Synthesis and screening for antiacetylcholinesterase activity of (1-benzyl-4-oxopiperidin-3-ylidene)methylindoles and -pyrroles related to donepezil

The design, synthesis, and rapid evaluation of a new class of acetylcholinesterase (AChE) inhibitors related to donepezil are reported. A molecular dynamics simulation of the complex between AChE and one representative compound of the series showed a possible inhibitor binding mode in which favorable interactions are formed between the benzylpiperidinone moiety and some active-site residues. The biochemical evaluation of this newly synthesized series was performed using a chemiluminescent method suitable for high-throughput screening.

Synthesis and antitubercular activity of imidazo[2,1-b]thiazoles

A number of selected imidazo[2,1-b]thiazoles entered the screening at the Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF) and one of these compounds, 2-chloro-6-phenylimidazo[2,1-b]thiazole, showed antitubercular activity. On this basis we planned the synthesis of new analogues bearing a substituted ring at the 6 position. For one compound only (2-chloro-6-p-chlorophenylimidazo[2,1-b]thiazole) the 5-nitroso derivative was also prepared. The antitubercular activity of these compounds was compared with the known analogues lacking the chlorine at the 2 position. 5-Nitroso-6-p-chlorophenylimidazo[2,1-b]thiazole showed potent antitubercular activity.

Synthesis and antitumor activity of substituted 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones

The synthesis of 3-(5-imidazo]2,1-blthiazolylmethylene)-2-indolinones, analogs of compounds recently published, is described. The EIZ isomerism was studied by means of nuclear Overhauser effect experiments and X-ray crystallography. All the compounds were tested as potential antitumor agents. They were also tested as potential inhibitors of cyclin-dependent kinase 1 (CDK1), in order to determine if the antitumor activity was related to this mechanism of action. The results showed that under certain substitution conditions (5-methoxy group for the indole benzene ring and 2-methyl group for the imidazothiazole system), an interesting antitumor activity was found for some compounds. From the analysis of the antitumor data, 3-1(2,6-dimethylimidazo[2,1-bJ-thiazol-5-yl)methylenel-5-methoxy-2-indolinone was the most active of the whole series.

Imidazo[2,1 -b]thiazolylmethylene- and indolylmethylene-2-indolinones: a new class of cyclin-dependent kinase inhibitors. Design, synthesis, and CDK1/cyclin B inhibition

Compounds containing a 2-indolinone moiety linked to imidazothiazole and indole fragments were studied as cyclin-dependent kinase inhibitors. The activity of all the new derivatives was tested in vitro against CDK1/cyclinB and the selectivity towards two other kinases was determined for the most promising compounds. The binding mode of one representative compound was investigated by means of a three-dimensional model of the inhibitor-CDK1 complex. The work allowed us to identify (2-chloroindolyl)methylene-2-indolinone as a new lead of a class of CDK1/cyclinB inhibitors, whose potency can be improved by the introduction of suitable variations on the basic molecular skeleton.

Potential antitumor agents. Part 29(1): synthesis and potential coanthracyclinic activity of imidazo[2,1-b]thiazole guanylhydrazones

This paper reports the synthesis of new imidazo[2,1-b]thiazole guanylhydrazones which were tested as potential antitumor agents. Three of these derivatives (those bearing a 3- or 4-nitrophenyl group) were the most potent and one of these showed a mild effect as CDK1 inhibitor. These same three derivatives were also tested as positive inotropic agents and two of them were more potent than amrinone at 10(-5) M. These two guanylhydrazones could be useful coanthracyclinic agents.

Synthesis and antisecretory activity of 6-substituted 5-cyanomethylimidazo[2,1-b]thiazoles and 2,6-dimethyl-5-hydroxymethylimidazo[2,1-b][1,3,4]thiadiazole

The synthesis of imidazo[2,1-b]thiazole and imidazo[2,1-b][1,3,4]thiadiazole derivatives, related to known antiulcer agents, is reported. 5-Cyanomethyl-6-methylimidazo[2,1-b]thiazole showed significant antisecretory activity in the isolated rabbit gastric glands assay.

4-Aminopyridine derivatives with antiamnesic activity

Acetylcholine (Ach) enhancement, useful in the treatment of Alzheimer's disease (AD), may be obtained by means of ion channel modulators such as 4-aminopyridine (4-AP). 4-AP is also the central ring of tacrine, the first drug approved for the treatment of AD. The synthesis and pharmacological activity of three 4-AP derivatives, prepared with the aim of improving their antiamnesic activity, is here described. In two of these compounds 4-AP is connected to 4-aminobutyric acid (GABA), whereas in the third it is connected to 2-indolinone, i.e., the skeleton of linopirdine, another Ach enhancing agent. The new compounds showed potent antiamnesic activity in comparison with piracetam.

Potential coanthracyclinic activity of pyridylmethylene-2-indolinones

The paper reports the cytotoxic activity of pyridylmethylene-2-indolinones previously described as cardiotonics and the synthesis of three analogs of the most potent cytotoxic agent. Some of these compounds could be useful, when associated with anthracyclines, to reduce the cardiotoxicity of these potent antitumor drugs.

In vivo cardiotonic activity of pyridylmethylene-2-indolinones

The synthesis of 5-chloro-3-pyridylmethylene-2-indolinone is reported. This compound was subjected to an in vivo cardiotonic assay with 10 analogs whose synthesis and in vitro cardiotonic activity were previously reported. All the compounds tested (except the 5-hydroxyindole derivative) showed significant positive inotropic activity. The 3-pyridyl derivative without substituents at the indole system was the most active of the whole series.

In vivo cardiotonic activity of aryl- and pyridyl-substituted fused imidazoles

Two new imidazo[2,1-b]thiazoles related to sulmazole were synthesized and subjected to an in vivo cardiotonic assay with 14 analog compounds which gave the best results in previously reported in vitro tests. The data obtained show that three substituents (3-pyridyl, 4-pyridyl and 2,5-dimethoxyphenyl group) are useful pharmacophoric groups in modulating the in vivo cardiotonic activity of the fused imidazoles considered.