Giovanni Greco - Academia.edu (original) (raw)
Papers by Giovanni Greco
Pharmaceutica Acta Helvetiae, 1995
An approach to series design in the framework of the comparative molecular field analysis three-d... more An approach to series design in the framework of the comparative molecular field analysis three-dimensional quantitative structure-activity relationship (COMFA 3D-QSAR) method is proposed. This procedure is based on performing cluster analysis on principal components generated from CoMFA energy descriptors. The results of our case study suggest that a CoMFA model derived from a relatively small series of properly selected structures can provide nearly the same amount of information which could be obtained from a much larger data set of analogues.
![Research paper thumbnail of 3-Aryl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-ones: A New Class of Selective A1 Adenosine Receptor Antagonists](https://attachments.academia-assets.com/111143680/thumbnails/1.jpg)
](Journal of Medicinal Chemistry, 2001
Radioligand binding assays using bovine cortical membrane preparations and biochemical in vitro s... more Radioligand binding assays using bovine cortical membrane preparations and biochemical in vitro studies revealed that various 3-aryl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one (ATBI) derivatives, previously reported by us as ligands of the central benzodiazepine receptor (BzR) (Primofiore, G.; et al. J. Med. Chem. 2000, 43, 96-102), behaved as antagonists at the A 1 adenosine receptor (A 1 AR). Alkylation of the nitrogen at position 10 of the triazinobenzimidazole nucleus conferred selectivity for the A 1 AR vs the BzR. The most potent ligand of the ATBI series (10-methyl-3-phenyl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one 12) displayed a K i value of 63 nM at the A 1 AR without binding appreciably to the adenosine A 2A and A 3 nor to the benzodiazepine receptor. Pharmacophore-based modeling studies in which 12 was compared against a set of well-established A 1 AR antagonists suggested that three hydrogen bonding sites (HB1 acceptor, HB2 and HB3 donors) and three lipophilic pockets (L1, L2, and L3) might be available to antagonists within the A 1 AR binding cleft. According to the proposed pharmacophore scheme, the lead compound 12 engages interactions with the HB2 site (via the N2 nitrogen) as well as with the L2 and L3 sites (through the pendant and the fused benzene rings). The results of these studies prompted the replacement of the methyl with more lipophilic groups at the 10-position (to fill the putative L1 lipophilic pocket) as a strategy to improve A 1 AR affinity. Among the new compounds synthesized and tested, the 3,10-diphenyl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one (23) was characterized by a K i value of 18 nM which represents a 3.5-fold gain of A 1 AR affinity compared with the lead 12. A rhodopsin-based model of the bovine adenosine A 1 AR was built to highlight the binding mode of 23 and two wellknown A 1 AR antagonists (III and VII) and to guide future lead optimization projects. In our docking simulations, 23 receives a hydrogen bond (via the N1 nitrogen) from the side chain of Asn247 (corresponding to the HB1 and HB2 sites) and fills the L1, L2, and L3 lipophilic pockets with the 10-phenyl, 3-phenyl, and fused benzene rings, respectively.
Bioorganic & Medicinal Chemistry, 2005
A series of quinoline derivatives have been designed on the basis of results from a 3D search of ... more A series of quinoline derivatives have been designed on the basis of results from a 3D search of the Cambridge Structural Database using the nicotinic pharmacophore as a query and further modified using molecular modeling. Some of the synthesized compounds show nanomolar affinity for the central nicotinic receptor on rat cerebral cortex.
Bioorganic & Medicinal Chemistry, 2000
Three pyrrolyl heteroaryl sulfones (ethyl 1-[(1H-benzimidazol-2(3H)one-5-yl)sulfonyl]-1H-pyrrole-... more Three pyrrolyl heteroaryl sulfones (ethyl 1-[(1H-benzimidazol-2(3H)one-5-yl)sulfonyl]-1H-pyrrole-2-carboxyla te, ethyl 1-[(1H-benzimidazol-5(6)-yl)sulfonyl]-1H-pyrrole-2-carboxylate and ethyl 1-[(1H-benzotriazol-5(6)-yl)sulfonyl]-1H-pyrrole-2-carboxylate) were designed as novel HIV-1 reverse transcriptase non-nucleoside inhibitors using structure-based computational methods. Although these compounds were inactive in the cell-based assay, they inhibited the target enzyme with micromolar potency (IC50s = 2 microM, 3 microM and 9 microM, respectively).
Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Small-molecules acting as positive allosteric modulators (PAMs) of the A 2B adenosine receptor (A... more Small-molecules acting as positive allosteric modulators (PAMs) of the A 2B adenosine receptor (A 2B AR) could potentially represent a novel therapeutic strategy for pathological conditions characterised by altered bone homeostasis, including osteoporosis. We investigated a library of compounds (4-13) exhibiting different degrees of chemical similarity with three indole derivatives (1-3), which have been recently identified by us as PAMs of the A 2B AR able to promote mesenchymal stem cell differentiation and bone formation. Evaluation of mineralisation activity of 4-13 in the presence and in the absence of the agonist BAY60-6583 allowed the identification of lead compounds with therapeutic potential as anti-osteoporosis agents. Further biological characterisation of one of the most performing compounds, the benzofurane derivative 9, confirmed that such a molecule behaves as PAM of the A 2B AR.
Reviews in Computational Chemistry
The 3D means that the compounds are described by the relative loca-tions of properties in three... more The 3D means that the compounds are described by the relative loca-tions of properties in three-dimensional space. Usually the methods consider steric, electronic, hydrogen bonding, and hydrophobic (i,e., lipophilic) proper-ties. The 3D molecular descriptors of ...
Journal of Peptide Science, 2002
The C-terminal domain of the heterotrimeric G protein α-subunits plays a key role in selective ac... more The C-terminal domain of the heterotrimeric G protein α-subunits plays a key role in selective activation of G proteins by their cognate receptors. Several C-terminal fragments of Gα s (from 11 to 21 residues) were recently synthesized. The ability of these peptides to stimulate agonist binding was found to be related to their size. Gα s (380-394) is a 15-mer peptide of intermediate length among those synthesized and tested that displays a biological activity surprisingly weak compared with that of the corresponding 21-mer peptide, shown to be the most active. In the present investigation, Gα s (380-394) was subjected to a conformational NMR analysis in a fluorinated isotropic environment. An NMR structure, calculated on the basis of the data derived from conventional 1D and 2D homonuclear experiments, shows that the C-terminal residues of Gα s (380-394) are involved in a helical arrangement whose length is comparable to that of the most active 21-mer peptide. A comparative structural refinement of the NMR structures of Gα s (380-394) and Gα s (374-394)C 379 A was performed using molecular dynamics calculations. The results give structural elements to interpret the role played by both the backbone conformation and the side chain arrangement in determining the activity of the G protein C-terminal fragments. The orientation of the side chains allows the peptides to assume contacts crucial for the G protein/receptor interaction. In the 15-mer peptide the lack as well as the disorder of some N-terminal residues could explain the low biological activity observed.
Journal of Medicinal Chemistry, 2008
A number of derivatives of 4-amino-6-hydroxy-2-mercaptopyrimidine (5) were synthesized and biolog... more A number of derivatives of 4-amino-6-hydroxy-2-mercaptopyrimidine (5) were synthesized and biologically evaluated as A 3 adenosine receptor (A 3 AR) antagonists. The new compounds were designed as open chain analogues of a triazolopyrimidinone derivative displaying submicromolar affinity for the A 3 AR, which had been previously identified using a 3D database search. Substituents R, R′, and R′′ attached to the parent compound 5 were chosen according to factorial design and stepwise lead optimization approaches, taking into account the essentially hydrophobic nature of the A 3 AR binding site. As a result, 5m (R) n-C 3 H 7 , R′) 4-ClC 6 H 4 CH 2 , R′′) CH 3) was identified among the pyrimidine derivatives as the ligand featuring the best combination of potency and selectivity for the target receptor. This compound binds to the A 3 AR with a K i of 3.5 nM and is devoid of appreciable affinity for the A 1 , A 2A , and A 2B ARs.
Journal of Medicinal Chemistry, 2008
Novel N,N-disubstituted indol-3-ylglyoxylamides (1-56), bearing different combinations of substit... more Novel N,N-disubstituted indol-3-ylglyoxylamides (1-56), bearing different combinations of substituents R 1-R 5 , were synthesized and evaluated as ligands of the translocator protein (TSPO), the 18 kDa protein representing the minimal functional unit of the "peripheral-type benzodiazepine receptor" (PBR). Most of the new compounds showed a nanomolar/subnanomolar affinity for TSPO and stimulated steroid biosynthesis in rat C6 glioma cells with a potency similar to or higher than that of classic TSPO ligands such as PK 11195. Moreover, when evaluated in vivo by means of the elevated-plus-maze (EPM) paradigm in the rat, compound 32, the best-performing derivative in terms of TSPO affinity and pregnenolone production, showed clear anxiolytic effects. The results of this study suggested that the novel N,N-disubstituted indol-3ylglyoxylamides may represent a promising class of compounds potentially suited for the treatment of anxiety disorders.
Journal of Medicinal Chemistry, 2010
The 18 kDa translocator protein (TSPO) is a mitochondrial protein whose basal density is altered ... more The 18 kDa translocator protein (TSPO) is a mitochondrial protein whose basal density is altered in several diseases, with the result that the evaluation of its expression levels by means of molecular imaging techniques represents a promising diagnostic approach. Experimental procedures using a labeled ligand often cause loss of the bound probe, and consequently high affinity ligands covalently binding the receptor protein are needed to overcome this problem. We have previously described a series of N,N-dialkyl-(2-phenylindol-3-yl)glyoxylamides as potent and selective TSPO ligands. Starting from these derivatives, we designed novel TSPO irreversible ligands bearing an electrophilic isothiocyanato group (7, 8), together with an irreversible NBD-fluorescent probe (18). The TSPO affinity of the new irreversible ligands was measured on rat tissue homogenates by [ 3 H]Ro 5-4864 radiobinding kinetic assays, all compounds showing high affinities for the target protein. Further biological characterization of the fluorescent irreversible TSPO probe 18 was carried out by using fluorescent spectroscopy in human glioma cells.
Journal of Medicinal Chemistry, 1999
Results and Discussion Computer-Assisted Design of Novel DABOs. The computational work was carrie... more Results and Discussion Computer-Assisted Design of Novel DABOs. The computational work was carried out by molecular mechanics (Tripos force field 26), conformational analysis, docking, and graphics routines available within the SYBYL program. 27 Details of these procedures are described in the Experimental Section, whereas the results are summarized below.
Journal of Medicinal Chemistry, 1996
Two novel classes of pyrrolobenzothiazepinones and pyrrolobenzoxazepinones were investigated as p... more Two novel classes of pyrrolobenzothiazepinones and pyrrolobenzoxazepinones were investigated as potential anti-AIDS drugs. These compounds were found to inhibit HIV-1 reverse transcriptase (RT) enzyme in vitro and to prevent HIV-1 cytopathogenicity in T4 lymphocytes, without appreciable activity on HIV-2 cytopathic effects, and against HBV as well as calfthymus DNA R-polymerase. Their potency is influenced by substituents at position 6 and on the fused aromatic ring. Specifically, small lipophilic substituents at C-6 were preferred, whereas substitutions on the benzo-fused ring were found to be detrimental to activity, with respect to the unsubstituted compounds. Modification of the π-system at C-6 is well tolerated, although the replacement of the benzo-fused with a [2,3]naphtho-fused ring leads to a less active compound. Maximum potency and specificity is achieved with a phenyl and an ethyl group at position 6 of the pyrrolobenzoxazepinone system. In the enzymatic assay the oxazepinone derivative (()-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)-one 16e (IC 50) 0.25 µM) was found to be more potent than nevirapine (IC 50) 0.5 µM), tested in the same experimental conditions using rC‚dG as a template-primer. In cell culture assay benzoxazepine 16e was active against HIV-1, both wild type and AZT-sensitive, and HIV-1 (IIIB) strains, but not against HIV-2. In enzyme assay although 16e inhibited HIV-1 RT, it was inactive against the nevirapine-resistant recombinant RT Y181C at 50 µM. Molecular modeling studies suggest that these derivatives present a 3D pharmacophoric arrangement similar to that of other nonnucleoside inhibitors such as nevirapine.
![Research paper thumbnail of [1,2,4]Triazino[4,3-a]benzimidazole Acetic Acid Derivatives: A New Class of Selective Aldose Reductase Inhibitors](https://attachments.academia-assets.com/97281343/thumbnails/1.jpg)
](Journal of Medicinal Chemistry, 2001
Acetic acid derivatives of [1,2,4]triazino[4,3-a]benzimidazole (TBI) were synthesized and tested ... more Acetic acid derivatives of [1,2,4]triazino[4,3-a]benzimidazole (TBI) were synthesized and tested in vitro and in vivo as a novel class of aldose reductase (ALR2) inhibitors. Compound 3, (10benzyl[1,2,4]triazino[4,3-a]benzimidazol-3,4(10H)-dion-2-yl)acetic acid, displayed the highest inhibitory activity (IC 50) 0.36 µM) and was found to be effective in preventing cataract development in severely galactosemic rats when administered as an eyedrop solution. All the compounds investigated were selective for ALR2, since none of them inhibited appreciably aldehyde reductase, sorbitol dehydrogenase, or glutathione reductase. The activity of 3 was lowered by inserting various substituents on the pendant phenyl ring, by shifting the acetic acid moiety from the 2 to the 3 position of the TBI nucleus, or by cleaving the TBI system to yield benzimidazolylidenehydrazines as open-chain analogues. A three-dimensional model of human ALR2 was built, taking into account the conformational changes induced by the binding of inhibitors such as zopolrestat, to simulate the docking of 3 into the enzyme active site. The theoretical binding mode of 3 was fully consistent with the structure-activity relationships in the TBI series and will guide the design of novel ALR2 inhibitors.
![Research paper thumbnail of Design, Synthesis and Biological Evaluation of Novel N -Alkyl- and N -Acyl-(7-substituted-2-phenylimidazo[1,2- a ][1,3,5]triazin-4-yl)amines (ITAs) as Novel A 1 Adenosine Receptor Antagonists](https://attachments.academia-assets.com/97281292/thumbnails/1.jpg)
](Journal of Medicinal Chemistry, 2002
Histone deacetylase 8 (HDAC8) is a promising drug target for multiple therapeutic applications. H... more Histone deacetylase 8 (HDAC8) is a promising drug target for multiple therapeutic applications. Here, we describe the modeling, design, synthesis, and biological evaluation of a novel series of C1-substituted tetrahydroisoquinoline (TIQ)-based HDAC8 inhibitors. Minimization of entropic loss upon ligand binding and use of the unique HDAC8 "open" conformation of the binding site yielded a successful strategy for improvement of both HDAC8 potency and selectivity. The TIQ-based 3g and 3n exhibited the highest 82 and 55 nM HDAC8 potency and 330-and 135-fold selectivity over HDAC1, respectively. Selectivity over other class I isoforms was comparable or better, whereas inhibition of HDAC6, a class II HDAC isoform, was below 50% at 10 μM. The cytotoxicity of 3g and 3n was evaluated in neuroblastoma cell lines, and 3n displayed concentration-dependent cytotoxicity similar to or better than that of PCI-34051. The selectivity of 3g and 3n was confirmed in SH-SY5Y cells as both did not increase the acetylation of histone H3 and α-tubulin. Discovery of the novel TIQ chemotype paves the way for the development of HDAC8 selective inhibitors for therapeutic applications.
Bioorganic & Medicinal Chemistry, 2005
The 2,3-dihydrospiro[4H-thiopyrano[2,3-b]pyridin-4,4&... more The 2,3-dihydrospiro[4H-thiopyrano[2,3-b]pyridin-4,4'-imidazolidine]-2',5'-dione 3 and its 7-methyl analogue 4 were synthesized and tested for their ability to inhibit aldose reductase (ALR2). To expand the structure-activity relationships, the sulfone 5 and the acetic acid derivative 7 were also prepared and tested. Compounds 3 and 4 proved to be potent ALR2 inhibitors, with IC50 values in the submicromolar range (0.96 and 0.94 microM, respectively) similar to that of sorbinil (0.65 microM). Moreover, compound 3 was found to be highly potent in preventing cataract development in severely galactosemic rats, like tolrestat, when administered as an eyedrop solution. Docking simulations of both R- and S-isomers of 3 into the ALR2 crystal structure were carried out to guide, prospectively, the design of new analogues.
Journal of Medicinal Chemistry, 1998
Frontiers in Pharmacology, 2021
The development of GPCR (G-coupled protein receptor) allosteric modulators has attracted increasi... more The development of GPCR (G-coupled protein receptor) allosteric modulators has attracted increasing interest in the last decades. The use of allosteric modulators in therapy offers several advantages with respect to orthosteric ones, as they can fine-tune the tissue responses to the endogenous agonist. Since the discovery of the first A1 adenosine receptor (AR) allosteric modulator in 1990, several efforts have been made to develop more potent molecules as well as allosteric modulators for all adenosine receptor subtypes. There are four subtypes of AR: A1, A2A, A2B, and A3. Positive allosteric modulators of the A1 AR have been proposed for the cure of pain. A3 positive allosteric modulators are thought to be beneficial during inflammatory processes. More recently, A2A and A2B AR allosteric modulators have also been disclosed. The A2B AR displays the lowest affinity for its endogenous ligand adenosine and is mainly activated as a consequence of tissue damage. The A2B AR activation ha...
MedChemComm, 2018
Three A adenosine receptor (AR) antagonists () selected from 4-acylamino-6-alkyloxy-2-alkylthiopy... more Three A adenosine receptor (AR) antagonists () selected from 4-acylamino-6-alkyloxy-2-alkylthiopyrimidines previously investigated by us were modified by inserting a methyl group on their ether or thioether side chains. These compounds gave us the chance to evaluate whether their higher lipophilicity, reduced conformational freedom and chirality might improve the potency towards the A AR. Racemic mixtures of were resolved using chiral HPLC methods and the absolute configurations of the enantiomers were assigned by chiroptical spectroscopy and density functional theory calculations. We measured the affinity for human A, A, A and A ARs of the racemic mixtures and the pure enantiomers of by radioligand competition binding experiments. Cell-based assays of the most potent enantiomers confirmed their A AR antagonist profiles. Our research led to the identification of ()- with high potency (0.5 nM) and selectivity as an A AR antagonist. Moreover we built a docking-model useful to design n...
ChemInform, 2010
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Pharmaceutica Acta Helvetiae, 1995
An approach to series design in the framework of the comparative molecular field analysis three-d... more An approach to series design in the framework of the comparative molecular field analysis three-dimensional quantitative structure-activity relationship (COMFA 3D-QSAR) method is proposed. This procedure is based on performing cluster analysis on principal components generated from CoMFA energy descriptors. The results of our case study suggest that a CoMFA model derived from a relatively small series of properly selected structures can provide nearly the same amount of information which could be obtained from a much larger data set of analogues.
Journal of Medicinal Chemistry, 2001
Radioligand binding assays using bovine cortical membrane preparations and biochemical in vitro s... more Radioligand binding assays using bovine cortical membrane preparations and biochemical in vitro studies revealed that various 3-aryl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one (ATBI) derivatives, previously reported by us as ligands of the central benzodiazepine receptor (BzR) (Primofiore, G.; et al. J. Med. Chem. 2000, 43, 96-102), behaved as antagonists at the A 1 adenosine receptor (A 1 AR). Alkylation of the nitrogen at position 10 of the triazinobenzimidazole nucleus conferred selectivity for the A 1 AR vs the BzR. The most potent ligand of the ATBI series (10-methyl-3-phenyl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one 12) displayed a K i value of 63 nM at the A 1 AR without binding appreciably to the adenosine A 2A and A 3 nor to the benzodiazepine receptor. Pharmacophore-based modeling studies in which 12 was compared against a set of well-established A 1 AR antagonists suggested that three hydrogen bonding sites (HB1 acceptor, HB2 and HB3 donors) and three lipophilic pockets (L1, L2, and L3) might be available to antagonists within the A 1 AR binding cleft. According to the proposed pharmacophore scheme, the lead compound 12 engages interactions with the HB2 site (via the N2 nitrogen) as well as with the L2 and L3 sites (through the pendant and the fused benzene rings). The results of these studies prompted the replacement of the methyl with more lipophilic groups at the 10-position (to fill the putative L1 lipophilic pocket) as a strategy to improve A 1 AR affinity. Among the new compounds synthesized and tested, the 3,10-diphenyl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one (23) was characterized by a K i value of 18 nM which represents a 3.5-fold gain of A 1 AR affinity compared with the lead 12. A rhodopsin-based model of the bovine adenosine A 1 AR was built to highlight the binding mode of 23 and two wellknown A 1 AR antagonists (III and VII) and to guide future lead optimization projects. In our docking simulations, 23 receives a hydrogen bond (via the N1 nitrogen) from the side chain of Asn247 (corresponding to the HB1 and HB2 sites) and fills the L1, L2, and L3 lipophilic pockets with the 10-phenyl, 3-phenyl, and fused benzene rings, respectively.
Bioorganic & Medicinal Chemistry, 2005
A series of quinoline derivatives have been designed on the basis of results from a 3D search of ... more A series of quinoline derivatives have been designed on the basis of results from a 3D search of the Cambridge Structural Database using the nicotinic pharmacophore as a query and further modified using molecular modeling. Some of the synthesized compounds show nanomolar affinity for the central nicotinic receptor on rat cerebral cortex.
Bioorganic & Medicinal Chemistry, 2000
Three pyrrolyl heteroaryl sulfones (ethyl 1-[(1H-benzimidazol-2(3H)one-5-yl)sulfonyl]-1H-pyrrole-... more Three pyrrolyl heteroaryl sulfones (ethyl 1-[(1H-benzimidazol-2(3H)one-5-yl)sulfonyl]-1H-pyrrole-2-carboxyla te, ethyl 1-[(1H-benzimidazol-5(6)-yl)sulfonyl]-1H-pyrrole-2-carboxylate and ethyl 1-[(1H-benzotriazol-5(6)-yl)sulfonyl]-1H-pyrrole-2-carboxylate) were designed as novel HIV-1 reverse transcriptase non-nucleoside inhibitors using structure-based computational methods. Although these compounds were inactive in the cell-based assay, they inhibited the target enzyme with micromolar potency (IC50s = 2 microM, 3 microM and 9 microM, respectively).
Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Small-molecules acting as positive allosteric modulators (PAMs) of the A 2B adenosine receptor (A... more Small-molecules acting as positive allosteric modulators (PAMs) of the A 2B adenosine receptor (A 2B AR) could potentially represent a novel therapeutic strategy for pathological conditions characterised by altered bone homeostasis, including osteoporosis. We investigated a library of compounds (4-13) exhibiting different degrees of chemical similarity with three indole derivatives (1-3), which have been recently identified by us as PAMs of the A 2B AR able to promote mesenchymal stem cell differentiation and bone formation. Evaluation of mineralisation activity of 4-13 in the presence and in the absence of the agonist BAY60-6583 allowed the identification of lead compounds with therapeutic potential as anti-osteoporosis agents. Further biological characterisation of one of the most performing compounds, the benzofurane derivative 9, confirmed that such a molecule behaves as PAM of the A 2B AR.
Reviews in Computational Chemistry
The 3D means that the compounds are described by the relative loca-tions of properties in three... more The 3D means that the compounds are described by the relative loca-tions of properties in three-dimensional space. Usually the methods consider steric, electronic, hydrogen bonding, and hydrophobic (i,e., lipophilic) proper-ties. The 3D molecular descriptors of ...
Journal of Peptide Science, 2002
The C-terminal domain of the heterotrimeric G protein α-subunits plays a key role in selective ac... more The C-terminal domain of the heterotrimeric G protein α-subunits plays a key role in selective activation of G proteins by their cognate receptors. Several C-terminal fragments of Gα s (from 11 to 21 residues) were recently synthesized. The ability of these peptides to stimulate agonist binding was found to be related to their size. Gα s (380-394) is a 15-mer peptide of intermediate length among those synthesized and tested that displays a biological activity surprisingly weak compared with that of the corresponding 21-mer peptide, shown to be the most active. In the present investigation, Gα s (380-394) was subjected to a conformational NMR analysis in a fluorinated isotropic environment. An NMR structure, calculated on the basis of the data derived from conventional 1D and 2D homonuclear experiments, shows that the C-terminal residues of Gα s (380-394) are involved in a helical arrangement whose length is comparable to that of the most active 21-mer peptide. A comparative structural refinement of the NMR structures of Gα s (380-394) and Gα s (374-394)C 379 A was performed using molecular dynamics calculations. The results give structural elements to interpret the role played by both the backbone conformation and the side chain arrangement in determining the activity of the G protein C-terminal fragments. The orientation of the side chains allows the peptides to assume contacts crucial for the G protein/receptor interaction. In the 15-mer peptide the lack as well as the disorder of some N-terminal residues could explain the low biological activity observed.
Journal of Medicinal Chemistry, 2008
A number of derivatives of 4-amino-6-hydroxy-2-mercaptopyrimidine (5) were synthesized and biolog... more A number of derivatives of 4-amino-6-hydroxy-2-mercaptopyrimidine (5) were synthesized and biologically evaluated as A 3 adenosine receptor (A 3 AR) antagonists. The new compounds were designed as open chain analogues of a triazolopyrimidinone derivative displaying submicromolar affinity for the A 3 AR, which had been previously identified using a 3D database search. Substituents R, R′, and R′′ attached to the parent compound 5 were chosen according to factorial design and stepwise lead optimization approaches, taking into account the essentially hydrophobic nature of the A 3 AR binding site. As a result, 5m (R) n-C 3 H 7 , R′) 4-ClC 6 H 4 CH 2 , R′′) CH 3) was identified among the pyrimidine derivatives as the ligand featuring the best combination of potency and selectivity for the target receptor. This compound binds to the A 3 AR with a K i of 3.5 nM and is devoid of appreciable affinity for the A 1 , A 2A , and A 2B ARs.
Journal of Medicinal Chemistry, 2008
Novel N,N-disubstituted indol-3-ylglyoxylamides (1-56), bearing different combinations of substit... more Novel N,N-disubstituted indol-3-ylglyoxylamides (1-56), bearing different combinations of substituents R 1-R 5 , were synthesized and evaluated as ligands of the translocator protein (TSPO), the 18 kDa protein representing the minimal functional unit of the "peripheral-type benzodiazepine receptor" (PBR). Most of the new compounds showed a nanomolar/subnanomolar affinity for TSPO and stimulated steroid biosynthesis in rat C6 glioma cells with a potency similar to or higher than that of classic TSPO ligands such as PK 11195. Moreover, when evaluated in vivo by means of the elevated-plus-maze (EPM) paradigm in the rat, compound 32, the best-performing derivative in terms of TSPO affinity and pregnenolone production, showed clear anxiolytic effects. The results of this study suggested that the novel N,N-disubstituted indol-3ylglyoxylamides may represent a promising class of compounds potentially suited for the treatment of anxiety disorders.
Journal of Medicinal Chemistry, 2010
The 18 kDa translocator protein (TSPO) is a mitochondrial protein whose basal density is altered ... more The 18 kDa translocator protein (TSPO) is a mitochondrial protein whose basal density is altered in several diseases, with the result that the evaluation of its expression levels by means of molecular imaging techniques represents a promising diagnostic approach. Experimental procedures using a labeled ligand often cause loss of the bound probe, and consequently high affinity ligands covalently binding the receptor protein are needed to overcome this problem. We have previously described a series of N,N-dialkyl-(2-phenylindol-3-yl)glyoxylamides as potent and selective TSPO ligands. Starting from these derivatives, we designed novel TSPO irreversible ligands bearing an electrophilic isothiocyanato group (7, 8), together with an irreversible NBD-fluorescent probe (18). The TSPO affinity of the new irreversible ligands was measured on rat tissue homogenates by [ 3 H]Ro 5-4864 radiobinding kinetic assays, all compounds showing high affinities for the target protein. Further biological characterization of the fluorescent irreversible TSPO probe 18 was carried out by using fluorescent spectroscopy in human glioma cells.
Journal of Medicinal Chemistry, 1999
Results and Discussion Computer-Assisted Design of Novel DABOs. The computational work was carrie... more Results and Discussion Computer-Assisted Design of Novel DABOs. The computational work was carried out by molecular mechanics (Tripos force field 26), conformational analysis, docking, and graphics routines available within the SYBYL program. 27 Details of these procedures are described in the Experimental Section, whereas the results are summarized below.
Journal of Medicinal Chemistry, 1996
Two novel classes of pyrrolobenzothiazepinones and pyrrolobenzoxazepinones were investigated as p... more Two novel classes of pyrrolobenzothiazepinones and pyrrolobenzoxazepinones were investigated as potential anti-AIDS drugs. These compounds were found to inhibit HIV-1 reverse transcriptase (RT) enzyme in vitro and to prevent HIV-1 cytopathogenicity in T4 lymphocytes, without appreciable activity on HIV-2 cytopathic effects, and against HBV as well as calfthymus DNA R-polymerase. Their potency is influenced by substituents at position 6 and on the fused aromatic ring. Specifically, small lipophilic substituents at C-6 were preferred, whereas substitutions on the benzo-fused ring were found to be detrimental to activity, with respect to the unsubstituted compounds. Modification of the π-system at C-6 is well tolerated, although the replacement of the benzo-fused with a [2,3]naphtho-fused ring leads to a less active compound. Maximum potency and specificity is achieved with a phenyl and an ethyl group at position 6 of the pyrrolobenzoxazepinone system. In the enzymatic assay the oxazepinone derivative (()-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)-one 16e (IC 50) 0.25 µM) was found to be more potent than nevirapine (IC 50) 0.5 µM), tested in the same experimental conditions using rC‚dG as a template-primer. In cell culture assay benzoxazepine 16e was active against HIV-1, both wild type and AZT-sensitive, and HIV-1 (IIIB) strains, but not against HIV-2. In enzyme assay although 16e inhibited HIV-1 RT, it was inactive against the nevirapine-resistant recombinant RT Y181C at 50 µM. Molecular modeling studies suggest that these derivatives present a 3D pharmacophoric arrangement similar to that of other nonnucleoside inhibitors such as nevirapine.
Journal of Medicinal Chemistry, 2001
Acetic acid derivatives of [1,2,4]triazino[4,3-a]benzimidazole (TBI) were synthesized and tested ... more Acetic acid derivatives of [1,2,4]triazino[4,3-a]benzimidazole (TBI) were synthesized and tested in vitro and in vivo as a novel class of aldose reductase (ALR2) inhibitors. Compound 3, (10benzyl[1,2,4]triazino[4,3-a]benzimidazol-3,4(10H)-dion-2-yl)acetic acid, displayed the highest inhibitory activity (IC 50) 0.36 µM) and was found to be effective in preventing cataract development in severely galactosemic rats when administered as an eyedrop solution. All the compounds investigated were selective for ALR2, since none of them inhibited appreciably aldehyde reductase, sorbitol dehydrogenase, or glutathione reductase. The activity of 3 was lowered by inserting various substituents on the pendant phenyl ring, by shifting the acetic acid moiety from the 2 to the 3 position of the TBI nucleus, or by cleaving the TBI system to yield benzimidazolylidenehydrazines as open-chain analogues. A three-dimensional model of human ALR2 was built, taking into account the conformational changes induced by the binding of inhibitors such as zopolrestat, to simulate the docking of 3 into the enzyme active site. The theoretical binding mode of 3 was fully consistent with the structure-activity relationships in the TBI series and will guide the design of novel ALR2 inhibitors.
Journal of Medicinal Chemistry, 2002
Histone deacetylase 8 (HDAC8) is a promising drug target for multiple therapeutic applications. H... more Histone deacetylase 8 (HDAC8) is a promising drug target for multiple therapeutic applications. Here, we describe the modeling, design, synthesis, and biological evaluation of a novel series of C1-substituted tetrahydroisoquinoline (TIQ)-based HDAC8 inhibitors. Minimization of entropic loss upon ligand binding and use of the unique HDAC8 "open" conformation of the binding site yielded a successful strategy for improvement of both HDAC8 potency and selectivity. The TIQ-based 3g and 3n exhibited the highest 82 and 55 nM HDAC8 potency and 330-and 135-fold selectivity over HDAC1, respectively. Selectivity over other class I isoforms was comparable or better, whereas inhibition of HDAC6, a class II HDAC isoform, was below 50% at 10 μM. The cytotoxicity of 3g and 3n was evaluated in neuroblastoma cell lines, and 3n displayed concentration-dependent cytotoxicity similar to or better than that of PCI-34051. The selectivity of 3g and 3n was confirmed in SH-SY5Y cells as both did not increase the acetylation of histone H3 and α-tubulin. Discovery of the novel TIQ chemotype paves the way for the development of HDAC8 selective inhibitors for therapeutic applications.
Bioorganic & Medicinal Chemistry, 2005
The 2,3-dihydrospiro[4H-thiopyrano[2,3-b]pyridin-4,4&... more The 2,3-dihydrospiro[4H-thiopyrano[2,3-b]pyridin-4,4'-imidazolidine]-2',5'-dione 3 and its 7-methyl analogue 4 were synthesized and tested for their ability to inhibit aldose reductase (ALR2). To expand the structure-activity relationships, the sulfone 5 and the acetic acid derivative 7 were also prepared and tested. Compounds 3 and 4 proved to be potent ALR2 inhibitors, with IC50 values in the submicromolar range (0.96 and 0.94 microM, respectively) similar to that of sorbinil (0.65 microM). Moreover, compound 3 was found to be highly potent in preventing cataract development in severely galactosemic rats, like tolrestat, when administered as an eyedrop solution. Docking simulations of both R- and S-isomers of 3 into the ALR2 crystal structure were carried out to guide, prospectively, the design of new analogues.
Journal of Medicinal Chemistry, 1998
Frontiers in Pharmacology, 2021
The development of GPCR (G-coupled protein receptor) allosteric modulators has attracted increasi... more The development of GPCR (G-coupled protein receptor) allosteric modulators has attracted increasing interest in the last decades. The use of allosteric modulators in therapy offers several advantages with respect to orthosteric ones, as they can fine-tune the tissue responses to the endogenous agonist. Since the discovery of the first A1 adenosine receptor (AR) allosteric modulator in 1990, several efforts have been made to develop more potent molecules as well as allosteric modulators for all adenosine receptor subtypes. There are four subtypes of AR: A1, A2A, A2B, and A3. Positive allosteric modulators of the A1 AR have been proposed for the cure of pain. A3 positive allosteric modulators are thought to be beneficial during inflammatory processes. More recently, A2A and A2B AR allosteric modulators have also been disclosed. The A2B AR displays the lowest affinity for its endogenous ligand adenosine and is mainly activated as a consequence of tissue damage. The A2B AR activation ha...
MedChemComm, 2018
Three A adenosine receptor (AR) antagonists () selected from 4-acylamino-6-alkyloxy-2-alkylthiopy... more Three A adenosine receptor (AR) antagonists () selected from 4-acylamino-6-alkyloxy-2-alkylthiopyrimidines previously investigated by us were modified by inserting a methyl group on their ether or thioether side chains. These compounds gave us the chance to evaluate whether their higher lipophilicity, reduced conformational freedom and chirality might improve the potency towards the A AR. Racemic mixtures of were resolved using chiral HPLC methods and the absolute configurations of the enantiomers were assigned by chiroptical spectroscopy and density functional theory calculations. We measured the affinity for human A, A, A and A ARs of the racemic mixtures and the pure enantiomers of by radioligand competition binding experiments. Cell-based assays of the most potent enantiomers confirmed their A AR antagonist profiles. Our research led to the identification of ()- with high potency (0.5 nM) and selectivity as an A AR antagonist. Moreover we built a docking-model useful to design n...
ChemInform, 2010
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.