Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 13  |  Issue : 2  |  Page : 71-86

Synthesis, antifungal activity, and molecular docking study of some novel highly substituted 3-indolylthiophene derivatives


1 Department of Chemistry Natural Compounds, National Research Centre, Giza, Egypt
2 Department of Pharmacognosy, National Research Centre, Giza, Egypt

Date of Submission11-Jun-2014
Date of Acceptance27-Jul-2014
Date of Web Publication18-Dec-2014

Correspondence Address:
Heba M Abo-Salem
Department of Chemistry Natural Compounds, National Research Centre, Giza
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-4315.147064

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  Abstract 

Background and objectives
The currently available antifungal drugs have the limitations of toxicity, potential drug interaction with other drugs, insufficient pharmacokinetics properties, and development of resistance. Thus, development of new antifungal agents with less toxicity is urgently required. The present work aimed to synthesize new 3-indolylthiophene derivatives and evaluate their antifungal activity by studying their molecular docking.
Materials and methods
New series of thiadiazoles 4a-c , morpholinyl-acetamides 6a-c , 4-methylpiperazinylacetamides 7a-c , thiazolidines 10a-c , azetidines 12a-c - 13a-c , sulfonamides 14a-c - 15a-c , benzamides 16a-c , pyrrolidines 17a-c , succinamic acids 18a-c , acetamides 19a-c , thieno(2,3-c)pyridines 20a-c , thieno(2,3-e)-1,2,4-triazolo(1,5-c)pyrimidines 23a-c , thieno(2,3-d) pyrimidines 24a-c - 26a-c , and thieno(2,3-b)pyridines 27a-c derivatives incorporated into N-substituted 3-indolylthiophenes were prepared by an initial reaction of 2-amino-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 1a-c with different reagents. The antifungal activity of the newly synthesized compounds was evaluated against two strains of fungi, namely, Candida albicans (ATCC-10231) and Aspergillus niger (ATCC-10535). However, the mode of action of the most promising antifungal compounds was assessed by docking with cytochrome P450 14 α-sterol demethylase (CYP51) (PDB ID: 1EA1).
Results and conclusion
Compound 4a showed good inhibitory activity against both C. albicans (ATCC-10231) and A. niger ( ATCC-10535), with minimum inhibitory concentrations values of 9 and 36 μg/disk, respectively, compared with fluconazole, with minimum inhibitory concentrations values of 8 and 34 μg/disk. Docking results showed that compound 4a had the highest docking score, with a binding energy of −30.25 kJ/mol, which is in agreement with the experimental activity value.

Keywords: 2-aminothiophene-3-carbonitriles, antifungal activity, heterocycles, indole, molecular docking


How to cite this article:
Abo-Salem HM, El-Sawy ER, Fathy A, Mandour AH. Synthesis, antifungal activity, and molecular docking study of some novel highly substituted 3-indolylthiophene derivatives. Egypt Pharmaceut J 2014;13:71-86

How to cite this URL:
Abo-Salem HM, El-Sawy ER, Fathy A, Mandour AH. Synthesis, antifungal activity, and molecular docking study of some novel highly substituted 3-indolylthiophene derivatives. Egypt Pharmaceut J [serial online] 2014 [cited 2017 Oct 18];13:71-86. Available from: http://www.epj.eg.net/text.asp?2014/13/2/71/147064


  Introduction Top


Thiophene derivatives are important heterocyclics found in various biologically active and natural compounds [1],[2],[3],[4],[5]. Especially, 2-aminothiophene has a broad spectrum, and is used in pharmaceuticals [6],[7] and as starting materials for of the construction of fused heterocycle systems [8],[9],[10],[11]. Also, indole nucleus and its derivatives have unique biological activities such as anti-inflammatory [12],[13], anticancer [13],[14], and antimicrobial activities [15],[16]. On the basis of these findings and in view of our continuous work on the synthesis of new indole heterocycle derivatives with biological activities [12],[13],[14],[16], here, we report on the synthesis of a novel series of thiophene derivatives starting from and 2-amino-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 1a-c [17] and evaluate their antifungal activity. In addition, a molecular docking study of the most biologically active compounds was carried out using the Molecular Operating Environment (MOE) program and cytochrome P450 14 α-sterol demethylase (CYP51) (PDB ID: 1EA1) for a better understanding of the drug-receptor interaction.


  Materials and methods Top


Chemistry

The chemicals and solvents were of commercial grade and used without further purification. Melting points were determined in open capillary tubes on an Electrothermal 9100 digital melting point apparatus (serial no. 8694; Electrothermal Engineering Ltd, Rochford, UK) and were uncorrected. Elemental analyses were carried out on a Perkin-Elmer 2400 analyzer (Perkin-Elmer, Waltham, Massachusetts, USA) and were found to be within ±0.4% of the theoretical values. Infrared (IR) spectra were recorded on a Perkin-Elmer 1600 FTIR spectrophotometer (Perkin-Elmer). The nuclear magnetic resonance (NMR) spectra were recorded on a Bruker Avance digital spectrometer at 500 MHz for 1 H and at 125 MHz for 13 C (Bruker BioSpin GmbH, Rheinstetten, Germany) in DMSO-d6 ; chemical shifts (δ) are reported in ppm units relative to the internal tetramethylsilane standard. Mass spectra (EI) were recorded using a Jeol-JMS-AX500 mass spectrometer (Jeol Ltd, Tokyo, Japan) at 70 eV.

Ethyl-2-(3-cyano-4-(N-substituted-1 H-indol-3-yl)

thiophen-2-ylamino)acetate
2a-c

A mixture of compound 1a , 1b , or 1c (0.35 mol), ethyl chloroacetate (42.87 g, 0.35 mol), and potassium carbonate (6.21 g, 0.045 mol) in absolute methanol (300 ml) was kept overnight at room temperature. The reaction mixture was heated at reflux on a steam bath for 1-3 h. After cooling, the reaction mixture was poured onto cold water (20 ml) and the solid formed was filtered off, air-dried, and crystallized from absolute ethanol.

2-(2-(3-Cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-ylamino)acetyl)hydrazine carbothioamides
3a-c

A mixture of compound 2a , 2b , or 2c (0.17 mol) and thiosemicarbazide (15.49 g, 0.17 mol) in absolute methanol (250 ml) was heated at reflux on a steam bath for 10-13 h. The reaction mixture was filtered while hot. After cooling, the filtrate was poured onto cold water (20 ml). The solid formed was filtered off, air-dried, and crystallized from absolute ethanol.

2-(5-Amino-1, 3, 4-thiadiazol-2-yl-methylamino)-4-

(N-substituted-1H-indol-3-yl) thiophene-3-carbonitriles
4a-c

A mixture of compound 3a , 3b , or 3c (0.15 mol) and concentrated sulfuric acid (6 ml) in absolute methanol (50 ml) was kept overnight at room temperature. The reaction mixture was heated under reflux on a steam bath for 7-8 h. After cooling, the reaction mixture was neutralized with an ammonia solution (25%) and the solid formed was filtered off, washed with water, air-dried, and crystallized from absolute ethanol.

N-(3-Cyano-4-(N-substituted-1H-indol-3-yl)

thiophen-2-yl)-2-morpholinyl-acetamides
6a-c

and N-(3-cyano-4-(N-substituted-1H-indol-3-yl)

thiophen-2-yl)-2- (4-methylpiperazinyl)acetamides
7a-c

A mixture of compound 5a , 5b , or 5c (0.006 mol) and morpholine or N-methylpiperazine (0.006 mol) in acetone (50 ml) containing potassium carbonate (1.65 g, 0.012 mol) was heated at reflux for 15-20 h. The solvent was evaporated under vacuo to half its volume and the solid formed was filtered off, washed with a 5% sodium bicarbonate solution and then with water, air-dried, and crystallized from absolute ethanol.

N-(3-Cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)-2-hydrazinyl acetamides 8a-c

A mixture of compound 5a , 5b , or 5c (0.02 mol) and hydrazine hydrate (1 ml, 0.02 mol, 80%) in absolute methanol (30 ml) was heated at reflux for 9-10 h. After cooling, the solid formed was filtered off, air-dried, and crystallized from chloroform.

2-(N-Benzylidenehydrazinyl)-N-(3-cyano-4-(N-substituted-1H-indol-3-yl) thiophen-2-yl)acetamides 9a-c

A mixture of compound 8a , 8b , or 8c (0.01 mol) and benzaldehyde (1.06 g, 0.01 mol) in absolute methanol containing a few drops of glacial acetic acid was heated at reflux for 4-6 h. After cooling, the reaction mixture was concentrated to half its volume and the solid formed was filtered off, air-dried, and crystallized from chloroform.

N-(3-Cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)-2-(4-oxo-2-phenylthiazolidin-3-ylamino)acetamides 10a-c

To a stirred solution of compound 9a , 9b , or 9c (0.01 mol) in absolute methanol (25 ml), thioglycolic acid (1.39 g, 0.015 mol) was added. The reaction mixture was stirred for 4 h; then, anhydrous sodium sulfate (30 g) was added and heated at reflux for a further 6 h. The reaction mixture was filtered while hot. After cooling, the solid formed was filtered off, air-dried, and crystallized from chloroform.

2-(3-Chloro-2-(4-nitrophenyl)-4-oxo-azetidin-1-yl)-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 12a-c and 4-(N-substituted-1H-indol-3-yl)-2-(2-(4-nitrophenyl)-4-oxo-3-phenylazetidin-1-yl)thiophene-3-carbonitriles 13a-c

To a solution of compound 11a , 11b , or 11c (0.01 mol) in dry dioxane (5 ml), a solution of chloroacetyl chloride or phenacyl bromide (0.01 mol) in dry dioxane and triethylamine (0.59 ml, 0.01 mol) was added. The reaction mixture was heated at reflux for 15-16 h. The reaction mixture was filtered off while hot and the solvent was removed under vacuum. The residue that formed was collected, washed with water, air-dried, and crystallized from absolute ethanol.

N-(3-Cyano-4-(N-substituted-1H-indol-3-yl)

thiophen-2-yl)benzene-sulfonamides
14a-c and 4-bromo-N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)benzenesulfonamides 15a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol) and benzenesulfonyl chloride or 4-bromobenzenesulfonyl chloride (0.01 mol) in dry dioxane (30 ml) containing a few drops of triethylamine was heated at reflux for 8 h. After cooling, the reaction mixture was poured onto cold water (20 ml). The solid formed was filtered off, air-dried, and crystallized from dioxane.

N-(3-Cyano-4-(substituted-1H-indol-3-yl)thiophen-2-yl)benzamides 16a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol) and benzoyl chloride (0.01 mol) in dry dioxane (30 ml) containing a few drops of triethylamine was heated at reflux for 8 h. After cooling, the reaction mixture was poured onto cold water (20 ml). The solid formed was filtered off, air-dried, and crystallized from dioxane.

2-(2,5-Dioxopyrrolidin-1-yl)-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 17a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol) and succinic anhydride (1 g, 0.01 mol) was heated at 180°C in a test tube on a sand bath for 4 h. After cooling, the product was solidified by the addition of absolute ethanol (50 ml). The solid formed was filtered off, washed with water, air-dried, and crystallized from dimethylformamide.

N-(3-Cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)succinamic acids 18a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol) and succinic anhydride (1 g, 0.01 mol) in absolute ethanol (10 ml) was heated at reflux for 10 h. After cooling, the reaction mixture was poured onto cold water (20 ml). The solid formed was filtered off, air-dried, and crystallized from dimethylformamide-water.

N-(3-Cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)acetamides 19a-c

A solution of compound 1a , 1b , or 1c (0.01 mol) in a mixture of (10 ml) acetic anhydride and glacial acetic acid (2 : 1) was heated at reflux for 8-10 h. After cooling, the reaction mixture was poured onto ice-water (20 ml) and the solid formed was filtered off, air-dried, and crystallized from absolute ethanol.

3-(N-Substituted-1H-indol-3-yl)-6-methyl-5H-thieno(2,3-c)pyridin-4-ones 20a-c

A solution of compound 1a , 1b , or 1c (0.01 mol) in a mixture of concentrated hydrochloric acid and glacial acetic acid (20 ml, 3 : 1) was heated at reflux for 6 h. After cooling, the reaction mixture was poured onto ice-water (20 ml) and the solid formed was filtered off, air-dried, and crystallized from dioxane.

Ethyl N-3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl formamidates 21a-c

A solution of compound 1a , 1b , or 1c (0.01 mol) in triethylorthoformate (12 ml) was heated at reflux for 18 h. Excess triethylorthoformate was removed under vacuo and the residue was triturated with ethanol (10 ml). The solid separated was filtered, air-dried, and crystallized from absolute ethanol.

4-Imino-5-(N-substituted-1H-indol-3-yl)-4H-thieno(2,3-d)pyrimidin-3-yl-amines 22a-c

A mixture of compound 21a , 21b , or 21c (0.01 mol) and hydrazine hydrate (10 ml, 0.2 mol, 80%) was stirred in absolute ethanol (20 ml) for 2 h at room temperature. The reaction mixture was poured onto cold water (10 ml) and the solid formed was filtered off, air-dried, and crystallized with dioxane.

9-(N-Substituted-1H-indol-3-yl)thieno(2,3-e) [1, 2, 4]triazolo(1,5-c)pyrimidines 23a-c

A mixture of compound 22a , 22b , or 22c (0.05 mol) and triethylorthoformate (0.6 ml) in dimethylformamide (2 ml) was heated at reflux on a water bath for 2-3 h. After cooling, the reaction mixture was poured onto cold water (10 ml) and the solid formed was filtered off, air-dried, and crystallized from absolute ethanol-chloroform.

5-(N-Substituted-1H-indol-3-yl)-1, 2, 3, 4-tetrahydrothieno(2,3-d)pyramidi-ne-2,4-dithiones 24a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol) and excess of carbon disulfide (10 ml) in absolute ethanolic potassium hydroxide solution [1.12 g, 0.02 mol of KOH in absolute ethanol (20 ml)] was heated at reflux for 12 h. The excess carbon disulfide was evaporated under vacuo and the residue obtained was dissolved in water (20 ml). The reaction mixture was filtered off and the filtrate was acidified with diluted hydrochloric acid (1 : 1). The solid that formed was filtered off, washed with water, air-dried, and crystallized from dimethylformamide - water.

4-Amino-5-(N-substituted-1H-indol-3-yl)-1H-thieno(2,3-d)pyrimidin-2-ones 25a-c and 4-amino-5-(N-substituted-1H-indol-3-yl)-1H-thieno(3,2-d)pyrimidine-2-thiones 26a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol), urea, and/or thiourea (0.01 mol) was heated at 180°C in a test tube on a sand bath for 4 h. After cooling, the reaction mixture was solidified with the addition of absolute ethanol (50 ml). The solid formed was filtered off, washed with water, air-dried, and recrystallized from dimethylformamide.

5-Amino-6-hydroxy-3-(N-substituted-1H-indol-3-yl)thieno(2,3-b)pyridine-6-carbonitriles 27a-c

A mixture of compound 1a , 1b , or 1c (0.01 mol) and ethylcyanoacetate (1.13 g, 0.01 mol) in dry dioxane (30 ml) containing a few drops of piperidine was heated at reflux for 8-10 h. After cooling, the reaction mixture was poured onto cold water (20 ml). The solid formed was filtered off, air-dried, and crystallized from dioxane.

Biological assay

Cells

Fungal strains, namely, Candida albicans (ATCC-10231) and Aspergillus niger (ATCC-10535), were supplied from the American Type Culture Collection (Biomerieux Inc., Durham, North Carolina, USA).

Antifungal assay

Antifungal activity of new synthesized compounds was determined in vitro using the disc diffusion method [18] against C. albicans (ATCC-10231) and A. niger ( ATCC-10535). The antifungal activities of the tested compounds were estimated by placing presterilized filter paper discs (6 mm in diameter) impregnated with tested compounds at 200 μg/disc on nutrient and Sabouraud dextrose agar. Dimethylformamide was used as a solvent for impregnation. Inhibition zones of the test compounds were measured after 5 days of incubation at 28°C. Fluconazole (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) was used as the reference drug. Minimum inhibitory concentration (MIC) was read as the lowest concentration of the test compounds at which the test strain dose shows no visible growth. MIC was determined twice in duplicate experiments.

Molecular docking study

Docking studies of the most active compounds were carried out using the MOE 2008.10 release (Chemical Computing Group, Montreal, Quebec, Canada; http://www.chemcomp.com). The program operated on an Intel(R) core(TM) i5-3210M CPU@2.50 GHz, 2.50 GHz processor, 4.00 GB memory, with a Windows 7 Ultimate operating system. The protein crystal structure of cytochrome P450 14 α-sterol demethylase (CYP51) (PDB ID: 1EA1) in complex with 2-(2,4-difluorophenyl)-1,3-di(1H-1, 2, 4-triazol-1-yl)propan-2-ol (fluconazole) was downloaded from http://www.rcsb.org/-pdb (ID: 1EA1) [19], refinement of the crude PDB structure was performed, and then saved as MOE file to be used for docking simulation.

The active pocket was considered to be the site where fluconazole complexes with cytochrome P450 14 α-sterol demethylase (CYP51) (PDB ID: 1EA1). The active pocket consisted of 23 amino acid residues such as Ala256, Gln72, Phe255, Met79, Leu100, Arg96, Tyr76, Arg326, His392, Leu324, Gly388, Leu321, Cys394, Pro386, Phe78, Thr264, Ala400, Ser261, Phe399, Gly396, and Thr260. The structures of ligands were drawn in ChemDraw Ultra 7.0 (Cheminformatics Software company based in Cambridge, Massachusetts, USA) and saved as mol. The two-dimensional structure of the selected compounds was converted into their three-dimensional form and energy minimized using the MMFF94x force field until a root-mean-square deviation of atomic position gradient of 0.01 Kcal/mol/Ε was reached [20]. The docking scores were expressed in negative energy terms; the lower the binding free energy, the better the binding affinity [21].


  Results and discussion Top


Chemistry

The reaction route for the synthesis of the target compounds is outlined in Schemes 1-3. The reaction of 2-amino-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 1a-c [17] with chloroethyl acetate in absolute methanol in the presence of potassium carbonate as a base yielded ethyl-2-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-ylamino)acetate 2a-c (Scheme 1 [Additional file 1]). Treatment of compounds 2a-c with thiosemicarbazide yielded hydrazine carbothioamide derivatives 3a-c . Cyclization of the latter compounds by their reaction with equimolar amounts of sulfuric acid in absolute methanol led to the formation of 2-(5-amino-1, 3, 4-thiadiazol-2-ylmethylamino)-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 4a-c (Scheme 1).

The reaction of compounds 1a-c with chloroacetyl chloride in dry benzene led to the formation of N-chloroacetamido derivatives 5a-c (Scheme 1) [17]. The reaction of 5a-c with morpholine or N-methylpiperazine in acetone and in the presence of potassium carbonate yielded N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)-2-(morpholinyl)acetamides 6a-c and N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)-2-(4-methylpiperazinyl)acetamides 7a-c , respectively (Scheme 1).

Amination of chloroacetamido compounds 5a-c with hydrazine hydrate in absolute methanol yielded the corresponding hydrazinylacetamide derivatives 8a-c (Scheme 1). Acid-catalyzed reaction of the latter compounds with benzaldehyde under reflux in absolute methanol yielded the corresponding Schiff's bases, namely, N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)-2-(N-benzylidenehydrazino) acetamides 9a-c (Scheme 1). Cyclization of the latter Schiff's bases by their reaction with thioglycolic acid in dry dioxane in the presence of anhydrous sodium sulfate led to the formation of N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)-2-(4-oxo-2-phenyl thiazolidin-3-yl)amino)acetamides 10a-c (Scheme 1).

However, acid-catalyzed reaction of compounds 1a-c with 4-nitrobenzaldehyde yielded the corresponding Schiff's bases 11a-c [17] (Scheme 2 [Additional file 2]). The reaction of 11a-c with chloroacetyl chloride and/or phenacyl bromide in dry dioxane in the presence of triethylamine as a base led to the formation of 2-(3-chloro-2-(4-nitrophenyl)-4-oxo-cyclobutyl)-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 12a-c and 4-(N-substituted-1H-indol-3-yl)-2-(2-(4-nitrophenyl)-4-oxo-3-phenylcyclobutyl)thiophene-3-carbonitriles 13a-c , respectively (Scheme 2).

The reaction of compounds 1a-c with benzenesulfonyl chloride, 4-bromobenzenesulfonyl chloride and/or benzoyl chloride under reflux in dry dioxane and in the presence of triethylamine yielded the corresponding N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)benzene sulfonamides 14a-c , 4-bromo-N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)benzene sulfonamides 15a-c and N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)benzamides 16a-c , respectively (Scheme 2).

However, fusion of compounds 1a-c with succinic anhydride yielded 2-(2,5-dioxopyrrolidin-1-yl)-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles 17a-c (Scheme 2), whereas heating of compounds 1a-c with succinic anhydride in absolute ethanol yielded N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)succinamic acids 18a-c (Scheme 2).

Moreover, acetylation of compounds 1a-c under reflux in acetic anhydride and glacial acetic acid (2 : 1) yielded the corresponding N-(3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-yl)acetamides 19a-c (Scheme 3 [Additional file 3]), whereas heating of compounds 1a-c in a mixture of concentrated hydrochloric acid and glacial acetic acid (3 : 1) yielded the fused 5-(N-substituted-1H-indol-3-yl)-2-methyl-3H-thieno(2,3-d) pyrimidin-4-ones 20a-c (Scheme 3).

Condensation of compounds 1a-c with excess triethylorthoformate at reflux yielded ethyl N-3-cyano-4-(N-substituted-1H-indol-3-yl)thiophen-2-ylformamidates 21a-c (Scheme 2). Cyclization of the latter compounds upon treatment with hydrazine hydrate in absolute ethanol under reflux yielded the fused thieno(2,3-d)pyrimidine derivatives 22a-c , which, under further cyclization, upon heating with triethylorthoformate in dimethylformamide, led to the formation of fused thieno(2,3-e)-1, 2, 4-triazolo(1,5-c)pyrimidine derivatives 23a-c (Scheme 3).

The reaction of compounds 1a-c with excess carbon disulfide in absolute ethanolic potassium hydroxide solution yielded the fused 1, 2, 3, 4-tetrahydrothieno(2,3-d)pyrimidine-2,4-dithione derivatives 24a-c (Scheme 3).

However, fusion of compounds 1a-c with urea and/or thiourea yielded the fused thieno(2,3-d)pyrimidine derivatives 25a-c and thieno(2,3-d)pyrimidine-2-thione derivatives 26a-c , respectively (Scheme 3), whereas the reaction of compounds 1a-c with ethyl cyanoacetate under reflux in dry dioxane and in the presence of piperidine as a catalyst yielded thieno(2,3-b)pyridine-5-carbonitrile derivatives 27a-c (Scheme 3).

The structures of the newly synthesized compounds were confirmed on the basis of elemental analyses [Table 1] as well as IR, NMR, and mass spectral data [Table 2].
Table 1: Physical and analytical data of the synthesized compounds

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Table 2: Spectral characterization of the prepared compounds

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Antifungal activity

The in-vitro antifungal activity of the newly prepared compounds was evaluated against C. albicans (ATCC-10231) and A. niger ( ATCC-10535) using fluconazole as a reference drug. The preliminary antifungal screening for all the synthesized compounds at a concentration of 200 μg/disk showed that compounds 4a , b , 6a , b , 7a , b , 10a , 12a , 13a , 15a , c , 16a-c , 17a , b , 18b , 20a , b , 23a , b , 25a , b , and 27a , c were the most active ones. The MICs results of the active compounds were estimated and compared with fluconazole [Table 3]. From the data obtained, compound 4a , in which the 5-amino-1, 3, 4-thiadiazol moiety incorporated into N-benzoylindole through the thiophene bridge, was found to be highly active toward both C. albicans (ATCC-10231) and A. niger ( ATCC-10535), with MICs of 9 and 36 μg/disk, respectively, compared with fluconazole of MICs of 8 and 32 μg/disk.
Table 3: In-vitro antifungal activity of the most active compounds in comparison with fluconazole

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Molecular docking study

The result of the antifungal activity of the test compounds led us to carry out molecular docking studies to understand the ligand-protein interactions in detail. Compounds 4a , 4b , 6a , 7a , 7b , 10a , 12a , 13a , 16a-c , 18b , and 23a were docked using the MOE 2008.10 program and cytochrome P450 14 α-sterol demethylase (CYP51) (PDB ID: 1EA1). From the data obtained [Table 4] and [Figure 1],[Figure 2],[Figure 3],[Figure 4] and [Figure 5], it was found that most of the docked compounds showed a high docking score, with minimum binding energy ranging from −30.25 to −20.02 kJ/mol, in comparison with the cocrystallized ligand, namely, 2-(2,4-difluorophenyl)-1,3-di(1H-1, 2, 4-triazol-1-yl)propan-2-ol(fluconazole), which had a binding energy of −18.46 kJ/mol, an root-mean-square deviation value of 4.48, and formed only an arene-cation bond between the benzyl ring and Arg96 [Table 4] and [Figure 1]a and b.
Table 4: Docking results of the most active compounds that docked with cytochrome P450 14 a-sterol demethylase (CYP51) (PDB ID: 1EA1)

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Figure 1:

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Figure 2:

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Figure 3:

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Figure 4:

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Figure 5:

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Compound 4a had highest docked score, with a binding energy of −30.25 kJ/mol, and showed good fitting inside the pocket of the protein residue through two H-bonds formed between (a) NH of His259 and C = N of the thiadiazole ring and (b) C = O of Met433 and NH of the thiadiazole ring at a good distance for interaction, 2.93 and 2.87 Ε, respectively [Figure 2]a and b.

We can conclude that biological results were supported by docking results, which suggested that compound 4a is a promising agent as an antifungal with drug likeness approach that has 1EA1 inhibitory activity.


  Conclusion Top


New series of thiadiazoles 4a-c , morpholinyl-acetamides 6a-c , 4-methylpiperazinylacetamides 7a-c , thiazolidines 10a-c , azetidines 12a-c - 13a-c , sulfonamides 14a-c - 15a-c , benzamides 16a-c , pyrrolidines 17a-c , succinamic acids 18a-c , acetamides 19a-c , thieno(2,3-c)pyridines 20a-c , thieno(2,3-e)-1, 2, 4-triazolo(1,5-c)pyrimidines 23a-c , thieno(2,3-d)pyrimidines 24a-c - 26a-c , and thieno(2,3-b)pyridines 27a-c derivatives incorporated into N-substituted 3-indolylthiophenes were prepared. The antifungal activity of the newly synthesized compounds was tested against C. albicans (ATCC-10231) and A. niger (ATCC-10535). Compound 4a , in which the 5-amino-1, 3, 4-thiadiazol moiety was incorporated into N-benzoylindole through the thiophene bridge, showed good inhibitory activity against both C. albicans (ATCC-10231) and A. niger ( ATCC-10535), with MICs values of 9 and 36 μg/disk, respectively, compared with fluconazole, with MICs values of 8 and 34 μg/disk. The mode of action of the most promising antifungal compounds was assessed by docking with cytochrome P450 14 α-sterol demethylase (CYP51) (PDB ID: 1EA1) and the result showed that compound 4a had the highest docking score, with a binding energy of −30.25 kJ/mol; thus, it may interact at the active site of cytochrome P450 14 α-sterol demethylase (CYP51), which is in agreement with the experimental activity value.


  Acknowledgements Top


The authors thank El-Bazza ZE and her team, Pharmaceutical Microbiology Lab., National Centre for Radiation Research and Technology, Atomic Energy Authority, Cairo, Egypt, for carrying out the antifungal activity screening. Also, the authors are thankful to Micro-analytical Unit, National Research Centre, Giza, Egypt for carrying out elemental analyses and spectral data.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Heyde C, Zug I, Hartmann HA. Simple route to N,N-dialkyl derivatives of 2-amino-5-thiophenecarboxylates. Eur J Org Chem 2000; 2000:3273-3278.  Back to cited text no. 1
    
2.
Saeidian H, Sadeghi A, Mirjafary Z, Moghaddam F. Solvent-free synthesis of 2-amino-3-aryl-5-substituted thiophene as anti-inflammatory agents using KF-Al 2 O 3 under microwave irradiation. Synthesis Commun 2008; 38:2043-2053.  Back to cited text no. 2
    
3.
Jagodzinski TS. Thioamides as useful synthons in the synthesis of heterocycles. Chem Rev 2003; 103:197-277.  Back to cited text no. 3
    
4.
Zeika O, Hartmann H. Preparation and characterization of 3,4-diaryl-substituted 2-diarylaminothiophenes. Synthesis 2004; 3:377-380.  Back to cited text no. 4
    
5.
Zeika O, Hartmann H. On the oxidative coupling of N,N-disubstituted 2-aminothiophenes-synthesis of N,N¢-persubstituted 5,5¢-diamino-2,2¢-bithiophenes. Tetrahedron 2004; 60:8213-8219.  Back to cited text no. 5
    
6.
Nikolakopoulos G, Figler H, Linden J, Scammells PJ. 2-Aminothiophene-3-carboxylates and carboxamides as adenosine A1 receptor allosteric enhancers. Bioorg Med Chem 2006; 14:2358-2365.  Back to cited text no. 6
    
7.
Yen MS, Wang IJ. Synthesis and absorption spectra of hetarylazo dyes derived from coupler 4-aryl-3-cyano-2-aminothiophenes. Dyes Pigments 2004; 61:243-250.  Back to cited text no. 7
    
8.
El-Saghier AMM. A simple synthesis of some new thienopyridine and thienopyrimidine derivatives. Molecules 2002; 7:756-766.  Back to cited text no. 8
    
9.
El-Gazzar ABA, Hussein HAR, Hafez HN. Synthesis and biological evaluation of thieno(2,3-d)pyrimidine derivatives for anti-inflammatory, analgesic and ulcerogenic activity. Acta Pharm 2007; 57:395-411.  Back to cited text no. 9
    
10.
Shetty NS, Lamani RS, Khazi IAM. Synthesis and antimicrobial activity of some novel thienopyrimidines and triazolothieno-pyrimidines. J Chem Sci 2009; 121:301-307.  Back to cited text no. 10
    
11.
Rashad AE, Shamroukh AH, Abdel-Megeid RE, Mostafa A, El-Shesheny R, Kandeil A, et al. Synthesis and screening of some novel fused thiophene and thienopyrimidine derivatives for anti-avian influenza virus (H5N1) activity. Eur J Med Chem 2010; 45:5251-5257.  Back to cited text no. 11
    
12.
Mandour AH, El-Sawy ER, Shaker KH, Mustafa MA. Synthesis, anti-inflammatory, analgesic and anticonvulsant activities of 1,8-dihydro-1-aryl-8-alkyl pyrazolo(3,4-b)indole. Acta Pharm 2010; 60:73-88.  Back to cited text no. 12
    
13.
Mandour AH, El-Sawy ER, Ebaid MS, Hassan SM. Synthesis and potential biological activity of some novel 3-((N-substituted-indol-3-yl)methyleneamino)-6-amino-4-aryl-pyrano(2,3-c)pyrazole-5-carbonitriles and 3,6-diamino-4-(N-substituted-indol-3-yl)pyrano(2,3-c)pyrazole-5-carbonitriles. Acta Pharm 2012; 62:15-30.  Back to cited text no. 13
    
14.
El-Sawy ER, Mandour AH, El-Hallouty SM, Shaker KH, Abo- HM. Synthesis, antimicrobial and anticancer activities of some new N-methylsulphonyl and N-benzenesulphonyl-3-indolyl heterocycles. Arab J Chem 2012; [In press]. doi: 10.1016/j.arabjc.2012.04.003  Back to cited text no. 14
    
15.
George S, Waran MP, Chakraborty A, Ravi TK. Synthesis and evaluation of the biological activities of some 3-[5-(6-methyl-4-aryl-2-oxo-1,2,3,4-tetrahydropyrimidin-5-yl)-1,3,4-oxadiazol-2-yl]-imino-1,3-di-hydro-2H-indol-2-one derivatives. Acta Pharm 2008; 58:119-129.  Back to cited text no. 15
    
16.
El-Sawy ER, Bassyouni FA, Abu-Bakr SH, Rady HM, Abdlla MM. Synthesis and biological activity of some new 1-benzyl and 1-benzoyl 3-heterocyclic indole derivatives. Acta Pharm 2010; 60:55-71.  Back to cited text no. 16
    
17.
El-Sawy ER, Mandour AH, Mahmoud NA, Abo-Salem HM. Some new 2-amino-4-(N-substituted-1H-indol-3-yl)thiophene-3-carbonitriles and their antimicrobial properties. Egypt J Chem 2012; 55:[In press].  Back to cited text no. 17
    
18.
Bauer AW, Kirby WWM, Sherris JC, Turck M. Antibiotic susceptibility testing by a standardized single disc method. Am J Clin Pathol 1966; 36:493-496.  Back to cited text no. 18
    
19.
Podust LM, Poulos TL, Waterman MR. Crystal structure of cytochrome P450 14alpha-sterol demethylase (CYP51) from Mycobacterium tuberculosis in complex with azole inhibitors. Proc Natl Acad Sci USA 2001; 98:3068-3073.  Back to cited text no. 19
    
20.
Kaminski G, Jorgensen WL. Performance of the AMBER94, MMFF94 and OPLS-AA forcefields for modeling organic liquids. J Phys Chem 1996; 100:18010-18013.  Back to cited text no. 20
    
21.
Lensink MF, Méndez R, Wodak SJ. Docking and scoring protein complexes: CAPRI 3rd edition. Proteins 2007; 69:704-718.  Back to cited text no. 21
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]


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