Design,synthesis and evaluation against Mycobacterium tuberculosis of azole piperazine derivatives as dicyclotyrosine (cYY) mimics

Three series of azole piperazine derivatives that mimic dicyclotyrosine (cYY), the natural substrate of the essential Mycobacterium tuberculosis cytochrome P450 CYP121A1, were prepared and evaluated for binding affinity and inhibitory activity (MIC) against M. tuberculosis. Series A replaces one phenol group of cYY with a C3-imidazole moiety, series B includes a keto group on the hydrocarbon chain preceding the series A imidazole, whilst series C explores replacing the keto group of the piperidone ring of cYY with a CH₂-imidazole or CH₂-triazole moiety to enhance binding interaction with the heme of CYP121A1. The series displayed moderate to weak type II binding affinity for CYP121A1, with the exception of series B 10a, which displayed mixed type I binding. Of the three series, series C imidazole derivatives showed the best, although modest, inhibitory activity against M. tuberculosis (17d MIC?=?12.5?μg/mL, 17a 50?μg/mL). Crystal structures were determined for CYP121A1 bound to series A compounds 6a and 6b that show the imidazole groups positioned directly above the haem iron with binding between the haem iron and imidazole nitrogen of both compounds at a distance of 2.2?Å. A model generated from a 1.5?Å crystal structure of CYP121A1 in complex with compound 10a showed different binding modes in agreement with the heterogeneous binding observed. Although the crystal structures of 6a and 6b would indicate binding with CYP121A1, the binding assays themselves did not allow confirmation of CYP121A1 as the target.     

Design,synthesis, and bioevaluation of a novel class of (E)-4-oxo-crotonamide derivatives as potent antituberculosis agents

A series of novel (E)-4-oxo-2-crotonamide derivatives were designed and synthesized to find potent antituberculosis agents. All the target compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis H₃₇Rv(MTB). Results reveal that 4-phenyl moiety at part A and short methyl group at part C were found to be favorable. Most of the derivatives displayed promising activity against MTB with MIC ranging from 0.125 to 4?µg/mL. Especially, compound IIIa16 was found to have the best activity with MIC of 0.125?μg/mL against MTB and with MIC in the range of 0.05–0.48?µg/mL against drug-resistant clinical MTB isolates.     

Azoalkyl ether imidazo[2,1-b]benzothiazoles as potentially antimicrobial agents with novel structural skeleton

A series of new azoalkyl ether imidazo[2,1-b]benzothiazoles were developed via a convenient synthetic procedure. The antimicrobial assays showed that a good number of the prepared derivatives exhibited significant inhibitory properties against most of the tested strains. Especially 2-methyl-5-nitroimidazole derivative 5a presented superior inhibit activity against MRSA and B. typhi with MIC?=?4?μg/mL and MIC?=?1?μg/mL, respectively. The highly active compound 5a showed low toxicity against mammalian cells without obvious triggering of the development of bacterial resistance, and it also possessed rapid bactericidal efficacy. Molecular docking study exposed that the active molecule 5a could interact with the active site of S. aureus gyrase through hydrogen bond. Quantum chemical studies were also performed to explain the high antibacterial activity. Further investigation revealed that compound 5a could significantly associate with gyrase–DNA complex by mean of hydrogen bonds and could efficiently intercalate into MRSA DNA to form 5a–DNA supramolecular complex, which impart potent bioactivity.     

Synthesis,biological evaluations and computational studies of N-(3-(-2-(7-Chloroquinolin-2-yl)vinyl) benzylidene)anilines as fungal biofilm inhibitors

In the present investigation, new chloroquinoline derivatives bearing vinyl benzylidene aniline substituents at 2nd position were synthesized and screed for biofilm inhibitory, antifungal and antibacterial activity. The result of biofilm inhibition of C. albicans suggested that compounds 5j (IC₅₀ value?=?51.2?μM) and 5a (IC₅₀ value?=?66.2?μM) possess promising antibiofilm inhibition when compared with the standard antifungal drug fluconazole (IC₅₀?=?40.0?μM). Two compounds 5a (MIC?=?94.2?μg/mL) and 5f (MIC?=?98.8?μg/mL) also exhibited good antifungal activity comparable to standard drug fluconazole (MIC?=?50.0?μg/mL). The antibacterial screening against four strains of bacteria viz. E. coli, P. aeruginosa, B. subtilis, and S. aureus suggested their potential antibacterial activity and especially all the compounds except 5g were found more active than the standard drug ciprofloxacin against B. subtilis. To further gain insights into the possible mechanism of these compounds in biofilm inhibition through the agglutinin like protein (Als), molecular docking and molecular dynamics simulation studies were carried out. Molecular modeling studies suggested the clear role in inhibition of this protein and the resulting biofilm inhibitory activity.     

Synthesis,characterization, antifungal evaluation and 3D-QSAR study of phenylhydrazine substituted tetronic acid derivatives

A series of 3-(1-(2-(substituted phenyl)hydrazinyl)alkylidene)furan-2,4(3H,5H)-diones were designed and prepared using two synthetic routes. Their structures were confirmed by FT-IR, ¹H NMR, ¹³C NMR, MS, elemental analysis and single-crystal X-ray diffraction. Their bioactivity was evaluated against Botrytis cinerea in vitro. Most target compounds exhibited remarkable antifungal activity. Two compounds 7f and 7h were highly effective and their EC₅₀ values were 0.241 μg/mL and 0.167 μg/mL, respectively, close to that of the control drug procymidone. 3D-QSAR studies of CoMFA and CoMSIA were carried out. Models with good predictive ability were generated with the cross validated q² values for CoMFA and CoMSIA being 0.565 and 0.823. Conventional r² values were 0.983 and 0.945, respectively. The results provided a practical tool for guiding the design and synthesis of novel and more potent tetronic acid derivatives containing substituted phenylhydrazine moiety.     

Design,synthesis and molecular modeling of new 4-phenylcoumarin derivatives as tubulin polymerization inhibitors targeting MCF-7 breast cancer cells

A new set of 4-phenylcoumarin derivatives was designed and synthesized aiming to introduce new tubulin polymerization inhibitors as anti-breast cancer candidates. All the target compounds were evaluated for their cytotoxic effects against MCF-7 cell line, where compounds 2f, 3a, 3b, 3f, 7a and 7b, showed higher cytotoxic effect (IC₅₀?=?4.3–21.2?μg/mL) than the reference drug doxorubicin (IC₅₀?=?26.1?μg/mL), additionally, compounds 1 and 6b exhibited the same potency as doxorubicin (IC₅₀?=?25.2 and 28.0?μg/mL, respectively). The thiazolidinone derivatives 3a, 3b and 3f with potent and selective anticancer effects towards MCF-7 cells (IC₅₀?=?11.1, 16.7 and 21.2?μg/mL) were further assessed for tubulin polymerization inhibition effects which showed that the three compounds were potent tubulin polymerization suppressors with IC₅₀ values of 9.37, 2.89 and 6.13?μM, respectively, compared to the reference drug colchicine (IC₅₀?=?6.93?μM). The mechanistic effects on cell cycle progression and induction of apoptosis in MCF-7 cells were determined for compound 3a due to its potent and selective cytotoxic effects in addition to its promising tubulin polymerization inhibition potency. The results revealed that compound 3a induced cell cycle cessation at G2/M phase and accumulation of cells in pre-G1 phase and prevented its mitotic cycle, in addition to its activation of caspase-7 mediating apoptosis of MCF-7 cells. Molecular modeling studies for compounds 3a, 3b and 3f were carried out on tubulin crystallography, the results indicated that the compounds showed binding mode similar to the co-crystalized ligand; colchicine. Moreover, pharmacophore constructed models and docking studies revealed that thiazolidinone, acetamide and coumarin moieties are crucial for the activity. Molecular dynamics (MD) studies were carried out for the three compounds over 100?ps. MD results of compound 3a showed that it reached the stable state after 30?ps which was in agreement with the calculated potential and kinetic energy of compound 3a.     

Synthesis, anti-tuberculosis activity, and 3D-QSAR study of 4-(adamantan-1-yl)-2-substituted quinolines

Structural optimization of the previously identified 4-(adamantan-1-yl)-2-quinolinecarbohydrazide (AQCH, MIC=6.25 microg/mL, 99% inhibition, Mycobacterium tuberculosis H37Rv) has led to two series of 4-(adamantan-1-yl)-2-substituted quinolines (Series 1-2). All new derivatives were evaluated in vitro for antimycobacterial activities against drug-sensitive M. tuberculosis H37Rv strain. Several 4-adamantan-1-yl-quinoline-2-carboxylic acid N'-alkylhydrazides (Series 1) described herein showed promising inhibitory activity. In particular, analogs 7, 9, 20, and 21 displayed MIC of 3.125 microg/mL. Further investigation of AQCH by its reaction with various aliphatic, aromatic, and heteroaromatic aldehydes led to the synthesis of 4-adamantan-1-yl-quinoline-2-carboxylic acid alkylidene hydrazides (Series 2). Analogs 42-44 and 48 have produced promising antimycobacterial activities (99% inhibition) at 3.125 microg/mL against drug-sensitive M. tuberculosis H37Rv strain. The most potent analog 35 of the series produced 99% inhibition at 1.00 microg/mL against drug-sensitive strain, and MIC of 3.125 microg/mL against isoniazid-resistant TB strain. To understand the relationship between structure and activity, a 3D-QSAR analysis has been carried out by three methods-comparative molecular field analysis (CoMFA), CoMFA with inclusion of a hydropathy field (HINT), and comparative molecular similarity indices analysis (CoMSIA). Several statistically significant CoMFA, CoMFA with HINT, and CoMSIA models were generated. Prediction of the activity of a test set of molecules was the best for the CoMFA model generated with database alignment. Based on the CoMFA contours, we have tried to explain the structure-activity relationships of the compounds reported herein.     

Synthesis and biological evaluation of a new series of N-acyldiamines as potential antibacterial and antifungal agents

In continuation of our efforts to find new antimicrobial compounds, series of fatty N-acyldiamines were prepared from fatty methyl esters and 1,2-ethylenediamine, 1,3-propanediamine or 1,4-butanediamine. The synthesized compounds were screened for their antibacterial activity against Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and for their antifungal activity against four species of Candida (C. albicans, C. tropicalis, C. glabrata and C. parapsilosis). Compounds 5a (N-(2-aminoethyl)dodecanamide), 5b (N-(2-aminoethyl)tetracanamide) and 6d (N-(3-aminopropyl)oleamide) were the most active against Gram-positive bacteria, with MIC values ranging from 1 to 16 μg/mL and were evaluated for their activity against 21 clinical isolates of methicillin-resistant S. aureus. All the compounds exhibited good to moderate antifungal activity. Compared to chloramphenicol, compound 6b displayed a similar activity (MIC₅₀ = 16 μg/mL). A positive correlation could be established between lipophilicity and biological activity.     

Synthesis and antibacterial evaluation of novel 11-O-aralkylcarbamoyl-3-O-descladinosylclarithromycin derivatives

A series of novel 11-O-aralkylcarbamoyl-3-O-descladinosylclarithromycin derivatives were designed, synthesized and evaluated for their in vitro antibacterial activity. The results showed that the majority of the target compounds displayed potent activity against erythromycin-susceptible S. pyogenes, erythromycin-resistant S. pneumoniae A22072 expressing the mef gene and S. pneumoniae AB11 expressing the mef and erm genes. Besides, most of the target compounds exhibited moderate activity against erythromycin-susceptible S. aureus ATCC25923 and B. subtilis ATCC9372. In particular, compounds 11a, 11b, 11c, 11e, 11f and 11h were found to exert favorable antibacterial activity against erythromycin-susceptible S. pyogenes with the MIC values of 0.015–0.125?μg/mL. Furthermore, compounds 10e, 11a, 11b and 11c showed superior activity against erythromycin-resistant S. pneumoniae A22072 with the MIC values of 0.25–0.5?μg/mL. Additionally, compound 11c was the most effective against all the erythromycin-resistant S. pneumoniae strains (A22072, B1 and AB11), exhibiting 8-, 8- and 32-fold more potent activity than clarithromycin, respectively.     

Synthesis and evaluation of the antibacterial activities of aryl substituted dihydrotriazine derivatives

Five series of dihydrotriazine derivatives containing chalcone (13a–i), phenoxy acetophenone (14a–b), benzyl benzene (15a–c), naphthoxyl acetophenone (16a–b) and benzyl naphthalene (17a–h) moieties were designed and synthesized. The antibacterial and antifungal activities of these compounds were evaluated against several strains of Gram-positive and Gram-negative bacteria, as well as a single fungus. Compound 17h was found to be the most potent of all of the compounds tested, with an MIC value of 0.5?μg/mL against several Gram-positive (Staphylococcus aureus 4220 and QRSA CCARM 3505) and Gram-negative (Escherichia coli 1924) strains of bacteria. However, this compound was inactive against Pseudomonas aeruginosa 2742 and Salmonella typhimurium 2421, indicating that its antibacterial spectrum is similar to those of the positive controls gatifloxacin and moxifloxacin. The cytotoxic activity of the compound 13i, 16b and 17h was assessed in Human normal liver cells.     

Synthesis and biological evaluation of glycal-derived novel tetrahydrofuran 1,2,3-triazoles by ‘click’ chemistry

Thirteen new 1,2,3-triazoles (5a-e, 15a-d, 17a-b, 19, and 21) were synthesized by ‘click’ reaction of sugar-derived azides with commercially available acetylenes. The synthesized triazoles were tested in vitro for their biological activity, and compound 5b displayed both antibacterial and antifungal activities at an MIC value of 12.5 μg/mL, while compounds 15b and 19 showed antibacterial activity at an MIC value of 25 μg/mL.     

Dihydropyrazothiazole derivatives as potential MMP-2/MMP-8 inhibitors for cancer therapy

MMP-2/MMP-8 is established as one of the most important metalloenzymes for targeting cancer. A series of dihydropyrazothiazole derivatives (E1–E18) bearing a salicylaldehyde group linked to Pyrazole ring were designed, synthesized, and evaluated for their pharmacological activity as MMP-2/MMP-8 inhibitors. Among them, compound E17 exhibited most potent inhibitory activity (IC₅₀?=?2.80?μM for MMP-2 and IC₅₀?=?5.6?μM for MMP-8), compared to the positive drug CMT-1 (IC₅₀?=?1.29?μM). Compounds (E1–E18) were scrutinized by CoMFA and CoMSIA techniques of Three-dimensional quant. structure-activity relationship (3D-QSAR), as well as a docking simulation. Moreover, treatment with compound E4 could induce MCF-7 cell apoptosis. Overall, the biological profile of E1–E18 may provide a research basis for the development of new agents against cancer.     

Antimicrobial,anticoagulant, and cytotoxic evaluation of multidrug resistance of new 1,4-dihydropyridine derivatives

A new series of 1,4-dihydropyridine derivatives (2a–h, 3a–e, and 4a–e) were systematically designed and synthesized via ultrasound irradiation methods with easy work-up and good yields. Compounds structures were confirmed by IR, ¹H NMR, ¹³C NMR, and mass spectra. The synthesized compounds were screened for both antimicrobial and anticoagulant activities. Compound 2e (MIC: 0.25?μg/mL) was highly active against Escherichia coli and compound 2c (MIC: 0.5?μg/mL) was also highly active against Pseudomonas aeruginosa compared with ciprofloxacin. (MIC: 1?μg/mL) The antifungal activity of 2c (MIC: 0.5?μg/mL) against Candida albicans was high relative to that of clotrimazole (MIC: 1?μg/mL). Anticoagulant activity was determined by activated partial thromboplastin time (APTT) and prothrombin time (PT) coagulation assays. Compound 4-(4-hydroxyphenyl)-2,6-dimethyl-N³,N⁵-bis(5-phenyl-1,3,4-thiadiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide 3d (>1000?s in APTT assays) was highly active in anticoagulant screening compared with the reference of heparin.Cytotoxicity was evaluated using HepG2 (liver), HeLa (cervical), and MCF-7 (breast) cancer cell lines, with high toxicities observed for 2c (GI₅₀?=?0.02?μm) against HeLa cell line and 2e (GI₅₀?=?0.03?μm) equipotant against MCF-7 cell line. Therefore, the compounds 2e, 2c and 3d can serve as lead molecules for the development of new classes of antimicrobial and anticoagulant agent.     

Rational design,synthesis and antitubercular evaluation of novel 2-(trifluoromethyl)phenothiazine-[1,2,3]triazole hybrids

Molecular hybridization is an emerging structural modification tool to design molecules with better pharmacophoric properties. A series of novel 2-(trifluoromethyl)phenothiazine-1,2,3-triazoles 5a–v designed by hybridizing two antitubercular drugs trifluoperazine and I-A09 in a single molecular architecture, were synthesized in very good yields using click chemistry. Among the all ‘22’ compounds screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (Mtb), three analogs 5c, 5l and 5o were found to be most potent (MIC: 6.25 μg/mL) antitubercular agents with good selectivity index.     

Three-dimensional quantitative structure–activity relationship study on paullones as CDK inhibitors using CoMSIA and CoMFA

3D-QSAR studies were conducted on a series of paullones as CDK inhibitors using three-dimensional quantitative structure-activity relationship (3D-QSAR) methods. Two methods were compared: the widely used comparative molecular field analysis (CoMFA) and the recently reported comparative molecular similarity indices analysis (CoMSIA). Systematic variations of some parameters in CoMSIA and CoMFA were performed to search for the best 3D-QSAR model. The computed results showed that the 3D-QSAR models from CoMSIA were clearly superior to those from CoMFA. Using the best model from CoMSIA analysis, a significant cross-validated q² was obtained and the predicted biological activities of the five compounds in the test set were in good agreement with the experimental values. The correlation results obtained from CoMSIA were graphically interpreted in terms of field contribution maps allowing physicochemical properties relevant for binding to be easily mapped back onto molecular structures. The features in the CoMSIA contour maps intuitively suggested where to modify a molecular structure in terms of physicochemical properties and functional groups in order to improve its binding affinity, which is very important for improving our understanding of the ligand-receptor interactions and in helping to design compounds with improved activity.     

Synthesis and antitubercular evaluation of amidoalkyl dibenzofuranols and 1H-benzo[2,3]benzofuro[4,5-e][1,3]oxazin-3(2H)-ones

A new class of amidoalkyl dibenzofuranols and 1H-benzo[2,3]benzofuro[4,5-e][1,3]oxazin-3(2H)-ones was synthesized in very good yields through polyphosphoric acid supported on silica (PPA-SiO₂) catalyzed one-pot three component condensation of 2-dibenzofuranol; aromatic aldehydes and acetamide or benzamide or urea under solvent free conditions. At 125 °C the reaction led to the formation of amidoalkyl dibenzofuranols 5a-k where as at 160 °C cyclization take place to give oxazin-3(2H)-one analogues 6a-e. Screening all the 16 compounds for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MTB) resulted 1-((4-chlorophenyl)(2-hydroxydibenzo[b,d]furanyl)methyl)urea 5h; 1-((4-bromophenyl)(2-hydroxydibenzo[b,d]furanyl)methyl)urea 5i; 1-phenyl-1H-benzo[2,3]benzo furo[4,5-e][1,3]oxazin-3(2H)-one 6a (MIC 3.13 μg/mL) and 1-(4-chlorophenyl)-1H-benzo[2,3]benzofuro[4,5-e][1,3]oxazin-3(2H)-one 6b; 1-(4-bromophenyl)-1H-benzo[2,3]benzofuro [4,5-e][1,3]oxazin-3(2H)-one 6c (MIC 1.56 μg/mL) as most active antitubercular agents.     

Dibenzofuran,dibenzothiophene and N-methyl carbazole tethered 2-aminothiazoles and their cinnamamides as potent inhibitors of Mycobacterium tuberculosis

Herein described the design, synthesis and antitubercular evaluation of novel series of dibenzofuran, dibenzothiophene and N-methyl carbazole tethered 2-aminothiazoles and their cinnamamide analogs. One pot condensation of N-methyl carbazole, dibenzofuran and dibenzothiophene methyl ketones with thiourea in the presence of Iodine and CuO gave respective 2-aminothiazoles 4–6 in very good yields. Aminothiazoles were further coupled with substituted cinnamic acids using acid-amine coupling conditions to give desired cinnamamide analogs 8a–e, 9a–e and 10a–e. All the newly synthesized compounds were fully characterized by their NMR and mass spectral analysis. In vitro screening of new derivatives against Mycobacterium tuberculosis H37Rv (Mtb) resulted 8c, 10d and 10e (MIC: 0.78?µg/mL) and 2-aminothiazoles 5 and 6 (MIC: 1.56?µg/mL) as potent compounds with lower cytotoxicity profile.     

Design,synthesis and antimycobacterial activity of 3,5-dinitrobenzamide derivatives containing fused ring moieties

We report herein the design, synthesis and antimycobacterial activity of 3,5-dinitrobenzamide derivatives containing fused ring moieties. Results reveal that many of the target compounds have considerable in vitro antitubercular activity. Especially, N-((2-(4-fluorophenyl)/N-((2-(3-fluorobenzyl)-1,2,3,4-tetrahydroisoquilin-6-yl)methyl)-3,5-dinitrobenzamides 18a and 20e exhibit potent MIC values of 0.056–0.078?μg/mL against both drug-sensitive Mycobacterium tuberculosis (MTB) H37Rv strain and two clinically isolated multidrug-resistant MTB (MDR-MTB) strains, opening a new direction for further SAR studies.     

Design,synthesis and antifungal evaluation of borrelidin derivatives

Borrelidin, a nitrile containing 18-membered polyketide macrolide, display potent antifungal activity. In this study, a library of borrelidin derivatives were synthesized. Their structures were elucidated by detailed spectroscopic data analysis. The antifungal activity and cytotoxicity of these target compounds were evaluated by broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-3,5-phenytetrazoliumromide (MTT) methods. Among forty-seven prepared analogues, compound 3b had the inhibitory effect on Candida albicans and Candida parapsilosis (MIC: 50 and 12.5?μg/mL, respectively). Furthermore, compounds 4n and 4r presented better antifungal activity against Aspergillus fumigatus with 12.5?μg/mL MIC value, which were insensitive to borrelidin. Preliminary structure-activity relationships (SAR) revealed that the ester analogues containing fragment -OCH₂CH₂N- had an important effect on the antifungal activity. Meanwhile, the molecular docking study indicated the carboxyl substituents in BN could provide extra interaction with pathogenic fungal threonyl-tRNA synthetase (ThrRS).     

Design,synthesis, antiviral activity,and SARs of 13a-substituted phenanthroindolizidine alkaloid derivatives

On the basis of our previous structure–activity relationship (SAR) and antiviral mechanism studies, a series of 13a-substituted phenanthroindolizidine alkaloid analogues (3a–16a, 3b, 4b, 6b, 7b, 10b, and 14b) were designed targeting tobacco mosaic virus (TMV) RNA, synthesized, and evaluated for their antiviral activity against TMV for the first time. The bioassay results showed that most of the synthesized compounds (such as 4a, 6a, 7a, 11a, 14a, 6b, and 14b) exhibited good to excellent antiviral activity against TMV both in vitro and in vivo. Especially, for inactivation effect and curative effect, compounds 4a, 6a, 7a, 11a, 14a, and 14b showed higher activity at both concentrations (500 μg mL⁻¹ and 100 μg mL⁻¹) than commercial Ningnanmycin. Preliminary SARs showed that the substituted groups with hydrogen donor at 13a position were found to be favorable for keeping high antiviral activity. The present work demonstrates that 13a-substituted phenanthroindolizidines can be used as possible lead compounds for developing anti-TMV agents.