Structural analogues of some highly active non-competitive AMPA antagonists

Some 5-methyl analogues (14a-e) of the non-competitive AMPA antagonists 3-acylated 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-4,5-dihydro-3H-2,3-benzodi azepines (2,3) have been synthesized. Generally they show diminished or low biological activity but two derivatives (14a,b) reveal effects comparable to those of GYKI 52466 (1), the prototype non competitive AMPA antagonist.     

Novel benzodiazepines derivatives as analgesic modulating for Transient receptor potential vanilloid 1

A new series of derivatives of 3-(7-chloro-5-(2-fluorophenyl)-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)propanoic acid were designed and synthesized as analgesic modulating for Transient receptor potential vanilloid 1. They were investigated for TRPV1 antagonistic activity in vitro, analgesic activity and sedative activity in vivo and aqueous solubility. Preliminary studies identified 3-(7-chloro-5-(2-fluorophenyl)-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)-N,N-dimethylpropanamide(Compound 11), as a potent analgesic modulating for TRPV1 with potent activity and good aqueous solubility.     

Synthesis, molecular modeling and preliminary biological evaluation of a set of 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole as potential antibacterial, anti-Trypanosoma cruzi and antifungal agents

A series of 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole derivatives was synthesized and their activity screened in vitro against Staphylococcus aureus, Trypanosoma cruzi, and Candida albicans. The bioactivity was expressed as minimum inhibitory concentration (MIC) for S. aureus strains, and as fifty-percent inhibitory concentration (IC(50)) of parasite population growth for T. cruzi. A molecular modeling approach was performed to establish qualitative relationships regarding the biological data and the compounds' physicochemical properties. The 5-(4-OC(4)H(9)Ph, 5l), and 5-(4-CO(2)CH(3)Ph, 5o) derivatives were the most active compounds for S. aureus ATCC 25923 (MIC=1.95-1.25 μg/mL) and T. cruzi (IC(50)=7.91 μM), respectively. Also, a preliminary evaluation against C. albicans involving some compounds was performed and the 5-(4-CH(3)Ph, 5e) derivative was the most active compound (MIC=3.28-2.95 μg/mL). In this preliminary study, all synthesized 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole derivatives were active against all microorganisms tested.     

Oxadiazole mannich bases: synthesis and antimycobacterial activity

A series of oxadiazole mannich bases were synthesized by reacting oxadiazole derivatives, dapsone and appropriate aldehyde in the presence of methanol. The synthesized compounds were evaluated for antimycobacterial activity against M. tuberculosis H(37)Rv and INH resistant M. tuberculosis. Among the synthesized compounds, compound (4) 3-{2-furyl[4-(4-{2-furyl[5-(2-naphthyloxymethyl)-2-thioxo-2,3-dihydro-1,3,4-oxadiazol-3-yl]methylamino}phenylsulfonyl)anilino]methyl}-5-(2-naphthyloxymethyl)-2,3-dihydro-1,3,4-oxadiazole-2-thione was found to be the most promising compound active against M. tuberculosis H(37)Rv and isoniazid (INH) resistant M. tuberculosis with Minimum inhibitory concentration (MIC) 0.1 microM & 1.10 microM respectively.     

Synthesis and cytotoxicity of 2-methyl-1-substituted-imidazo [4,5-g]quinoline-4,9-dione and 7,8-dihydro-10H-[1,4]oxazino[3',4':2,3]imidazo[4,5-g]quinoline-5,12-dio ne derivatives

2-Methyl-1-substituted-imidazo[4,5-g]quinoline-4,9-diones and 7,8-dihydro-10H-[1,4]oxazino-[3',4':2,3]imidazo[4,5-g]quinoline-5, 12-dione (19) derivatives have been synthesized from 6,7-dichloro-5,8-quinolinedione for developing the new anticancer drugs. Our study on the cytotoxicity of imidazoquinolinedione derivatives has revealed that 7,8-dihydro-10H-[1,4]oxazino-[3',4':2,3]imidazo[4,5-g]quinoline-5, 12-dione (19), a tetracyclic heteroquinone analogue, exhibited high cytotoxicity on human colon tumor cell (HCT 15) in vitro SRB assay. The IC50 value of this compound was 0.026 microg/mL whereas those of doxorubicin and cisplatin were 0.023 microg/mL and 1.482 microg/mL, respectively. Meanwhile compounds 5-7 and 12 in the series of 1-substituted-imidazoquinolinediones showed relatively good activity on human brain tumor cell lines (XF 498).     

Synthesis of Schiff Bases and Secondary Amines with Indane Skeleton; Evaluation of Their Antioxidant,Antibiotic, and Antifungal Activities

In this study, Schiff bases were synthesized by utilizing the reaction of 4- and 5-aminoindane with substituted benzaldehydes. After the reduction of isolated Schiff bases with NaBH₄, the corresponding secondary amine derivatives were obtained. The structures of all synthesized molecules were confirmed by ¹H-NMR, ¹³C-NMR, FT-IR, and ESI-MS. Antioxidant activities of all synthesized molecules were investigated by DPPH method, and IC₅₀ values were calculated. In addition, antibacterial activities of targets were investigated by the well diffusion method, and then MIC99 values were calculated. While only four of the sixteen synthesized molecules showed a high level of antioxidant activity, all of the molecules exhibited biological activity against Gram-positive and Gram-negative bacteria to varying degrees. In addition, all the synthesized molecules showed high antifungal activity. In antioxidant capacity studies, the IC₅₀ values of 2-(((2,3-dihydro-1H-inden-5-yl)amino)methyl)-6-methoxyphenol ( 4 d ) and 2-(((2,3-dihydro-1H-inden-4-yl)amino)methyl)-6-methoxyphenol ( 7 d ) were determined to be 18.1 μg and 35.1 μg, respectively, and these values are much stronger than BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole) used as positive controls. The fact that targets have the same core structure with different substituents has revealed a good structure-activity relationship.     

Synthesis and structure elucidation of novel fused 1,2,4-triazine derivatives as potent inhibitors targeting CYP1A1 activity

Synthesis and structure elucidation of new series of novel fused 1,2,4-triazine derivatives 3a-3f, 4a-4i and 6a-6b and their inhibitory activities are presented. Molecular structures of the synthesized compounds were confirmed by (1)H NMR, (13)C NMR, MS spectra and elemental analyses. X-ray crystallographic analysis was performed on 2-acetyl-8-(N,N-diacetylamino)-6-(4-methoxybenzyl)-3-(4-methoxy-phenyl)-7-oxo-2,3-dihydro-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazine 3d and 2-acetyl-8-(N-acetylamino)-6-benzyl-3-(4-chlorophenyl)-3-methyl-7-oxo-2,3-dihydro-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazine 4e to secure their structures. The inhibitory effect of these compounds toward the CPY1A1 activity was screened to determine their potential as promising anticancer drugs. Our data showed that compounds 4e, 5a, 5b and 6b possess the highest inhibitory effects among all tested compounds. Furthermore, analysis of triazolotriazine derivatives docking showed that these compounds bind only at the interface of substrate recognition site 2 (SRS2) and (SRS6) at the outer surface of the protein. Amino-acids ASN214, SER216 and ILE462 participate in the binding of these compounds through H-bonds.     

Synthesis and antihepatotoxic activity of 5-(2,3-dihydro-1,4-benzodioxane-6-yl)-3-substituted-phenyl-4,5-dihydro-1H-pyrazole derivatives

In continuance of our search for newer antihepatotoxic agents some novel pyrazoline derivatives containing 1,4-dioxane ring system were synthesized starting from 3-(2,3-dihydro-1,4-benzodioxane-6-yl)-1-substituted-phenylprop-2-en-1-one. Some of the synthesized compounds were evaluated for antihepatotoxic activity against CCl(4)-induced hepatotoxicity in rats. Among them some compounds have shown significant antihepatotoxic activity comparable to standard drug silymarin.     

Three isoflavanones with cannabinoid-like moieties from Desmodium canum

Three further derivatives of 5,7,2',4'-tetrahydroxy-6-methyl isoflavanone have been isolated from the root extract of Desmodium canum and assigned the structures 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(1a,2,3,3a,8b,8c-hexahydro-6-hydroxy-1,1,3a-trimethyl-1H-4-oxabenzo[f]cyclobut[c,d]inden-7-yl)-4H-1-benzopyran-4-one (1) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(6a,7,8,10a-tetrahydro-3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl)-4H-1-benzopyran-4-one (2) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl) 4H-1-benzopyran-4-one (3). The three compounds and the previously isolated chromene 4 all derive from the geranylated precursor 5 by a series of cannabinoid-like oxidative rearrangements.     

Synthesis and bioactivity studies on new 4-(3-(4-Substitutedphenyl)-3a,4-dihydro-3H-indeno[1,2-c]pyrazol-2-yl) benzenesulfonamides

A series of new 4-(3-(4-substitutedphenyl)-3a,4-dihydro-3H-indeno[1,2-c]pyrazol-2-yl) benzenesulfonamides (7–12) was synthesized starting from 2-(4-substitutedbenzylidene)-2,3-dihydro-1H-inden-1-one (1–6) and 4-hydrazinobenzenesulfonamide. The substituted benzaldehydes from which the key intermediate was prepared by introducing 2- or 4-substituents such as fluorine, hydroxy, methoxy, or the 3,4,5-trimethoxy moieties. The compounds were tested for their cytotoxicity, tumor-specificity and potential as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. The 3,4,5-trimethoxy and the 4-hydroxy derivatives showed interesting cytotoxic activities, which may be crucial for further anti-tumor activity studies, whereas some of these sulfonamides strongly inhibited both human (h) cytosolic isoforms hCA I and II.     

Synthesis and structure-activity relationships of 3-substituted 1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridines as novel antitumor agents

In order to obtain clinically useful antitumor agent, we have designed and synthesized various 3-substituted 1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridines, and evaluated their cytotoxic activity. The series of novel 3-substituted derivatives synthesized in this study showed good antitumor activity against murine P388 leukemia. Particularly, the 3-formyl 1,8-naphthyridine displayed an antitumor activity equal to that of the 3-carboxy 1,8-naphthyridine against murine and human tumor cell lines as well as in vivo test for mouse leukemia. These results demonstrate that the carboxy group at the C-3 position of 1,8-naphthyridine ring is not essential for antitumor activity. In addition, the trend of cytotoxic activity for the 3-substituted 1,8-naphthyridines was different from that of antibacterial activity.     

Design, synthesis and biological evaluation of pyrazolyl-thiazolinone derivatives as potential EGFR and HER-2 kinase inhibitors

A series of pyrazolyl-thiazolinone derivatives (E1-E36) have been designed and synthesized and their biological activities were also evaluated as potential EGFR and HER-2 kinase inhibitors. Thirty-four of the 36 compounds were reported for the first time. Among them, compound 2-(5-(4-bromophenyl)-3-p-tolyl-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one (E28) displayed the most potent inhibitory activity (IC(50)=0.24μM for EGFR and IC(50)=1.07μM for HER-2). Antiproliferative assay results indicated that compound E28 owned high antiproliferative activity against MCF-7, B16-F10 and HCT-116 in vitro, with IC(50) value of 0.30, 0.54, and 0.70μM, respectively. Docking simulation was further performed to position compound E28 into the EGFR active site to determine the probable binding model. Based on the preliminary results, compound E28 with potent inhibitory activity in tumor growth would be a potential anticancer agent.     

1,3-Dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines as potent caspase-3 inhibitors

Synthesis, biological evaluation and structure-activity relationships for a series of novel nonpeptide small molecule inhibitors of caspase-3 are described. Among the studied compounds, 8-sulfamide derivatives of 1,3-dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines have been identified as potent inhibitors of caspases-3. The most active compound within this series (8f) inhibited caspase-3 with IC(50)=4 nM.     

Antibacterial profile against drug-resistant Staphylococcus epidermidis clinical strain and structure-activity relationship studies of 1H-pyrazolo[3,4-b]pyridine and thieno[2,3-b]pyridine derivatives

Antibacterial resistance is a complex problem that contributes to health and economic losses worldwide. The Staphylococcus epidermidis is an important nosocomial pathogen that affects immunocompromised patients or those with indwelling devices. Currently, there are several resistant strains including S. epidermidis that became an important medical issue mainly in hospital environment. In this work, we report the biological and theoretical evaluations of a 4-(arylamino)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acids series (1, 1a-m) and the comparison with a new isosteric ring nucleus series, 4-(arylamino)thieno[2,3-b]pyridine-5-carboxylic acids derivatives (2, 2a-m). Our results revealed the 1H-pyrazolo[3,4-b]pyridine derivatives significant antibacterial activity against a drug-resistant S. epidermidis clinical strain in contrast to the thieno[2,3-b]pyridine series. The minimal inhibitory concentration (MIC) of the most active derivatives (1a, 1c, 1e, and 1f) against S. epidermidis was similar to that of oxacillin and twofold better than chloramphenicol. Interestingly, the position of the functional groups has a great impact on the activity as observed in our structure-activity relationship (SAR) study. The SAR of 1H-pyrazolo[3,4-b]pyridine derivatives shows that the highest inhibitory activity is observed when the meta position is occupied by electronegative substituents. The molecular modeling analysis of frontier molecular orbitals revealed that the LUMO density is less intense in meta than in ortho and para positions for both series (1 and 2), whereas HOMO density is overconcentrated in 1H-pyrazolo[3,4-b]pyridine ring nucleus compared to the thieno[2,3-b]pyridine system. The most active derivatives of series 1 were submitted to in silico ADMET screening, which confirmed these compounds as potential antibacterial candidates.     

Synthesis and structure-antituberculosis activity relationship of 1H-indole-2,3-dione derivatives

New series of 5-fluoro-1H-indole-2,3-dione-3-thiosemicarbazones 2a-k and 5-fluoro-1-morpholino/piperidinomethyl-1H-indole-2,3-dione-3-thiosemicarbazones 3a-r were synthesized. The structures of the synthesized compounds were confirmed by spectral data, elemental and single crystal X-ray diffraction analysis. The new 5-fluoro-1H-indole-2,3-dione derivatives, along with previously reported 5-nitro-1H-indole-2,3-dione-3-thiosemicarbazones 2l-v, 1-morpholino/piperidinomethyl-5-nitro-1H-indole-2,3-dione-3-thiosemicarbazones 4a-l, and 5-nitro-1H-indole-2,3-dione-3-[(4-oxo-1,3-thiazolidin-2-ylidene)hydrazones] 5a-s, were evaluated for in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv. Among the tested compounds, 5-nitro-1H-indole-2,3-dione-3-thiosemicarbazones (2p, 2r, and 2s) and its 1-morpholinomethyl derivatives (4a, 4e, 4g, and 4i) exhibited significant inhibitory activity in the primary screen. The antituberculosis activity of molecules with diverse skeletons was investigated by means of the Electronic-Topological Method (ETM). Ten pharmacophores and ten anti-pharmacophores that have been found by this form the basis of the system capable of predicting the structures of potentially active compounds. The forecasting ability of the system has been tested on structures that differ from those synthesized. The probability of correct identification for active compounds was found as equal to 93% in average. To obtain the algorithmic base for the activity prediction, Artificial Neural Networks were used after the ETM (the so-called combined ETM-ANN method). As the result, only 9 pharmacophores and anti-pharmacophores were chosen as the most important ones for the activity. By this, ANNs classified correctly 94.4%, or 67 compounds from 71.     

Synthesis of novel 2-pyrazoline analogues with potent anti-inflammatory effect mediated by inhibition of phospholipase A2: Crystallographic,in silico docking and QSAR analysis

Oxidative-stress induces inflammatory diseases. Further, infections caused by drug-resistant microbial strains are on the rise. This necessitates the discovery of novel small-molecules for intervention therapy. A series of 3-(2,3-dichlorophenyl)-1-(aryl)prop-2-en-1-ones are synthesized as intermediates via Claisen-Schmidt reaction approach. Subsequently, these intermediates were transformed into 2-pyrazolines by their reaction with phenylhydrazine hydrochlorides in methanol and few drops of acetic acid under reflux conditions. Synthesized compounds were characterized by spectroscopic, crystallographic and elemental analyses studies and then, were evaluated for their in vitro antimicrobial and anti-inflammatory activities. Amongst the series, 3-(4-chlorophenyl)-5-(2,3-dichlorophenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (5e), 5-(2,3-dichlorophenyl)-3-(4-fluorophenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (5c) and 5-(2,3-dichlorophenyl)-3-(4-methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (5h) showed significant inhibition of phospholipase A2 with IC₅₀ values of 10.2, 11.1 and 11.9 µM, respectively. Protein structure modelling and docking studies indicated that the compounds showed binding to a highly conserved calcium-binding pocket on the enzyme. Further, compounds (5e), 1-(3-chlorophenyl)-5-(2,3-dichlorophenyl)-3-phenyl-4,5-dihydro-1H-pyrazole (5b), and 1-(3-chlorophenyl)-3-(4-chlorophenyl)-5-(2,3-dichlorophenyl)-4,5-dihydro-1H-pyrazole (5f) showed excellent antimicrobial activities against various bacterial and fungal strains. In conclusion, this study is a successful attempt at the synthesis and characterization of chalcone derivatives that can target phospholipase A2, an enzyme that is a prominent player in the physiological inflammatory cascade. Thus, these compounds show promise for development as next-generation nonsteroidal anti-inflammatory drugs.     

Inhibition of monoamine oxidase by 3,4-dihydro-2(1H)-quinolinone derivatives

In the present study, a series of 3,4-dihydro-2(1H)-quinolinone derivatives were synthesized and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. The 3,4-dihydro-2(1H)-quinolinone derivatives are structurally related to a series of coumarin (1-benzopyran-2-one) derivatives which have been reported to act as MAO-B inhibitors. The results document that the quinolinones are highly potent and selective MAO-B inhibitors with most homologues exhibiting IC₅₀ values in the nanomolar range. The most potent MAO-B inhibitor, 7-(3-bromobenzyloxy)-3,4-dihydro-2(1H)-quinolinone, exhibits an IC₅₀ value of 2.9 nM with a 2750-fold selectivity for MAO-B over the MAO-A isoform. An analysis of the structure–activity relationships for MAO-B inhibition shows that substitution on the C7 position of the 3,4-dihydro-2(1H)-quinolinone scaffold leads to significantly more potent inhibition compared to substitution on C6. In this regard, a benzyloxy substituent on C7 is more favourable than phenylethoxy and phenylpropoxy substitution on this position. It may be concluded that C7-substituted 3,4-dihydro-2(1H)-quinolinones are promising leads for the therapy of Parkinson’s disease.     

Novel 5-(2-hydroxyphenyl)-3-substituted-2,3-dihydro-1,3,4-oxadiazole-2-thione derivatives: promising anticancer agents

A series of 5-(2-hydroxyphenyl)-3-substituted-2,3-dihydro-1,3,4-oxadiazole-2-thione derivatives was synthesized and 13 of them were selected by the National Cancer Institute (NCI) and evaluated for their in vitro anticancer activity. Seven of the investigated compounds, 3i, 3j, 3k, 3o, 3p, 3q, and 3r, displayed high anticancer activity in the primary assay. These compounds have been selected for a full anticancer screening against a 60-cell panel assay where they showed non-selective broad spectrum and promising activity against all cancer cell lines. Compounds 3j and 3k proved to be the active members in this study compared to 5-fluorouracil and cyclophosphamide as reference drugs, respectively. Compounds 3j and 3k were identified as promising lead compounds.     

Synthesis of pro-apoptotic indapamide derivatives as anticancer agents

Abstract

4-Chloro-3-({[(substitutedamino)carbonothioyl]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide (1–20) and 4-chloro-3-({[3-(substituted)-4-oxo-1,3-thiazolidine-2-ylidene]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide derivatives (21–31) were synthesized from 4-chloro-N-(2-methyl-2,3-dihydroindol-1-yl)-3-sulfamoylbenzamide (indapamide). 4-Chloro-3-({[(4-chlorophenyl) amino) carbonothioyl]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide 12 demonstrated the highest proapoptotic activity among all synthesized compounds on melanoma cell lines MDA–MB-435 with 3.7% growth inhibition at the concentration of 10?µM. Compound 12 (SGK 266) was evaluated in vitro using the MTT colorimetric method against melanoma cancer cell line MDA–MB435 growth inhibition for different doses and exhibited anticancer activity with IC₅₀ values of 85–95?µM against melanoma cancer cell line MDA–MB435. In addition, this compound was investigated as inhibitors of four physiologically relevant human carbonic anhydrase isoforms, hCA I, II, IX and XII. The compund inhibited these enzymes with IC₅₀ values ranging between 0.72 and 1.60?µM.     

Benzopyrans from Curvularia sp., an endophytic fungus associated with Ocotea corymbosa (Lauraceae)

An isolate of Curvularia sp. was obtained from the leaves of Ocotea corymbosa, a native plant of the Brazilian Cerrado. The ethyl acetate extract from culture of this fungus afforded two benzopyran derivatives: (2'S)-2-(propan-2'-ol)-5-hydroxy-benzopyran-4-one (2) and 2,3-dihydro-2-methyl-benzopyran-4,5-diol (4); and two known benzopyrans: 2-methyl-5-methoxy-benzopyran-4-one (1) and (2R)-2,3-dihydro-2-methyl-5-methoxy-benzopyran-4-one (3). The structures of 2 and 4 were established on the basis of comprehensive spectroscopic analysis, mainly using 1D and 2D NMR experiments. The benzopyrans 1 and 2 showed weak in vitro antifungal activity against Cladosporium sphaerospermum and C. cladosporioides. Analyses of the biological activities were also carried out on HeLa (human cervix tumor) and CHO (Chinese hamster ovary) cells, aiming to evaluate their potential effects on mammalian cell line proliferation. Results from both cell lines indicated that compound 2 was able to induce cell proliferation: 70% on HeLa cells and 25% on CHO cells.