Synthesis and anti-mycobacterial activities of triazoloquinolones

A number of quinolone derivatives have been reported to possess anti-mycobacterial activity. Generally. Mycobacterium tuberculosis isolates expressing resistance to both isoniazid and rifampin are susceptible to fluoroquinolones. Benzotriazole is a hetero-bicyclic aromatic ring endowed with interesting chemical and biological properties and pharmacological activities. In a preliminary study we have recently reported the activity of triazolo[4,5-h]quinolone-carboxylic acids, a new class of benzotriazole derivatives active against multi-drug resistant M. tuberculosis (MDR-Mtb). In this study we confirm that this novel class of quinolones is endowed with a selective anti-mycobacterial activity, coupled with absence of cytotoxicity.The SAR analysis of the new derivatives in comparison with the previous series shows that the methyl group is the most effective substituent in both N-3 and N-9 positions of the ring system.     

Synthesis and biological activities of diflunisal hydrazide-hydrazones

Several diflunisal hydrazide-hydrazone derivatives namely 2',4'-difluoro-4-hydroxybiphenyl-3-carboxylic acid [(5-nitro-2-furyl/substitutedphenyl)methylene] hydrazide (3a-o) have been synthesised. Methyl 2',4'-difluoro-4-hydroxybiphenyl-3-carboxylate (1) and 2',4'-difluoro-4-hydroxybiphenyl-3-carboxylic acid hydrazide (2) were also synthesised and used as intermediate compounds. All synthesised compounds were screened for their antimycobacterial activity against Mycobacterium tuberculosis H37 Rv, antimicrobial activities against various bacteria, fungi and yeast species. Compound 3a have shown activity against Staphylococcus epidermis HE-5 and Staphylococcus aureus HE-9 at 18.75 and 37.5 microg mL(-1), respectively. Compound 3o have exhibited activity against Acinetobacter calcoaceticus IO-16 at a concentration of 37.5 microg mL(-1), whereas Cefepime, the drug used as standard, have been found less active against the microorganisms mentioned above. The synthesised compounds were found to provide 12-34% inhibition of mycobacterial growth of M. tuberculosis H37 Rv in the primary screen at 6.25 microg mL(-1). Anticonvulsant activity of the compounds were also determined by maximal electroshock (MES) and subcutaneous metrazole (scMET) tests in mice and rats following the procedures of antiepileptic drug development (ADD) program of the National Institutes of Health (NIH). Compound 3k showed 25% protection against MES induced seizures in p.o. rat screening at a dose level of 30 mg kg(-1) whereas 3n and 3o showed neurotoxicity after 4 and 0.5 h at a dose level of 100 and 300 mg kg(-1), respectively.     

Synthesis and antinociceptive activities of some pyrazoline derivatives

In the present study, some pyrazoline derivatives were synthesized to investigate their potential antinociceptive activities. 1-[(Benzoxazole/benzimidazole-2-yl)thioacetyl]pyrazoline derivatives were obtained by reacting 3,5-diaryl-1-(2-chloroacetyl)pyrazolines with 2-marcaptobenzoxazole/benzimidazole. The chemical structures of the compounds were elucidated by IR, (1)H NMR and FAB(+)-MS spectral data and Elemental Analyses. All of the compounds (100 mg/kg) exhibited significant antinociceptive activities in both hot plate and acetic acid-induced writhing tests. Naloxone (5 mg/kg) pre-treatment reversed the antinociceptive activities suggesting the involvement of opioid system in the analgesic actions. None of the compounds impaired motor coordination of animals when assessed in the Rota-Rod model. These results support the previous papers reporting the opioid sensitive antinociceptive activities of various benzoxazole/benzimidazole-pyrazoline derivative compounds.     

Synthesis and antiproliferative activities of isoindigo and azaisoindigo derivatives

In the course of structure-activity relationship studies, diversely substituted 1-(beta- d-acetylatedglucopyranosyl)isoindigo derivatives were prepared from indolines. New 7'-azaisoindigo analogues were also synthesized by coupling a glycosylated isatine and a 7-azaindolin-2-one derivative. Compounds containing a 7'-azaisoindigo framework have never been described before. To get an insight into the substitution pattern required for the best biological potencies, their antiproliferative activities were evaluated toward a human buccal carcinoma cell line (KB) and two human myeloid leukaemia cell lines (K562, HL60).     

Synthesis and antimicrobial activities of 7-O-modified genistein derivatives

Three series of genistein derivatives with heterocycles were prepared, in which genistein and heterocyclic moieties were separated by 2-carbon, 3-carbon and 4-carbon spacers. Among the 33 compounds we prepared 11 of them (2c and 5a-j) are reported for the first time, while the preparation of 2a,b, 3a-j and 4a-j was reported in our recent paper. All the derivatives were screened for antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescence) and antifungal (Aspergillus niger, Candida albicans and Trichophyton rubrum) activities by MTT method. Among the compounds tested, 4a, 4e, 4f, 4h, 5e and 5f exhibited good antibacterial activities while 4a also showed notable antifungal activity. Especially, 5f exhibited stronger antibacterial activity against B. subtilis and S. aureus comparable to positive controls.     

Synthesis and anti-microbial activities of choline-like quaternary ammonium chlorides

New choline-like quaternary ammonium chlorides were obtained. The work-up procedure of synthesis was quick and efficient. The obtained chlorides showed anti-microbial activities. Quaternary ammonium chlorides derivatives of deanol esters exhibited strong activity and wide anti-bacterial spectra, similar to the activity of benzalkonium chloride. The relationship between chemical structure and anti-microbial activity was analyzed by the QSAR method.     

Synthesis, anti-HIV and antitubercular activities of lamivudine prodrugs

The synthesis of a novel series of lamivudine prodrugs involving N4-substitution with isatin derivatives is described. The in-vitro antiretroviral activities indicated that compound 3b was found to be equipotent to lamivudine with EC50 of 0.0742+/-0.04 microM. Lamivudine prodrugs bearing fluoroquinoles antibacterial showed 92-100% inhibition against Mycobacterium tuberculosis strain H37Rv at 6.25 microg ml(-1). At pH 7.4, 37 degrees C, the hydrolytic t(1/2) ranged between 120 and 240 min.     

Synthesis and antiproliferative activities of diversely substituted glycosyl-isoindigo derivatives

In the course of structure-activity relationship studies, diversely substituted 1-(beta-D-glucopyranosyl)-isoindigo derivatives were prepared from commercially available indolines. Their antiproliferative activities were evaluated toward a panel of human solid cancer cell lines (PC 3, DLD-1, MCF-7, M4Beu, A549, PA 1), a murine cell line (L929) and a human fibroblast primary culture to get an insight into the substitution pattern required for the best biological potencies.     

Synthesis of 2,6-diaryl-substituted pyridines and their antitumor activities

For the development of novel antitumor agents, we designed and synthesized 2,6-diaryl-substituted pyridine derivatives bearing three aryl groups, which are the bioisosteres of terpyridine, and evaluated their biological activities. Most of the 18 prepared compounds showed moderate cytotoxicity against several human cancer cell lines. From the structure-activity relationships we may conclude that the number of aryl groups employed would be critical for their biological activities.     

Synthesis and in vitro antibacterial activities of novel oxazolidinones

Design and synthesis of novel piperazinylaryloxazolidinones possessing heteroaryl groups are described and their in vitro antibacterial activities have been evaluated by MIC assay. Compounds (S)-N-[3-{3-fluoro-4-[4-[3-(5-nitrofuran-2-yl)-acryloyl]-piperazin-1-yl]-phenyl}-2-oxo-oxazolidin-5-yl-methyl] acetamide (6o), (S)-N-[3-{3-fluoro-4-[4-[3-(5-nitrothien-2-yl)-acryloyl]-piperazin-1-yl]-phenyl}-2-oxo-oxazolidin-5-yl-methyl] acetamide (6p) and N-oxide of (S)-N-[3-{3-fluoro-4-[4-[3-(5-nitrofuran-2-yl)-acryloyl]-piperazin-1-yl]-phenyl}-2-oxo-oxazolidin-5-yl-methyl] acetamide (9) showed superior antibacterial activities than linezolid and also active against the linezolid resistant Staphylococcus aureus strains.     

Synthesis and antimycobacterial activities of glycosylated amino alcohols and amines

Reduction of glycosyl beta-amino esters (6-14 and 25-30) with lithium aluminum hydride resulted in glycosyl amino alcohols (15-23 and 31-36) in good yields. However, reductive amination of glycosyl aldehydes (1-3) with different amines in presence of sodium borohydride resulted in good to moderate yields of glycosyl amines (37-41). All the compounds were evaluated for antitubercular activity against Mycobacterium tuberculosis H37Ra and H37Rv. Compounds 18, 21, 35 and 36 exhibited antitubercular activities with MIC ranging from 6.25 to 3.12 microg ml(-1).     

Synthesis and antiprotozoal activities of simplified analogs of naphthylisoquinoline alkaloids

The naphthylisoquinoline alkaloids (NIQs) represent a class of natural products with manifold activities against various tropical diseases. They are isolated from rare and difficult-to-cultivate tropical plants. In order to find novel, more easily accessible analogs and to study structure-activity relationships, a variety of simplified analogs were produced, which bear the functional groups typical of the NIQs, but avoid the synthetically difficult elements of chirality, stereogenic centers and rotationally hindered axes. Their syntheses and activities against Plasmodium falciparum, Trypanosoma cruzi, and Leishmania donovani are described and compared with those of the natural NIQs. Remarkably, quite good activities were found for naphthalene-devoid halogenated isoquinolinic analogs.     

Synthesis and antidepressant activities of some 3,5-diphenyl-2-pyrazolines

Ten new 3,5-diphenyl-2-pyrazoline derivatives were synthesised by reacting 1,3-diphenyl-2-propen-1-one with hydrazine hydrate. The chemical structures of the compounds were proved by means of their IR, 1H-NMR spectroscopic data and microanalyses. The antidepressant activities of these compounds were evaluated by the 'Porsolt Behavioural Despair Test' on Swiss-Webster mice. 3-(4-Methoxyphenyl)-5-(3,4-dimethoxyphenyl)-2-pyrazoline, 3-(4-methoxyphenyl)-5-(2-chloro-3,4-dimethoxyphenyl)-2-pyrazoline and 3-(4-chlorophenyl)-5-(2-chloro-3,4-dimethoxyphenyl)-2-pyrazoline reduced 41.94-48.62% immobility times at 100 mgkg(-1) dose level. In addition, it was found that 4-methoxy and 4-chloro substituents on the phenyl ring at position 3 of the pyrazoline ring increased the antidepressant activity; the replacement of these groups by bromo and methyl substituents decreased activity in mice.     

Synthesis and biological activities of indolocarbazoles bearing amino acid residues

Three indolocarbazole compounds bearing a tripeptide or a lysine group attached to one of the indole nitrogens via a propylamino chain and two rebeccamycin derivatives bearing a lysine residue on the sugar moiety were synthesised with the aim of improving the binding to DNA and the antiproliferative activities. Four tumour cell lines, from murine L1210 leukemia, human HT29 colon carcinoma, A549 non-small cell lung carcinoma and K-562 leukemia, were used to evaluate the cytotoxicity of the drugs. Their effects on the cell cycle of L1210 cells and their antimicrobial properties against two Gram-positive bacteria Bacillus cereus and Streptomyces chartreusis, a Gram-negative bacterium Escherichia coli and a yeast Candida albicans were also investigated.     

Synthesis and antimalarial activities of some furoxan sulfones and related furazans

Furoxan derivatives bearing a sulfone moiety at position 3 or 4 were synthesized and tested for their antimalarial action on the chloroquine-sensitive D10 and the chloroquine-resistant W2 strains of Plasmodium falciparum. The furazan analogues were considered for comparison. The most active compounds were the products in which the -SO2R groups are at the 3-position of the furoxan system. These latter substances displayed an antimalarial activity in the microM range, possibly related in part to their ability to release NO.     

Synthesis and antimicrobial activities of new pyridinium and benzimidazolium chlorides.

A novel class of pyridinium and benzimidazolium chloride has been obtained in high yield. The antimicrobial activities of three homologous series of pyridinium and benzimidazolium chlorides against cocci, rods, fungi and bacillus have been measured. The antimicrobial activities of N,N'-bis[3-(1-alkoxymethyl)pyridinium chloride]methylenediamines, 1-undecyloxymethyl-3-(1-benzimidazolmethylamino)pyridinium, 1-undecyloxymethyl- and 1-dodecyloxymethyl-3-[1(benzotriazol-1-yl)methylamino]pyridinium chlorides exhibited strong activity and wide antibacterial spectra similar to the activity of benzalkonium chloride.     

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.     

Synthesis and antimicrobial activities of Schiff bases derived from 5-chloro-salicylaldehyde

A series of Schiff bases (compounds 1-26) were synthesized by reacting 5-chloro-salicylaldehyde and primary amines, 15 (compounds 2-4, 6, 7, 10, 12-17, 23, 25 and 26) of which were first reported. The chemical structures of these compounds were confirmed by means of (1)H NMR, (13)C NMR, ESI-MS and elemental analyses. The compounds were assayed for antibacterial (Bacillus subtilis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus) and antifungal (Aspergillus niger, Candida albicans and Trichophyton rubrum) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl trtrazolium bromide) method. Among the compounds tested, (E)-4-chloro-2-((4-fluorobenzylimino)methyl)phenol (2) showed the most favorable antimicrobial activity with MICs of 45.2, 1.6, 2.8, 3.4, and 47.5 microg/mL against B. subtilis, E. coli, P. fluorescence, S. aureus and A. niger, respectively.     

Ala scan analogues of HOE 140. Synthesis and biological activities

The role of the amino acids contained in the sequence of HOE 140 (H-DArg(1)-Arg(2)-Pro(3)-Hyp(4)-Gly(5)-Thi(6)-Ser(7)-DTic(8)-Oic(9 )-Arg(10)-OH), a potent and selective bradykinin B(2) receptor peptide antagonist, has been investigated by the replacement of each original residue (one by one) with Ala. The resulting set of decapeptides has been tested for the B(2) antagonist activity as well as for competition with the binding of [3H]BK to plasma membranes of the human umbilical vein (hUV). Positive correlations have been established between data obtained with the bioassay and with the binding in the hUV (same species, same tissue) and also between the two bioassays, the guinea-pig ileum (GPI) and the hUV (different species, different tissue). The structure-activity study has shown that the replacement of any of the residues that constitute HOE 140 with Ala is accompanied by a decrease of potency of at least 1 log unit. The analogues can be divided into three groups, with Ala(1) and Ala(7) showing affinities lower than HOE 140 by a factor of 10, Ala(4) and Ala(10) by a factor of 100 and Ala(2), Ala(5), Ala(6), Ala(8) and Ala(9) by a factor higher than 100 (100-1000). To verify the effect of chirality, the DAla(5) and DSer(7) analogues were synthesized and it was found that the substitution with a D-residue in position 5 is not tolerated while that in position 7 is favourable. The DSer(7) derivative is the most potent analogue found in this study: it shows potency as high as that of HOE 140 in the bioassays.     

Synthesis and antimycobacterial activities of novel 6-nitroquinolone-3-carboxylic acids

Various 1-(substituted)-1,4-dihydro-6-nitro-4-oxo-7-(sub-secondary amino)-quinoline-3-carboxylic acids were synthesized from 2,4-dichlorobenzoic acid by six step synthesis. The compounds were evaluated for antimycobacterial in vitro and in vivo against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB) and Mycobacterium smegmatis (MC(2)) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. smegmatis. Among the 48 synthesized compounds, 7-(4-((benzo[d][1,3]dioxol-5-yl)methyl)piperazin-1-yl)-1-cyclopropyl-1,4-dihydro-6-nitro-4-oxoquinoline-3-carboxylic acid (8c) was found to be the most active compound in vitro with MIC of 0.08 and 0.16 microM against MTB and MDR-TB, respectively. In the in vivo animal model 8c decreased the bacterial load in lung and spleen tissues with 2.78 and 4.15-log10 protections, respectively, at the dose of 50 mg/kg body weight.