Synthesis and Antimicrobial Activity of Some Novel 2‐[4‐(Substituted Piperazin‐/Piperidin‐1‐ylcarbonyl)phenyl]‐1H‐benzimidazole Derivatives

In this study, we report the synthesis and antimicrobial evaluation of several new 4‐(1H‐benzimidazol‐2‐yl)benzamides ( 11 – 30 ) and 5‐chloro‐1‐(p‐fluorobenzyl)‐2‐{4‐[(4‐methylpiperazin‐1‐yl)carbonyl]phenyl}‐1H‐benzimidazole ( 33 ). Compound 20 exhibited the best antibacterial activity with MIC value of 6.25 μg/mL against Staphylococcus aureus and methicillin‐resistant Staphylococcus aureus (MRSA). Significant antifungal activities were obtained with the compounds 13 , 14, 18 , 19, and 33 with MIC values of 3.12 μg/mL which are close to fluconazole.     

Synthesis and Antiproliferative Activitiy of Novel Diaryl Ureas Possessing a 4H‐Pyrido[1,2‐a]pyrimidin‐4‐one Group

We herein disclose a series of novel diaryl urea derivatives possessing a 4H‐pyrido[1,2‐a]pyrimidin‐4‐one group as novel potent anticancer compounds. The structures were confirmed by IR, ¹H‐NMR, and MS. All the compounds were screened for their antiprofilerative activity agaist the human breast cancer cell line (MDA‐MB‐231). The pharmacological results indicated that most of the compounds showed moderate activity. The best of this series is compound 4c (IC₅₀ = 0.7 μmol/L), with a potency 3.6‐fold higher than Sorafenib (IC₅₀ = 2.5 μmol/L), which was approved in 2005.     

Synthesis and antimicrobial activity of new 2‐piperazin‐1‐yl‐N‐1,3‐thiazol‐2‐ylacetamides of cyclopenta[c]pyridines and pyrano[3,4‐c]pyridines

In this study, we report the synthesis and antimicrobial activity of some new disubstituted piperazines. Thus, 3‐chlorocyclopenta[c]pyridines and 6‐chloropyrano[3,4‐c]pyridine 1 under mild reaction conditions with piperazine gave the 3(6)‐piperazine‐substituted cyclopenta[c]pyridines and pyrano[3,4‐c]pyridine 2 . Furthermore, the latter, by alkylation with 2‐chloro‐N‐1,3‐thiazol‐2‐ylacetamide, led to the formation of the target compounds. The evaluation of the antibacterial activity revealed that 3k was the most potent compound. The most sensitive bacterium was found to be Listeria monocytogenes, whereas Staphylococcus aureus was the most resistant one. Three compounds, 3d , 3g , and 3k , were tested also against the following resistant strains: methicillin‐resistant S. aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. All three compounds appeared to be more potent than ampicillin against MRSA. Moreover, compound 3d showed a better activity than the reference drug ampicillin against P. aeruginosa, whereas 3g was more efficient against E. coli. The best antifungal activity was observed again for compound 3k . The most resistant fungi appeared to be Aspergillus fumigatus, whereas Trichoderma viride seemed the most sensitive one toward the compounds tested. Molecular docking studies on E. coli MurB, as well as on Candida albicans CYP51 and dihydrofolate reductase, were used for the prediction of the mechanisms of the antibacterial and antifungal activities, confirming the experimental results.     

Synthesis and Biological Evaluation of [1,2,4]Triazolo[3,4‐a]phthalazine and Tetrazolo[5,1‐a]phthalazine Derivatives Bearing Substituted Benzylpiperazine Moieties as Positive Inotropic Agents

Two series of [1,2,4]triazolo[3,4‐a]phthalazine and tetrazolo[5,1‐a]phthalazine derivatives bearing substituted benzylpiperazine moieties have been synthesized and evaluated for their positive inotropic activity by measuring left atrium stroke volume on isolated rabbit heart preparations. The majority of the derivatives exhibited better in vitro activity than the existing drug, milrinone, and 6‐((4‐(4‐methoxyphenyl)piperazin‐1‐yl)methyl)tetrazolo[5,1‐a]phthalazine. 8 m in particular was identified as the most potent with an increased stroke volume of 12.02 ± 0.20% (milrinone: 2.46 ± 0.07%) at a concentration of 3 × 10^–5 m . The chronotropic effects of the compounds that exhibited good potency were also evaluated.     

Fluorinated 1,2,4‐Triazolo[1,5‐a]pyrimidine‐6‐carboxylic Acid Derivatives as Antimycobacterial Agents

A series of fluorinated 1,2,4‐triazolo[1,5‐a]pyrimidine‐6‐carboxylic acid derivatives was designed and synthesized as fluoroquinolone analogues. The synthesized compounds were screened against Mycobacterium tuberculosis H₃₇R_v strain at 6.25 μg/mL concentration. Compound 4 , the 7‐oxo‐2‐(trifluoromethyl)‐4,7‐dihydro‐1,2,4‐triazolo[5,1‐a]pyrimidine‐6‐carboxylic acid was found to be a very potent inhibitor, being able to inhibit 92% growth of M. tuberculosis H₃₇R_v at 6.25 μg/mL concentration. At the same time, it proofed to be nontoxic to mammalian cells (IC₅₀ > 62.5 μg/mL in VERO cells).     

Synthesis and Anticonvulsant Activity of 5‐Phenyl‐[1,2,4]‐triazolo[4,3‐a]quinolines

A series of novel 5‐phenyl‐[1,2,4]‐triazolo[4,3‐a]quinoline derivatives was synthesized by the cyclization of 2‐chloro‐4‐phenyl‐1,2‐dihydronaphthalene with formohydrazide. The starting material 2‐chloro‐4‐phenyl‐1,2‐dihydronaphthalene was synthesized from ethyl‐3‐oxo‐3‐phenylpropanoate and substituted aniline. Their anticonvulsant activities were evaluated by the maximal electroshock (MES) test and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). The maximal electroshock test showed that 7‐hexyloxy‐5‐phenyl‐[1,2,4]‐triazolo[4,3‐a]quinoline 4f was found to be the most potent compound with an ED₅₀ value of 6.5 mg/kg and a protective index (PI = ED₅₀ / TD₅₀) value of 35.1, which was much higher than the PI of the reference drug phenytoin.     

Synthesis and In‐Vitro Anti‐Hepatitis‐B Virus Activity of 6H‐[1]Benzothiopyrano[4,3‐b] quinolin‐10‐ols

A series of 9‐methoxy‐6H‐[1]benzothiopyrano[4,3‐b]quinolin‐10‐ols with a Mannich side chain were synthesized and evaluated for their anti‐Hepatitis B virus (HBV) activity in HepG2.2.15 cells. Some compounds showed significant anti‐HBV activity with IC₅₀ values less than 41 μM. Among them, compound 9b was the most effective anti‐HBV agent (IC₅₀ = 1.7 μM, SI = 60.3).     

Synthesis and Anticonvulsant Activity of 6‐Alkoxy‐[1,2,4]Triazolo[3,4‐a]Phthalazines

A new series of 6‐alkoxy‐[1,2,4]triazolo[3,4‐a]phthalazines ( 3a – 3v ) were synthesized and their anticonvulsant activity and neurotoxicity were evaluated by the maximal electroshock test and the rotarod test respectively. Significant anticonvulsant activity was displayed by a number of compounds. The most promising compounds 6‐(4‐chlorobenzyloxy)‐[1,2,4]triazolo[3,4‐a]phthalazine ( 3f) and 6‐heptyloxy‐[1,2,4]triazolo[3,4‐a]phthalazine ( 3s) showed a median effective dose of 7.1 and 11.0 mg/kg, and had protective index value of 5.2 and 8.0 respectively. The two compounds were further found to have potent activity against seizures induced by pentylenetetrazole, isoniazid, thiosemicarbazide, 3‐mercaptopropionic acid but not seizures induced by strychnine, indicating that the two compounds might function by enhancing gamma‐aminobutyric acid neurotransmission.     

New insights into the mechanism of action of pyrazolo[1,2‐a]benzo[1,2,3,4]tetrazin‐3‐one derivatives endowed with anticancer potential

Due to the scarce biological profile, the pyrazolo[1,2‐a]benzo[1,2,3,4]tetrazine‐3‐one scaffold (PBT) has been recently explored as promising core for potential anticancer candidates. Several suitably decorated derivatives (PBTs) exhibited antiproliferative activity in the low‐micromolar range associated with apoptosis induction and cell cycle arrest on S phase. Herein, we selected the most active derivatives and submitted them to further biological explorations to deepen the mechanism of action. At first, a DNA targeting is approached by means of flow Linear Dichroism experiments so as to evaluate how small planar molecules might interact with DNA, including the interference with the catalytic cycle of topoisomerase II and the influence on the cleavable complex stabilization (poisoning effect). In support of the experimental data, in silico studies have been achieved to better understand the chemical space of the interactions. Interestingly some meaningful structural features, useful for further developments, were found. The 8,9‐di‐Cl substituted derivative revealed as the most effective in the intercalative process, as well as on the inhibition of catalytic activity of topoisomerase II. Predicted ADME studies confirm that PBTs are promising as potential drug candidates.     

Anti‐anxiety and sedative profile evaluation of imidazo[1,2‐a]pyridine derivatives

Three imidazo[1,2‐a]pyridine‐3‐nitrosated (L‐1, L‐2, L‐3) and a 3‐formyl imidazo[1,2‐a]pyridine thiosemicarbazone (L‐4) were synthesized and evaluated for their effects in the elevated plus maze, burying behavior test, rotarod performance, the horizontal wire test, and locomotor activity. L‐2 and L‐3 increased the percent time spent in the open arms of the plus maze at doses of 1 and 2 mg/kg without modifying the number of total entries. In addition, L‐2 and L‐3 (1 mg/kg) increased the number of open arm entries indicating anxiolytic‐like activity at this dose. In the burying behavioral test, L‐1 (2–8 mg/kg), L‐2 (8 mg/kg), and L‐3 (4 and 8 mg/kg), induced a clear reduction in cumulative burying behavior, without modifying burying behavior latency, thus reducing experimental anxiety. In the rotarod test, L‐1 and L‐2 impaired rotarod performance only at the highest evaluated dose (64 mg/kg) at which reduction of motor activity was observed and thereby no conclusions about myorelaxant effects can be proposed. All compounds showed a clear sedative effect and corresponding ED₅₀ values were obtained. Results indicate that compounds L‐1, L‐2, and L‐3 show a sedative and an anxiolytic profile. Drug Dev Res 71:371–381, 2010. © 2010 Wiley‐Liss, Inc.     

Synthesis and Positive Inotropic Evaluation of 2‐(4‐(4‐Substituted benzyloxy)‐3‐methoxybenzyl)‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐methyl[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)‐acetamides

In an attempt to search for more potent positive inotropic agents, a series of 2‐(4‐(4‐substituted benzyloxy)‐3‐methoxybenzyl)‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐methyl[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamides was synthesized and their positive inotropic activities were evaluated by measuring left atrium stroke volume on isolated rabbit‐heart preparations. Several compounds showed favorable activity compared with the standard drug Milrinone among which 2‐(4‐(4‐(2‐chlorobenzyloxy)‐3‐methoxybenzyl)‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐methyl‐[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamide 6e was found to have the most desirable potency with the 6.79 ± 0.18% increased stroke volume (Milrinone: 1.67 ± 0.64%) at a concentration of 1×10^–5 M in our in‐vitro study. The chronotropic effects of those compounds having inotropic effects were also evaluated in this work.     

Synthesis of New N‐Substituted 5‐Arylidene‐2,4‐thiazolidinediones as Anti‐Inflammatory and Antimicrobial Agents

A novel series of 5‐arylidene ‐ 2,4‐thiazolidinediones (TZDs) 2a – p was synthesized from the condensation of 3‐((2‐phenylthiazol‐4‐yl)methyl)thiazolidine‐2,4‐dione with different benzaldehyde derivatives. All the structures were confirmed by their spectral (IR, ¹H NMR, ¹³C NMR and mass) and elemental analytical data. The new molecules were evaluated in vivo as anti‐inflammatory agents in an acute experimental inflammation, evaluating the acute phase bone marrow response and phagocyte activity. All compounds, excepting one, reduced the absolute leukocytes count due to the lower neutrophil percentage. Phagocytary index was decreased by the same molecules, while only half of them reduced the phagocytary activity. The effect was superior to meloxicam, the reference anti‐inflammatory drug, for the majority of the TZD derivatives. The new molecules were also investigated for their antimicrobial properties on Gram‐positive and Gram‐negative bacteria and one fungal strain. Two compounds ( 2e and 2n ) manifested growth inhibition capacity on all the tested strains.     

Design,synthesis, and in vitro antituberculosis activity of benzo[6,7]cyclohepta[1,2‐b]pyridine‐1,3,4‐oxadiazole derivatives

A new antitubercular agents, benzo[6,7]cyclohepta[1,2‐b]pyridine‐1,3,4‐ oxadiazole hybrids ( 6a–o ), have been designed and synthesized involving oxidative cyclization of hydrazones by use of di(acetoxy)iodobenzene, characterized by IR,¹H NMR,¹³C NMR, and HRMS, and further confirmed by X‐ray analysis. All the newly synthesized compounds 4a–o evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (ATCC27294). Among the compounds tested, the compounds 4o (MIC: 1.56  μg/ml) and 4l, 4m (MIC: 3.125  μg/ml) are promising lead analogues and have shown lower cytotoxicity.     

Inhibitory action of naphtho[1,2‐b]furan‐4,5‐dione on hepatocyte growth factor‐induced migration and invasion of MDA‐MB‐231 cells: Mechanisms of action

Naphtho[1,2‐b]furan‐4,5‐dione (NFD), a bioactive component of Avicennia marina, has been shown to exhibit anticancer activity. The aim of the present study was to explore the effect of NFD on hepatocyte growth factor (HGF)‐induced cell migration and invasion of MDA‐MB‐231 human breast cancer cells, as well as the underlying mechanism of action. Cell viability was determined using the 3‐(4,5‐dimethyl‐2 thiazoyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide assay, western blot analysis was used to measure protein expression and cell migration and invasion were evaluated by the cell wound healing assay, Boyden chamber assay and gelatin zymography. When cells were treated with non‐toxic concentrations of NFD (1–3 μmol/L, 24 h), NFD concentration‐dependently inhibited HGF‐promoted cell migration and invasion. Simultaneously, NFD efficiently suppressed c‐Met phosphorylation and downstream activation of phosphatidylinositol 3‐kinase (PI3K) and Akt. In addition, NFD inhibited the phosphorylation of IκB kinases and IκBα and nuclear translocation of nuclear factor (NF)‐κB, as well as matrix metalloproteinase (MMP)‐9 activity. Furthermore, the c‐Met inhibitor PHA665752 (10 μmol/L) inhibited HGF‐induced MMP‐9 expression, cell migration and invasion, as well as the activation of PI3K/Akt, suggesting that PI3K/Akt activation occur downstream of c‐Met activation. In conclusion, the results of the present study suggest that NFD inhibits HGF‐induced invasion and migration of MDA‐MB‐231 cells via HGF‐ and/or c‐Met‐mediated PI3K/Akt and NF‐κB signalling pathways, leading to downregulation of MMP‐9 expression and cell migration.     

Synthesis and in-vitro anti-hepatitis B virus activity of ethyl 6-bromo-8-hydroxyimidazo[1,2-a]pyridine-3-carboxylates

A series of ethyl 6‐bromo‐8‐hydroxyimidazo[1,2‐a]pyridine‐3‐carboxylate derivatives were synthesized and evaluated for their anti‐hepatitis B virus (HBV) activity and cytotoxicity in HepG2.2.15 cells. Nearly half of the tested compounds were proved to be highly effective in inhibiting the replication of HBV DNA with IC₅₀ values ranging from 1.3 to 9.1 µM. Among them, 10o and 10s were identified as the most promising compounds.