Biomedical subjects
Publications and source records attributed to Francesco Ortuso.
A new series of arylalkyl- and alkenylamines was designed, synthesized, and evaluated for binding to sigma(1) and sigma(2) receptors. Many compounds exhibited nanomolar affinity for sigma(1) subtype receptor with good selectivity over sigma(2). A molecular modeling study was conducted in order to rationalize the experimental data, and the structure-receptor affinities are discussed.
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.
A novel series of N,N'-bis[2-oxo-2H-1-benzopyran]-3-carboxamide derivatives have been synthesized and investigated for the ability to inhibit the activity of the A and B isoforms of monoamine oxidase (MAO). Some of the synthesized compounds show good selective inhibitory activity against the MAO-A isoform. Both the MAO-A and -B isoforms, deposited in the Protein Data Bank as the 2BXR and 1GOS models, respectively, were considered in a computational study performed with docking techniques on the most active and selective inhibitors.
MOTIVATION: Automatic procedures to obtain pharmacophore models from experimentally determined macromolecular complexes can help in the drug discovery process, especially when protein-protein recognition plays an important biological role. RESULTS: The GRID-based pharmacophore model (GBPM) is a fully objective method for defining most relevant interaction areas in complexes deriving pharmacophore models from three-dimensional (3D) molecular structure information. It is based on logical and clustering operations with 3D maps computed by the GRID program on structurally known molecular complexes. In this manuscript we describe the concept and discuss application examples regarding protein-protein recognition. In particular two complexes selected in the Protein Data Bank have been tested to evaluate the GBPM capability to identify interaction areas. The results obtained show the capabilities of this new bioinformatic method.
The methanol extract from Hypericum hircinum leaves exhibited in vitro inhibition of monoamine oxidases (MAO). Bioassay-guided fractionation led to the isolation of quercetin and five compounds identified for the first time from H. hircinum. Quercetin was the only compound with a selective inhibitory activity against MAO-A, with an IC50 value of 0.010 microM. To explain MAO selective inhibition at the molecular level, a computational study was carried out by conformational search and docking techniques using recently determined crystallographic models of both enzymatic isoforms. An in vivo study in mice was carried out using the forced swimming test in order to elucidate the behavioral effects of quercetin.
This report describes novel pyrazoline derivatives investigated for their ability to selectively inhibit the activity of the A and B isoforms of monoamine oxidase. These new synthetic compounds proved to be reversible, potent, and selective inhibitors of monoamine oxidase-A rather than of monoamine oxidase-B, and are promising candidates to further advance drug discovery efforts. The most active compounds show inhibitory activity on monoamine oxidase-A in the 1.0x10(-8)-8.6x10(-9) M range. Moreover, it should be pointed out that for some compounds a high IC50>or=10(-9) M value is associated with a high A-selectivity (Selectivity Index monoamine oxidase-B/monoamine oxidase-A in the 10,000-12,500 range). Further insight to understand enzyme-inhibitor molecular interaction was obtained by docking experiments with the monoamine oxidase-A and monoamine oxidase-B isoforms.
The present report provides a extended study of the chemistry, the inhibitory activity against monoamino oxidases (MAO), and molecular modeling including the 3D-QSAR hypothesis of 1,3,5-trisubstituted-4,5-dihydro-(1H)-pyrazole derivatives. Four series of about eighty novel pyrazoline derivatives were prepared and investigated for their ability to inhibit the activity of the A and B isoforms of MAO selectively. Most of the new synthesized compounds proved more reversible, potent, and selective inhibitors of MAO-A than of MAO-B, and could be taken into account to develop the search further in this field, knowing that reversible and selective MAO-A inhibitors are used as antidepressant and antianxiety drug. The 30 most active compounds show inhibitory activity on MAO-A in the 8.6 x 10(-8) - 9.0 x 10(-9)M range. Moreover, it should be pointed out that for most of them a high IC(50) > or = 10(-9)M value is associated with a high A-selectivity (Selectivity Index MAO-B/MAO-A in the 10,000-16,250 range). Furthermore, due to the presence of a chiral centre at the C5 position of the pyrazole moiety, we performed the semi-preparative chromatographic enantioseparation of the most potent, selective, and chiral compounds. The separated enantiomers were then submitted to in vitro biological evaluation, and from the results of these experiments it has been possible to point out a difference in inhibiting the two isoforms selectively between the racemic mixture and the single enantiomers. The molecular modeling work was carried out combining the Glide docking approach with CoMFA with the aim to rationalize the structure-activity relationships of each pyrazoline inhibitor toward MAO-A and MAO-B isoforms and to derive a suitable selectivity model.
A novel series of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-(1H)-pyrazole derivatives have been synthesized and investigated for the ability to inhibit selectively the activity of the A and B isoforms of monoamine oxidase (MAO). All the synthesized compounds show high activity against both the MAO-A and the MAO-B isoforms with Ki values between 27 and 4 nM and between 50 and 1.5 nM, respectively, except for a few derivatives whose inhibitory activity against MAO-B was in the micromolar range. Knowing that stereochemistry may be an important modulator of biological activity, we performed the semipreparative chromatographic enantioseparation of the most potent, selective, and chiral compounds. The separated enantiomers were then submitted to in vitro biological evaluation. The selectivity of the (-)-(S)-1 enantiomer against MAO-B increases twice and a half, while the selectivity of the (-)-(S)-4 enantiomer against MAO-A triples. Both the MAO-A and MAO-B isoforms respectively of the 1O5W and 1GOS models deposited in the Protein Data Bank were considered in the computational study. The docking study was carried out using several computational approaches with the aim of proposing possible binding modes of the MAO enantioselective compounds 1 and 4.
Changes in the GSH/GST system have been found to correlate with resistance to anticancer alkylating agents, presumably through accelerated detoxification of these drugs since some GSTs have been shown to catalyze the conjugation of GSH to specific antineoplastic agents. GSH-alkyl derivatives were designed by molecular modeling, synthesized, and tested as inhibitors of human GST-Pi.
Novel arylpiperazine derivatives bearing lipophilic probes were designed, synthesized, and evaluated for their potential ability to interact with the 5-hydroxytryptamine(3) (5-HT(3)) receptor. Most of the new compounds show subnanomolar 5-HT(3) receptor affinity. Ester 6bc showing a picomolar K(i) value is one of the most potent 5-HT(3) receptor ligands so far synthesized. The structure-affinity relationship study suggests the existence of a certain degree of conformational freedom of the amino acid residues interacting with the substituents in positions 3 and 4 of the quipazine quinoline nucleus. Thus, the tacrine-related heterobivalent ligand 6o was designed in an attempt to capitalize on the evidence of such a steric tolerance. Compound 6o shows a nanomolar potency for both the 5-HT(3) receptor and the human AChE and represents the first example of a rationally designed high-affinity 5-HT(3) receptor ligand showing nanomolar AChE inhibitory activity. Finally, the computational analysis performed on compound 6o allowed the rationalization of the structure-energy determinants for AChE versus BuChE selectivity and revealed the existence of a subsite at the boundary of the 5-HT(3) receptor extracellular domain, which could represent a "peripheral" site similar to that evidenced in the AChE gorge.
In pursuing research on the antiviral, interferon (IFN)-inducing tilorone congeners, a new series of fluoren-carboxyhydroxyesters has been prepared and biologically explored. These esters have subsequently been used as sugar acceptors in the enzymatic transglycosylation reaction using the 'retaining' beta-glycosidase from the archaeon Sulfolobus solfataricus (Ssbeta-Gly). Both aglycones (1-6) and corresponding beta-glucosides (beta-glu 1-beta-glu 6) have been screened for cytotoxicity, interferon-stimulating and antiviral properties against HSV-2. It was found that the addition of compounds beta-glu 5, beta-glu 6 and beta-glu 4 to HSV-2 infected U937 cells downregulates viral replication and triggers cells to release IFN-alpha/beta. Taken together, the results showed improved pharmacological profiles as a consequence of glycosylation. A molecular modelling study carried out on this series of compounds completed the structural characterisation of the novel compounds.
Mammalian NADH-cytochrome b5 reductase (b5R) is an N-myristoylated protein that is dually targeted to ER and mitochondrial outer membranes. The N-linked myristate is not required for anchorage to membranes because a stretch of hydrophobic amino acids close to the NH2 terminus guarantees a tight interaction of the protein with the phospholipid bilayer. Instead, the fatty acid is required for targeting of b5R to mitochondria because a nonmyristoylated mutant is exclusively localized to the ER. Here, we have investigated the mechanism by which N-linked myristate affects b5R targeting. We find that myristoylation interferes with interaction of the nascent chain with signal recognition particle, so that a portion of the nascent chains escapes from cotranslational integration into the ER and can be post-translationally targeted to the mitochondrial outer membrane. Thus, competition between two cotranslational events, binding of signal recognition particle and modification by N-myristoylation, determines the site of translation and the localization of b5R.
In order to obtain rigidity within the sugar moiety of nucleosides, the bicyclic pyrimidine derivatives of N,O-isoxazolidines were designed and synthesized by using 1,3-dipolar cycloaddition of Delta(1)-pyrrolidine-1-oxide and the appropriate vinyl-nucleobases.
A series of coumarin-3-acyl derivatives have been synthesized and investigated for the ability to inhibit selectively monoamine oxidases. The coumarin-3-carboxylic acids, 2a-e, proved to be reversible and selective inhibitors of the MAO-B isoform, displaying pIC(50) values of particular interest: 2a shows pIC(50) 7.76 and a selectivity index (pS.I.) 2.94 and 2b shows pIC(50) 7.72 and a pS.I. of 2.80. The coumarin-3-acyl chlorides 3a-e showed high pIC(50) values against both MAO-A and MAO-B isoforms, 3d being the highest against MAO-B with a pIC(50) value of 8.00. In order to rationalize the activity/selectivity results, molecular descriptors were generated. Further insight about enzyme-inhibitor interaction was obtained by docking experiments with the MAO-B isoform.
In this study is presented the phosphorotioate nucleotide compound (1) possessing an unusual moiety with a chiral P and a Se atoms double bonded. It required a force field parameterization for carrying out standard molecular mechanics calculations. A new set of MMFF parameters was developed and applied for the complete conformational search of the diastereoisomers, using both Monte Carlo and molecular dynamics, with the purpose to validate them by the comparison between calculated structural properties and NMR measurements.
Using the Protein Data Bank crystallographic model of paclitaxel with tubulin as reference, a comparative interaction study of the antitumor drug with known macromolecular targets such as beta-cyclodextrin and Dickerson's DNA dodecamer was carried out by molecular modeling techniques. AMBER* united atoms was found to be the most appropriate force field for our study. Conformational search of paclitaxel was performed using a water environment. A large set of conformers was selected for automatic "quasi-flexible" docking calculations performed by the "in-house" software MOLINE. A proper docking protocol was based on a crystallographic model and validated by a remarkable low atomic coordinate deviation. Using this method, a similar pattern via benzamide interaction was established for molecular recognition of paclitaxel cyclodextrin and DNA. The results are supported by our previous observations and other author's experimental data.
Pivaloyl-choline iodide 1 interactions with acetylcholinesterase (AChE) have been studied by theoretical and enzymatic methods. An integrated computational approach has clearly shown a substrate rather than inhibitory profile for 1. Enzymatic experiments have also supported the same theoretical conclusion indicating that AChE was able to hydrolyze 1 to choline.
Within the series of chiral 3,3'-(1,2-ethanediyl)bis[2-arylthiazolidin-4-ones], the 3,4-dimethoxyphenyl substituted derivative was found in the primary anti-inflammatory screening to be endowed with superior in vivo properties and good safety profile. Such a lead compound was modified by eliminating 3-methoxy group while retaining 4-methoxy group on the aryl rings at 2 and 2' stereogenic carbons. The 2R,2'S-meso isomer (VIG3b) of the resulting bisthiazolidinone has been widely investigated. The inhibitory effects on cyclo-oxygenase-1 and cyclo-oxygenase-2 isoenzymes were measured in a human whole blood assay. VIG3b was almost 50 times more selective on the inducible isoform. The cyclo-oxygenase-2 preferential selectivity has been confirmed by modeling VIG3b into the cyclo-oxygenase-1 and cyclo-oxygenase-2 active sites. Furthermore, VIG3b was assayed in the experimental model of carrageenan-induced lung injury by evaluating its ability to inhibit: (1) fluid accumulation in the pleural cavity, (2) neutrophil infiltration, (3) prostaglandin E(2) production and (4) lung injury. VIG3b exhibited interesting activity in all these tests.