Microwave-assisted synthesis,molecular docking and antimicrobial activity of novel 2-(3-aryl,1-phenyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-4-yl)-8<Emphasis Type="Italic">H</Emphasis>-pyrano[2,3-f]chromen-4-ones

An efficient synthetic protocol of microwave-assisted synthesis of some novel 2-(3-aryl,1-phenyl-1H-pyrazol-4-yl)-8H-pyrano[2,3-f]chromen-4-ones 6a–j in excellent yields starting from 3-(3-aryl,1-phenyl-1H-pyrazol-4-yl)-1-(5-hydroxy-2H-chromen-6-yl)-propenones 5a–j was described. This approach offers the advantages of short reaction time (3–5 min), mild reaction conditions, high yields (80–88 %) and convenient operation. All the synthesized compounds were tested in vitro for their antimicrobial activity. The compounds 5h (Ar = 3-ethoxyphenyl), 6c (Ar = 4-chlorophenyl), 6e (Ar = 4-hydroxyphenyl) and 6i (Ar = 3,4-methoxyphenyl) were found to be potent against tested bacterial strains, and compounds 5g (Ar = 4-ethoxyphenyl), 6c (Ar = 4-chlorophenyl) and 6i (Ar = 3,4-methoxyphenyl) were found to be potent against tested fungal strains. The final compounds were subjected to molecular docking studies for the inhibition of enzyme DNA gyrase. The in silico molecular docking results are matching with the in vitro antimicrobial studies, and they may be considered as good inhibitor of DNA gyrase.     

Synthesis and antifungal activity of 3-aryl-4,4(5<Emphasis Type="Italic">H</Emphasis> )-dicarbonitrile-5-phenylisoxazolines

A series of 3-aryl-4,4(5H)-dicarbonitrile-5-phenyloxazolines have been synthesized and tested for activity against Candida albicans, Microsporum canis, and Trichophyton rubrum fungal species.     

Synthesis and antitumor evaluation of some 1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione and 1,2,4-triazole-5(1<Emphasis Type="Italic">H</Emphasis>)-thione derivatives

A series of 1,3,4-oxadiazole-2-thione and 1,2,4-triazole-5-thione derivatives have been successfully synthesized and studied for their antitumor activity. These compounds were prepared from carboxylic acids and chiral aminoacid esters. The prepared compounds were evaluated for their cytotoxicity against cancer in vitro using hydroxyurea (HU) as positive control. A fair number of compounds were found to have significant antitumor activity. To study the molecular basis of interaction and affinity of binding of the target molecules, all the compounds were docked into the ATPase domain of TP-II and tubulin using Schrödinger.     

Synthesis and biological evaluation of 3-(1<Emphasis Type="Italic">H</Emphasis>-indol-3-yl)pyrazole-5-carboxylic acid derivatives

A series of novel compounds bearing a 3-(1H-indol-3-yl)pyrazole-5-carboxylic acid nucleus were synthesized. Analytical and spectral data confirmed the structures of the new compounds. The structures of the regioisomers in this series were determined by ¹H-NMR spectra. The title compounds were evaluated for their endothelin-1 antagonist activities. In the in vitro functional assay, compounds 23, 24, 28 and 29 exhibited significant efficacy at the concentration of 1 μg/mL, and compounds 5b, 5c, 26 and 28 were as potent as the positive control bosentan at high concentration. In the experiment to assess prevention of endothelin-1-induced sudden death in mice, compound 5b showed comparable activity to bosentan, and 30 was more potent than bosentan. The final compounds were also screened for antibacterial activity against four Gram-positive and -negative bacteria. Some of the tested compounds showed weak antibacterial activity.     

Synthesis and biological testing of (5<Emphasis Type="Italic">Z</Emphasis>)-2-aryl-5-arylmethylidene-3,5-dihydro-4<Emphasis Type="Italic">H</Emphasis>-imidazol-4-ones as antimitotic agents

Compounds interacting with cell protein tubulin and microtubules represent an important type of antimitotic agents. A series of tubulin-targeted 2-aryl-4-benzoyl-imidazoles were reported to possess high cytotoxicity, and so, we prepared a series of structural isomers of these to be evaluated as antimitotic agents. The synthesis of the novel (Z)-2-aryl-5-arylmethylidene-3,5-dihydro-4H-imidazol-4-ones involved coupling of substituted hippuric acids with aromatic aldehydes. Subsequent conversion of the resulting oxazolones to the corresponding imidazolones was carried out under microwave irradiation in the presence of urea and ammonium acetate. The cytotoxicity of the majority of the compounds to human epithelial carcinoma cancer cell line A549 was in the sub-micromolar range and was found to be more sensitive to the substituents on the 5-arylmethylidene fragment than on the 2-aryl ring in general. The cytotoxicities of the synthesized compounds were lower than those of the previously reported isomeric 2-aryl-4-benzoyl-imidazoles, and the basic structure–activity relationships in the isomeric pairs were different. Synthesized (5Z)-5-[(4-bromophenyl)methylidene]-2-(4-methylphenyl)-3,5-dihydro-4H-imidazol-4-one, which had the highest cytotoxicity (IC₅₀ ~ 440 nM) in the series of novel compounds, had a definite cytostatic effect on the A549 cells, but its antiproliferative properties were not linked to action on the microtubules. This would be an interesting lead compound for additional investigation into the mechanism of cytostatic action, and further structural optimization.     

Synthesis and antinociceptive activity of (5-chloro-2(3<Emphasis Type="Italic">H</Emphasis>)-benzoxazolon-3-yl) propanamide derivatives

In this study, (5-chloro-2(3H)-benzoxazolon-3-yl)propanamide derivatives were synthesized. The chemical structures of the compounds were elucidated by their IR and 1H-NMR spectral data and microanalysis. The compounds were tested for antinociceptive activity by using the tail clip, tail flick, hot plate, and writhing methods. The varying levels of antinociceptive activity of the compounds were compared with those of dipyrone and aspirin. Among these compounds, compound 5e, 5g, and 5h have been found to be significantly more active than the others and the standards in all the tests.     

Synthesis and anti-inflammatory activity evaluation of novel 3-alkyl-6-(4<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazol-4-yl)-3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">e</Emphasis>][1,3]oxazine derivatives

To discover new compounds with anti-inflammatory activity, a series of novel 3-alkyl-6-(4H-1,2,4-triazol-4-yl)-3,4-dihydro-2H-benzo[e][1,3]oxazine derivatives were synthesized and their structures were confirmed by spectroscopic techniques. In vivo anti-inflammatory activity of the synthesized compounds was determined using the xylene-induced mouse ear edema model. 3-Heptyl-6-(4H-1,2,4-triazol-4-yl)-3,4-dihydro-2H-benzo[e] [1,3]oxazine and 3-p-tolyl-6-(4H-1,2,4-triazol-4-yl)-3,4-dihydro-2H-benzo[e][1,3]oxazine demonstrated higher anti-inflammatory activity (74.04?% and 64.99?%, respectively) at 0.5?h after intraperitoneal administration than the reference drug ibuprofen (62.65?%). Further, the time of peak effect after oral administration was 4?h for both compounds. Our results identify new compounds with anti-inflammatory activity in vivo that may have improved safety/side effect profiles relative to the currently approved nonsteroidal anti-inflammatory drugs.     

Synthesis and antidepressant activity of 5-(benzo[b]furan-2-ylmethyl)-6-methylpyridazin-<Emphasis Type="Italic">3</Emphasis>(<Emphasis Type="Italic">2H</Emphasis>)-one derivatives

A new series of pyridazin-3-one derivatives were designed, synthesized and evaluated for their preclinical antidepressant effect on Swiss mice. Among the series, compounds 6c, 6d and 6f exhibited significant activity profile in forced swimming test. Compounds 6c and 6d were most efficacious, which at dose of 50 mg kg^?1 reduced the time of immobility by 42.85 and 38.09 %, respectively, as compared to the standard drug fluoxetine which reduced the immobility time by 45.23 % at the dose of 32 mg kg^?1. All the test and standard compounds were administered orally 60 min before the test. Interestingly, all active compounds did not cause any significant alteration of locomotor activity in mice as compared to control, indicating that the hybrids did not produce any motor impairment effects. The results indicate that pyridazin-3(2H)-one derivatives may have potential therapeutic value for the management of mental depression.     

Synthesis and antimicrobial activity of novel 5-amino-4-cyano-<Emphasis Type="Italic">1H</Emphasis>-pyrazole and quinazolin-4(<Emphasis Type="Italic">3H</Emphasis>)-one derivatives

New substituted aroylhydrazones (4a-f) were synthesized from the acid hydrazide (3) and the corresponding aldehyde or aldose. 5-Amino-4-cyano-1H-pyrazole derivatives (6a-f) were prepared by the reaction of the aroylhydrazones (4a-f) with malononitrile. The synthesized compounds were tested for antimicrobial activity against various bacteria and fungi and showed moderate to high inhibition activities. Compounds incorporating a sugar moiety as well as a pyrazolyl ring in their structure displayed the highest antimicrobial activity.     

Synthesis and antimicrobial screening of <Emphasis Type="Italic">N</Emphasis>-(1-methyl-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-4-carbonyl)-thiourea derivatives

In the search of bioactive molecules in the class of functionally 4-substituted pyrazolic compounds, a series of N-(1-methyl-1H-pyrazole-4-carbonyl)-thiourea derivatives were prepared by addition of various substituted anilines to 1-methyl-1H-pyrazole-4-carbonyl isothiocyanate. The new thioureides and the intermediary compounds were characterized by spectroscopic data and elemental analyses and were evaluated for antibacterial and antifungal activities.     

Synthesis of 2-substituted-6-(4<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazol-4-yl)benzo[<Emphasis Type="Italic">d</Emphasis>]oxazoles as potential anticonvulsant agents

A series of 2-substituted-6-(4H-1,2,4-triazol-4-yl)benzo[d]oxazoles were synthesized. The anticonvulsant effect and neurotoxicity of the compounds (intraperitoneally) were evaluated with the maximal electroshock (MES) test, subcutaneous pentylenetetrazole (sc-PTZ), and rotarod tests in mice. 2-Phenyl-6-(4H-1,2,4-triazol-4-yl)benzo[d]oxazole (3g) was the most active and also had the lowest toxicity. In the anti-MES potency test, it showed median effective dose (ED₅₀) of 29.5 mg/kg, a median toxicity dose (TD₅₀) of 285 mg/kg, and a protective index (PI) of 9.7, which is greater than the reference drug, carbamazepine, which has a PI of 6.4.     

Synthesis and <Emphasis Type="Italic">in Vitro</Emphasis> cytotoxic activities of 2-alkyl-2,3-dihydro-1<Emphasis Type="Italic">H</Emphasis>-2,6-diazacyclopenta[<Emphasis Type="Italic">b</Emphasis>]anthracene-5,10-diones

A series of 2-alkyl-2,3-dihydro-1H-2,6-diazacyclopenta[b]anthracene-5,10-diones (4a–f) was synthesized and their in vitro cytotoxic activities were evaluated against six human cancer cell lines (HCT15, SK-OV-3, SNB19, A549, MCF7 and MCF7/ADR). They all appeared to be less potent than doxorubicin against all doxorubicin sensitive human cancer cell lines tested. However, these compounds retained considerable cytotoxic activity against the doxorubicin-resistant cell line MCF7/ADR, implying their therapeutic potential to treat doxorubicin-resistant tumors. The most active compound 4c was equipotent with doxorubicin against HCT15 cell line.     

Antituberculosis agents x. synthesis and evaluation of<Emphasis Type="Italic">In Vitro</Emphasis> antituberculosis activity of 2-(5-nitro-2-furyl)- and 2-(1-methyl-5-nitro-1<Emphasis Type="Italic">H</Emphasis>-imidazol-2-yl)-1,3,4-thiadiazole derivatives

Two series of 2-(5-nitro-2-furyl)- and 2-(1-methyl-5-nitro-1H-imidazol-2-yl)-5-propyl, allyl and propargyl)thio-1,3,4-thiadiazoles (6a-f) and 2-(5-nitro-2-furyl)- and 2-(1-methyl-5-nitro-1H-imidazol-2-yl)-5-(nitrobenzyl)thio-1,3,4-thiadiazole derivatives (8a-f) have been synthesized and evaluated against Mycobacterium tuberculosis, as part of the TAACF TB screening program under direction of the US National Institute of Health, the NIAID division. Primary screening was conducted at a single concentration, 6.25 microg mL(-1), against M. tuberculosis H37Rv in BACTEC 12B medium, using the Microplate Alamar Blue Assay (MABA). The minimum inhibitory concentration (MIC) was determined for the compounds that demonstrated > or = 90% growth inhibition in the primary screening. A varying degree of antituberculosis activity (from 0-97% of growth inhibition) was observed with the alkylthio series (6a-f), and the nitroimidazole derivative with a propylthio group (6b) and the nitrofuran derivative with a propargylthio group (6e), were the most active compounds (MIC=3.13 and 1.56 microg mL(-1), respectively). Among the nitrobenzylthio derivatives (8a-f), all the ortho, meta and para nitrobenzyl isomers in the nitrofuran series exhibited good antituberculosis activity (MIC=3.13 microg mL(-1)), while the corresponding nitroimidazole analogues were completely inactive (Inhibition=0%).     

An expeditious green route toward 2-aryl-4-phenyl-1<Emphasis Type="Italic">H</Emphasis>-imidazoles

Background

Azaheterocycles are an important class of compounds because of their highly potent medicinal activities, and the imidazole subcategory is of special interest in regard to drug discovery research.

Findings

An expeditious synthetic protocol of 2-aryl-4-phenyl-1H-imidazoles has been accomplished by reacting phenylglyoxal monohydrate, ammonium acetate, and aldehyde under sonication. Following this green approach a series of 2-aryl-4-phenyl-1H-imidazoles has been synthesized using diversely substituted aldehydes.

Conclusions

A rapid and simple synthetic procedure to synthesize diversely substituted 2-aryl-4-phenyl-1H-imidazoles has been reported. Other salient features of this protocol include milder conditions, atom-economy, easy extraction, and minimum wastes. The present procedure may find application in the synthesis of biologically active molecules.

Open image in new window

Graphical Abstract An expeditious synthetic protocol of 2-aryl-4-phenyl-1H-imidazoles has been accomplished by reacting phenylglyoxal monohydrate, ammonium acetate, and diversely substituted aldehydes under sonication.

     

Synthesis and analgesic activity of 4-aroyl-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">c</Emphasis>]oxepin-3-ones

A series of 4-aroyl-1H-benzo[c]oxepin-4-ones have been prepared by heating ethyl 2-aroyl-3-(2-bromophenyl)propenoates. The synthesized compounds possess higher analgesic activity than the reference drug (analgin) and exhibit low toxicity.     

Synthesis and preliminary evaluation of selected 2-aryl-5(6)-nitro- 1<Emphasis Type="Italic">H</Emphasis>-benzimidazole derivatives as potential anticancer agents

In this study we report the synthesis and preliminary evaluation of a series of six 2-aryl-5(6)-nitro-1H-benzimidazole derivatives (1–6) as potential anticancer agents. Cytotoxicity was evaluated against seven human neoplastic cell lines using the MTT assay. Compound 6 [2-(4-chloro-3-nitrophenyl)-5(6)-nitro-1H-benzimidazole] was the most active of the series, showing an IC₅₀ of 28 nM against the A549 cell line. This compound displayed a selective in vitro cytotoxic activity index (>700) in non neoplastic HACAT cells (IC₅₀ = 22.2 μM). Compounds 3 and 6 induce arrest in the S phase of the cell cycle, and compounds 1–6 induce apoptosis in the K562 cell line. Compound 6 induces poly (ADP-ribose) polymerase (PARP) inhibition activity as a potential mechanism of action. These results suggest that compound 6 could be a potent anticancer agent. Compound 3 displayed the best inhibitory activity against PARP with an IC₅₀ value of 0.05 μM, compared to the activity shown by the positive control 3-aminobenzamide (IC₅₀ = 28.5 μM).     

Synthesis and biological evaluation of some functionalized 1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole tethered pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridin-6(7<Emphasis Type="Italic">H</Emphasis>)-ones as antimicrobial and apoptosis inducing agents

A series of novel molecular hybrids containing pyrazole, pyridinone and 1,2,3-triazoles have been synthesized by one-pot four-component reaction of Meldrum’s acid, substituted aryl azides, 4-(prop-2-yn-1-yloxy)aryl aldehyde and 3-methyl-1-phenyl-1H-pyrazol-5-amine using L-proline as a basic organocatalyst besides CuSO₄.5H₂O and sodium ascorbate as catalysts for click chemistry in PEG-400 as a highly efficient and green media. Apoptosis studies have been carried out on ovarian follicles of goat (Capra hircus) and in vitro antibacterial activity has been done against six strains namely Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa and antifungal activity against two yeast strains namely, Candida albicans and Saccharomyces cerevisiae.