Synthesis and anti-HIV studies of 2- and 3-adamantyl-substituted thiazolidin-4-ones

A series of novel thiazolidin-4-ones bearing a lipophilic adamantyl substituent at position 2 or 3 were synthesized. A majority of them showed a modest anti-HIV-1 activity, whereas 2-adamantan-1-yl-3-(4,6-dimethylpyrimidin-2-yl)-thiazolidin-4-one (8) was endowed with a remarkable antiviral potency (EC(50)=0.67 microM). The new series of compounds (22-29) with an adamantyl moiety at the 3-position of the thiazolidinone ring showed good to modest anti-HIV-1 activity (EC(50)=1.0-11 microM) but also pronounced cytostatic activity. For example 24, 26 and 29 showed an EC(50) of 1.0-2.0 microM, while the 50% effective concentrations for 23 and 28 were 7.8 and 11.0 microM, respectively. X-ray studies and quantum chemical calculations revealed that the anti-HIV activity of the compounds strongly depends on their dipole moments and conformation of the thiazolidinones.     

Cytotoxic 5-aryl-1-(4-nitrophenyl)-3-oxo-1,4-pentadienes mounted on alicyclic scaffolds

The 5-aryl-1-(4-nitrophenyl)-3-oxo-1,4-pentadienyl pharmacophore was incorporated into four series of compounds 1-4. Compounds 1a-g comprised a cluster of 3-arylidene-1-(4-nitrophenylmethylene)-2-oxo-3,4-dihydro-1H-naphthalenes while the analogues 2a-g consisted of a group of 6-arylidene-2-(4-nitrophenylmethylene)cyclohexanones. Three other compounds prepared in this study were 1-(4-nitrophenylmethylene)-3-(3,4,5-trimethoxyphenylmethylene)-2-oxo-2,3-dihydro-1H-indene 3a as well as two 5-arylidene-2-(4-nitrophenylmethylene)cyclopentanones 4a,b. The compounds were evaluated against human Molt 4/C8 and CEM T-lymphocytes as well as murine L1210 cells. In general, the compounds in series 1 displayed marked cytotoxicity having IC50 values in the 1-5 microM range while the related cyclohexyl analogues in series 2 were slightly less potent (IC50 figures were mainly 5-10 microM). The relative locations of two aryl rings present in all four series were considered to contribute significantly to bioactivity and may have accounted for the virtual absence of cytotoxic properties in series 3 and 4. Most of the compounds were administered intraperitoneally to mice using doses up to and including 300 mg/kg. No mortalities were noted. The inhibiting effect of most of the compounds towards Helicobacter pylori is noteworthy. The modes of action of representative compounds include the induction of apoptosis while some compounds weakly inhibited tubulin polymerisation and human N-myristoyltransferase.     

Cytotoxic N-[4-(3-aryl-3-oxo-1-propenyl)phenylcarbonyl]-3,5-bis(phenylmethylene)-4-piperidones and related compounds

A series of 4-carboxychalcones 1 were prepared and coupled to 3,5-bis(phenylmethylene)-4-piperidone (2) giving rise to a novel series of N-[4-(3-aryl-3-oxo-1-propenyl)phenylcarbonyl]-3,5-bis(phenylmethylene)-4-piperidones (3). Molecular simplification of the amides 3 led to the formation of the corresponding N-(3-aryl-1-oxo-2-propenyl)-3,5-bis(phenylmethylene)-4-piperidones (4). A cytotoxic evaluation of the compounds in series 1-4 utilized murine P388 and L1210 cells as well as human Molt 4/C8 and CEM T-lymphocytes. In general, the compounds displayed significant toxicity; the IC(50) values of 54% of the enones were less than 10 microM when all four screens were considered and less than 1 microM for all members of series 3 in the P388 assay. Various correlations were established between the potencies of the compounds in series 1, 3 and 4 and the Hammett sigma, Hansch pi and molecular refractivity constants of the aryl substituents. Several torsion angles and interatomic distances of five representative compounds in series 3 and 4 were determined by X-ray crystallography, some of which contributed to the observed bioactivity. The marked cytotoxicity and lack of murine toxicity of most of the compounds described in this study, as well as their selective toxicity towards different tumour cell lines, revealed that development of the enones 2-4 as novel candidate antineoplastic agents should be pursued.     

Synthesis and pharmacological study of ethyl 1-methyl-5-(substituted 3,4-dihydro-4-oxoquinazolin-3-yl)-1H-pyrazole-4-acetates.

Several new ethyl 1-methyl-5-(substituted 3,4-dihydro-4-oxoquinazolin-3-yl)-1H-pyrazole-4-acetates 2, substituted at 2 and, alternatively at, 6, 7 or 8 positions of the quinazolinone nucleus, were synthesised. The compounds were screened for their analgesic and antiinflammatory activities, acute toxicity and ulcerogenic effect. Substitution in the benzene moiety of the quinazolinone ring did not show any advantage for the analgesic activity, whereas it improved in some cases the antiinflammatory activity. Some compounds showed appreciable antiinflammatory activity and, at the same time, very low ulcerogenic index.     

Anti-Pneumocystis carinii pneumonia activity of dicationic 2,4-diarylpyrimidines

A synthesis of 2,4-bis-(4-amidinophenyl)pyrimidine 6, 2,4-bis-[(4-imidazolin-2-yl)phenyl)]pyrimidine 7, 2,4-bis [(4-tetrahydropyrimidinyl-2-yl)phenyl]pyrimidine 8, 2,4-bis[(4-N-n-propylamidino)phenyl]pyrimidine 9, 2,4-bis[(4-N-isopropylamidino)-phenyl]pyrimidine 10 and 2,4-bis[(4-N-isobutylamidino)phenyl]pyrimidine 11 starting from 4-bromobenzamidine and 4-bromoaceto-phenone is reported. A synthesis of 2-(4-amidinopnenyl)-4-(2-methoxy-4-amidinophenyl)pyrimidine 20, 2-[4-(imidazolin2-yl)-phenyl]-4-[2-me thoxy-4-(imidazolin-2-yl)phenyl]pyrimidine 21, and 2-[4-(N-iso-propylamidino)phenyl]-4-[2-methoxy-4-(N-isopro-pylamidino)phenyl]pyrimidine 22 beginning with 4-bromobenzamidine and 2-methoxy-4-bromoacetophenone is described. Compounds 6-11 and 20-22 all bind strongly to DNA. Compounds 6, 9-11, and 20 given at 5 mg/kg are more active and less toxic than pentamidine at its effective dose when evaluated against Pneumocystis carinii pneumonia (PCP) in the immunosuppressed rat model. Several compounds in this series are being evaluated further as potential new anti-PCP agents.     

Synthesis and antileishmanial activity of novel 5-(5-nitrofuran-2-y1)-1,3,4-thiadiazoles with piperazinyl-linked benzamidine substituents

In order to optimize the antileishmanial activity of piperazinyl-linked 5-(5-nitrofuran-2-yl)-1,3,4-thiadiazoles, we synthesized a series of 5-(5-nitrofuran-2-y1)-1,3,4-thiadiazoles with piperazinyl-linked benzamidine substituent as scaffold found in pentamidine related antiprotozoals. The structure of target compounds was confirmed by IR, 1H NMR, 13C NMR and Mass spectral data. All compounds were tested for in vitro activity against the promastigote and amastigote forms of Leishmania major. From the results, we found that the substitution on amidine nitrogen has profound role in the biological activity of these compounds. The 5-nitrofuran-2-yl-1,3,4-thiadiazoles having n-propyl, n-butyl and benzyl side chain on benzamidine (as in compounds 2d, 2e and 2g, respectively) showed very good activity in both forms of promastigote and amastigote. The most active compound was N-propyl-4-(4-(5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-yl)piperazin-1-yl) benzamidine hydrochloride (2d) with IC50 value of 0.08 μM in promastigote model. This compound showed a very low level of toxicity against macrophages (CC50=785 μM), with the highest selectivity index (SI=78.5) among the tested compounds.     

Design, synthesis and structure-activity relationship study of novel pyrazole-based heterocycles as potential antitumor agents

The versatile hitherto unreported 3-[(E)-3-(dimethylamino)acryloyl]-1,5-diphenyl-1H-pyrazole-4-carbonitrile (3) was prepared via the reaction of 3-acetyl-1,5-diphenyl-1H-pyrazole-4-carbonitrile (1) with dimethylformamid-dimethylacetal (DMF-DMA). The latter product and 3-((E)-3-morpholin-4-yl-acryloyl)-1,5-diphenyl-1H-pyrazole-4-carbonitrile (4) underwent regioselective 1,3-dipolar cycloaddition with nitrilimines to afford the corresponding pyrazole derivatives. In vivo anti-estrogenic activity and acute toxicity after single oral dose of the newly synthesized compounds were evaluated. In vitro disease-oriented primary antitumor screening utilizing 14 cell lines of breast and ovarian tumor subpanels has been also carried out. All tested compounds showed anti-estrogenic properties equipotent or superior to the reference drug, letrozole. 3-[3-(4-Cyano-1,5-diphenyl-1H-pyrazole-3-yl)-1-(4-methylphenyl)-1H-pyrazole-4-carbonyl]-1,5-diphenyl-1H-pyrazole-4-carbonitrile (27c) and 3-(3-acetyl-1-phenyl-1H-pyrazole-4-carbonyl)-1,5-diphenyl-1H-pyrazole-4-carbonitrile (8a) showed a significant cytotoxic activity in a nanomolar range against certain types of breast and ovarian tumors with tolerable toxicity.     

Synthesis, anti-HIV-1 integrase, and cytotoxic activities of 4-chloro-N-(4-oxopyrimidin-2-yl)-2-mercaptobenzenesulfonamide derivatives

Several 4-chloro-N-(4-oxopyrimidin-2-yl)-2-mercaptobenzenesulfonamide derivatives 13-28 and 35-44 have been synthesized and tested as potential HIV-1 integrase (IN) inhibitors. Compounds 15-17, 19, 21-28, 36 and 41 inhibited IN with IC(50) values in the range of 3.3-63.0 microM. The compounds 13, 15, 16, 21-24 and 26-28 were further tested at the US National Cancer Institute for their in vitro activity against a panel of 53-57 human tumor cell lines. The compounds 26-28 were inactive, whereas the other compounds exhibited high or reasonable activity (GI(50)<0.01-20.0 microM) against one or more human tumor cell lines.     

Synthesis, crystal structure and biological evaluation of novel 2-(5-(hydroxymethyl)-3-phenyl-1H-pyrazol-1-yl)-1-phenylethanol derivatives

A series of novel 2-(5-(hydroxymethyl)-3-phenyl-1H-pyrazol-1-yl)-1-phenylethanol derivatives (4) was synthesized from ethyl 1-(2-oxo-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylate derivatives (3) and characterized by means of IR, 1H NMR, HRMS and X-ray crystal diffraction. Structures of 4a, 4d, 4e and 4f were also determined by 13C NMR. Isomeric intermediates, 3a and 5a, were unambiguously confirmed by X-ray crystal structure analysis and successfully differentiated with 1H NMR chemical shifts of methylene bonded to pyrazole ring. Preliminary biological evaluation showed that compounds 4d and 4e could suppress A549 lung cancer cell growth through cell cycle arrest and autophagy.     

Synthesis of oxysterols and nitrogenous sterols with antileishmanial and trypanocidal activities

Two sterol families have been synthesized: the first one is nitrogenous sterols containing amino, N-hydroxyimino or cyano group and the second one is oxysterols such as ketosterol and hydroxysterols. These compounds were then evaluated in vitro against Leishmania donovani promastigotes and Trypanosoma brucei brucei trypomastigotes. The most active compounds against L. donovani promastigotes were 7beta-aminomethylcholesterol and 7alpha,beta-aminocholesterol (IC50 in a range from 1 to 3 microM, pentamidine: 2.8 microM). These compounds were active on intramacrophage amastigotes with IC50 of 1.3 microM. Such an activity justifies further in vivo antileishmanial evaluation. Against T. b. brucei, (24R,S)-24-hydroxy-24-methylcholesterol (MEC, 12.5 microM) was the most active compound from these series.     

Identification of hydrolytically stable and selective P2Y(1) receptor agonists

P2Y nucleotide receptors (P2YRs) are attractive pharmaceutical targets. Most P2YR agonists proposed as drugs consist of a nucleotide scaffold, but their use is limited due to their chemical and enzymatic instabilities. To identify drug candidates, we developed non-hydrolyzable P2YR agonists. We synthesized ATP-beta,gamma-CH(2) analogues 2-4, and evaluated their chemical and metabolic stabilities and activities at P2Y(1,2,4,6) receptors. Analogues 2-4 exhibited t(1/2) values of 14.5-65 h in gastric juice pH. They were completely resistant to alkaline phosphatase for 30 min at 37 degrees C and slowly hydrolyzed in human blood serum (t(1/2) 12.7-71.9 h). In comparison to ATP, analogues 2-4 were barely hydrolyzed by nucleoside triphosphate diphosphohydrolases, NTPDase1,2,3,8 (< 8% hydrolysis), and nucleotide pyrophosphatases, NPP1,3 (< or = 10% hydrolysis). Analogues 2 and 4B were selective agonists of the P2Y(1)R with EC(50)s of 0.08 and 17.2 microM, respectively. These features make analogues 2 and 4B potential therapeutic agents for health disorders involving the P2Y(1)R.     

Synthesis of novel 3-amino-2-(4-chloro-2-mercaptobenzenesulfonyl)-guanidine derivatives as potential antitumor agents

Novel 3-amino-2-(4-chloro-2-mercaptobenzenesulfonyl)guanidine derivatives have been synthesized as potential anticancer agents. The in vitro antitumor activity of these compounds has been evaluated in the US National Cancer Institute (NCI), and relationships between structure and antitumor activity are discussed. The prominent compound was 1-allyl-2-[4-chloro-5-(4-chlorophenylcarbamoyl)-2-methylthiobenzenesulfonyl]-3-(5-nitrofurfurylideneamino)guanidine (8) with remarkable activity against 21 human tumor cell lines representing leukemia, lung, colon, melanoma, ovarian, renal, prostate and breast (GI(50)=0.3-3.0microM), and selectivity toward leukemia RPMI-8226 cell line (GI(50)=0.3microM, TGI=1.4microM).     

Stereoselective synthesis and QSAR study of cytotoxic 2-(4-oxo-thiazolidin-2-ylidene)-2-cyano-N-arylacetamides

(2Z,5Z) 2-[(5-Arylidene-4-oxo-3-phenyl)-thiazolidin-2-ylidine]-2-cyano-N-arylacetamides 4a-l were stereoselectively prepared via condensation of aromatic aldehydes with 4-thiazolidinones 3a-c. The latters were obtained via electrophilic attack of phenylisothiocyanate on 2-cyano-N-arylacetamides 1a-c followed by reaction with chloroacetyl chloride under basic condition. Single crystal X-ray study of 3a allows good confirmation for the assigned structure. Additionally, 5-arylhydrazono analogs 5a-e were prepared via condensation of the appropriate diazonium salts with 4-thiazolidinones 3a,b. Many of the synthesized compounds exhibited promising antitumor properties against colon HCT116, breast MCF7 and liver HEPG2 cell lines. 3D-Pharmacophore modeling and QSAR analysis were combined to explain the observed antitumor properties.     

New highly potent GABA uptake inhibitors selective for GAT-1 and GAT-3 derived from (R)- and (S)-proline and homologous pyrrolidine-2-alkanoic acids

We synthesized proline and pyrrolidine-2-alkanoic acid derivatives in their enantiomerically pure form and evaluated them for their affinity to the GABA transport proteins GAT-1 and GAT-3. Among the compounds presented herein, (R)-pyrrolidine-2-acetic acid (R)-4d substituted with a 2-[tris(4-methoxyphenyl)methoxy]ethyl residue at the nitrogen atom showed the highest affinity at GAT-3 (IC(50) = 3.1 microM) comparable with the well-known GAT-3 blocker (S)-SNAP-5114. Compound (R)-4d displayed excellent subtype selectivity for GAT-3 (GAT-3:GAT-1 = 20:1). (S)-2-pyrrolidineacetic acid derivatives (S)-4b provided with a 4,4-diphenylbut-3-en-1-yl moiety and (S)-4c substituted with a 4,4-[di(3-methylthiophen-2-yl)]phenylbut-3-en-1-yl residue at the nitrogen atom exhibited IC(50) values of 0.396 microM and 0.343 microM at the GAT-1 protein, respectively.     

Synthesis and antiproliferative activity of 3-aryl-2-(1H-benzotriazol-1-yl)acrylonitriles. Part III

A new series of 30 3-aryl-2-(1H-benzotriazol-1-yl)acrylonitriles were synthesized and tested for biological activity as part of our research in the antimicrobial and antitumor fields. In particular, title compounds were evaluated in vitro against representative strains of Gram-positive and Gram-negative bacteria (S. aureus, Salmonella spp), mycobacteria (M. fortuitum, M. smegmatis ATCC 19420 and M. tuberculosis ATCC 27294), yeast and mould (C. albicans ATCC 10231 and A. fumigatus). Furthermore, their antiretroviral activity against HIV-1 was determined in MT-4 cells together with cytotoxicity. In these assays title compounds and 47 additional derivatives described previously (P. Sanna, A. Carta, M.E. Rahbar Nikookar, Eur. J. Med. Chem. 35 (2000) 535-543; P. Sanna, A. Carta, L. Gherardini, M.E. Rahbar Nikookar, Farmaco 57 (2002) 79-87) were tested for their capability to prevent MT-4 cell growth. All compounds resulted devoid of antibacterial, antifungal and anti-HIV-1 activity. In anti-mycobacterial assays several compounds resulted active (MIC(50)=6.0-70 microM) against M. tuberculosis. However, since they showed cytotoxicity against MT-4 cells at lower concentrations (CC(50)=0.05-25 microM), their anti-mycobacterial activity was not selective. For this reason, the most cytotoxic compounds were also evaluated for antiproliferative activity against a panel of human cell lines derived from both hematological and solid tumors. Compound 34 resulted the most potent compound against the above human tumor-derived cell lines.     

Piperazine-linked bisbenzamidines: a novel class of antileishmanial agents

A series of 13 1,4-diarylpiperazines has been prepared, evaluated for antileishmanial activity and their binding affinity to DNA was measured. Among these compounds, 1,4-bis[4-(1H-benzimidazol-2-yl)phenyl]piperazine (14) emerged as the most active compound with an IC(50) value of 0.41 microM which is about sevenfold more potent than pentamidine.     

Synthesis of some novel thiourea derivatives obtained from 5-[(4-aminophenoxy)methyl]-4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thiones and evaluation as antiviral/anti-HIV and anti-tuberculosis agents

As a continuation of our previous efforts on N-alkyl/aryl-N'-[4-(4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thione-5-yl)phenyl]thioureas 1-19 and N-alkyl/aryl-N'-[4-(3-aralkylthio-4-alkyl/aryl-4H-1,2,4-triazole-5-yl)phenyl]thioureas 20-22, a series of novel 5-[(4-aminophenoxy)methyl]-4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thiones 23-26 and several related thioureas, N-alkyl/aryl-N'-{4-[(4-alkyl/aryl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)methoxy]phenyl}thioureas 27-42 were synthesized for evaluation of their antiviral potency. Structures of the synthesized compounds were confirmed by the use of (1)H NMR, (13)C NMR and HR-MS data. All compounds 1-42 were evaluated in vitro against HIV-1 (IIIB) and HIV-2 (ROD) strains in MT-4 cells, as well as other selected viruses such as HSV-1, HSV-2, Coxsackie virus B4, Sindbis virus and Varicella-zoster virus using HeLa, Vero, HEL and E6SM cell cultures, and anti-tuberculosis activity against Mycobacterium tuberculosis H37Rv. Compounds 4 and 5 showed weak activity against HSV-1, HSV-2 and TK(-) HSV, whereas eight compounds showed marginal activity against Coxsackie virus B4. The most active derivative in this series was compound 38 which showed moderate protection against Coxsackie virus B4 with an MIC value of 16 microg/ml and a selectivity index of 5. This compound was also active against thymidine kinase positive Varicella-zoster virus (TK(+) VZV, OKA strain) with an EC(50) value of 9.9 microg/ml. Compound 38 was the most active compound with 79% inhibition against M. tuberculosis H37Rv.     

Synthesis and antimicrobial activity of 4-phenyl/cyclohexyl-5-(1-phenoxyethyl)-3-[N-(2-thiazolyl)acetamido]thio-4H-1,2,4-triazole derivatives

The increasing clinical importance of drug-resistant fungal and bacterial pathogens has lent additional urgency to microbiological research and new antimicrobial compound development. For this purpose, new thiazole derivatives of triazoles were synthesized and evaluated for antifungal and antibacterial activity. The reaction of propionic acid hydrazides with various aryl/alkyl isothiocyanates gave thiosemicarbazides which furnished the mercaptotriazoles by alkali cyclization. The 4-phenyl/cyclohexyl-5-(1-phenoxyethyl)-3-[N-(2-thiazolyl)acetamido]thio-4H-1,2,4-triazole derivatives were synthesized by reacting the mercaptotriazoles with 2-chloro-N-(2-thiazolyl)acetamide. The chemical structures of the compounds were elucidated by IR, 1H-NMR, FAB+-MS spectral data. Their antimicrobial activities against Candida albicans (two strains), Candida glabrata, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa were investigated. The results showed that some of the compounds have very strong antifungal activity.