Synthesis, characterization, molecular modeling studies, and biological evaluation of metal piroxicam complexes (M = Ni(II), Pt(IV), Pd(II), Ag(I)) as antibacterial and anticancer agents.

Four piroxicam metal complexes; NiL2 , PtL2 , PdL2 , and AgL were synthesized and characterized by different techniques with enhanced antibacterial and anticancer activity. Regarding in vitro antimicrobial activity, complex NiL2 displayed potent antibacterial effect against Escherichia coli and Pseudomonas aeruginosa that was 1.9-folds higher than piroxicam (minimum inhibitory concentration [MIC] = 31.85, 65.32 µM), respectively. In case of G+ve bacteria, complex PtL2 had potent activity on Staphylococcus aureus which was 2.1-folds higher than piroxicam (MIC = 43.12 µM), while activity of complex AgL against Enterococcus faecalis was threefolds higher than piroxicam (MIC = 74.57 µM. Complexes PtL2 and PdL2 exhibited higher inhibition of DNA gyrase than piroxicam (IC50 = 6.21 µM) in the range of 1.9-1.7-folds. The in vitro antiproliferative activity depicted that all investigated complexes showed better cytotoxic effect than piroxicam, specifically Pt and Pd complexes which had lower IC50 values than piroxicam on human liver cancer cell line HepG2 by 1.8 and 1.7-folds, respectively. While Pd and Ag complexes showed 2 and 1.6-folds better effect on human colon cancer cell line HT-29 compared with piroxicam. Molecular modeling studies including docking on Stranded DNA Duplex (1juu) and DNA gyrase enzyme (1kzn) that gave good insight about interaction of complexes with target molecules, calculation of electrostatic potential map and global reactivity descriptors were performed.

N4-Substituted Piperazinyl Norfloxacin Derivatives with Broad-Spectrum Activity and Multiple Mechanisms on Gyrase, Topoisomerase IV, and Bacterial Cell Wall Synthesis.

Fluoroquinolones are an important class of antibiotics with broad-spectrum antibacterial and antitubercular activity. Here, we describe the design and synthesis of a series of 38 N4-substituted piperazinyl norfloxacin derivatives. Their activity and mechanism of action were characterized using in silico, in vitro, and in vivo approaches. Several compounds displayed interesting activities against both Gram-negative and Gram-positive bacteria, and few displayed antimycobacterial activity, whereby some were as potent as norfloxacin and ciprofloxacin. Molecular docking experiments suggested that the new derivatives inhibit both DNA gyrase and DNA topoisomerase IV in a similar manner as norfloxacin. Selecting the most promising candidates for experimental mode of action analysis, we confirmed DNA gyrase and topoisomerase IV as targets of all tested compounds using enzymatic in vitro assays. Phenotypic analysis of both Escherichia coli and Bacillus subtilis confirmed a typical gyrase inhibition phenotype for all of the tested compounds. Assessment of possible additional targets revealed three compounds with unique effects on the B. subtilis cell wall synthesis machinery, suggesting that they may have an additional target in this pathway. Comparison with known cell wall synthesis inhibitors showed that the new compounds elicit a distinct and, so far, unique phenotype, suggesting that they act differently from known cell wall synthesis inhibitors. Interestingly, our phenotypic analysis revealed that both norfloxacin and ciprofloxacin displayed additional cellular effects as well, which may be indicative of the so far unknown additional mechanisms of fluoroquinolones.

Rational design, synthesis, molecular modeling, biological activity, and mechanism of action of polypharmacological norfloxacin hydroxamic acid derivatives.

Fluoroquinolones are broad-spectrum antibiotics that target gyrase and topoisomerase IV, involved in DNA compaction and segregation. We synthesized 28 novel norfloxacin hydroxamic acid derivatives with additional metal-chelating and hydrophobic pharmacophores, designed to enable interactions with additional drug targets. Several compounds showed equal or better activity than norfloxacin against Gram-positive, Gram-negative, and mycobacteria, with MICs as low as 0.18 µM. The most interesting derivatives were selected for in silico, in vitro, and in vivo mode of action studies. Molecular docking, enzyme inhibition, and bacterial cytological profiling confirmed inhibition of gyrase and topoisomerase IV for all except two tested derivatives (10f and 11f). Further phenotypic analysis revealed polypharmacological effects on peptidoglycan synthesis for four derivatives (16a, 17a, 17b, 20b). Interestingly, compounds 17a, 17b, and 20b, showed never seen before effects on cell wall synthetic enzymes, including MreB, MurG, and PonA, suggesting a novel mechanism of action, possibly impairing the lipid II cycle.

Design, Synthesis, Molecular Modeling, Biological Activity, and Mechanism of Action of Novel Amino Acid Derivatives of Norfloxacin.

Two series of N4-substituted piperazinyl amino acid derivatives of norfloxacin (24 new compounds) were designed and synthesized to attain structural surrogates with additional binding sites and enhanced antibacterial activity. Synthesized derivatives showed increased antibacterial and antimycobacterial activity compared to their lead structure, norfloxacin. Molecular modeling studies supported the notion that the derivatives can establish additional bonds with the target enzymes gyrase and topoisomerase IV. In vitro enzyme inhibition assays confirmed that the tested compounds were significant inhibitors of these enzymes. Inhibition of gyrase and topoisomerase IV was then confirmed in living bacterial cells using bacterial cytological profiling of both Gram-negative Escherichia coli and Gram-positive Bacillus subtilis, revealing a typical topoisomerase inhibition phenotype characterized by severe nucleoid packing defects. Several derivatives exhibited additional effects on the Gram-positive cell wall synthesis machinery and/or the cytoplasmic membrane, which likely contributed to their increased antibacterial activity. While we could not identify specific cell wall or membrane targets, membrane depolarization was not observed. Our experiments further suggest that cell wall synthesis inhibition most likely occurs outside the membrane-bound lipid II cycle.

Effects of Lidocaine-Derived Organic Compounds on Eosinophil Activation and Survival.

Lidocaine, a local anesthetic, is known to possess anti-inflammatory properties. However, its clinical use is limited by inconveniences, such as its local synesthetic effects. This study evaluated lidocaine analogs designed and synthesized to overcome the disadvantages of lidocaine, having anti-inflammatory properties. Interleukin 5 (IL-5)-induced eosinophil activation and survival were evaluated using 36 lidocaine analogs with modified lidocaine structure on the aromatic or the acyl moiety or both. Eosinophil survival was evaluated using a CellTiter 96® aqueous cell proliferation assay kit. Superoxide production was determined using the superoxide dismutase-inhibitable reduction of cytochrome C method. Eosinophil cationic protein (ECP), IL-8, and transcription factor expression were determined using enzyme-linked immunosorbent assay. The platelet-activating factor (PAF)-induced migration assay was performed using a Transwell insert system. Compounds EI137 and EI341 inhibited IL-5-induced eosinophil survival and superoxide and ECP production in a concentration-dependent manner. These compounds also significantly reduced IL-8 production. Although compounds EI137 and EI341 significantly reduced phosphorylated ERK 1/2 expression, they did not influence other total and phosphorylated transcription factors. Moreover, 1000 µM of compound EI341 only inhibited PAF-induced migration of eosinophils. Lidocaine analogs EI137 and EI341 inhibited IL-5-mediated activation and survival of eosinophils. These compounds could be new therapeutic agents to treat eosinophilic inflammatory diseases.

Fatty Acid Conjugated Chalcones as Tubulin Polymerization Inhibitors: Design, Synthesis, QSAR, and Apoptotic and Antiproliferative Activity.

Cancer is often associated with an aberrant increase in tubulin and microtubule activity required for cell migration, invasion, and metastasis. A new series of fatty acid conjugated chalcones have been designed as tubulin polymerization inhibitors and anticancer candidates. These conjugates were designed to harness the beneficial physicochemical properties, ease of synthesis, and tubulin inhibitory activity of two classes of natural components. New lipidated chalcones were synthesized from 4-aminoacetophenone via N-acylation followed by condensation with different aromatic aldehydes. All new compounds showed strong inhibition of tubulin polymerization and antiproliferative activity against breast and lung cancer cell lines (MCF-7 and A549) at low or sub-micromolar concentrations. A significant apoptotic effect was shown using a flow cytometry assay that corresponded to cytotoxicity against cancer cell lines, as indicated by a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay. Decanoic acid conjugates were more potent than longer lipid analogues, with the most active being more potent than the reference tubulin inhibitor, combretastatin-A4 and the anticancer drug, doxorubicin. None of the newly synthesized compounds caused any detectable cytotoxicity against the normal cell line (Wi-38) or hemolysis of red blood cells below 100 µM. It is unlikely that the new conjugates described would affect normal cells or interrupt with cell membranes due to their lipidic nature. A quantitative structure-activity relationship analysis was performed to determine the influence of 315 descriptors of the physicochemical properties of the new conjugates on their tubulin inhibitory activity. The obtained model revealed a strong correlation between the tubulin inhibitory activity of the investigated compounds and their dipole moment and degree of reactivity.

Synthesis, computational study and biological evaluation of 9-acridinyl and 1-coumarinyl-1,2,3-triazole-4-yl derivatives as topoisomerase II inhibitors.

Topoisomerase (IIB) inhibitors have been involved in the therapies of tumour progression and have become a major focus for the development of anticancer agents. New three-component hybridised ligands, 1,4-disubstituted-1,2,3-triazoles (8-17), were synthesised via a 1,3-dipolar cycloaddition reaction of 9-azidoacridine/3-azidocoumarin with N/O-propargyl small molecules under click reaction conditions. Cancer cell growth inhibition of the synthesised triazoles was tested against human cell-lines in the NCI-60-cell-panel, and the most active compounds tested against topoisomerase (IIB)-enzymes. The acridinyl ligands (8-10) revealed 60-97% cell growth inhibition in six cancer cell-panels. Cell-cycle analysis of MCF7 and DU-145 cells treated with the active acridinyl ligands exhibited cell-cycle arrest at G2/M phase and proapoptotic activity. In addition, compound 8 displayed greater inhibitory activity against topoisomerase (IIB) (IC50 0.52 µM) compared with doxorubicin (IC50 0.83 µM). Molecular dynamics simulation studies showed the acridine-triazole-pyrimidine hybrid pharmacophore was optimal with respect to protein-ligand interaction and fit within the binding site, with optimal orientation to allow for intercalation with the DNA bases (DG13, DC14, and DT9).

Design, synthesis, and antibacterial evaluation of new quinoline-1,3,4-oxadiazole and quinoline-1,2,4-triazole hybrids as potential inhibitors of DNA gyrase and topoisomerase IV.

DNA gyrase and topoisomerase IV (topo IV) inhibitors are among the most interesting antibacterial drug classes without antibacterial pipeline representative. Twenty-four new quinoline-1,3,4-oxadiazole and quinoline-1,2,4-triazole hybrids were developed and tested against DNA gyrase and topoisomerase IV from Escherichia coli and Staphylococcus aureus. The most potent compounds 4c, 4e, 4f, and 5e displayed an IC50 of 34, 26, 32, and 90 nM against E. coli DNA gyrase, respectively (novobiocin, IC50 = 170 nM). The activities of 4c, 4e, 4f, and 5e on DNA gyrase from S. aureus were weaker than those on E. coli gyrase. Compound 4e showed IC50 values (0.47 µM and 0.92 µM) against E. coli topo IV and S. aureus topo IV, respectively in comparison to novobiocin (IC50 = 11, 27 µM, respectively). Antibacterial activity against Gram-positive and Gram-negative bacterial strains has been studied. Some compounds have demonstrated superior antibacterial activity to ciprofloxacin against some of the bacterial strain studied. The most active compounds in this study showed no cytotoxic effect with cell viability>86%. Finally, a molecular docking analysis was performed to investigate the binding mode and interactions of the most active compounds to the active site of DNA gyrase and topoisomerase IV (topo IV) enzymes.

Bioactive fluorenes. Part III: 2,7-dichloro-9H-fluorene-based thiazolidinone and azetidinone analogues as anticancer and antimicrobial against multidrug resistant strains agents.

BACKGROUND: Thiazoles, thiazolidinones and azetidinones are highly ranked amongst natural and synthetic heterocyclic derivatives due to their great pharmaceutical potential. RESULTS: New thiazolidinone and azetidinone class of bioactive agents based on 4-(2,7-dichloro-9H-fluoren-4-yl)thiazole moiety have been successfully synthesized. 4-(2,7-dichloro-9H-fluoren-4-yl)thiazol-2-amine was synthesized and allowed to react with various aryl/heteroaryl aldehydes to afford the corresponding Schiff base intermediates. The target thiazolidinone and azetidinone analogues have derived from Schiff bases by their reactions with thioglycolic acid and chloroacetyl chloride, respectively. The newly synthesized compounds were then evaluated for their antimicrobial activity against some multidrug resistant strains and examined for cytotoxic activity against normal lung fibroblast (WI-38), human lung carcinoma (A549), and human breast carcinoma (MDA-MB-231) cell lines to develop a novel class of fluorene-based bioactive agents. The mode of action and the binding interaction of the synthesized compound with the active sites of dihydrofolate reductase enzyme were well identified by fluorescence-activated cell sorting (FACS) analysis and molecular docking study. CONCLUSION: Some of the synthesized compounds showed remarkable activity against A-549 and MDA-MB-231 when compared to Taxol, which was used as a reference drug. 2,7-dichloro-9H-fluorene-based azetidinones are more efficient as antimicrobial and anticancer agents compared to dichloro-9H-fluorene-based thiazolidinones derivatives.

Utilization of tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidinone as a cap moiety in design of novel histone deacetylase inhibitors.

A series of novel 5,6,7,8-Tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one derivatives bearing a hydroxamic acid, 2-aminoanilide and hydrazide moieties as zinc-binding group (ZBG) were designed, synthesized and evaluated for the HDAC inhibition activity and antiproliferative activity. Most of the tested compounds displayed strong to moderate HDAC inhibitory activity. Some of these compounds showed potent anti-proliferative activity against human HepG2, MCF-7 and HCT-116 cell lines. In particular, compounds IVa, IVb, IXa and IXb exhibited significant anti-proliferative activity against the three cell lines tested compared to SAHA as a reference. Compound IVb is equipotent inhibitor for HDAC1 and HDAC2 as SAHA. It is evident that the presence of free hydroxamic acid group is essential for Zn binding affinity with maximal activity with a linker of aliphatic 6 carbons. Docking study results revealed that compound IVb could occupy the HDAC2 binding site and had the potential to exhibit antitumor activity through HDAC inhibition, which merits further investigation.

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 Šcrystal 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, docking studies and biological evaluation of novel chalcone derivatives as potential histone deacetylase inhibitors.

A group of novel chalcone derivatives comprising hydroxamic acid or 2-aminobenzamide group as zinc binding groups (ZBG) were synthesized. The structure of the prepared compounds was fully characterized by IR, NMR and elemental microanalyses. Most of the tested compounds displayed strong to moderate HDAC inhibitory activity. Some of these compounds showed potent anti-proliferative activity against human HepG2, MCF-7 and HCT-116 cell lines. In particular, compounds 4a and 4b exhibited significant anti-proliferative activity against the three cell lines compared to SAHA as reference drug and displayed promising profile as anti-tumor candidates. The results indicated that these chalcone derivatives could serve as a promising lead compounds for further optimization as antitumor agents.

Design, synthesis and pharmacophoric model building of new 3-alkoxymethyl/3-phenyl indole-2-carboxamides with potential antiproliferative activity.

Novel 3-alkoxymethyl/3-phenyl indole-2-carboxamide derivatives were synthesized and evaluated for their anticancer activity. Most of the tested compounds showed moderate to excellent activity against the tested cell lines (MCF7 and HCT116). 3-Phenyl substitution on indole with p-piperidinyl phenethyl 24a and p-dimethylamino phenethyl 24c exhibited anticancer activity against MCF7 with IC50 of 0.13 and 0.14 µm, respectively. Further mechanistic study of the most active compounds through their action on cell cycle showed disturbance in cell cycle progression and cell cycle arrest. For future development of this series of compounds, pharmacophore study was conducted which indicated that the enhancement of the activity could be achieved through the addition of acceptor or donating groups to the already-present indole nucleus.

Small-molecule inhibitors of 25-hydroxyvitamin D-24-hydroxylase (CYP24A1): synthesis and biological evaluation.

The synthesis of imidazole styrylbenzamide, tert-butyl styrylimidazole, and tert-butyl styrylsulfonate derivatives is described. Evaluation of binding affinity and inhibitory activity against CYP24A1 identified the imidazole styrylbenzamides as potent inhibitors of CYP24A1, having selectivity with respect to CYP27B1 comparable with or greater than that of the standard ketoconazole. Further evaluation of the 3,5-dimethoxy and 3,4,5-trimethoxy derivatives in chronic lymphocytic leukemia cells revealed that co-treatment of 1α,25-dihydroxyvitamin D3 plus inhibitor coordinately upregulated GADD45α and CDKN1A. Docking experiments on the inhibitors in the CYP24A1 enzyme active site suggest the compounds reach the active site through the vitamin D access tunnel and are exposed to multiple hydrophobic residues. The imidazole styrylbenzamides are optimally positioned to allow interaction of the imidazole with the heme, and, in the case of the methoxy derivatives, a hydrogen bond between the 3-methoxy group and Gln82 stabilizes the molecule in a favorable active conformation.

Small molecule inhibitors of retinoic acid 4-hydroxylase (CYP26): synthesis and biological evaluation of imidazole methyl 3-(4-(aryl-2-ylamino)phenyl)propanoates.

The synthesis and potent inhibitory activity of novel imidazole methyl 3-(4-(aryl-2-ylamino)phenyl)propanoates in a MCF-7 CYP26A1 microsomal assay is described. The induction of CYP26A1 mRNA was used to evaluate the ability of the compounds to enhance the biological effects of all-trans retinoic acid (ATRA) in a retinoid-responsive neuroblastoma cell line. The most promising inhibitor, 3-imidazol-1-yl-2-methyl-3-[4-(naphthalen-2-ylamino)-phenyl]-propionic acid methyl ester (20), with an IC(50) of 3 nM (compared with liarozole IC(50) of 540 nM and R116010 IC(50) of 10 nM) was further evaluated for CYP selectivity using a panel of CYP enzymes, mutagenicity (Ames screen), and hepatic stability.

Synthesis and CYP24A1 inhibitory activity of (E)-2-(2-substituted benzylidene)- and 2-(2-substituted benzyl)-6-methoxy-tetralones.

A series of (E)-2-(2-substituted benzylidene)- and 2-(2-substituted benzyl)-6-methoxy-tetralones were prepared, using an efficient synthetic scheme, and evaluated for their inhibitory activity against cytochrome P450C24A1 (CYP24A1) hydroxylase. In general the reduced benzyl tetralones were more active than the parent benzylidene tetralones. The 2-ethyl and 2-trifluoromethyl benzyl tetralone derivatives (4c and 4b) showed optimal activity in this series with IC(50) values of 1.92 microM and 2.08 microM, respectively compared with the standard ketoconazole IC(50) 0.52 microM. The 2-bromobenzyl tetralone (4d) showed a preference for CYP27A1 (IC(50) 59 nM) over CYP24A1 (IC50 16.3 microM) and may be a useful lead in CYP27A1 inhibition studies. The 2-ethylphenyl benzyl derivative (9c), which showed weak activity against the wild type CYP24A1 (IC(50) 25.57 microM), exhibited enhanced inhibitory activity towards L148F and M416T mutants, this difference in activity for the L148F mutant has been explained using molecular modelling.

Synthesis and CYP24A1 inhibitory activity of N-(2-(1H-imidazol-1-yl)-2-phenylethyl)arylamides.

A series of N-(2-(1H-imidazol-1-yl)-2-phenylethyl)arylamides were prepared, using an efficient three- to five-step synthesis, and evaluated for their inhibitory activity against human cytochrome P450C24A1 (CYP24A1) hydroxylase. Inhibition ranged from IC50 0.3-72 microM compared with the standard ketoconazole IC50 0.52 microM, with the styryl derivative (11c) displaying enhanced activity (IC50=0.3 microM) compared with the standard, providing a useful preliminary lead for drug development.

Design and synthesis of substituted imidazole and triazole N-phenylbenzo[d]oxazolamine inhibitors of retinoic acid metabolizing enzyme CYP26.

The design of N-phenylbenzo[d]oxazolamines as CYP26A1 inhibitors involved ligand docking experiments using molecular modeling (FlexX) and analysis of ligand interactions at the binding domain. The synthesis of the benzooxazol-2-yl-[phenyl-imidazol-1-yl-methyl)phenyl]amines was achieved by cyclisation of the corresponding isothiocyanates with subsequent introduction of the haem-binding heterocycle. Triazole and tetrazole derivatives were also prepared for comparison with the lead imidazole derivative. The benzooxazol-2-yl-[phenyl-imidazol-1-yl-methyl)phenyl]amines with small substituents in the phenyl ring were moderately potent CYP26A1 inhibitors (IC(50) 8 and 12 microM) and comparable with liarozole (IC(50) 7 microM).

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.