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Biomedical subjects

Maurizio Botta

Publications and source records attributed to Maurizio Botta.

At least 19 recordsLinked to original sources
PubMed2007

Pyrazolo-pyrimidine-derived c-Src inhibitor reduces angiogenesis and survival of squamous carcinoma cells by suppressing vascular endothelial growth factor production and signaling.

Src tyrosine kinase family cooperates with activated growth factor receptors to regulate growth, invasion and metastasis. The authors examined the influence of a novel c-Src inhibitor, 1l, derived from 4-amino-substituted-pyrazolo-pyrimidines, on tumor angiogenesis and on the angiogenic output of squamous carcinoma cells, A431 and SCC-4. The effect of 1l was assessed on growth and microvessel density in A431 tumors and its effect compared with the established c-Src inhibitor PP-1. The effects of c-Src inhibition were investigated on vascular endothelial growth factor (VEGF) expression and activity in tumor cells grown in vivo and in vitro, as well as on VEGF mediated signaling and on endothelial cell functions. Nanomolar concentrations of 1l decreased tumor volume promoted by A431 implanted in nude mice, without affecting in vitro cell tumor survival. This effect was related to 1l inhibition of VEGF production, and secondary to an effect on tumor microvessel density. The rabbit cornea assay confirmed that 1l markedly decreased neovessel growth induced by VEGF. In cultured endothelial cells, 1l inhibited the VEGF-induced phosphorylation on tyr416 of c-Src, resulting in a reduced cell proliferation and invasion. Consistently, 1l dowregulated endothelial nitric oxide synthase, MAPK-extracellular receptor kinase 1-2 (ERK1-2) activity and matrix metalloproteinases (MMP-2/MMP-9), while the tissue inhibitors of metalloproteinases (TIMP2/TIMP-1) were upregulated. These results demonstrate that nM concentrations of c-Src kinase inhibitors (1l and PP-1), by reducing the production of VEGF released by tumor cell and its endothelial cell responses, have a highly selective antiangiogenesis effect, which might be useful in combination therapies.

Animals↗
PubMed2006

Analysis of guazatine mixture by LC and LC-MS and antimycotic activity determination of principal components.

Guazatine is a non-systemic contact fungicide, a mixture of reaction products from polyamines, comprising mainly octa-methylenediamine, iminodi(octamethylene)diamine, octamethylenebis(imino-octamethylene) diamine and carbamonitrile. In this work, the analysis of guazatine mixture by LC and LC-MS has been treated for the first time. In the guazatine mixture diamine derivatives account for 40% of the constituents of guazatine, triamines for 46%, tetramines for 11% and other amine derivatives for 3%. The most abundant individual components are the fully guanidated triamine (GGG, 30.6%) and the fully guanidated diamine (GG, 29.5%) followed by the monoguanidated diamine (GN, 9.8%) and a diguanidated triamine (GGN, 8.1%). The identification and separation of main components of commercial guazatine was performed through a new LC-MS method. The separation was performed on an Alltima C(18) column using linear gradient elution (formic acid in water and acetonitrile) with UV-detection at 200 nm and the identification was performed by ESI(+)-mass spectrometry analysis. The main components (GN, GG, GNG, GGN, GGG and GGGG) were then purified and separated from the mixture. Antimycotic activity of guazatine derivatives was determined on different species and strains belonging to genus Candida. The results obtained suggest that GNG and GGGG components can further be developed in new antifungal compounds with high potential for the treatment of Candida infections.

Antifungal Agents↗
PubMed2006

Gas-phase enantioselectivity of chiral amido[4]resorcinarene receptors.

Diastereomeric proton-bound [1(L)HA]+ complexes between selected amino acids (A=phenylglycine (Phg), tryptophan (Trp), tyrosine methyl ester (TyrOMe), threonine (Thr), and allothreonine (AThr)) and a chiral amido[4]resorcinarene receptor (1(L)) display a significant enantioselectivity when undergoing loss of the amino acid guest A by way of the enantiomers of 2-aminobutanes (B) in the gas phase. The enantioselectivity of the B-to-A displacement is ascribed to a combination of thermodynamic and kinetic factors related to the structure and the stability of the diastereomeric [1(L)HA]+ complexes and of the reaction transition states. The results of the present and previous studies allow classification of the [1(L)HA]+ complexes in three main categories wherein: i) guest A does not present any additional functionalities besides the amino acid one (alanine (Ala), Phg, and phenylalanine (Phe)); ii) guest A presents an additional alcohol function (serine (Ser), Thr, and AThr); and iii) guest A contains several additional functionalities on its aromatic ring (tyrosine (Tyr), TyrOMe, Trp, and 3,4-dihydroxyphenylalanine (DOPA)). Each category exhibits a specific enantioselectivity depending upon the predominant [1(L)HA]+ structures and the orientation of the 2-aminobutane reactant in the relevant adducts observed. The results may contribute to the understanding of the exceptional selectivity and catalytic properties of enzyme mimics towards unsolvated biomolecules.

Amino Acids↗
PubMed2006

Synthesis and biological evaluation of 4-alkylamino-6-(2-hydroxyethyl)-2-methylthiopyrimidines as new rubella virus inhibitors.

In the search for new chemotherapeutic agents useful against Rubella virus (RV) infections, a solution-phase parallel approach for the synthesis of a small library of 4-alkylamino-6-(2-hydroxyethyl)-2-methylthiopyrimidines has been set up, based on previous results from our research group. Biological evaluation of the newly synthesized compounds pointed out their interesting properties as anti-RV agents with IC(50) values in the micromolar range.

Animals↗
PubMed2006

Simplified analogues of immucillin-G retain potent human purine nucleoside phosphorylase inhibitory activity.

A set of deazaguanine derivatives 1-3 targeting human purine nucleoside phosphorylase (hPNP) have been designed and synthesized. The new compounds are characterized by the presence of a structurally simplified "azasugar" motif to be more easily accessible by chemical synthesis than previous inhibitors. In the enzymatic assays, some of the new derivatives proved to be able to inhibit hPNP at low nanomolar concentration, thereby showing the same inhibitory potency in vitro as immucillin-H (IMH). Molecular docking experiments revealed a binding mode to hPNP essentially identical to that of IMH. As a result, the lower in vivo activity exhibited by 1d, compared with that exhibited by IMH, might be ascribed to differences in the pharmacokinetic, rather than pharmacodynamic, profile between these compounds. Derivatives 1a, 1d, and 2c emerged as the most active compounds within this new set and may represent interesting leads in the search for novel hPNP inhibitors.

Antineoplastic Agents↗
PubMed2006

Pyrazolo[3,4-d]pyrimidines c-Src inhibitors reduce epidermal growth factor-induced migration in prostate cancer cells.

During its biological progression, prostate cancer frequently develops dependence on growth factor receptors and their downstream signalling messengers, including c-Src. Evidence for this supports the choice of c-Src as a therapeutic target in the prevention of tumour spreading. Two new pyrazolo[3,4-d]pyrimidines c-Src inhibitors, SI35 and SI40, were used to investigate the role of c-Src in the control of the aggressive phenotype of prostate carcinoma cell line, PC3. SI molecules reduced the proliferation of PC3 cells in a time- and dose-dependent manner, with an IC50 of approximately 50 microM. PC3 cells responded to the presence of epidermal growth factor (EGF) by increasing their migratory ability, and this effect was strongly reduced by the addition of SI at concentrations less than IC50. Further observations demonstrated that SI molecules modulated cell morphology and their adhesive capacity on different physiological substrates. The action of SI molecules appeared to involve, in parallel with c-Src inhibition, the down-modulation of the active forms of paxillin and extracellular signal-regulated kinase (ERK). Our data suggest a promising role for pyrazolo[3,4-d]pyrimidines c-Src inhibitors in the control of a highly invasive tumour phenotype.

Cell Adhesion↗
PubMed2006

Antimycobacterial agents. Novel diarylpyrrole derivatives of BM212 endowed with high activity toward Mycobacterium tuberculosis and low cytotoxicity.

On the basis of suggestions derived either from a pharmacophoric model for antitubercular agents or from a structure-activity relationship analysis of many pyrroles previously described by us, we report here the design and synthesis of new analogues of 1,5-(4-chlorophenyl)-2-methyl-3-(4-methylpiperazin-1-yl)methyl-1H-pyrrole (BM212). Various substituents with different substitution patterns were added to both positions 1 and 5 of the pyrrole nucleus to evaluate their influence on the activity toward Mycobacterium tuberculosis (MTB) and atypical mycobacteria. Biological data showed that, although some nontuberculosis mycobacterial strains were found to be sensitive, MIC values were higher than those found toward MTB. The best compound (1-(4-fluorophenyl)-2-methyl-3-(thiomorpholin-4-yl)methyl-5-(4-methylphenyl)-1H-pyrrole, 5) possessed a MIC of 0.4 microg/mL (better than BM212 and streptomycin) and a very high protection index (160), better than BM212, isoniazid, and streptomycin (6, 128, and 128, respectively). Finally, molecular modeling studies were performed to rationalize the activity of the new compounds in terms of both superposition onto a pharmacophoric model for antitubercular compounds and their hydrophobic character.

Animals↗
PubMed2006

Pharmacophore based receptor modeling: the case of adenosine A3 receptor antagonists. An approach to the optimization of protein models.

To design and synthesize new potent and selective antagonists of the human A(3) adenosine receptor, pharmacophoric hypotheses were generated with the software Catalyst for a comprehensive set of compounds retrieved from previous literature. Three of these pharmacophores were used to drive the optimization of a molecular model of the receptor built by homology modeling. The alignment of the ligands proposed by Catalyst was then used to manually dock a set of known A(3) antagonists into the binding site, and as a result, the model was able to explain the different binding mode of very active compounds with respect to less active ones and to reproduce, with good accuracy, free energies of binding. The docking highlighted that the nonconserved residue Tyr254 could play an important role for A(3) selectivity, suggesting that a mutagenesis study on this residue could be of interest in this respect. The reliability of the whole approach was successfully tested by rational design and synthesis of new compounds.

Adenosine A3 Receptor Antagonists↗
PubMed2006

The betaI/betaIII-tubulin isoforms and their complexes with antimitotic agents. Docking and molecular dynamics studies.

Both microtubule destabilizer and stabilizer agents are important molecules in anticancer therapy. In particular, paclitaxel has been demonstrated to be effective for the treatment of ovarian, breast, and nonsmall cell lung carcinomas. It has been shown that emergence of resistance against this agent correlates with an increase in the relative abundance of tubulin isoform betaIII and that the more recently discovered IDN5390 can be effectively used once resistance has emerged. In this paper, we analyze the binding modes of these antimitotic agents to type I and III isoforms of beta-tubulin by computational methods. Our results are able to provide a molecular explanation of the experimental data. Using the same protocol, we could also show that no preference for any of the two isoforms can be detected for epothilone A, a potentially very interesting drug for which no data about the emergence of resistance is currently available. Our analysis provides structural insights about the recognition mode and the stabilization mechanism of these antimitotic agents and provides useful suggestions for the design of more potent and selective antimitotic agents.

Algorithms↗
PubMed2006

A combination of docking/dynamics simulations and pharmacophoric modeling to discover new dual c-Src/Abl kinase inhibitors.

A computational protocol was applied to identify molecular scaffolds untested toward the c-Src tyrosine kinase. A combination of docking and dynamics calculations allowed us to build three-dimensional models of the complexes between Src and several of its known inhibitors. Interactions most contributing to activity of the inhibitors, in terms of hydrogen bonds and hydrophobic contacts, were codified into pharmacophoric models that were in turn applied to perform a search of commercially available compounds within the Asinex database. As a result, we identified 1,3,4-thiadiazoles and pyrazolydine-3,5-diones showing inhibitory activity in the submicromolar range in a cell-free assay toward Src. Moreover, since several of the compounds used to generate pharmacophores were also known as Abl inhibitors, we tested the identified hits toward Abl tyrosine kinase, finding activity in the submicromolar range. Such biological data suggested that the computational protocol is an efficient tool for identifying new hits toward both Src and Abl.

CSK Tyrosine-Protein Kinase↗
PubMed2006

Pyrazolo[3,4-d]pyrimidines as potent antiproliferative and proapoptotic agents toward A431 and 8701-BC cells in culture via inhibition of c-Src phosphorylation.

We report here the synthesis of new pyrazolo[3,4-d]pyrimidine derivatives along with their biological properties as inhibitors of isolated Src and cell line proliferation (A431 and 8701-BC cells). Such compounds block the growth of cancer cells by interfering with the phosphorylation of Src, and they act as proapoptotic agents through the inhibition of the anti apoptotic gene BCL2. Several of them were found to be more active than the reference compound (1-(tert-butyl)-3-(4-chlorophenyl)-4-aminopyrazolo[3,4-d]pyrimidine, PP2) in inhibiting cell proliferation and in inducing apoptosis, and as active as PP2 in the inhibition of the phosphorylation of isolated Src. Moreover, molecular modeling simulations have been performed to hypothesize the way, at the molecular level, by which the inhibitors were able to act as antiproliferative agents.

Antineoplastic Agents↗
PubMed2006

Ligand-based virtual screening, parallel solution-phase and microwave-assisted synthesis as tools to identify and synthesize new inhibitors of mycobacterium tuberculosis.

In an attempt to identify new inhibitors of the growth of Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis, a procedure for the generation, design, and screening of a ligand-based virtual library was applied. This used both an in silico protocol centered on a recursive partitioning (RP) model described herein, and a pharmacophoric model for antitubercular agents previously generated by our research group. Two candidates emerged from databases of commercially available compounds, both characterized by a minimum inhibitory concentration (MIC) of 25 microg mL(-1). Based on these compounds, two series of derivatives were synthesized by both parallel solution-phase and microwave-assisted synthesis, leading to enhanced antimycobacterial activity. During both the design and synthesis, attention was focused on the efficient allocation of available resources with the aim of reducing the overall costs associated with calculation and synthesis.

Antitubercular Agents↗
PubMed2006

Flavin-containing polyamine oxidase is a hydrogen peroxide source in the oxidative response to the protein phosphatase inhibitor cantharidin in Zea mays L.

In this study, the specific contribution of polyamine oxidase (PAO), a hydrogen peroxide (H2O2)-producing enzyme, to the oxidative burst induced in maize mesocotyl by the phosphatase inhibitor cantharidin was examined. For this purpose, a pharmacological approach was applied using, either in vitro or in vivo, two strong inhibitors of maize PAO (MPAO), N-prenylagmatine (G3) and its structural analogue Ro5, as well as diphenyleneiodonium (DPI), an inhibitor of the phagocyte NAD(P)H oxidase. DPI was shown to be a good MPAO inhibitor in vitro. G3, Ro5, and DPI were very effective in inhibiting in vivo the extracellular accumulation of H2O2 that is released by mesocotyl segments upon spermidine supply. G3 and Ro5 did not show any inhibition in vitro of either horseradish peroxidase or barley oxalate oxidase. Moreover, G3 and Ro5 did not inhibit the extracellular accumulation of superoxide radical that is released in vivo upon NADH supply. G3, Ro5, and DPI strongly affected H2O2 production induced in maize mesocotyl by cantharidin. Histochemical localization of H2O2 in cantharidin-treated mesocotyl cross-sections revealed an increase of H2O2-specific staining in the epidermal and subepidermal tissues. The effect was also inhibited by G3 and DPI. Moreover, an increase in MPAO activity was observed in the same tissues upon cantharidin treatment. All these data suggest that G3 and Ro5 behave as powerful and selective inhibitors of MPAO activity either in vitro or in vivo and that MPAO activity contributes to a major part of the cantharidin-induced H2O2 synthesis in the apoplastic milieu of maize mesocotyl.

Agmatine↗
PubMed2006

Inhibition of polyamine and spermine oxidases by polyamine analogues.

Polyamine oxidase (PAO) and spermine oxidase (SMO) are involved in the catabolism of polyamines--basic regulators of cell growth and proliferation. The discovery of selective inhibitors of PAO and SMO represents an important tool in studying the involvement of these enzymes in polyamine homeostasis and a starting point for the development of novel antineoplastic drugs. Here, a comparative study on murine PAO (mPAO) and SMO (mSMO) inhibition by the polyamine analogues 1,8-diaminooctane, 1,12-diaminododecane, N-prenylagmatine (G3), guazatine and N,N1-bis(2,3-butadienyl)-1,4-butanediamine (MDL72527) is reported. Interestingly, 1,12-Diaminododecane and G3 behave as specific inhibitors of mPAO, values of K(i) for mPAO inhibition being lower than those for mSMO inactivation by several orders of magnitude. The analysis of molecular models of mPAO and mSMO indicates a significant reduction of the hydrophobic pocket located in maize PAO (MPAO) at the wider catalytic tunnel opening. This observation provides a rationale to explain the lower affinity displayed by G3, guazatine and MDL72527 for mPAO and mSMO as compared to MPAO. The different behaviour displayed by 1,12-diaminododecane towards mPAO and mSMO reveals the occurrence of basic differences in the ligand binding mode of the two enzymes, the first enzyme interacting mainly with substrate secondary amino groups and the second one with substrate primary amino groups. Thus, the data reported here provide the basis for the development of novel and selective inhibitors able to discriminate between mammalian SMO and PAO activities.

Amino Acid Sequence↗
PubMed2005

Parallel solution-phase and microwave-assisted synthesis of new S-DABO derivatives endowed with subnanomolar anti-HIV-1 activity.

A simple and efficient methodology for the parallel solution-phase synthesis has been set up to obtain a series of thiouracils, in turn selectively S-benzylated under microwave irradiation to give new S-DABOs. Biological screening led to the identification of compounds with nanomolar activity toward both the highly purified recombinant human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) enzyme (wild-type and mutants) and wild-type (wt) and mutant HIV-1 strains. In particular, 20 was found to be the most potent S-DABO reported so far (ID50 = 26 nM toward the isolated wt enzyme) with subnanomolar activity toward both the wt and the pluriresistant virus (IRLL98) HIV-1 strain (EC50 < 0.14 nM and EC50 = 0.22 nM, respectively). Molecular modeling calculations were also performed to investigate the binding mode of such compounds onto the non-nucleoside reverse transcriptase inhibitor binding site and to rationalize the relationships between their chemical structure and activity values toward wt RT.

Anti-HIV Agents↗
PubMed2005

Synthesis and 3D QSAR of new pyrazolo[3,4-b]pyridines: potent and selective inhibitors of A1 adenosine receptors.

A number of 4-aminopyrazolo[3,4-b]pyridines 5-carboxylic acid esters (2-8) were synthesized and evaluated for their binding affinity at the A1, A2A, and A3 adenosine receptors (AR), in bovine cortical membranes, as well as for their affinity toward human A1AR (hA1AR). Some of the new compounds were characterized by a high affinity and selectivity toward the A1 receptor subtype, showing a significant improvement in comparison with other pyrazolo-pyridines previously reported in the literature. In particular the methyl ester 2h as well as the isopropyl ester 5h, both of them bearing a p-methoxyphenylethylamino side chain at the position 4, presented Ki values of 6 and 7 nM, respectively. To rationalize the relationships between structure and affinity of the novel compounds, a 3D QSAR model was also generated starting from compounds belonging to different classes of known A1AR antagonists.

Adenosine A1 Receptor Antagonists↗