4-Thiazolidinone Derivatives as MMP Inhibitors in Tissue Damage: Synthesis, Biological Evaluation and Docking Studies.

Nine 2-(1,2-benzothiazol-3-yl)-N-(4-oxo-2-phenyl-1,3-thiazolidin-3-yl)propanamides combining a benzisothiazole and 4-thiazolidinone in one framework were designed and synthesized. The aim of the study was to verify their effectiveness to affect the inflammatory/oxidative process in which free oxygen and nitrite (ROS and RNS) radicals, inflammatory mediators, such as nuclear factor κB (NF-κB), and matrix metalloproteinases (MMPs) are involved. Docking studies of all the compounds were performed in order to explore their binding mode at the MMP-9 protein. An appreciable anti-inflammatory/potential wound healing effects of the tested compounds was highlighted. Derivative 23, bearing a 4-carboxyphenyl substituent at C2 of the 4-thiazolidinone ring, exhibited the highest activity, being able to inhibit MMP-9 at nanomolar level(IC50 = 40 nM).

Exploiting Free-Energy Minima to Design Novel EphA2 Protein-Protein Antagonists: From Simulation to Experiment and Return.

The free-energy surface (FES) of protein-ligand binding contains information useful for drug design. Here we show how to exploit a free-energy minimum of a protein-ligand complex identified by metadynamics simulations to design a new EphA2 antagonist with improved inhibitory potency.

2-Benzisothiazolylimino-5-benzylidene-4-thiazolidinones as protective agents against cartilage destruction.

We report the synthesis, the antioxidant and the inhibitory activity (IC50) on metalloproteinases (MMPs) 3 and 13 of 2-benzo[d]isothiazolylimino-5-benzylidene-4-thiazolidinones. Their potential as protective agents in osteoarthritis (OA) was evaluated by biological assays on chondrocytes cultures, stimulated by IL-1ß. The chondroprotective capability, related both to antioxidant activity and to inhibition of MMPs, was studied in vitro, by determining nitric oxide production and glycosaminoglycans release. Moreover, selected derivatives 1h and 1g was studied for nuclear factor kappaB (NF-κB) inhibition by Western Blot analysis and for MMP-3 protein release using ELISA test. The structure-activity relationship of tested compounds demonstrates a favorable effect of the para substitution on the 5-benzilydene ring. Compound 1g shows a potent and selective activity on MMP-3 versus MMP-13. Accordingly, 1g possesses high antioxidant effect, NO lowering and GAGs restoring capability and also reduces the production of MMPs and NF-κB expression. Thus 1g can be considered as new potential chondroprotective agents.

Design synthesis and antibacterial activity studies of new thiadiazoloquinolone compounds.

Abstract New 9-(alkyl/aryl)-4-fluoro-6-oxo[1,2,5]thiadiazolo[3,4-h]quinoline-5-carboxylic acids and their esters were designed and synthesized. A detailed discussion of the reactions utilized in the preparation of the intermediate and target compounds is reported. All the newly synthesized compounds were fully characterized using all the physico-chemical means needed. All the intermediates and the final esters and acids were tested against bacterial and fungal strains. The acids 25a and 25c proved to be very active against Gram positive and Gram negative bacteria with MIC 0.15-3 µg/mL. The structure-activity relationship of antibacterial thiadiazoloquinolones shows that compounds 25a and 25c are twice less potent than the corresponding cyclopropyl derivative 16. Therefore, the cyclopropyl moiety on N-9 seems to be the most suitable substituent.

Synthesis and structure-activity relationships of amino acid conjugates of cholanic acid as antagonists of the EphA2 receptor.

The Eph-ephrin system plays a critical role in tumor growth and vascular functions during carcinogenesis. We had previously identified cholanic acid as a competitive and reversible EphA2 antagonist able to disrupt EphA2-ephrinA1 interaction and to inhibit EphA2 activation in prostate cancer cells. Herein, we report the synthesis and biological evaluation of a set of cholanic acid derivatives obtained by conjugation of its carboxyl group with a panel of naturally occurring amino acids with the aim to improve EphA2 receptor inhibition. Structure-activity relationships indicate that conjugation of cholanic acid with linear amino acids of small size leads to effective EphA2 antagonists whereas the introduction of aromatic amino acids reduces the potency in displacement studies. The b-alanine derivative 4 was able to disrupt EphA2-ephrinA1 interaction in the micromolar range and to dose-dependently inhibit EphA2 activation on PC3 cells. These findings may help the design of novel EphA2 antagonists active on cancer cell lines.

Synthesis and biological evaluation of tetracyclic thienopyridones as antibacterial and antitumor agents.

A facile synthesis of model 4-oxopyrido[3',2':4,5]thieno[3,2-b]indole-3-carboxylic acids 9a-e was achieved via Stille arylation of 2-chloro-3-nitro-4-oxothieno[2,3-b]pyridine-5-carboxylate and a subsequent microwave-assisted phosphite-mediated Cadogan reaction. The new compounds were tested for their in vitro antimicrobial and antiproliferative activity. Compounds 9a-c and 9e exhibited very high potency against Gram positive Bacillus subtilis and Bacillus megaterium at concentrations 0.000015-0.007 µg/mL. They also displayed excellent activity towards other Gram positive bacilli and staphylococci and Gram negative Haemophilus influenzae, being in most cases superior or equal to commercial fluoroquinolones. Both 9a and 9c were inhibitors of the DNA gyrase activity. As concerns antitumor properties, compounds 9b-e showed growth inhibition of MCF-7 breast tumor and A549 non-small cell lung cancer cells with IC(50) 1.6-2.8 µM and 2.6-6.9 µM, respectively, coupled with absence of cytotoxicity towards normal cells. These compounds are promising as dual acting chemotherapeutics.

Heteroarylimino-4-thiazolidinones as inhibitors of cartilage degradation.

2-Benzo[d]thiazolyl- and 2-benzo[d]isothiazolyl-imino-5-benzylidene-4-thiazolidinone derivatives were investigated as potential metalloproteinases (MMPs) inhibitors and evaluated for their antidegenerative activity on human chondrocyte cultures stimulated by IL-1ß, using an experimental model that reproduces the mechanisms involved in osteoarthritic (OA) diseases. Cell viability, the amount of glycosaminoglycans (GAGs) and the production of nitric oxide (NO) were measured. The most potent compound, 5-(4-methoxy-benzylidene)-2-(benzo[d]isothiazol-3-ylimino)-thiazolidin-4-one (4b), a MMP-13 inhibitor at nanomolar concentration (IC(50)=0.036 µM), could be considered as a lead compound for the development of novel clinical agents, inhibitors of cartilage degradation, for the treatment of OA.

Synthesis and biological evaluation of tetracyclic fluoroquinolones as antibacterial and anticancer agents.

A simple and efficient synthesis of 6-fluoro-4-oxopyrido[2,3-a]carbazole-3-carboxylic acids (13a-e) and a structurally related 6-fluoro-4-oxothieno[2',3':4,5]pyrrolo[3,2-h]quinoline (13f) was achieved via Stille arylation of 7-chloro-6-fluoro-8-nitro-4-oxoquinoline-3-carboxylate and a subsequent microwave-assisted phosphite-mediated Cadogan reaction. The new compounds were tested for their in vitro antimicrobial and antiproliferative activity. The ability of 13a-f to inhibit the activity of DNA gyrase and topoisomerase IV was also investigated. The thieno isostere (13f) emerged as the most active antibacterial, while the 9-fluoro derivative (13e) was the most potent against multidrug-resistant staphylococci. Compounds 13a, 13c-f displayed growth inhibition against MCF-7 breast tumor and A549 non-small cell lung cancer cells coupled with an absence of cytotoxicity toward normal human-derm fibroblasts (HuDe). Compound 13e was the most active anticancer against MCF-7 cells, with greater potency than ellipticine (IC(50) 0.8 and 1.6muM, respectively). The most active compounds in this series show promise as dual acting anticancer and antibacterial chemotherapeutics.

4-Chloro-N-(4-chloro-phenyl-sulfon-yl)-N-(3-oxo-2,3-dihydro-1,2-benzisothia-zol-2-yl)benzene-sulfonamide.

In the title compound, C(19)H(12)Cl(2)N(2)O(5)S(3), the benzene rings of the chloro-phenyl-sulfonyl groups form a dihedral angle of 35.85 (8)° and are inclined at angles of 23.51 (6) and 59.22 (6)° with respect to the essentially planar benzisothia-zole ring system [maximum deviation = 0.030 (2) Å]. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯O hydrogen bond. In the crystal packing, mol-ecules are linked into chains parallel to the a axis by inter-molecular C-H⋯O hydrogen bonds and π-π stacking inter-actions, with centroid-centroid distances of 3.592 (5) Å.

4-Methyl-N-(3-oxo-2,3-dihydro-1,2-benzisothia-zol-2-yl)benzene-sulfonamide.

In the title mol-ecule, C(14)H(12)N(2)O(3)S(2), the benzisothia-zolone ring system is essentially planar and forms a dihedral angle of 67.37 (6)° with the plane of the benzene ring. In the crystal structure, mol-ecules are linked via inter-molecular N-H⋯O and C-H⋯O hydrogen bonds to form chains parallel to the b axis.

2-Heteroarylimino-5-benzylidene-4-thiazolidinones analogues of 2-thiazolylimino-5-benzylidene-4-thiazolidinones with antimicrobial activity: synthesis and structure-activity relationship.

2-Heteroarylimino-5-benzylidene-4-thiazolidinones, unsubstituted or carrying hydroxy, methoxy, nitro and chloro groups on the benzene ring, were synthesised and assayed in vitro for their antimicrobial activity against gram positive and gram negative bacteria, yeasts and mould. The antimicrobial activity of the 2-benzo[d]thiazolyl- and of the 2-benzo[d]isothiazolyl-imino-5-benzylidene-4-thiazolidinones is, on the whole, lower in comparison with the high activity detected for the derivatives of the 2-thiazolylimino-5-benzylidene-4-thiazolidinone class. Nevertheless most of the benzo[d]thiazole analogues display good inhibition of the growth of gram positive bacilli and staphylococci, including methicillin-resistant Staphylococcus strains. Among the 2-benzo[d]isothiazole analogues a few derivatives show a strong and selective activity against bacilli. Moreover, it is worth noting that the replacement of the thiazole nucleus for the benzo[d]thiazole bicyclic system in the parent 2-(benzo[d]thiazol-2-ylimino)thiazolidin-4-one leads to significant antifungal properties against both yeasts and moulds, properties not shown by the analogous 2-thiazolyl- and 2-benzo[d]isothiazolyl-imino)thiazolidin-4-ones. The structure-activity relationship of 33 analogues possessing the 2-heteroarylimino-4-thiazolidinone structure is analysed through QSAR models.

Complete 1H and 13C NMR spectral assignment of benzo[d]isothiazole derivatives and of an isoindole isoster.

The complete (1)H and (13)C NMR assignments of the novel compound methyl 2-amino-3-(benzo[d]isothiazol-3-yl)propanoate (1), of 3-amino-5-methylbenzo[d]isothiazole (2) and N-(t-butyloxycarbonyl)-2-aminobenzo[d]isothiazol-3(2H)-one (3) and of the desulfurated isostere of 3, N-(t-butyloxycarbonyl)-2-aminoisoindolin-1-one (4), using 1D and 2D NMR techniques, including COSY, INADEQUATE, HSQC, and HMBC experiments are reported.

New N-(2-phenyl-4-oxo-1,3-thiazolidin-3-yl)-1,2-benzothiazole-3-carboxamides and acetamides as antimicrobial agents.

A series of 21 novel N-[2-phenyl-4-oxo-1,3-thiazolidin-3-yl]-1,2-benzothiazole-3-carboxamides/acetamides (4a-4p) as well as a series of N'-(halophenylmethylidene)-1,2-benzothiazole-3-acetohydrazides (3h-3p) have been synthesized and evaluated for their antimicrobial activity against eight bacterial and eight fungal species, among them plant, animal and human pathogens and food contaminating species. All compounds appeared to be potent and the best activity was exhibited by compound 4d with MIC in the range of 10.7-21.4 µmol mL-1 × 10-2 and MBC of 21.4-40.2 µmol mL-1 × 10-2. The best antifungal activity was observed for compounds 4p and 3h. Elucidation of the relationship between the antimicrobial activity and molecular properties of the synthesized compounds was also performed. Synthetic intermediates were also tested with several exhibiting good antimicrobial activities. Docking studies for some compounds were performed.

Metadynamics for Perspective Drug Design: Computationally Driven Synthesis of New Protein-Protein Interaction Inhibitors Targeting the EphA2 Receptor.

Metadynamics (META-D) is emerging as a powerful method for the computation of the multidimensional free-energy surface (FES) describing the protein-ligand binding process. Herein, the FES of unbinding of the antagonist N-(3α-hydroxy-5ß-cholan-24-oyl)-l-ß-homotryptophan (UniPR129) from its EphA2 receptor was reconstructed by META-D simulations. The characterization of the free-energy minima identified on this FES proposes a binding mode fully consistent with previously reported and new structure-activity relationship data. To validate this binding mode, new N-(3α-hydroxy-5ß-cholan-24-oyl)-l-ß-homotryptophan derivatives were designed, synthesized, and tested for their ability to displace ephrin-A1 from the EphA2 receptor. Among them, two antagonists, namely compounds 21 and 22, displayed high affinity versus the EphA2 receptor and resulted endowed with better physicochemical and pharmacokinetic properties than the parent compound. These findings highlight the importance of free-energy calculations in drug design, confirming that META-D simulations can be used to successfully design novel bioactive compounds.

Synthesis and antiproliferative activity of benzo[d]isothiazole hydrazones.

Several benzo[d]isothiazole hydrazones have been evaluated for their potential antiretroviral activity. Since a number of these compounds were found to be inactive against viruses, but showed cytotoxicity at micromolar concentrations against the human CD4+ lymphocytes (MT-4) that were used to support HIV-1 growth, they were further tested for antiproliferative activity. The compounds resulted as being cytotoxic for MT-4 cells and new derivatives which were rationally designed and synthesized, were tested for antiproliferative activity against several leukaemia and solid tumour cell lines. In addition, these compounds were evaluated against "normal" cell lines. Compound 2h proved to be the most active compound and the fragment -CO-NH-N=CH-2-hydroxyphenyl was identified as being very important for biological activity, suggesting intramolecular hydrogen bond formation or favourable mutual disposition between two important centres in the pharmacophore. 1H-NMR spectra have been explained with the support of a conformational analysis.

Synthesis and antimicrobial properties of 2-(benzylidene-amino)-benzo[d]isothiazol-3-ones.

The in vitro antimicrobial activity of 2-amino-benzo[d]isothiazol-3-one and of several 2-arylideneamino derivatives carrying in the second position a substituted or unsubstituted aromatic ring or an arylalkenylidene moiety was determined by the broth dilution method against several strains selected to define their spectrum and potency. All the compounds demonstrated good antibacterial properties against Bacillus subtilis, streptococci, enterococci and staphylococci including penicillin-resistant clinical isolates. Several compounds showed excellent inhibitory properties against Streptococcus pyogenes, which is the most sensitive microorganism tested. Many benzisothiazolones exhibited good activity against Gram-negative Haemophilus influenzae. As regards antifungal activity, several of the tested compounds inhibited Saccharomyces cerevisiae at concentrations of 3-6 microg ml-1. In all cases the parent 2-amino-benzo[d]isothiazol-3-one was the most effective agent, with minimum inhibitory concentration (MIC) values ranging from 0.07 to 6 microg ml-1. The results obtained indicate that most of these compounds are wide-spectrum antimicrobial substances and promising agents against penicillin-resistant staphylococci.

Hydrazones of 1,2-benzisothiazole hydrazides: synthesis, antimicrobial activity and QSAR investigations.

A series of hydrazones of 1,2-benzisothiazole hydrazides 1a-m, 2a-m, 3a-m, 4a-m, 5a-m as well as their cyclic (1 and 4) and acyclic (2, 3 and 5) 1,2-benzisothiazole parent hydrazides, were synthesised and evaluated as antibacterial and antifungal agents. All of the 2-amino-1,2-benzisothiazol-3(2H)-one derivatives, belonging to series I and IV, showed a good antibacterial activity against Gram positive bacteria. Most of them were active against yeasts too. Compounds 1 and 4, together with 1l, proved to be the most effective compounds. Quantitative structure-activity relationship (QSAR) investigation with a 2D-QSAR analysis was applied to find a correlation between different experimental or calculated physicochemical parameters of the compounds studied. A 3D-QSAR study was performed, applying Comparative Molecular Similarity Indices Analysis (CoMSIA) method, to derive quantitative models relating the structural features of 1,2-benzisothiazole derivatives 1, 1a-m and 4, 4a-m and their antimicrobial activity against Bacillus subtilis, resulted the most sensitive micro-organism.

Amidinobenzisothiazole derivatives with antidegenerative activity on cartilage.

N-(Benzo[d]isothiazol-3-yl)amidines were synthesised and evaluated for their antiinflammatory activity. Encouraging results led us to evaluate these derivatives on the prevention of cartilage destruction in articular disease. Antidegenerative activity was assayed on culture of porcine nasal cartilage and diarthroidal joint human cartilage in the presence of interleukin-1beta (IL-1beta). The amount of glycosaminoglycans (GAGs) and the production of nitric oxide (NO) in the culture medium were determined. The obtained results showed that all the compounds, in the presence of IL-beta, blocked the cartilage breakdown, with different behaviour. The antidegenerative activity is more evident in human cartilage.

Synthesis and pharmacological properties of benzisothiazole/benzimidazole derivatives with acidic groups.

The synthesis and the pharmacological evaluation of benzisothiazole and benzimidazole tetrazolyl- and carboxyl- derivatives 1-6 are described. Structural modification was aimed at investigating the influence of two isosteric substituents (tetrazolyl- and carboxyl-) on the title benzofused heterocycles. The antiphlogistic, antipyretic and analgesic activities have been investigated in in vivo experimental models. Additional investigations have been performed in vitro to study the antiplatelet and spasmolytic activity of the compounds synthetized. All the compounds produced peripheral analgesic effects, but were less effective in hot plate test. The tetrazole and the carboxylic benzisothiazole derivatives 2 and 3 proved to be the most effective drugs within the series, exhibiting maximal inhibition of writhes with a potency 3-fold higher than that of acetaminophen. Only compound 5 provided indication for a central analgesic activity since it was active in hot plate test although with a low potency. The findings obtained in these in vivo and in vitro studies indicate that these compounds do not share the same mechanism of action of acetaminophen. All of the compounds under study present lower acute toxicity than acetaminophen when orally administered in mice.

A new efficient route to 7-aryl-6-fluoro-8-nitroquinolones as potent antibacterial agents.

A series of 7-aryl-6-fluoro-8-nitroquinolones (6a-e) were synthesized through a novel, simple and clean synthetic procedure, through a Suzuki-Miyaura reaction. The target compounds were evaluated in vitro for their antimicrobial properties against bacterial and fungal strains. All of them showed antibacterial activity higher than the activity of ciprofloxacin, both towards Gram positive Bacillus subtilis and Staphylococcus aureus, and Gram negative Haemophilus influenzae strains. Compound 6d, containing the trisubstituted 7-aryl moiety, emerged as the most active quinolone derivative with MIC values ranging from 0.00007 µg/mL to 0.015 µg/mL.