Synthesis and preliminary in vitro biological evaluation of new carbon-11-labeled celecoxib derivatives as candidate PET tracers for imaging of COX-2 expression in cancer

The enzyme cyclooxygenase-2 (COX-2) is overexpressed in a variety of malignant tumors. This study was designed to develop new radiotracers for imaging of COX-2 in cancer using biomedical imaging technique positron emission tomography (PET). Carbon-11-labeled celecoxib derivatives, [(11)C]4a-c and [(11)C]8a-d, were prepared by O-[(11)C] methylation of their corresponding precursors using [(11)C]CH(3)OTf under basic conditions and isolated by a simplified solid-phase extraction (SPE) method in 52 ± 2% (n = 5) and 57 ± 3% (n = 5) radiochemical yields based on [(11)C]CO(2) and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 23 min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 277.5 ± 92.5 GBq/μmol (n = 5). The IC(50) values to block COX-2 for known compounds celecoxib (4d), 4a and 4c were 40, 290 and 8 nM, respectively, and preliminary findings from in vitro biological assay indicated that the synthesized new compounds 4b and 8a-d display similar strong inhibitory effectiveness in the MDA-MB-435 human cancer cell line in comparison with the parent compound 4d. These results encourage further in vivo evaluation of carbon-11-labeled celecoxib derivatives as new potential PET radiotracers for imaging of COX-2 expression in cancer.     

Synthesis of new carbon-11 labeled benzoxazole derivatives for PET imaging of 5-HT(3) receptor

5-HT(3) receptor is an attractive target for the development of therapeutic agents for use in brain, heart and cancer diseases, and imaging agents for use in biomedical imaging technique PET. Benzoxazole derivatives are a novel class of 5-HT(3) receptor partial agonists with high binding affinity. Carbon-11 labeled benzoxazole derivatives have been synthesized as new potential PET radioligands for imaging 5-HT(3) receptor. The target tracers were prepared by N-[(11)C]methylation of their corresponding precursors using [(11)C]CH(3)OTf and isolated by HPLC purification procedure in 40-50% radiochemical yields, which were decay corrected to the end of bombardment (EOB), based on [(11)C]CO(2). The overall synthesis time was 20-25min from EOB. The radiochemical purity was >99%, and specific activity was in a range of 74-111 GBq/micromol at the end of synthesis (EOS).     

Simple synthesis of carbon-11 labeled styryl dyes as new potential PET RNA-specific, living cell imaging probes

A new type of styryl dyes have been developed as RNA-specific, live cell imaging probes for fluorescent microscopy technology to study nuclear structure and function. This study was designed to develop carbon-11 labeled styryl dyes as new probes for biomedical imaging technique positron emission tomography (PET) imaging of RNA in living cells. Precursors (E)-2-(2-(1-(triisopropylsilyl)-1H-indol-3-yl)vinyl)quinoline (2), (E)-2-(2,4,6-trimethoxystyryl)quinoline (3) and (E)-4-(2-(6-methoxyquinolin-2-yl)vinyl)-N,N-diemthylaniline (4), and standards styryl dyes E36 (6), E144 (7) and F22 (9) were synthesized in multiple steps with moderate to high chemical yields. Precursor 2 was labeled by [(11)C]CH(3)OTf, trapped on a cation-exchange CM Sep-Pak cartridge following a quick deprotecting reaction by addition of (n-Bu)(4)NF in THF, and isolated by solid-phase extraction (SPE) purification to provide target tracer [(11)C]E36 ([(11)C]6) in 40-50% radiochemical yields, decay corrected to end of bombardment (EOB), based on [(11)C]CO(2). The target tracers [(11)C]E144 ([(11)C]7) and [(11)C]F22 ([(11)C]9) were prepared by N-[(11)C]methylation of the precursors 3 and 4, respectively, using [(11)C]CH(3)OTf and isolated by SPE method in 50-70% radiochemical yields at EOB. The specific activity of the target tracers [(11)C]6, [(11)C]7 and [(11)C]9 was in a range of 74-111GBq/mumol at the end of synthesis (EOS).     

Synthesis and preliminary evaluation of new 5-pyrazolinone derivatives as analgesic agents

New 4-(aroyloxyalkanoyl)-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one s (5) were cyclized to 4-(2-aryl-5-unsubstituted/substituted oxazol-4-yl)-2,3-dimethyl-1-phenyl-3-pyrazolin-5-ones (6) employing the Davidson procedure. Preliminary evaluation of analgesic activity revealed that the effect of 4-(2-phenyl-5-ethyloxazol-4-yl)-2, 3-dimethyl-1-phenyl-3-pyrazolin-5-one and 4-[2-(4-chlorophenyl)-5-ethyloxazol-4-yl]-2, 3-dimethyl-1-phenyl-3-pyrazoline-5-one on acetic acid induced writhing was superior to that of antypyrine and aminopyrine. 4-[2-(4-Chlorophenyl)-5-methyloxazol-4-yl]-2, 3-dimethyl-1-phenyl-3-pyrazolin-5-one and 4-[2-(4-methoxyphenyl)-5-ethyloxazol-4-yl]-2, 3-dimethyl-1-phenyl-3-pyrazolin-5-one were more potent than aminopyrine, whereas 4-(2-phenyl-5-methyloxazol-4-yl)-2, 3-dimethyl-1-phenyl-3-pyrazolin-5-one and 4-[2-(4-methoxyphenyl)-5-methyl-oxazol-4-yl]-2, 3-dimethyl-1-phenyl-3-pyrazolin-5-one were not as active (modified Koster's Test; 0.19-0.21 mmol.kg(-1)). None of the selected entries showed inhibition of formaldehyde-induced paw oedema.     

Synthesis of [11C]FEDAA1106 as a new PET imaging probe of peripheral benzodiazepine receptor expression

Peripheral benzodiazepine receptor (PBR) is associated with neuroinflammation and tumor progression. [(11)C]DAA1106 and [(18)F]FEDAA1106 are two promising radioligands for positron emission tomography (PET) imaging of PBR. This study was designed to develop a new radiolabeled analog of [(11)C]DAA1106 and [(18)F]FEDAA1106, [(11)C]FEDAA1106, for PET imaging of PBR expression in brain and cancer. Precursor N-(5-fluoro-2-phenoxyphenyl)-N-(2-(2-fluoroethoxy)-5-hydroxybenzyl)acetamide (9) was synthesized in multiple steps with moderate to high chemical yields. Precursor 9 was labeled by [(11)C]CH(3)OTf and isolated by high pressure liquid chromatography (HPLC) purification to provide target radioligand N-(5-fluoro-2-phenoxyphenyl)-N-(2-(2-fluoroethoxy)-5-[(11)C]methoxybenzyl)acetamide ([(11)C]FEDAA1106, [(11)C]10) in 60-70% radiochemical yields, decay corrected to end of bombardment (EOB), based on [(11)C]CO(2). The specific activity of the target radiotracer [(11)C]10 was in a range of 111-185GBq/micromol at the end of synthesis (EOS).     

Synthesis and preliminary evaluation of benzimidazole derivatives as antimicrobial agents

A series of 2-alkylsulphanylbenzimidazoles was synthesised and the compounds were evaluated for their in vitro antimicrobial activity. The structures of the compounds were confirmed by 1H-NMR and IR data, and their purity by elemental analysis. Antimycobacterial activities against Mycobacterium tuberculosis and non-tuberculous mycobacteria as well as antifungal activities against Candida albicans, Candida tropicalis, Candida krusei, Candida glabrata, Trichosporon beigelii, Trichophyton mentagrophytes and Aspergillus fumigatus were expressed as the corresponding MIC values. The substances exhibited appreciable antimycobacterial activity, in particular, against non-tuberculous mycobacteria. The activity of the most active compound in the set, 3,5-dinitro derivative 4t, exceeded that of the standard isoniazide against M. kansasii and M. avium. The antifungal activities of the compounds were relatively low. A weak antifungal effect was observed against the dermatophyte Trichophyton mentagrophytes. None of the compounds showed significant inhibitory activity against yeasts.     

Synthesis and biological evaluation of new derivatives of 2-substituted 4-hydroxybutanamides as GABA uptake inhibitors

This study presents the synthesis of novel substituted 4-hydroxybutanamides and their influence on the activity of murine GABA transport proteins GAT1-GAT4. The active compounds, derivatives of N-arylalkyl-2-(4-diphenylmethylpiperazin-1-yl)-4-hydroxybutyramide, are characterized by pIC₅₀ values in range of 3.92-5.06 and by slight subtype-selectivity. Among them N-4-chlorobenzylamide was the most potent GAT inhibitor (mGAT3), while N-benzylamide was the most active in GAT1-binding assay (pK_i = 4.96). The results pointed out that benzhydryl and benzylamide moieties are crucial for the activity of this class of compounds as murine GAT inhibitors.     

Synthesis and biological evaluation of novel luteolin derivatives as antibacterial agents

A series of luteolin derivatives 2-20 were prepared, 3-20 of which were first reported. The chemical structures of these compounds were confirmed by means of 1H NMR, ESI-MS and elemental analyses. The compounds were assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Pseudomonas fluorescens and Escherichia coli) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl trtrazolium bromide) method. Among the compounds tested, most of them displayed significant activity against the tested strains, and 2-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-5-hydroxy-7-(2-(3-morpholinopropylamino)ethoxy)-4H-chromen-4-one (17) showed the most favorable antibacterial activity in vitro with MICs of 1.562, 3.125, 3.125, and 6.25 microg/mL against B. subtilis, S. aureus, P. fluorescens and E. coli, respectively. Structure-activity relationships (SAR) were also discussed based on the obtained experimental data.     

Synthesis and biological evaluation of indazole derivatives

The inhibition of neuronal and inducible nitric oxide synthases (nNOS and iNOS) by a series of 36 indazoles has been evaluated, showing that most of the assayed derivatives are better iNOS than nNOS inhibitors. A parabolic model relating the iNOS inhibition percentage with the difference, E_rel, between stacking and apical interaction energies of indazoles with the active site of the NOS enzyme has been established.     

Synthesis and biological evaluation of derivatives of 4-deoxypodophyllotoxin as antitumor agents

In an attempt to generate compounds with superior bioactivity and reduced toxicity, a series of derivatives of deoxypodophyllotoxin were synthesized by reacting 4′-demethyl-4-deoxypodophyllotoxin with substituted piperazines or their amino acid amides. The cytotoxic activity of these compounds against three human cancer cell lines was evaluated. We found that p-nitrophenylpiperazine substitution (Compound 8b) led to an increase in the potency of the compound. Compound 8b exhibited the most potent cytotoxicity against A-549, HeLa and SiHa cells (IC₅₀ values were 0.102, 0.180 and 0.0195 μM, respectively). In addition, flow cytometric analysis showed that 8b induced cell cycle arrest in the G1 phase accompanied by apoptosis in A-549 cells.     

Synthesis and biological evaluation of 2-indolinone derivatives as potential antitumor agents

Three series of 3-substituted-indolin-2-ones and azaindolin-2-ones have been synthesized and showed potential antiproliferative activity to cancer cell lines. The inhibition activities on VEGF-induced VEGFR phosphorylation were observed for selected 2-indolinones. Among the compounds synthesized, 5-fluoroindolin-2-one derivative 23 with a pyridone unit showed the most significant enzymatic and cellular activities. Flow cytometric analysis indicates that 23 plays a role in suppressing HCT-116 cell proliferation via G1 phase arrest and apoptosis in a dose dependent manner. The binding mode of compound 23 complexed with VEGFR-2 was predicted using FlexX algorithm. Described here are the chemistry and biological testing for these series which will guide the design and optimization of novel 2-indolione antitumor agents.     

Synthesis, biological evaluation of chrysin derivatives as potential immunosuppressive agents

A series of novel chrysin derivatives was firstly synthesized and evaluated on their immunosuppressive activity in the search for potential immunosuppressive agents. Among them, compounds 5c displayed the most potent immunosuppressive inhibitory activity with IC₅₀ of 0.78 μM, which was comparable to that of cyclosporin A (IC₅₀ = 0.06 μM). The preliminary mechanism of compound 5c inhibition effects was also detected by flow cytometry (FCM), and the compound exerted immunosuppressive activity via inducing the apoptosis of activated lymph node cells in a dose dependent manner. Furthermore, the estimated LD₅₀ (in mg/kg) in vivo of compound 5c is 738.2, which indicated that compound 5c was low toxic.     

Synthesis and biological evaluation of some thiazolylpyrazole derivatives as dual anti-inflammatory antimicrobial agents

The synthesis of a novel series of 4-thiazolylpyrazolyl derivatives is described in the present report. All the newly synthesized compounds were examined for their anti-inflammatory activity using cotton pellet-induced granuloma and carrageenan-induced rat paw edema bioassays. Their inhibitory activities of cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2), ulcerogenic effect and acute toxicity were also determined. Furthermore, all compounds were evaluated for their in vitro antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans. A docking pose for compounds 8b, 10a and 10b separately in the active site of the human COX-2 enzyme and DNA-gyrase B was also obtained. The results revealed that compounds 8b, 10a and 10b exhibited good anti-inflammatory activity with no or minimal ulcerogenic effect and good safety margin. Compounds 10a and 10b were found to be the most potent anti-inflammatory agents in the present study. Meanwhile, 10a and 10b displayed higher selective inhibitory activity towards COX-2 compared to indomethacin. Moreover, compounds 10a and 10b exhibited promising antibacterial against both E. coli and S. aureus. Docking studies for 8b, 10a and 10b with COX-2 (PDB ID: 1CX2) and DNA-gyrase B (PDB ID: 1EI1) showed good binding profile.     

Synthesis and biological evaluation of oxindoles and benzimidazolinones derivatives

The synthesis of new oxindoles and benzimidazolinones derivatives bearing a sugar residue on the aromatic nitrogen is described. The presence of the glycoside moiety should enhance the solubility of these heterocyclic compounds and/or improve the interaction with the active site of the biological targets. The inhibitory activities of these new compounds toward five kinases were examined: KDR (VEGFR-2), FGFR-1, PDGFR-beta, EGFR and Tie 2. Furthermore, the antibacterial activities of the prepared compounds were tested against two Gram-positive bacteria Bacillus cereus and Streptomyces chartreusis, a Gram-negative bacterium Escherichia coli and a yeast Candida albicans.     

Synthesis, preliminary biological evaluation and molecular modeling of some new heterocyclic inhibitors of TACE

Central heteroaryl ring analogues belonging to a series of potent hydroxamate TACE inhibitors were synthesized. The TACE inhibitory activities of these compounds were evaluated by in vitro WBA and in silico molecular modeling studies using crystal structure of human TACE. Compound 14 showed very good in vitro inhibition, supported by the in silico docking studies.     

Synthesis and evaluation of some new benzimidazole derivatives as potential antimicrobial agents

The efficient synthesis of novel azetidin-2-ones 6 has been established. Thus, condensation of 5-[(2-methyl-1H-benzimidazol-1-yl)methyl]-1,3,4-thiadiazol-2-amine 4 with various aromatic aldehydes afforded 5-[(2-methyl-1H-benzimidazol-1-yl)methyl]-N-[(substituted) phenylmethylidene]-1,3,4-thiadiazol-2-amine 5 which on cycloaddition with chloroacetyl chloride in the presence of triethylamine catalyst yielded 3-chloro-1-{5-[(2-methyl-1H-benzimidazol-1-yl)methyl]-1,3,4-thiadiazol-2-yl}-4-(substituted) phenylazetidin-2-one 6. Structures of the synthesized compounds have been elucidated on the basis of their elemental analyses and spectral data. All the synthesized compounds were screened for their antimicrobial activity.     

Synthesis and biological evaluation of new clofibrate analogues as potential PPARalpha agonists

Clofibrate is a lipid-profile modifying agent belonging to the fibrate class of drugs. Fibrates are known to exhibit their beneficial effects by activating peroxisome proliferator-activated receptor-alpha (PPARalpha) and used in the treatment of dyslipidemia and atherosclerosis and for the prevention of heart failure. Hereby, the preparation of two new sets of clofibrate analogues, ethyl 2-(4-chlorophenoxy)-3-oxoalkanoates and ethyl 2-(4-chlorophenoxy)-3-hydroxyalkanoates is described starting from commercially available 3-oxoalkanoates in fair to good yields. Treatment of 3-oxoalkanoates with SO2Cl2 yielded the corresponding 2-chloro-3-oxoalkanoates, that were then converted into 2-(4-chlorophenoxy)-3-oxoalkanoates by reacting with sodium or caesium 4-chlorophenate. Reduction of the keto group with NaBH4 afforded the corresponding 2-(4-chlorophenoxy)-3-hydroxyalkanoates in very high yields and with variable diastereoselectivity. Biological evaluation of the compounds was performed by a transactivation assay in a transiently transfected monkey kidney fibroblast cell line. The newly synthesised clofibrate analogues failed to show noticeable levels of PPAR activation at concentrations where clofibrate showed an evident activity, suggesting that the structural modifications caused the loss of PPAR activity.     

Synthesis and biological evaluation of O-alkylated tropolones and related alpha-ketohydroxy derivatives as ribonucleotide reductase inhibitors

A series of O-alkylated tropolones and related alpha-ketohydroxy compounds were evaluated for their biological activities and were shown to present an expected ribonucleotide reductase inhibition and cytotoxicity against some cancer cell lines but no antitubulin activity. Pharmacomodulation studies were realised to understand and enhance the observed activities. These original benzylic, heterocyclic and allylic compounds have been synthesised by a phase-transfer catalysed O-alkylation developed in our laboratories.     

Synthesis and antimicrobial evaluation of new benzofuran derivatives

Thirteen compounds, based on benzofuran skeleton bearing aryl substituents at its C-3 position through methanone linker, were synthesized and screened for their antibacterial and antifungal activities against four bacteria Escherichia coli, Staphylococcus aureus, Methicillin-resistant S.aureus, Bacillus subtilis, and a fungus Candida albicans. Four hydrophobic benzofuran analogs were found to exhibit favorable antibacterial activities (MIC₈₀ = 0.39-3.12 μg/mL), which were better than the control drugs.     

Synthesis and in vitro biological evaluation of new polyamine conjugates as potential anticancer drugs

The synthesis of new polyamine derivatives containing dimeric quinoline (3a-c), cinnoline (4a-c) and phthalimide (7a-c and 8a-c) moieties is described. Three different polyamines: (1,4-bis(3-aminopropyl)piperazine (a), 4,9-dioxa-1,12-dodecanediamine (b), 3,3'-diamino-N-methyldipropylamine (c) were used as linkers. The new compounds were obtained according to known procedures. Their biological activity was assessed in vitro in a highly aggressive melanoma cell line A375. Polyamine diimides containing phthalimide moieties demonstrated no inhibitory activities against melanoma cells. Quinoline diamides were more efficient than cinnoline ones. Mainly cytostatic activity exerted as altered cell cycle profiles was observed at the concentrations causing about 50% reduction of adherent cell proliferation. Based on their structure as well as their biological activity, we assume that some of the newly synthesized compounds may act as DNA bisintercalators. This study might be useful for further designing and developing anticancer drugs with potent activities.