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.     

Design, synthesis and antifungal evaluation of 1-(2-(2,4-difluorophenyl)-2-hydroxy-3-(1H-1,2,4-triazol-1-yl)propyl)-1H-1,2,4-triazol-5(4H)-one

Based on the structure of the active site of cytochrome P450 14α-demethylase (CYP51) and the conclusions of the structure-activity relationships of azole antifungals, a series of 1-(2-(2,4-difluoro-phenyl)-2-hydroxy-3-(1H-1,2,4-triazol-1-yl)propyl)-1H-1,2,4-triazol-5(4H)-one of fluconazole analogs was synthesized. All compounds were characterized by IR, HRMS, ¹HNMR and ¹³C NMR spectroscopic analysis. Results of preliminary antifungal in vitro test using eight human pathogenic species showed that some compounds displayed comparable or even better antifungal activities than reference drug fluconazole and that compound 3i exhibited significant activity against Candida albicans being worthy of further optimization.     

Synthesis and structure-activity relationship of 2-thiopyrimidine-4-one analogs as antimicrobial and anticancer agents

Considering that some thiopyrimidines were previously reported as potential therapeutics, the present study achieved novel analogs of bioactive 2-substituted thiopyrimidines-4-(3H)-ones via base catalyzed alkylation reaction of 2-thiouracil using alkyl and aralkyl bromides. The title compounds were 2-(1-butylthio)pyrimidine-4(3H)-one (5a), 2-(2-butylthio)pyrimidine-4(3H)-one (5b), 2-(cyclohexylmethylthio)pyrimidine-4(3H)-one (5c), 2-(benzylthio)pyrimidine-4(3H)-one (5d) and 2-(1-adamantylthio)pyrimidine-4(3H)-one (5e). Bioactivity tests revealed that thiopyrimidines 5a, 5c, 5d and 5e exhibited antimicrobial activity. The thiopyrimidine-4-one (5c) showed complete inhibition against Streptococcus pyogenes and Branhamella catarrhalis as well as antifungal action against Candida albicans. Significantly, the 1-adamantylthiopyrimidine (5e) was shown to be the most potent cytotoxic compound against multidrug-resistant small cell lung cancer (H69AR). Their structure-activity relationships were discussed.     

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.     

Design, synthesis and potential 6 Hz psychomotor seizure test activity of some novel 2-(substituted)-3-{[substituted]amino}quinazolin-4(3H)-one

Thirty new 2-(substituted)-3-{[substituted]amino}quinazolin-4(3H)-one were designed and synthesized keeping in view the structural requirement of pharmacophore and evaluated for anticonvulsant activity and neurotoxicity. The anticonvulsant activity of the titled compounds was assessed using the 6 Hz psychomotor seizure test. The most active compound of the series was 3-({(E)-[3-(4-chloro-3-methylphenoxy)phenyl]methylidene}amino)-2-phenylquinazolin-4(3H)-one PhQZ 7, which showed 100% protection (4/4, 0.5 h) and 75% protection (3/4, 0.25 h) at a dose of 100 mg/kg in mice. A computational study was carried out for calculation of pharmacophore pattern and prediction of pharmacokinetic properties. Titled compounds have also exhibited good binding properties with epilepsy molecular targets such as glutamate, GABA (A) delta and GABA (A) alpha-1 receptors, in Lamarckian genetic algorithm based flexible docking studies.     

Cytotoxic Mannich bases of 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones

A series of 12 new Mannich bases with chalcone core structure were synthesized as potential antineoplastic agents, via N-aminomethylation of two parent 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones. The newly synthesized compounds as well as the chalcone prototypes were evaluated for cytotoxicity in the human pre-B-cell leukemia cell line BV-173 using the MTT-dye reduction assay. The tested compounds exhibited concentration-dependent cytotoxic effects at low micromolar concentrations. Ten of the Mannich bases characterized by significant activity in BV-173 were further evaluated against the chronic myeloid leukemia cell line K-562 and were found to suppress the growth of these cells at relatively higher concentrations as compared to the former tumor model. Selected Mannich bases induced programmed cell death in BV-173 at a concentration of 2.5muM as evidenced by the encountered DNA-laddering. Taken together our data suggest that the presented heterocyclic chalcone derived Mannich bases necessitate detailed pharmacological evaluation in order to define further the structure activity relationships, in a larger spectrum of tumor models and to elucidate the mechanisms implicated in the observed cytotoxic effects.     

Synthesis, anti-hypertensive and β-adrenoreceptor antagonist activities of 3-[4-[3-(4-aryl-1-piperazinyl)-isopropanoloxy]-phenyl]-4(3H quinazolones

The synthesis of seven 2-substituted 3-[4-[3-(4-aryl-1-piperazinyl)-isopropanoloxy]-phenyl]-4(3H)quinazolones is described. Pharmacological tests showed that some of the synthesized compounds (3a–c and 3e) possessed pronounced and sustained hypotensive effects, as tested in anesthetized normotensive rabbits, adrenoreceptor antagonist properties with respect to the α- and β-receptors and central nervous system depressant effect.     

Synthesis, structure and structure–activity relationship analysis of 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives as potential antibacterial agents

Nine 2-arylthiazolidine-4-carboxylic acid derivatives and nine 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives were synthesized to screen for their antibacterial activities. Compounds 5, 14–18 were first reported. Their chemical structures were clearly determined by ¹H NMR, ¹³C NMR, ESI mass spectra and elemental analyses, coupled with one selected single-crystal structure. All the compounds were assayed for antibacterial activities against two Gram-positive bacterial strains (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and two Gram-negative bacterial strains (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 13525) by MTT method. Most of the 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives exhibited better antibacterial activities against the four bacterial strains than relative 2-arylthiazolidine-4-carboxylic acid derivatives. Compound (2RS,4R)-3-(tert-butoxycarbonyl)-2-(5-fluoro-2-hydroxyphenyl)thiazolidine-4-carboxylic acid (14) showed powerful antibacterial activities against P. aeruginosa with IC₅₀ value of 0.195 μg/mL, which was superior to the positive controls Penicillin G and Kanamycin B, respectively. On the basis of the biological results, structure–activity relationships were discussed.     

Identification of 5-arylidene-4-thiazolidinone derivatives endowed with dual activity as aldose reductase inhibitors and antioxidant agents for the treatment of diabetic complications

In continuing the search for more effective 5-arylidene-4-thiazolidinones as aldose reductase inhibitors, a new set of suitably substituted compounds (4, 5 and 8) was explored. Acetic acids 5, particularly 5a and 5h, proved to be interesting inhibitors of the enzyme as well as excellent antioxidant agents that are potentially able to counteract the oxidative stress associated with both diabetic complications as well as other pathologies. Molecular docking experiments supported SAR studies.     

Synthesis, characterization and antibacterial activity of 2-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles

In the present investigation a series of novel 2-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles (4a–j) were synthesized by cyclization of substituted-benzoic acid N′-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1H-pyrazole-4-carbonyl]-hydrazide by using phosphorousoxychloride at 120 °C. The chemical structure of the newly synthesized compounds was characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR and LC–MS) methods. The title compounds were screened for qualitative (zone of inhibition) and quantitative antibacterial activity (MIC) by agar cup plate and microtitration methods, respectively. Among the synthesized compounds in this series compound 2-[1-(5-chloro-2-methoxyphenyl)-5-methyl-1H-pyrazol-4-yl]-5-(4-fluorophenyl)-1,3,4-oxadiazole (4b) was found to exhibit significant antibacterial activity with MICs of 22.4, 29.8, 29.6 and 30.0 μg/mL against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, respectively. The other compounds exhibited moderate activity when compared to standard substance Ampicillin.     

Synthesis, anticonvulsant and CNS depressant activity of some new bioactive 1-(4-substituted-phenyl)-3-(4-oxo-2-phenyl/ethyl-4H-quinazolin-3-yl)-urea

Several new 1-(4-substituted-phenyl)-3-(4-oxo-2-phenyl/ethyl-4H-quinazolin-3-yl)-urea were synthesized and screened for anticonvulsant, CNS depressant and sedative-hypnotic activity in the mice. After i.p. injection to mice at doses of 30, 100, and 300 mg/kg body weight synthesized compounds were examined in the maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. Spectroscopic data and elemental analysis were consistent with the newly synthesized compounds. The neurotoxicity was assessed using the rotorod method. Compounds E1, E6, E9, E12, P3, P4 and P6 were found to be active in the MES screen whereas E1, P4, P6 and P11 were found to be active in the scPTZ screen. All except E6, E11 and P6 showed more than 50% decrease in locomotor activity at 1 h of compound administration via actophotometer screen. CNS depressant activity screened with the help of the forced swim method resulted into some potent compounds. All the compounds were found to exhibit potent CNS depressants activity as indicated by increased immobility time. It can be concluded that newly synthesized compounds possessed promising CNS activities.     

Structure-activity relationship and enzyme kinetic studies on 4-aryl-1H-1,2,3-triazoles as indoleamine 2,3-dioxygenase (IDO) inhibitors

Previously, we have reported the design and synthesis of 4-aryl-1H-1,2,3-triazoles as inhibitors of indoleamine 2,3-dioxygenase (IDO), a promising therapeutic target of cancer. Here, we present the structure–activity relationship and enzyme kinetic studies on a series of 4-aryl-1H-1,2,3-triazoles. Three compounds (1, 6, 8) were found to possess more IDO inhibitory potency than the most commonly used 1-methyltryptophan. The results from the structure–activity relationship and molecular docking studies indicated that an electron-withdrawing group with low steric hindrance near the NH group of triazoles was necessary for the IDO inhibition.     

Design, synthesis and binding properties of novel and selective 5-HT(3) and 5-HT(4) receptor ligands

This work reports the synthesis and the binding tests on the 5-HT(3) and 5-HT(4) receptors of new thienopyrimidopiperazine and piperazinylacylaminodimethylthiophene derivatives, in order to identify potent and selective ligands for each receptor. The compound with higher affinity and selectivity for the 5-HT(3) over the 5-HT(4) receptor was the 3-amino-2-(4-benzyl-1-piperazinyl)-5,6-dimethyl-thieno[2,3-d]pyrimidin-4(3H)-one 28 (5-HT(3) K(i)=3.92 nM, 5-HT(4) not active), the compound with higher affinity and selectivity for the 5-HT(4) over the 5-HT(3) receptor was the 2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butanoylamino]-4,5-dimethyl-3-thiophenecarboxylic acid ethyl ester 41 (5-HT(4) K(i)=81.3 nM, 5-HT(3) not active). Conformational analyses were carried out on the compounds of the piperazinylacylaminodimethylthiophene series (39-42) taking compound 41 as the template.     

Synthesis and anti-tumor activity of 2-amino-3-cyano-6-(1H-indol-3-yl)-4-phenylpyridine derivatives in vitro

A series of novel 2-amino-3-cyano-6-(1H-indol-3-yl)-4-phenylpyridine derivatives were synthesized and their cytotoxic activity against A549, H460, HT-29 and SMMC-7721 cell lines was evaluated in vitro. Among them, ten compounds (10, 11, 14, 16, 17, 26, 27, 29, 30 and 31) displayed excellent anti-tumor activity against different cell lines. The most promising compound 27 showed strong anti-tumor activity against A549, H460, HT-29 and SMMC-7721 cell lines with IC₅₀ values of 22, 0.23, 0.65 and 0.77 nM, which were 2.6-, 83-, 1.1 × 10³- and 2.0 × 10³- fold more active than MX-58151 (IC₅₀ values of 0.058, 0.019, 0.70 and 1.53 μM), respectively.     

Biological evaluation of polyhalo 1,3-diazaheterocycle fused isoquinolin-1(2H)-imine derivatives

A series of polyhalo 1,3-diazaheterocycle fused isoquinolin-1(2H)-imines were evaluated in vitro against human tumour cell lines including A431, K562, HL60, HepG2 and Skov-3. As a result, some of the target compounds such as 5b, 5c, 5i, 5o, 6c, 6h and 7f showed stronger cytotoxicity against K562, H562 and Skov-3 cells in comparison with cisplatin, and the others displayed moderate cytotoxicity to A431 and HepG2. Biological investigations using the representative compounds 5c, 6c and 6h were also performed in mice bearing S₁₈₀ and H₂₂ tumours. The results indicated that these three compounds inhibit S₁₈₀ and H₂₂ growth. In addition, compounds 6c and 6h have very low acute toxicities. The preliminary analysis of structure-activity relationships is also discussed.     

One-pot synthesis and biological evaluation of 2-pyrrolidinyl-4-amino-5-(3',4',5'-trimethoxybenzoyl)thiazole: a unique, highly active antimicrotubule agent

A wide variety of small molecules with diverse molecular scaffolds inhibit microtubule formation. In this article we report a one-pot procedure for the preparation of a novel 2-(N-pyrrolidinyl)-4-amino-5-(3′,4′,5′-trimethoxybenzoyl)thiazole in which the size of the substituent at the C-2 position of the thiazole ring plays an essential role in compound activity. The most active agent (3f) inhibited at submicromolar concentrations the growth of tumor cell lines. It also inhibited tubulin polymerization with an activity quantitatively similar to that of CA-4, and treatment of HeLa cells resulted in their arrest at the G2-M phase of the cell cycle. Furthermore, 3f was effective against multidrug resistant cancer cells and inhibited the growth of the HT-29 xenograft in a nude mouse model. This indicated that 3f is a promising new antimitotic agent with encouraging preclinical potential.     

3-Aryl-2-[1H-benzotriazol-1-yl]acrylonitriles: a novel class of potent tubulin inhibitors

During a screening for compounds that could act against Mycobacterium tuberculosis, a series of new cellular antiproliferative agents was identified. The most cytotoxic molecules were evaluated against a panel of human cell lines derived from hematological and solid human tumors. In particular, (E)-2-(1H-benzo[d] [1,2,3]triazol-1-yl)-3-(4-methoxyphenyl)acrylonitrile (1) was found to be of a potency comparable to etoposide and greater than 6-mercaptopurine in all cell lines tested. Accordingly, a synthesis of a new series of (E)-2-(5,6-dichloro-1H-benzo[d] [1,2,3]triazol-1-yl)-3-(4-R-phenyl)acrylonitriles was conducted in order to extend the studies of structure-activity relationship (SAR) for this class of molecules. With the aim to evaluate if 3-aryl-2-[1H-benzotriazol-1-yl]acrylonitriles were able to act like tubulin binding agents, the effects on cell cycle distribution of the most active compounds (1, 2a, 3 and 4) were analyzed in K562 cells. A detailed molecular modeling study of the putative binding mode of this series of compounds on tubulin is also reported.     

One-pot microwave assisted synthesis under green chemistry conditions, antioxidant screening, and cytotoxicity assessments of benzimidazole Schiff bases and pyrimido[1,2-a]benzimidazol-3(4H)-ones

The synthesis of a number of benzimidazole Schiff bases 3 and 3-oxo-pyrimido[1,2-a]benzimidazoles 4 in excellent yields by a one-step sequence from the reaction of 2-aminobenzimidazole under green chemistry conditions is described. Structural assignments of the new compounds as well as complete assignment of ¹H and ¹³C NMR signals have been unambiguously achieved based on the analysis of their ¹H and ¹³C NMR (1D and 2D), IR, MS and elemental analysis data. To the synthesized Schiff bases the E-configuration was assigned on the basis of comparison of experimental and calculated (DFT) ¹³C NMR chemical shifts. Compounds 3 and 4 were evaluated as inhibitors of lipoxygenase (LOX) and of lipid peroxidation (LPO). All the tested derivatives showed inhibition of lipid peroxidation, whereas most of them were found to have higher activation than the reference compound trolox; The Schiff bases 3e, 3h, and 3i, and the pyrimidobenzimidazoles 4a, 4e and 4f were found to be the most potent. The most potent LOX inhibitor within the subset of Schiff bases was found compound 3i, followed by 3f, whereas compounds 4a and 4g were found the most potent of the 3-oxo-pyrimido[1,2-a]benzimidazole group. Moreover, some cytotoxicity assessments were undertaken, whereupon it was found that Schiff base 3i and pyrimidobenzimidazoles 4e and 4f did not exhibit cytotoxicity at similar concentrations resembling thus the inhibitory activity of lipid peroxidation. The most cytotoxic Schiff base and pyrimidobenzimidazole were found to be 3d and 4c, respectively.