Synthesis and in vitro antibacterial activity of novel methylamino piperidinyl oxazolidinones

Design and synthesis of a few novel methylamino piperidinyl substituted oxazolidinones are reported. Their antibacterial activities have been evaluated in a MIC assay against broader panel of both susceptible and resistant Gram-positive strains. (S)-N-{3-[3-Fluoro-4-(methyl-{1-[3-(5-nitrofuran-2-yl)-acryloyl]-piperidin-4-yl}-amino)-phenyl]-2-oxo-oxazolidin-5-ylmethyl}-acetamide 4i has shown comparable antibacterial activity to linezolid and eperezolid in the MIC assay, additionally compound 4i showed good antibacterial activity with an in vitro MIC value of 2-4 microg/mL against linezolid resistant Staphylococcus aureus (linezolid 16 microg/mL).     

Synthesis and antiproliferative evaluation of amide-containing flavone and isoflavone derivatives

Certain amide-containing flavone and isoflavone derivatives were synthesized and evaluated for their antiproliferative activities. These compounds were synthesized via alkylation of hydroxyl precursors followed by the reaction with H(2)SO(4) and NaN(3) (Schmidt reaction). The preliminary assays indicated that the inhibitory activity against the growth of NCI-H661 decreased in an order of linked chromophore flavone-6-yl 16a-d>flavone-7-yl 17a-d>flavone-3-yl 15a-d and isoflavone-7-yl 18a-d. Among these flavone-6-yl derivatives, N-(4-methoxyphenyl)-2-(4-oxo-2-phenyl-4H-chromen-6-yloxy)acetamide (16c) was the most potent with a GI(50) value of 0.84 microM. The inhibitory activity against the growth of NPC-TW01 decreased in an order of linked chromophore flavone-6-yl 16a-d>isoflavone-7-yl 18a-d>flavone-7-yl 17a-d>flavone-3-yl 15a-d. Flavone-6-yl derivatives 16a-d demonstrated significant inhibitory activities against the growth of NPC-TW01 cell with an average GI(50) value of 0.84 microM. The oxime derivatives 1 and 2 caused accumulation of NPC-TW01 cell in G(2)/M phase which were distinct from that of their amide isomers 16b and 16c, respectively, which induced cell-cycle arrest in G(0)/G(1) phase followed by apoptosis. Therefore, the antiproliferative mechanism of flavone derivatives was affected not only by the phenyl benzopyran-4-one pharmacophore but also by the peripheral substituents.     

Anti-Candida metabolites from endophytic fungi

Submerged cultures of some 1500 Ascomycota and Basidiomycota isolated from their fruit-bodies or as soil-borne, coprophilous or endophytic fungi were screened for activity against Candida albicans and a range of other pathogenic and saprotrophic fungi. Considerably more Ascomycota (11-16%) than Basidiomycota (3.5%) produced metabolites with activity against C. albicans. From five species of endophytes, six bioactive compounds were isolated and identified, viz. cerulenin (1), arundifungin (2), sphaeropsidin A (3), 5-(1,3-butadiene-1-yl)-3-(propene-1-yl)-2-(5H)-furanone (4), ascosteroside A (formerly called ascosteroside; 5) and a derivative of 5, ascosteroside B (6). 1, 3 and 5 were isolated from fungi belonging to different orders than previously described producers. Antifungal activities of 2 and 4-6 in the agar diffusion test were comparable with those of amphotericin B. Compound 6 exhibited a similar antifungal activity as 5 but its cytotoxicity towards Hep G2 cells was considerably lower. This study points to endophytic fungi related to hemibiotrophic or latent plant pathogens as an important source of bio- and chemodiversity.     

Synthesis and biological evaluation of nitroxide labeled pyrimidines as Aurora kinase inhibitors

To find novel effective Aurora kinases inhibitors, a series of structurally interesting nitroxide labeled pyrimidines were synthesized and evaluated their anti-proliferative and Aurora kinases inhibitory activities. Among them, butyl 2-(3-((5-fluoro-2-((4-((1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)carbamoyl) phenyl) amino)pyrimidin-4-yl)amino)-1H-pyrazol-5-yl)acetate (22) possessed the most potent anti-proliferative effects against four carcinoma cell lines with IC₅₀ values in range of 0.89–11.41?μM, and kinases inhibition against Aurora A and B with the IC₅₀ values were 9.3 and 2.8?nM, respectively. Furthermore, compound 22 blocked the phosphorylation of Aurora A (T288), Aurora B (Thr232) and HisH3, decreased the expression of proteins TPX2, Eg5 and Bora, as well as disrupted the mitotic spindle formation in HeLa cells. Molecular docking studies indicated that compound 22 well interact with both Aurora A and B. The results showed that compound 22 is a potential anticancer agent as promising pan-Aurora kinase inhibitor.     

1-[4-(1H-Benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea derivatives as small molecule heparanase inhibitors

A novel class of 1-[4-(1H-benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-ureas are described as potent inhibitors of heparanase. Among them are 1,3-bis-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea (7a) and 1,3-bis-[4-(5,6-dimethyl-1H-benzoimidazol-2-yl)-phenyl]-urea (7d), which displayed good heparanase inhibitory activity (IC(50) 0.075-0.27 microM). Compound 7a showed good efficacy in a B16 metastasis model.     

New pyrrolopyrimidin-6-yl benzenesulfonamides: potent A2B adenosine receptor antagonists

A new series of 4-(1,3-dialkyl-2,4-dioxo-2,3,4,5-tetrahydro-1H-pyrrolo[3,2-d]pyrimidin-6-yl)benzenesulfonamides has been identified as potent A2B adenosine receptor antagonists. The products have been evaluated for their binding affinities for the human A2B, A1 and A3 adenosine receptors. 6-(4-{[4-(4-Bromobenzyl)piperazin-1-yl]sulfonyl}phenyl)-1,3-dimethyl-1H-pyrrolo[3,2-d]pyrimidine-2,4(3H,5H)-dione (16) showed a high affinity for the A2B adenosine receptor (IC50=1 nM) and selectivity (A1: 183x; A3: 12660x). Synthesis and SAR of this novel class of compounds showing improved absorption properties is presented herein.     

Synthesis and in vitro antibiotic activity of 16-membered 9-O-arylalkyloxime macrolides

A series of novel 9-O-arylalkyloxime analogs based on three different 16-membered macrolide scaffolds-5-O-mycaminosyltylonolide (OMT), tilmicosin, and 20-deoxy-20-(3,5-dimethyl-1-piperidin-1-yl)-OMT-was synthesized. In vitro antibiotic activities were assayed against Gram-positive Streptococcus pneumoniae and Staphylococcus aureus and Gram-negative Haemophilus influenzae bacterial strains. Analogs derived from OMT (3-15) showed similar or better antibacterial activities against macrolide-susceptible strains and enhanced activities against macrolide-resistant strains compared with erythromycin A, tylosin, or OMT. Similar results were observed for tilmicosin 9-O-arylalkyloxime analogs (18-24). In contrast, most of the 20-deoxy-20-(3,5-dimethyl-1-piperidin-1-yl)-OMT analogs (25-33) showed reduced antibacterial activities compared with OMT. Ribosome-binding studies were performed on compounds 12 (OMT derivative), 20 (tilmicosin derivative), and 29 [20-deoxy-20-(3,5-dimethyl-1-piperidin-1-yl)-OMT derivative]. It was found that these compounds interacted with both domain V and domain II of the Escherichia coli 23S rRNA.     

Synthesis,single crystal and antitumor activities of benzimidazole–quinazoline hybrids

A series of novel regioisomeric hybrids of quinazoline/benzimidazole viz. (3-allyl-2-methyl-3H-benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)-amine and (1-allyl-2-methyl-1H-benzimidazol-5-yl)-(2-substituted-quinazolin-4-yl)-amine of biological interest were synthesized. All the synthesized compounds were well characterized by ¹H and ¹³C NMR as well as mass spectroscopy. The newly synthesized compounds were screened for in vitro antitumor activities against 60 tumor cell lines panel assay. A significant inhibition for cancer cells were observed with compound 9 and also more active against known drug 5-fluorouracil (5-FU) in some tumor cell lines. Compound 9 displayed appreciable anticancer activity against leukemia, colon, melanoma, renal and breast cancer cell lines.     

Synthesis, antimicrobial and antimycobacterial evaluation of [2-(substituted phenyl)-imidazol-1-yl]-pyridin-3-yl-methanones

A series of [2-(substituted phenyl)-imidazol-1-yl]-pyridin-3-yl-methanones (1-11) were synthesized and screened for their antimicrobial and antimycobacterial activities. Further, a series of [2-(substituted phenyl)-benzimidazol-1-yl]-pyridin-3-yl-methanones (12-20) reported in our earlier study was also screened for their antimycobacterial activity. The antimycobacterial activity results indicated that [2-(4-Nitro-phenyl)-imidazol-1-yl]-pyridin-3-yl-methanone (8, minimum inhibitory concentration [MIC]?=?3.13 μg) was equipotent as standard drug ciprofloxacin and [2-(4-Nitro-phenyl)-benzimidazol-1-yl]-pyridin-3-yl-methanone (16, MIC?=?1.56 μg) was equipotent as standard drug ethambutol. The results of antimicrobial screening demonstrated that 2-[1-(Pyridine-3-carbonyl)-1H-imidazol-2-yl]-benzoic acid (compound 11, MIC?=?0.002 μg) was two times more effective than standard drug ciprofloxacin (MIC?=?0.004 μg) against tested bacterial strains and [2-(2,5-Dimethyl-phenyl)-imidazol-1-yl]-pyridin-3-yl-methanone (compound 3, MIC?=?0.005 μg) was equipotent to the reference compound, fluconazole against tested fungal strains.     

Structure based design and syntheses of amino-1H-pyrazole amide derivatives as selective Raf kinase inhibitors in melanoma cells

The synthesis of a novel series of N-(5-amino-1-(4-methoxybenzyl)-1H-pyrazol-4-yl amide derivatives 6a-o, 7a-s and their antiproliferative activities against A375P melanoma cell line were described. Most compounds showed competitive antiproliferative activities to sorafenib, the reference standard. Among them, N-(5-amino-1-(4-methoxybenzyl)-1H-pyrazol-4-yl)-5-(3-(4-chloro-3-(trifluoromethyl)phenyl) ureido)-2-methylbenzamide 7c exhibited potent activities (GI(50)=0.27 μM). Especially, 7c was found to be a potent and selective B-Raf V600E and C-Raf inhibitor (IC(50)=0.26 μM, IC(50)=0.11 μM, respectively), showing a possibility as melanoma therapeutics.     

Synthesis and in vitro biological activity of new 4,6-disubstituted 3(2H)-pyridazinone-acetohydrazide derivatives

New 3(2H)-pyridazinone derivatives containing a N'-benzyliden-acetohydrazide moiety at position 2 were synthesized. The structures of these newly synthesized compounds were confirmed by IR, 1H NMR, and MS data. These compounds were tested for their antibacterial, antifungal, antimycobacterial, and cytotoxic activities. The compounds 2-[4-(4-chlorophenyl)-6-(morpholin-4-yl)-3-oxo-(2H)-pyridazin-2-yl]-N'-(4-tert-butylbenzyliden)acetohydrazide and 2-[4-(4-chlorophenyl)-6-(morpholin-4-yl)-3-oxo-(2H)-pyridazin-2-yl]-N'-(4-chlorobenzyliden) acetohydrazide exhibited activity against both Gram-positive and Gram-negative bacteria. Most of the compounds were active against E. coli ATCC 35218. The preliminary results of this study revealed that some target compounds exhibited promising antimicrobial activities.     

Antimicrobial activities of some synthesized 1-(3-(2-methylphenyl)-4-Oxo-3<Emphasis Type="Italic">H</Emphasis>-quinazolin-2-yl-4-(substituted)thiosemicarbazide derivatives

The substituted thiosemicarbazide moiety was placed at the C-2 position and 2-methylphenyl group at N-3 position of quinazoline ring and obtained compounds were tested for their antitubercular activities and antibacterial activities against selected gram-positive and gram-negative bacteria. The target compounds 1-(3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazides were obtained by the reaction of 2-hydrazino-3-(2-methylphenyl) quinazolin-4(3H)-one with different dithiocarbamic acid methyl ester derivatives. All synthesized compounds were also screened for their antimicrobial activity against selective gram-positive and gram-negative bacteria by agar dilution method. Among the series, 1-[3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl]-4-[4-chlorophenyl]-thiosemicarbazide exhibited the most potent activity against S. typhi, E. coli, and B. subtilis, while 1-[3-(2-methylphenyl)-4-oxo-3H-quinazolin-2-yl]-4-[4-nitrophenyl]-thiosemicarbazide was the most potent against E. coli, B. subtilis, P. aeruginosa, S. typhi, and S. flexneri. These two compounds exhibited the antitubercular activity at the minimum concentration (3 μg/mL) that offered potential for further optimization and development of new antitubercular agents. The obtained results demonstrated promising antimicrobial and antitubercular activities of the synthesized quinazoline compounds which could be used as new scaffolds for improving their antimicrobial activity.     

Synthesis, structure-activity relationship and in vitro biological evaluation of N-arylethyl isoquinoline derivatives as Coxsackievirus B3 inhibitors

Currently, there is no approved antiviral drug for the infection caused by enteroviruses. A series of novel N-arylethyl isoquinoline derivatives defined with substituents on the ring A and C were designed, synthesized and evaluated in vitro for their activities against Coxsackievirus B3 (CVB3). The primary structure-activity relationship revealed that substituents on the ring A were not beneficial for the activity. Among these analogs synthesized, compound 7f bearing a methylenedioxy at the R(4) and R(5) positions afforded an anti-CVB3 activity and a reasonable selectivity index (SI=26.8); furthermore, 7f exhibited a moderate activity against enterovirus 71 (EV71) with SI value of 9.0. Thus it has been selected as an anti-enteroviral lead compound for further investigation.     

Novel 1,3-dipropyl-8-(1-heteroarylmethyl-1H-pyrazol-4-yl)-xanthine derivatives as high affinity and selective A2B adenosine receptor antagonists

A series of new 1,3-dipropyl-8-(1-heteroarylmethyl-1H-pyrazol-4-yl)-xanthine derivatives as A(2B)-AdoR antagonists have been synthesized and evaluated for their binding affinities for the A(2B), A(1), A(2A), and A(3)-AdoRs. 8-(1-((3-phenyl-1,2,4-oxadiazol-5-yl)methyl)-1H-pyrazol-4-yl)-1,3-dipropyl-1H-purine-2,6(3H,7H)-dione (4) displayed high affinity (K(i)=1 nM) and selectivity for the A(2B)-AdoR versus A(1), A(2A), and A(3)-AdoRs (A(1)/A(2B), A(2A)/A(2B), and A(3)/A(2B) selectivity ratios of 370, 1100, and 480, respectively). The synthesis and SAR of this novel class of compounds are presented herein.     

Synthesis, spectral analysis and in vitro microbiological evaluation of novel ethyl 4-(naphthalen-2-yl)-2-oxo-6-arylcyclohex-3-enecarboxylates and 4,5-dihydro-6-(napthalen-2-yl)-4-aryl-2H-indazol-3-ols

A series of ethyl 4-(naphthalen-2-yl)-2-oxo-6-arylcyclohex-3-enecarboxylates 8-14 and 4,5-dihydro-6-(naphthalen-2-yl)-4-aryl-2H-indazol-3-ols 15-21 were synthesised and characterised by their spectroscopic data. In vitro microbiological evaluations were carried out for all the newly synthesised compounds 8-21 against clinically isolated bacterial and fungal strains. Compounds 9, 12 and 20 against Staphylococcus aureus, 10, 12, 20 against β-haemolytic streptococcus, 11, 17 against Bacillus subtilis, 12, 16 and 20 against Vibreo cholerae, 13, 16 against Escherichia coli, 13, 16, 18, 19 against Salmonella typhii, 12, 18 against Shigella flexneri, 10 against Salmonella typhii, 10, 13, 17, 18 against Aspergillus flavus, 12, 17, 21 against Aspergillus niger, 12, 15, 17, 18, 20 against Mucor, Rhizopus and Microsporeum gypsuem exhibit potent antimicrobial activity.     

1,3-Dipropyl-8-(1-phenylacetamide-1H-pyrazol-3-yl)-xanthine derivatives as highly potent and selective human A(2B) adenosine receptor antagonists

A new series of 1,3-dipropyl-8-(1-phenylacetamide-1H-pyrazol-3-yl)-xanthine derivatives has been identified as potent A(2B) adenosine receptor antagonists. The products have been evaluated for their binding affinities for the human A(2B), A(1), A(2A), and A(3) adenosine receptors. N-(4-chloro-phenyl)-2-[3-(2,6-dioxo-1,3-dipropyl-2,3,6,7-tetrahydro-1H-purin-8-yl)-5-methyl-pyrazol-1-yl] (11c) showed a high affinity for the human A(2B) adenosine receptor K(i)=7nM and good selectivity (A(1), A(2A), A(3)/A(2B)>140). Synthesis and SAR of this novel class of compounds is presented herein.     

Synthesis and evaluation of 2-[2-(phenylthiomethyl)-1H-benzo[d] imidazol-1-yl)acetohydrazide derivatives as antitumor agents

A novel class of acetylhydrazone derivatives (5a-x) containing 2-(phenylthiomethyl)-1H-benzo-[d]-imidazole moieties are synthesizer, and their antitumor activities against A549, HCT116, HepG2, PC-9, and A375 were determined by the MTT assay. Among them are N-(2,4-dihydroxybenzylidene)-2-(2-(phenylthiomethyl)-1H-benzo[d]-imidazol-1-yl)acetohydrazide (5a) and N-(5-bromo-2-hydroxy-benzylidene)-2-(2-(phenylthiomethyl)-1H-benzo[d]-imidazol-1-yl)acetohydrazide (5d) which displayed excellent cancer inhibitory activity against the tested cancer cells (IC(50) 4-17 μM), compared with 5-FU and SU11248. The others have moderate to weak inhibitory activity against the tested cancer cell lines.     

Benzimidazol-1-yl-1-phenylpropanone Analogs as Potent Antimicrobial Agents: Rational Design and Synthesis

Designed, synthesized a sequence of novel benzimidazol-1-yl-1-phenylpropanone hybrids and assessed for in vitro antimicrobial potential counter to several bacterial strains. Computational Methodology was carried out for designing of the target molecules and structures were confirmed by spectroscopic analysis. Amid the 12 integrated derivatives, (3-(2-((3-fluorobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6g ) and 3-(2-((4-fluorobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6k ) were found to acquire excellent antibacterial activity against all bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus), whereas derivative 3-(2-((2-fluorobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6c ), was potent against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and displayed moderate action against P. aeruginosa. Derivatives with NO₂ substituent at 3^rd and 4^th position, 3-(2-((3-nitroobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6h ) and 3-(2-((4-nitroobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6 l ) respectively declared good to moderate results against all bacterial strains. Further, 3-(2-((3-chlorobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6f ) and 3-(2-((4-chlorobenzylidene)amino)-1H-benzo[d]imidazol-1-yl)-1-phenylpropan-1-one ( 6j ) were found to be more competent against both fungal strains (C. albicans, A. niger). Serial two-fold dilution method was used for the entire study and standard drugs utilized were ciprofloxacin and clotrimazole. MIC values (μg/ml) of novel synthesized analogs were reported in comparison to standard drugs for antibacterial and antifungal actions. Molecular docking studies showed that designed molecules dynamically bound with effective area of the receptor (DNA gyrase B, Clotrimazole complex of cytochrome P 45046A1) and in vitro results were in accord with in silico studies.     

A novel series of parenteral cephalosporins exhibiting potent activities against both Pseudomonas aeruginosa and other gram-negative pathogens. Part 2: Synthesis and structure-activity relationships

A novel series of 7beta-[2-(2-amino-5-chloro-thiazol-4-yl)-2(Z)-((S)-1-carboxyethoxyimino)acetamido]cephalosporins bearing various pyridinium groups at the C-3' position were synthesized and their in vitro antibacterial activities against gram-negative pathogens including Pseudomonas aeruginosa and several gram-positive pathogens were evaluated. Among the cephalosporins prepared, we found that a cephalosporin bearing the 2-amino-1-(3-methylamino-propyl)-1H-imidazo[4,5-b]pyridinium group at the C-3' position (8a) showed potent and well-balanced antibacterial activities against P. aeruginosa and other gram-negative pathogens including the strains which produce class C beta-lactamase and extended spectrum beta-lactamase (ESBL). Compound 8a also showed efficacious in vivo activity and high stability against AmpC beta-lactamase. These findings indicate that 2-aminoimidazopyridinium having an aminoalkyl group at the 1-position as a C-3' side chain is suitable for cephalosporins bearing an aminochlorothiazolyl moiety and a carboxyethoxyimino moiety on the C-7 side chain.     

Novel azolyl-(phenylmethyl)]aryl/heteroarylamines: potent CYP26 inhibitors and enhancers of all-trans retinoic acid activity in neuroblastoma cells

The synthesis and potent inhibitory activity of novel 4-[(imidazol-1-yl and triazol-1-yl)(phenyl)methyl]aryl-and heteroaryl amines versus a MCF-7 CYP26A1 cell assay is described. Biaryl imidazole ([4-(imidazol-1-yl-phenyl-methyl)-phenyl]-naphthalen-2-yl-amine (8), IC(50)=0.5 microM; [4-(imidazol-1-yl-phenyl-methyl)-phenyl]-indan-5-yl-amine (9), IC(50)=1.0 microM) and heteroaryl imidazole derivatives ((1H-benzoimidazol-2-yl)-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (15), IC(50)=2.5 microM; benzooxazol-2-yl-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (16), IC(50)=0.9 microM; benzothiazol-2-yl-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (17), IC(50)=1.5 microM) were the most potent CYP26 inhibitors. Using a CYP26A1 homology model differences in activity were investigated. Incubation of SH-SY5Y human neuroblastoma cells with the imidazole aryl derivative 8, and the imidazole heteroaryl derivatives 16 and 17 potentiated the atRA-induced expression of CYP26B1. These data suggest that further structure-function studies leading to clinical development are warranted.