Synthesis and biological activity of 7H-benzo[4,5]indolo[2,3-b]-quinoxaline derivatives

New 7-(2-aminoethyl)-7H-benzo[4,5]indolo[2,3-b]quinoxalines (13-20) were synthesized with high yields starting from 3H-benzo[e]indole-1,2-dione. These compounds were screened for the cytotoxicity, anti-viral activity, interferon inducing ability and DNA affinity compared with the corresponding 6-(2-aminoethyl)-6H-indolo[2,3-b]quinoxaline derivatives (1-12). It was shown, that compounds 13-20 bind to DNA stronger (lg К_a = 6.23-6.87) than compounds 1-12 (lg К_a = 5.57-5.89). Anti-viral activity is significantly reduced with annulations of benzene ring in Indoloquinoxaline moiety 13-20.     

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.     

Synthesis of some novel 3-(1-(1-substitutedpiperidin-4-yl)-1H-1,2,3-triazol-4-yl)-5-substituted phenyl-1,2,4-oxadiazoles as antifungal agents

A novel series of 3-(1-(1-substituted piperidin-4-yl)-1H-1,2,3-triazol-4-yl)-5-substituted phenyl-1,2,4-oxadiazoles bearing 1,2,3-triazole and piperidine ring has been synthesized in one step from amidoxime using Carbonyl diimidazole (CDI) and K₂CO₃. All the synthesized compounds (4a-4r) are novel and evaluated for their in vitro antifungal activities. SAR for the series has been developed by comparing their MIC values with miconazole and fluconazole. Some of the compounds from the series like 4j was equipotent with miconazole against Cryptococcus neoformans whereas activities of compound 4m against Aspergillus niger and Aspergillus flavus were comparable to miconazole. Also compound 4r shows activity comparable to miconazole against Candida albicans, A. niger and A. flavus.     

Novel 4-aryl-pyrido[1,2-c]pyrimidines with dual SSRI and 5-HT(1A) activity. part 3

A number of 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine with 3-(1,2,3,6-tetrahydro-pyridin-4-yl)-1H-indole or 2-methyl-3-(1,2,3,6-tetrahydro-pyridin-4-yl)-1H-indole residues were synthesized for further investigation of SAR in a group of pyrido[1,2-c]pyrimidine derivatives with dual 5-HT_1A/SERT activity. Compounds 8a-8p were found to be potent ligands for both 5-HT_1A and SERT with K_i ranging from 28,3 to 642 nM and 42,4 nM-1,8 μM, respectively. Moreover compounds 8a, 8b, 8c, 8d, 8e and 8g were found to be selective agonists, while 8i as an antagonist of 5-HT_1A presynaptic receptors in the inducible hypothermia test in mice.     

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.     

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 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.     

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, 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.     

Design and synthesis of 2-phenylimidazo[1,2-a]pyridines as a novel class of melatonin receptor ligands

A novel class of imidazo[1,2-a]pyridines as melatonin receptor ligands is designed and synthesized. The affinities of 3-(6-methoxy-2-phenylimidazo[1,2-a]pyridine-3-yl)-N-methyl-propionamide 8, N-[2-(6-methoxy-2-phenylimidazo[1,2-a]pyridine-3-yl)-ethyl]-acetamide 13 and N-(1-hydroxy-3-(5-methoxy-2-phenyl-1H-indol-3-yl)propan-2-yl)acetamide 18 are evaluated for binding on melatonin receptors. Compound 8 present good selectivity for MT₂ over MT₁ (MT₁/MT₂ = 19) and compound 13 have good affinities for both MT₁ (Ki :28 nM) and MT₂ (Ki : 8 nM).     

Synthesis of 3-heteroarylthioquinoline derivatives and their in vitro antituberculosis and cytotoxicity studies

A series of 3-heteroarylthioquinoline derivatives has been synthesized by the Friedlander annulation of 2-[(5-methyl-1,3,4-thiadiazol-2-yl)sulfanyl]-1-aryl-1-ethanone/2-(1,3-benzothiazol-2-ylsulfanyl)-1-aryl-1-ethanone/1-aryl-2-[(2-phenyl-2H-1,2,3,4-tetraazol-5-yl)sulfanyl]-1-ethanone with 2-aminobenzophenone in good yields using YbCl₃ as the catalyst. These compounds have been screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and among the 21 compounds screened, 2-[2-(4-bromophenyl)-4-phenyl-3-quinolyl]sulfanyl-5-methyl-1,3,4-thiadiazole (5d) and 2-[2-(4-chlorophenyl)-4-phenyl-3-quinolyl]sulfanyl-5-methyl-1,3,4-thiadiazole (5c) were found to be the most active compounds with MIC of 3.2 and 3.5 μM respectively against MTB. The cytotoxic effects against mouse fibroblasts (NIH 3T3) in vitro were evaluated for 5c and 5d, which displayed no toxic effects (IC₅₀ > 1000 μM) against the mouse fibroblast cell line NIH 3T3.     

Synthesis and anticancer activities of some novel 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones

A series of 2-(benzo[d]thiazol-2-yl)-8-substituted-2H-pyrazolo[4,3-c]quinolin-3(5H)-ones (3a-g) have been synthesized and evaluated for their in vitro antiproliferative activities against four human cancer cell lines: MDA-MB-435 (breast), HL-60 (leukemia), HCT-8 (colon) and SF-295 (central nervous system). The results showed that the compounds 3b (2-(benzo[d]thiazol-2-yl)-8-methyl-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) and 3c (2-(benzo[d]thiazol-2-yl)-8-bromo-2H-pyrazolo[4,3-c]quinolin-3(5H)-one) exhibited good cytotoxicity for three cell lines with IC₅₀ values lower than 5 μg/mL. Analysis of theoretical toxicity risks have shown medium tumorigenic and irritant risks related to 3b and 3c in contrast to doxorubicin, the positive control.     

Synthesis and biological evaluation of 1-substituted-3(5)-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)pyrazoles as transforming growth factor-β type 1 receptor kinase inhibitors

A series of 1-substituted-3(5)-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)pyrazoles 14a-d, 15a-d, 17a, 17b, 18a-d, 19a, and 19b has been synthesized and evaluated for their ALK5 inhibitory activity in an enzyme assay and in a cell-based luciferase reporter assay. The 2-[3-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)-1H-pyrazol-1-yl]-N-phenylethanethioamide (18a) inhibited ALK5 phosphorylation with an IC₅₀ value of 0.013 μM and showed 80% inhibition at 0.1 μM in a luciferase reporter assay using HaCaT cells permanently transfected with p3TP-luc reporter construct.     

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.     

Synthesis, antiproliferative activity, and mechanism of action of a series of 2-{[(2E)-3-phenylprop-2-enoyl]amino}benzamides

Several new 2-{[(2E)-3-phenylprop-2-enoyl]amino}benzamides 12a-s and 17t-v were synthesized by stirring in pyridine the (E)-3-(2-R1-3-R2-4-R3-phenyl)acrylic acid chlorides 11c-k and 11t-v with the appropriate anthranilamide derivatives 10a-c or the 5-iodoanthranilic acid 13. Some of the synthesized compounds were evaluated for their in vitro antiproliferative activity against the full NCI tumor cell line panel derived from nine clinically isolated cancer types (leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate and breast). COMPARE analysis, effects on tubulin polymerization in cells and with purified tubulin, and effects on cell cycle distribution for 17t, the most active of the series, indicate that these new antiproliferative compounds act as antitubulin agents.     

Investigations on cytotoxicity and anti-inflammatory potency of licofelone derivatives

A series of C5-substituted licofelone ([2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro-1H-pyrrolizin-5-yl]acetic acid) derivatives were developed by a parallel synthesis approach and investigated for cytotoxicity against MCF-7 and MDA-MB-231 cells as well as for anti-inflammatory potency in vitro and in vivo. Dependent on the C5-substituent, the compounds showed high selectivity for MCF-7 cells. Especially 2-oxoethyl benzoate derivatives were inactive at the MDA-MB-231 cell line and as active as 5-FU at MCF-7 cells. C5-acetyl (8a), -2-oxoethyl formiate (8e), -2-oxoethyl acetate (8f) and -2-oxoethyl propionate (8g) derivatives showed growth inhibition at both cell lines, comparable with cisplatin. Modifications significantly reduced the inhibitory potency at COX-1 and COX-2 in vitro and in the xylene-induced ear swelling assay in mice. Only compound 8a was equipotent to licofelone, ibuprofen and celecoxibe in vivo.     

Synthesis and evaluation of monoamidoxime derivatives: toward new antileishmanial compounds

A new series of monoamidoxime derivatives was synthesized using manganese(III) acetate by microwave irradiation. Several amidoximes (27-31, 33, 38) showed valuable in vitro activities toward Leishmania donovani promastigotes, exhibiting IC₅₀ values between 5.21 and 7.89 μM. In parallel, the cytotoxicity of these compounds was evaluated on murine J774A.1 cells, revealing the corresponding selectivity index (SI). Among the 13 tested compounds, 4 monoamidoximes (27-30) exhibited an SI more than 20 times better than pentamidine. Moreover, monoamidoxime 28 (4-[5-Benzyl-3-(4-fluorophenylsulfonyl)-5-methyl-4,5-dihydrofuran-2-yl]-N′-hydroxybenzimidamide) is 40 times more selective than pentamidine, and 1.6 times more than amphotericin B, used as reference drug compounds.     

Design, synthesis and molecular docking studies of novel triazole as antifungal agent

In order to meet the urgent need for novel antifungal agents with improved activity and broader spectrum, a series of 1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-3-[(4-substituted trifluoromethyl phenyl)-piperazin-1-yl]-propan-2-ols were designed, synthesized and evaluated as antifungal agents. The MIC₈₀ values indicate that the compounds 7a-7q, 8a-8d showed higher antifungal activities against Candida albicans than 5a-5i, 6a-6j. Moreover, the molecular model for the binding between compound 5a, 7a and the active site of CACYP51 was provided based on the computational docking results, and the structure-activity relationship was analyzed.     

HIV-1 integrase strand-transfer inhibitors: design, synthesis and molecular modeling investigation

This study is focused on a new series of benzylindole derivatives with various substituents at the benzene-fused ring, suggested by our 3D pharmacophore model developed for HIV-1 integrase inhibitors (INIs). All synthesized compounds proved to be active in the nanomolar range (6-35 nM) on the strand-transfer step (ST). In particular, derivative 4-[1-(4-fluorobenzyl)-5,7-dimethoxy-1H-indol-3-yl]-2-hydroxy-4-oxobut-2-enoic acid (8e), presenting the highest best-fit value on pharmacophore model, showed a potency comparable to that of clinical INSTIs GS 9137 (1) and MK-0518 (2). The binding mode of our molecules has been investigated using the recently published crystal structure of the complex of full-length integrase from the prototype foamy virus in complex with its cognate DNA (PFV-IN/DNA). The results highlighted the ability of derivative 8e to assume the same binding mode of MK-0518 and GS 9137.     

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.