new series of diarylureas and diarylamides having 1H-pyrrolo[3,2-c]pyridine scaffold is described. Their in vitro antiproliferative activity against A375P human melanoma cell line was tested and the effect of substituents on pyrrolo[3,2-c]pyridine nucleus was investigated. The newly synthesized compounds, except three N-tolyl derivatives (8f, 9f, and 9h), generally showed superior activity against A375P to Sorafenib. Among all of these derivatives, compounds 8b, 8g, and 9a-e showed the highest potency against A375P with IC₅₀ in nanomolar range. In addition, compounds 8d, 8e, 8h, 9g, 9i, and 9j were more potent than Sorafenib but with IC₅₀ in micromolar range. Compounds 8b, 8g, 9b-d, and 9i demonstrated higher selectivity towards A375P compared with NIH3T3 fibroblasts. The most potent diarylurea 8g and diarylamide 9d were further tested and showed high potency over nine melanoma cell lines at the NCI.     

A class of novel N-isoquinoline-3-carbonyl-L-amino acid benzylesters: synthesis, anti-tumor evaluation and 3D QSAR analysis

Isoquinoline-3-carboxylic acid (2) was modified with amino acid benzylesters and 18 novel N-isoquinoline-3-carbonylamino acid benzylesters (3a-r) were provided. The IC₅₀ values of 3a-r against the proliferation of HL-60 and Hela cells were less than 1 × 10⁻⁸ M and 6 × 10⁻⁷ M, respectively. On S180 mice model 100 μmol/kg of 3a-r effectively inhibited the growth of the tumors. Using MFA based Cerius² QSAR module, two equations (r, 0.989 and 0.987) were established to correlate the structure with the in vitro and in vivo activities. The benefit of this modification was supported with both the in vitro membrane permeation test and the in vivo anti-tumor assay. The in vitro membrane permeability of N-isoquinoline-3-carbonyl-l-threonine benzylester (3n) and N-isoquinoline-3-carbonyl-l-leucine benzylester (3q) was 2.5 fold higher than that of 2, and the in vivo anti-tumor activity of 3n, q was 4.4-fold higher than that of 2.     

Synthesis, characterization and pharmacological activity of 4-{[1-substituted aminomethyl-4-arylideneamino-5-sulfanyl-4,5-dihydro-1H-1,2,4-triazol-3-yl]methyl}-2H-1,4-benzothiazin-3(4H)-ones

A new series of Schiff and Mannich bases derivatives (6) of 4-[(4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-2H-1,4-benzothiazin-3(4H)-one (4), derived from (3-oxo-2,3-dihydro-4H-1,4-benzothiazin-4-yl)acetic acid (3) were synthesized. The structures of all newly synthesized compounds were elucidated by elemental analysis, IR, ¹H NMR and mass spectral data. Synthesized compounds were evaluated for their anti-inflammatory and analgesic activity. Among the tested compounds, the (3-oxo-2,3-dihydro-4H-1,4-benzothiazin-4-yl)acetic acid (3) possess analgesic activity comparable to that of pentazocine; activity decreased on derivatization of the carboxylic acid group. However the anti-inflammatory activity of (3-oxo-2,3-dihydro-4H-1,4-benzothiazin-4-yl)acetic acid (3) increased by derivatization of the carboxylic acid group and some of the compounds showed anti-inflammatory activity comparable to that of indomethacin.     

A facile, one-pot synthesis, characterization and antimicrobial activity of o-hydroxy anilide derivatives and 1-substituted-1,3-dicyclohexylurea analogs of long chain carboxylic acids

A series of novel o-hydroxy anilide derivatives and 1-substituted-1,3-dicyclohexylurea analogs of long chain carboxylic acids have been synthesized. The structures of the synthesized compounds were elucidated by IR, ¹H NMR, ¹³C NMR and mass spectral data. All the synthesized compounds were tested for their antimicrobial activity by disk diffusion assay with slight modifications against Gram-positive, Gram-negative strains of bacteria as well as fungal strains. After that minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs) and minimum fungicidal concentrations (MFCs) of all the synthesized compounds were determined. The investigation of antimicrobial screening data revealed that all the tested compounds showed moderate to good microbial inhibitions. Compounds 3e, 4e, 3f and 4f were found to be the most potent antimicrobial agents.     

Synthesis, biological assessment and molecular modeling of new dihydroquinoline-3-carboxamides and dihydroquinoline-3-carbohydrazide derivatives as cholinesterase inhibitors, and Ca channel antagonists

The synthesis, biological evaluation, and molecular modeling of new 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxamides(4), 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carbohydrazide (6), and some hexahydropyrimido[5,4-c]quinoline-2,5-diones (9) produced earlier by our laboratory, as AChE/BuChE inhibitors, is described. From these analyses compound 4c resulted equipotent regarding the inhibition of cholinesterases’; inhibitors 6k, 9a, 9b were selective for AChE, whereas product 4d proved selective for BuChE. Docking analysis has been carry out in order to identify the binding mode in the active site, and to explain the observed selectivities. Only compound 9a has been shown to decrease K⁺-induced calcium signals in bovine chromaffin cells.     

Molecular modeling study and synthesis of quinazolinone-arylpiperazine derivatives as α1-adrenoreceptor antagonists

Three series of new 2-[(4-substituted piperazin-1-yl) methyl]quinazolin-4(3H)-ones 4a-c, Ethyl 6,7-dimethoxy-4-oxo-3-[2-(4-substituted piperazin-1-yl)acetamido/propanamido]-3,4-dihydroquinazoline-2-carboxylates 9a-f and their 2-methyl analogues 13a-l were designed and synthesized as promising α₁-adrenoceptor antagonists. The final compounds were evaluated for their in vivo hypotensive activity in normotensive cats. The most potent hypotensive quinazolinone derivatives 4b, 9e, 13i, 13j were further tested on isolated thoracic aortic rings of male Wister rats. All the tested compounds displayed α₁-blocking activity with IC₅₀ ranging from 0.2 to 0.4 mM less than prazosin. Furthermore, in the present work, molecular modeling study using Accelrys Discovery Studio 2.1 software was performed by mapping the synthesized compounds to the α₁-adrenoceptor antagonist hypothesis in order to predict their mechanism of action. Compound 13j which has the best-fitting score displayed the highest in vivo and in vitro activity among the tested compounds.     

Synthesis and evaluation of aroylthiourea derivatives of 4-β-amino-4'-O-demethyl-4-desoxypodophyllotoxin as novel topoisomerase II inhibitors

A novel series of aroylthiourea derivatives of 4-β-amino-4′-O-demethyl-4-desoxy- podophyllotoxin were synthesized. Their cytotoxicities against three cancer cell lines were investigated by MTT assay. The kDNA decatenation assay indicated that compounds 5a, 5f, 5h and 5l inhibited topoisomerase II-mediated kDNA decatenation. DNA flow cytometric analysis revealed that compound 5a induced cell cycle arrest at G2/M phase in HCT-116 cell line.     

Derivatives of pyrrolo[3,4-d]pyridazinone, a new class of analgesic agents

A series of N2-{2-[4-aryl(benzyl)-1-piperazinyl(piperidinyl)]ethyl}pyrrolo[3,4-d]pyridazinones 4 and related derivatives 5 were synthesized as potential analgesic agents. The structures of the new compounds were elucidated by micro, spectral and X-ray analysis. Analgesic activity of the compounds was investigated in the phenylbenzoquinone induced ‘writhing’ and ‘hot plate’ test in mice and at radioligand binding assay. At ‘writhing’ test all compounds, without exception, were more active than acetylsalicylic acid (ASA) with ED₅₀ values ranging from 0.04 to 11 mg/kg (i.p.) (ED₅₀ for ASA - 39.15 mg/kg). Analgesic effect at the ‘hot plate’ test was observed for three compounds 4c,e,f at the dose 3-5 times higher then that of morphine (ED₅₀-3.39 mg/kg). At radioligand binding assay of 4c,e,f only compound 4f exhibited affinity for the μ-opioid receptors similar to that of Tramadol. The acute toxicity of the pyrrolopyridazinones 4, 5 were also studied and non toxic effect was observed at the 2000 mg/kg (5a 1420 mg/kg) i.p. dose level. On the basis of the available pharmacological data S-A relationship is discussed. The preferred conformational characteristic of 4, taken 4c as an example, was also described.     

3-benzylamino-β-carboline derivatives induce apoptosis through G2/M arrest in human carcinoma cells HeLa S-3

β-Carboline derivatives are known as the lead compounds for anti-tumor agents. To examine an optimal structure for anti-tumor activity, we synthesized a variety of β-carboline derivatives, possessing a variety of substituents on the nitrogen atom of the amino group of 3-amino-β-carboline, and evaluated their anti-tumor activity for HeLa S-3 cell line. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that an optimal structure for anti-tumor activity was 3-cyclohexylmethylamino (1e) or 3-benzylamino-β-carboline (1f). An optimal counter anion of 2-methyl-3-benzylamino- β-carbolinium salts was a triflate anion 2c. In addition, the introduction of a hydroxyl group on the meta-position of the benzyl group of 3-benzylamino-β-carboline (3e) enhanced its anti-tumor activity. Hoechst 33342 staining and DNA fragmentation assay suggested that 1f, 2c and 3e induced cell death by apoptosis unlike 1e. Flow cytometry analysis showed that 1f, 2c and 3e induced cell apoptosis through arrest of the cell cycle in the G₂/M phase.     

Synthesis, antidepressant and antifungal evaluation of novel 2-chloro-8-methylquinoline amine derivatives

A new series of N-[(2-chloro-8-methylquinolin-3-yl)methyl]-(substituted)-aniline/butylamine/cyclohexylamine/benzylamine derivatives (4a-p) was synthesized by nucleophilic substitution reaction of 2-chloro-3-(chloromethyl)-8-methylquinoline 3 with various aliphatic and aromatic amines in absolute ethanol in the presence of triethylamine (TEA). The newly synthesized secondary amines were characterized by the combined use of IR, ¹H NMR, ¹³C NMR, mass spectral data and microanalyses. The antidepressant activity of the synthesized compounds (4a-p) was evaluated by Forced swim test in rats and their neurotoxicity was evaluated by the rotarod test. Test compounds and clomipramine were administered intraperitoneally at dose of 100 mg/kg and 20 mg/kg respectively. Preliminary antidepressant screening of compounds (4a-p) revealed that compounds 4b, 4c, 4d, 4e, 4i and 4o significantly (P < 0.01) reduces the duration of immobility time. These compounds were also tested in-vitro for MAO inhibitory effect. All the compounds were also screened for antifungal activity against Aspergillus niger MTCC 281, Aspergillus flavus MTCC 277, Monascus purpureus MTCC 369 and Penicillium citrinum NCIM 768 strains.     

Synthesis and cytotoxicity of 2-phenylquinazolin-4(3H)-one derivatives

Thirty 2-phenylquinazolin-4(3H)-one derivatives were prepared and their cytotoxic activities were tested in five human tumor cell lines. Some compounds (5e, 5k, 5t, 6c and 6f) showed relatively high cytotoxic activity. Especially, compound 6c showed the most cytotoxicity against all cell lines tested among the synthesized derivatives, and the inhibitory activity of 6c against HeLa cell was higher than that of adriamycin. The putative mechanism of antitumor action in apoptotic cell death was cell cycle arrest in the G0/G1 phase by compounds 5k, 5v, 5m, 6c, and 6f in HeLa cells. These compounds showed relatively high cytotoxicity in this cell type.