Stephanie Federico | Università degli Studi di Trieste (original) (raw)
Papers by Stephanie Federico
Current Pharmaceutical Design, 2009
The development of ligands for the A(3) adenosine receptor (AR) has been directed mainly by tradi... more The development of ligands for the A(3) adenosine receptor (AR) has been directed mainly by traditional medicinal chemistry, but the influence of structure-based approaches is increasing. Rhodopsin-based homology modeling had been used for many years to obtain three-dimensional models of the A(3)AR, and different A(3)AR models have been published describing the hypothetical interactions with known A(3)AR ligands having different chemical scaffolds. The recently published structure of the human A(2A)AR provides a new template for GPCR modeling, however even use of the A(2A)AR as a template for modeling other AR subtypes is still imprecise. The models compared here are based on bovine rhodopsin, the human beta(2)-adrenergic receptor, and the A(2A)AR as templates. The sequence of the human A(3)AR contains only one cysteine residue (Cys166) in the second extracellular loop (EL2), which putatively forms a conserved disulfide bridge with the respective cysteine residues of TM3 (Cys83). Homology models of the A(3)AR have been helpful in providing structural hypotheses for the design of new ligands. Site-directed mutagenesis of the A(3)AR shows an important role in ligand recognition for specific residues in TM3, TM6 and TM7.
In the last few years, the possibility to discover new potent and selective adenosine receptors (... more In the last few years, the possibility to discover new potent and selective adenosine receptors (ARs) antagonists was intensively explored. Briefly, the adenosine receptor (AR) family belongs to GPCR family A, which includes four different subtypes, referred to as A 1 , A 2A , A 2B and A 3 , which are widely but differentially distributed throughout the body. Diverse potent and selective ligands for each subtype have demonstrated the potential therapeutic role of the adenosine receptor in several physiopathological processes. In particular, A 1 AR selective antagonists have shown anxiolytic effects, and they have been reported as promising candidates for the treatment of cognitive disorders, such as dementia. The antagonism selectivity for hA 1 AR is also the proposed mechanism for some diuretic agents, which are considered effective in congestive hearth failure and in edema. A 2A AR antagonists have a neuroprotective activity during ischemic processes and seem to play a role in the reduction of neuronal damage in Parkinson's or Huntington's diseases. A potential therapeutic activity in the asthma disease has been discovered for A 2B AR selective antagonists or mixed antagonists to hA 2B AR and hA 3 AR. A 2B AR antagonists are also studied as hypoglycaemic agents in diabetes, while A 3 AR antagonists have a potential application in tumor growth inhibition and in the treatment of glaucoma.
Current Topics in Medicinal Chemistry, 2016
Adenosine was defined as a neuromodulator which exerts its action by interaction with specific G-... more Adenosine was defined as a neuromodulator which exerts its action by interaction with specific G-protein coupled receptor termed adenosine receptors. Adenosine receptors are expressed in several tissues and cells of our body and exist as four different subtypes of these receptors: A1, A2A, A2B and A3. In the last years significant efforts were made to obtain highly potent and selective ligands for the four adenosine receptors subtypes. Both agonists and antagonists were used as pharmacological tools to study therapeutic implications of enhancing or blocking the adenosine receptors activity, and some of these compounds have reached clinical phases. The pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines (PTPs) represent one of the several templates designed as adenosine receptor antagonists. A lot of synthetic work was made on this scaffold in order to obtain potent A2A and A3 antagonists. Here were reviewed the synthetic approaches followed by both academia and industry to introduce different substituents at different positions of the PTP nucleus, in particular at the 2, 5, 7, 8 and 9 positions. Nevertheless PTP derivatives are tricyclic compounds with a high molecular weight which exhibit limitations such as poor aqueous solubility and difficult synthetic preparation. With the aim to obtain derivatives with the same potency and selectivity of PTP but with better drug-like properties, researchers made structural simplification of this scaffold. Replacement of the pyrazole or triazole rings of PTP led to the [1,2,4]triazolo[1,5-c]pyrimidine and pyrazolo[3,4-d]pyrimidine derivatives, respectively. Synthetic strategies for these compounds were reported, combined with the SAR profile on the adenosine receptors.
European journal of medicinal chemistry, Jan 27, 2016
The structure-activity relationship of new 5,7-disubstituted-[1,2,4]triazolo[1,5-a][1,3,5]triazin... more The structure-activity relationship of new 5,7-disubstituted-[1,2,4]triazolo[1,5-a][1,3,5]triazines as adenosine receptors (ARs) antagonists has been explored. The introduction of a benzylamino group at C5 with a free amino group at C7 increases the affinity toward all the ARs subtypes (10: KihA1 = 94.6 nM; KihA2A = 1.11 nM; IC50hA2B = 2214 nM; KihA3 = 30.8 nM). Replacing the free amino group at C7 with a phenylureido moiety yields a potent and quite selective hA2A AR antagonist (14: hA2A AR Ki = 1.44 nM; hA1/hA2A = 216.0; hA3/hA2A = 20.6). This trend diverges from the analysis on the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine series previously reported. With the help of an in silico receptor-driven approach, we have rationalized these observations and elucidated from a molecular point of view the role of the benzylamino group at C5 in determining affinity toward the hA2A AR.
Journal of Medicinal Chemistry, 2011
The structure−activity relationship (SAR) of 1,2,4-triazolo[1,5-a]-1,3,5-triazine derivatives rel... more The structure−activity relationship (SAR) of 1,2,4-triazolo[1,5-a]-1,3,5-triazine derivatives related to ZM241385 as antagonists of the A 2A adenosine receptor (AR) was explored through the synthesis of analogues substituted at the 5 position. The A 2A AR X-ray structure was used to ...
PLOS ONE, 2015
A new series of pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine (PTP) derivatives has been develo... more A new series of pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine (PTP) derivatives has been developed in order to explore their affinity and selectivity profile at the four adenosine receptor subtypes. In particular, the PTP scaffold was conjugated at the C2 position with the 1-(3-trifluoromethyl-benzyl)-1H-pyrazole, a group believed to confer potency and selectivity toward the human (h) A2B adenosine receptor (AR) to the xanthine ligand 8-(1-(3-(trifluoromethyl)benzyl)-1H-pyrazol-4-yl)-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione (CVT 6975). Interestingly, the synthesized compounds turned out to be inactive at the hA2B AR but they displayed affinity at the hA3 AR in the nanomolar range. The best compound of the series (6) shows both high affinity (hA3 AR Ki = 11 nM) and selectivity (A1/A3 and A2A/A3 > 9090; A2B/A3 > 909) at the hA3 AR. To better rationalize these results, a molecular docking study on the four AR subtypes was performed for all the synthesized compounds. In addition, CTV 6975 and two close analogues have been subjected to the same molecular docking protocol to investigate the role of the 1-(3-trifluoromethyl-benzyl)-1H-pyrazole on the binding at the four ARs.
Trends in Pharmacological Sciences, 2015
G-protein-coupled receptors (GPCRs) are among the most intensely investigated drug targets. The r... more G-protein-coupled receptors (GPCRs) are among the most intensely investigated drug targets. The recent revolutions in protein engineering and molecular modeling algorithms have overturned the research paradigm in the GPCR field. While the numerous ligand-bound X-ray structures determined have provided invaluable insights into GPCR structure and function, the development of algorithms exploiting graphics processing units (GPUs) has made the simulation of GPCRs in explicit lipid-water environments feasible within reasonable computation times. In this review we present a survey of the recent advances in structure-based drug design approaches with a particular emphasis on the elucidation of the ligand recognition process in class A GPCRs by means of membrane molecular dynamics (MD) simulations.
Frontiers in Medicinal Chemistry - Online
ABSTRACT
Biochemical pharmacology
The physiological role of the A(3) adenosine receptor (AR) was explored in cardiac ischaemia, inf... more The physiological role of the A(3) adenosine receptor (AR) was explored in cardiac ischaemia, inflammatory diseases and cancer. We report a new fluorophore-conjugated human (h) A(3)AR antagonist for application to cell-based assays in ligand discovery and for receptor imaging. Fluorescent pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ylamine (pyrazolo-triazolo-pyrimidine, PTP) and triazolo[1,5-c]quinazolin-5-yl)amine (triazolo-quinazoline, TQ) AR antagonists were compared. A chain-extended and click-conjugated Alexa Fluor-488 TQ derivative (MRS5449) displayed a radioligand binding K(i) value of 6.4±2.5nM in hA(3)AR-expressing CHO cell membranes. MRS5449 antagonized hA(3)AR agonist-induced inhibition of cyclic AMP accumulation in a concentration-dependent manner (K(B)=4.8nM). Using flow cytometry (FCM), MRS5449 saturated hA(3)ARs with very high specific-to-nonspecific binding ratio with an equilibrium binding constant 5.15nM, comparable to the K(d) value of 6.65nM calculated from ...
Current pharmaceutical design, 2009
How do we communicate with the outside world? How are our senses of vision, smell, taste and pain... more How do we communicate with the outside world? How are our senses of vision, smell, taste and pain controlled at the cellular and molecular levels? What causes medical conditions like allergies, hypertension, depression, obesity and various central nervous system disorders? G protein-coupled receptors (GPCRs) provide a major part of the answer to all of these questions. GPCRs constitute the largest family of cell-surface receptors and in humans are encoded by more than 900 genes. GPCRs convert extracellular messages into ...
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.
Journal of Medicinal Chemistry, 2014
The structure-activity relationship (SAR) of new 5,8-disubstituted-1,2,4-triazolo[1,5-c]pyrimidin... more The structure-activity relationship (SAR) of new 5,8-disubstituted-1,2,4-triazolo[1,5-c]pyrimidines as adenosine receptors (ARs) antagonists has been explored. All the synthesized compounds show affinity for the hA2A and hA3 ARs depending on the substitution patterns at the 5 and 8 positions. In particular, a free amino group at the 5 position with an ethoxycarbonyl group at the 8 position leads to potent and quite selective hA2A antagonists (compound 12: hA2A AR Ki=3.32 nM; hA1/hA2A=55.6; hA2A/hA3=0.01), whereas the introduction of a methylamino function at the 5 position yields a good binding profile at the hA3 AR (compound 23: hA3 AR Ki=4.14 nM, hA1/hA3=236; hA2A/hA3=25). Through an in silico receptor-driven approach, we have determined the most favorable orientation of the substitutions at the 5 and 8 positions of the 1,2,4-triazolo[1,5-c]pyrimidine (TP) scaffold and, accordingly, we have elucidated the observed SAR.
The field of therapeutic application of the A₃ adenosine receptor (A₃AR) antagonists represents a... more The field of therapeutic application of the A₃ adenosine receptor (A₃AR) antagonists represents a rapidly growing and intense area of research in the adenosine field. Even if there are currently no A₃AR antagonists in clinical phases, in light of the plethora of biological effects attributed to A₃ARs, substantial efforts in medicinal chemistry have been directed toward developing antagonists for the A₃AR subtype. In this review, we summarize the more recent and promising evidences of the possible A₃AR application as drug candidates, and the role of the receptor-driven design in their in silico characterization.
Collection of Czechoslovak Chemical Communications, 2011
... unife.it c Dipartimento di Scienze Farmaceutiche, Università degli Studi di Trieste, Piazzale... more ... unife.it c Dipartimento di Scienze Farmaceutiche, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy; 1 stephanie.federico@phd.units ... 9-Methyl-8-(4-hydroxyphenyl)adenine (5) In a steel vial cooled to 80 °C, compound 20 (1.55 g, 5.95 mmol) and an excess ...
![Research paper thumbnail of A facile and novel synthesis of N(2)-, C(6)-substituted pyrazolo[3,4-d]pyrimidine-4 carboxylate derivatives as adenosine receptor antagonists](https://attachments.academia-assets.com/52847021/thumbnails/1.jpg)
](European journal of medicinal chemistry, Jan 22, 2015
An efficient synthetic procedure was adopted to synthesize a series of new molecules containing t... more An efficient synthetic procedure was adopted to synthesize a series of new molecules containing the pyrazolo[3,4-d]pyrimidine (PP) scaffold, which have been evaluated as promising human adenosine receptor (AR) antagonists. The effect of substitutions at the N(2), C(4) and C(6) positions of PPs on the affinity and selectivity towards the adenosine receptors were explored. Most of the pyrazolo[3,4-d]pyrimidine-4-carboxylates displayed from moderate to good affinity at the human A3AR (hA3AR), as indicated by the low micromolar range of Ki values (Ki hA3AR = 0.7-34 μM). In particular, compounds 60 and 62 displayed good affinity at the hA3AR (60, Ki hA3AR = 2.2 μM and 62, Ki hA3AR = 2.9 μM) and selectivity towards the other AR subtypes (60, >46-fold selective and 62, >34-fold selective, respectively). In view of these results, these novel PP analogues were docked both in the crystallographic structure of the hA2AAR and in a homology model of the hA3AR in order to support the struct...
International Journal of Medicinal Chemistry, 2011
In the past few decades, medicinal chemistry research towards potent and selective antagonists of... more In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A 1 , A 2A , A 2B , and A 3 ) has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR) profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4triazolo- [1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists.
Bioorganic & Medicinal Chemistry - BIOORGAN MED CHEM, 2010
A new series of triazolotriazines variously substituted at the C5 and N7 (5–25) positions was syn... more A new series of triazolotriazines variously substituted at the C5 and N7 (5–25) positions was synthesized and fully characterized at the four adenosine receptor (AR) subtypes. In particular, arylacetyl or arylcarbamoyl moieties were introduced at the N7 position, which enhanced affinity at the hA2B and hA3 ARs, respectively, when utilized on the pyrazolo-triazolopyrimidine nucleus as we reported in the past. In general, compounds with a free amino group at the 7 position (5, 6), showed good affinity at the rat (r) A2A AR (range 18.3–96.5nM), while the introduction of a phenylcarbamoyl moiety at the N7 position (12, 19, 24) slightly increased the affinity at the hA3 AR (range 311–633nM) with respect to the unsubstituted derivatives. The binding profiles of the synthesized analogues seemed to correlate with the substitutions at the C5 and N7 positions. At the hA2B AR, derivative 5, which contained a free amino group at the 7 position, was the most potent (EC50 3.42μM) and could repres...
Molecular Pharmaceutics, 2012
We propose a potential antiparkinsonian prodrug DP-L-A(2A)ANT (2) obtained by amidic conjugation ... more We propose a potential antiparkinsonian prodrug DP-L-A(2A)ANT (2) obtained by amidic conjugation of dopamine (1) via a succinic spacer to a new triazolo-triazine A(2A) adenosine receptor (AR) antagonist A(2A)ANT (3). The affinity of 2 and its hydrolysis products-1, 3, dopamine-linker DP-L (4) and A(2A)ANT-linker L-A(2A)ANT (5)-was evaluated for hA(1), hA(2A), hA(2B) and hA(3) ARs and rat striatum A(2A)ARs or D(2) receptors. The hydrolysis patterns of 2, 4 and 5 and the stabilities of 1 and 3 were evaluated by HPLC analysis in human whole blood and rat brain homogenates. High hA(2A) affinity was shown by compounds 2 (K(i) = 7.32 ± 0.65 nM), 3 (K(i) = 35 ± 3 nM) and 5 (K(i) = 72 ± 5 nM), whose affinity values were similar in rat striatum. These compounds were not able to change dopamine affinity for D(2) receptors but counteracted the CGS 21680-induced reduction of dopamine affinity. DP-L (4) was inactive on adenosine and dopaminergic receptors. As for stability studies, compounds 4 and 5 were not degraded in incubation media. In human blood, the prodrug 2 was hydrolyzed (half-life = 2.73 ± 0.23 h) mainly on the amidic bound coupling the A(2A)ANT (3), whereas in rat brain homogenates the prodrug 2 was hydrolyzed (half-life > eight hours) exclusively on the amidic bound coupling dopamine, allowing its controlled release and increasing its poor stability as characterized by half-life = 22.5 ± 1.5 min.
Current Pharmaceutical Design, 2009
The development of ligands for the A(3) adenosine receptor (AR) has been directed mainly by tradi... more The development of ligands for the A(3) adenosine receptor (AR) has been directed mainly by traditional medicinal chemistry, but the influence of structure-based approaches is increasing. Rhodopsin-based homology modeling had been used for many years to obtain three-dimensional models of the A(3)AR, and different A(3)AR models have been published describing the hypothetical interactions with known A(3)AR ligands having different chemical scaffolds. The recently published structure of the human A(2A)AR provides a new template for GPCR modeling, however even use of the A(2A)AR as a template for modeling other AR subtypes is still imprecise. The models compared here are based on bovine rhodopsin, the human beta(2)-adrenergic receptor, and the A(2A)AR as templates. The sequence of the human A(3)AR contains only one cysteine residue (Cys166) in the second extracellular loop (EL2), which putatively forms a conserved disulfide bridge with the respective cysteine residues of TM3 (Cys83). Homology models of the A(3)AR have been helpful in providing structural hypotheses for the design of new ligands. Site-directed mutagenesis of the A(3)AR shows an important role in ligand recognition for specific residues in TM3, TM6 and TM7.
In the last few years, the possibility to discover new potent and selective adenosine receptors (... more In the last few years, the possibility to discover new potent and selective adenosine receptors (ARs) antagonists was intensively explored. Briefly, the adenosine receptor (AR) family belongs to GPCR family A, which includes four different subtypes, referred to as A 1 , A 2A , A 2B and A 3 , which are widely but differentially distributed throughout the body. Diverse potent and selective ligands for each subtype have demonstrated the potential therapeutic role of the adenosine receptor in several physiopathological processes. In particular, A 1 AR selective antagonists have shown anxiolytic effects, and they have been reported as promising candidates for the treatment of cognitive disorders, such as dementia. The antagonism selectivity for hA 1 AR is also the proposed mechanism for some diuretic agents, which are considered effective in congestive hearth failure and in edema. A 2A AR antagonists have a neuroprotective activity during ischemic processes and seem to play a role in the reduction of neuronal damage in Parkinson's or Huntington's diseases. A potential therapeutic activity in the asthma disease has been discovered for A 2B AR selective antagonists or mixed antagonists to hA 2B AR and hA 3 AR. A 2B AR antagonists are also studied as hypoglycaemic agents in diabetes, while A 3 AR antagonists have a potential application in tumor growth inhibition and in the treatment of glaucoma.
Current Topics in Medicinal Chemistry, 2016
Adenosine was defined as a neuromodulator which exerts its action by interaction with specific G-... more Adenosine was defined as a neuromodulator which exerts its action by interaction with specific G-protein coupled receptor termed adenosine receptors. Adenosine receptors are expressed in several tissues and cells of our body and exist as four different subtypes of these receptors: A1, A2A, A2B and A3. In the last years significant efforts were made to obtain highly potent and selective ligands for the four adenosine receptors subtypes. Both agonists and antagonists were used as pharmacological tools to study therapeutic implications of enhancing or blocking the adenosine receptors activity, and some of these compounds have reached clinical phases. The pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines (PTPs) represent one of the several templates designed as adenosine receptor antagonists. A lot of synthetic work was made on this scaffold in order to obtain potent A2A and A3 antagonists. Here were reviewed the synthetic approaches followed by both academia and industry to introduce different substituents at different positions of the PTP nucleus, in particular at the 2, 5, 7, 8 and 9 positions. Nevertheless PTP derivatives are tricyclic compounds with a high molecular weight which exhibit limitations such as poor aqueous solubility and difficult synthetic preparation. With the aim to obtain derivatives with the same potency and selectivity of PTP but with better drug-like properties, researchers made structural simplification of this scaffold. Replacement of the pyrazole or triazole rings of PTP led to the [1,2,4]triazolo[1,5-c]pyrimidine and pyrazolo[3,4-d]pyrimidine derivatives, respectively. Synthetic strategies for these compounds were reported, combined with the SAR profile on the adenosine receptors.
European journal of medicinal chemistry, Jan 27, 2016
The structure-activity relationship of new 5,7-disubstituted-[1,2,4]triazolo[1,5-a][1,3,5]triazin... more The structure-activity relationship of new 5,7-disubstituted-[1,2,4]triazolo[1,5-a][1,3,5]triazines as adenosine receptors (ARs) antagonists has been explored. The introduction of a benzylamino group at C5 with a free amino group at C7 increases the affinity toward all the ARs subtypes (10: KihA1 = 94.6 nM; KihA2A = 1.11 nM; IC50hA2B = 2214 nM; KihA3 = 30.8 nM). Replacing the free amino group at C7 with a phenylureido moiety yields a potent and quite selective hA2A AR antagonist (14: hA2A AR Ki = 1.44 nM; hA1/hA2A = 216.0; hA3/hA2A = 20.6). This trend diverges from the analysis on the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine series previously reported. With the help of an in silico receptor-driven approach, we have rationalized these observations and elucidated from a molecular point of view the role of the benzylamino group at C5 in determining affinity toward the hA2A AR.
Journal of Medicinal Chemistry, 2011
The structure−activity relationship (SAR) of 1,2,4-triazolo[1,5-a]-1,3,5-triazine derivatives rel... more The structure−activity relationship (SAR) of 1,2,4-triazolo[1,5-a]-1,3,5-triazine derivatives related to ZM241385 as antagonists of the A 2A adenosine receptor (AR) was explored through the synthesis of analogues substituted at the 5 position. The A 2A AR X-ray structure was used to ...
PLOS ONE, 2015
A new series of pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine (PTP) derivatives has been develo... more A new series of pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine (PTP) derivatives has been developed in order to explore their affinity and selectivity profile at the four adenosine receptor subtypes. In particular, the PTP scaffold was conjugated at the C2 position with the 1-(3-trifluoromethyl-benzyl)-1H-pyrazole, a group believed to confer potency and selectivity toward the human (h) A2B adenosine receptor (AR) to the xanthine ligand 8-(1-(3-(trifluoromethyl)benzyl)-1H-pyrazol-4-yl)-1,3-dimethyl-1H-purine-2,6(3H,7H)-dione (CVT 6975). Interestingly, the synthesized compounds turned out to be inactive at the hA2B AR but they displayed affinity at the hA3 AR in the nanomolar range. The best compound of the series (6) shows both high affinity (hA3 AR Ki = 11 nM) and selectivity (A1/A3 and A2A/A3 > 9090; A2B/A3 > 909) at the hA3 AR. To better rationalize these results, a molecular docking study on the four AR subtypes was performed for all the synthesized compounds. In addition, CTV 6975 and two close analogues have been subjected to the same molecular docking protocol to investigate the role of the 1-(3-trifluoromethyl-benzyl)-1H-pyrazole on the binding at the four ARs.
Trends in Pharmacological Sciences, 2015
G-protein-coupled receptors (GPCRs) are among the most intensely investigated drug targets. The r... more G-protein-coupled receptors (GPCRs) are among the most intensely investigated drug targets. The recent revolutions in protein engineering and molecular modeling algorithms have overturned the research paradigm in the GPCR field. While the numerous ligand-bound X-ray structures determined have provided invaluable insights into GPCR structure and function, the development of algorithms exploiting graphics processing units (GPUs) has made the simulation of GPCRs in explicit lipid-water environments feasible within reasonable computation times. In this review we present a survey of the recent advances in structure-based drug design approaches with a particular emphasis on the elucidation of the ligand recognition process in class A GPCRs by means of membrane molecular dynamics (MD) simulations.
Frontiers in Medicinal Chemistry - Online
ABSTRACT
Biochemical pharmacology
The physiological role of the A(3) adenosine receptor (AR) was explored in cardiac ischaemia, inf... more The physiological role of the A(3) adenosine receptor (AR) was explored in cardiac ischaemia, inflammatory diseases and cancer. We report a new fluorophore-conjugated human (h) A(3)AR antagonist for application to cell-based assays in ligand discovery and for receptor imaging. Fluorescent pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ylamine (pyrazolo-triazolo-pyrimidine, PTP) and triazolo[1,5-c]quinazolin-5-yl)amine (triazolo-quinazoline, TQ) AR antagonists were compared. A chain-extended and click-conjugated Alexa Fluor-488 TQ derivative (MRS5449) displayed a radioligand binding K(i) value of 6.4±2.5nM in hA(3)AR-expressing CHO cell membranes. MRS5449 antagonized hA(3)AR agonist-induced inhibition of cyclic AMP accumulation in a concentration-dependent manner (K(B)=4.8nM). Using flow cytometry (FCM), MRS5449 saturated hA(3)ARs with very high specific-to-nonspecific binding ratio with an equilibrium binding constant 5.15nM, comparable to the K(d) value of 6.65nM calculated from ...
Current pharmaceutical design, 2009
How do we communicate with the outside world? How are our senses of vision, smell, taste and pain... more How do we communicate with the outside world? How are our senses of vision, smell, taste and pain controlled at the cellular and molecular levels? What causes medical conditions like allergies, hypertension, depression, obesity and various central nervous system disorders? G protein-coupled receptors (GPCRs) provide a major part of the answer to all of these questions. GPCRs constitute the largest family of cell-surface receptors and in humans are encoded by more than 900 genes. GPCRs convert extracellular messages into ...
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.
Journal of Medicinal Chemistry, 2014
The structure-activity relationship (SAR) of new 5,8-disubstituted-1,2,4-triazolo[1,5-c]pyrimidin... more The structure-activity relationship (SAR) of new 5,8-disubstituted-1,2,4-triazolo[1,5-c]pyrimidines as adenosine receptors (ARs) antagonists has been explored. All the synthesized compounds show affinity for the hA2A and hA3 ARs depending on the substitution patterns at the 5 and 8 positions. In particular, a free amino group at the 5 position with an ethoxycarbonyl group at the 8 position leads to potent and quite selective hA2A antagonists (compound 12: hA2A AR Ki=3.32 nM; hA1/hA2A=55.6; hA2A/hA3=0.01), whereas the introduction of a methylamino function at the 5 position yields a good binding profile at the hA3 AR (compound 23: hA3 AR Ki=4.14 nM, hA1/hA3=236; hA2A/hA3=25). Through an in silico receptor-driven approach, we have determined the most favorable orientation of the substitutions at the 5 and 8 positions of the 1,2,4-triazolo[1,5-c]pyrimidine (TP) scaffold and, accordingly, we have elucidated the observed SAR.
The field of therapeutic application of the A₃ adenosine receptor (A₃AR) antagonists represents a... more The field of therapeutic application of the A₃ adenosine receptor (A₃AR) antagonists represents a rapidly growing and intense area of research in the adenosine field. Even if there are currently no A₃AR antagonists in clinical phases, in light of the plethora of biological effects attributed to A₃ARs, substantial efforts in medicinal chemistry have been directed toward developing antagonists for the A₃AR subtype. In this review, we summarize the more recent and promising evidences of the possible A₃AR application as drug candidates, and the role of the receptor-driven design in their in silico characterization.
Collection of Czechoslovak Chemical Communications, 2011
... unife.it c Dipartimento di Scienze Farmaceutiche, Università degli Studi di Trieste, Piazzale... more ... unife.it c Dipartimento di Scienze Farmaceutiche, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy; 1 stephanie.federico@phd.units ... 9-Methyl-8-(4-hydroxyphenyl)adenine (5) In a steel vial cooled to 80 °C, compound 20 (1.55 g, 5.95 mmol) and an excess ...
European journal of medicinal chemistry, Jan 22, 2015
An efficient synthetic procedure was adopted to synthesize a series of new molecules containing t... more An efficient synthetic procedure was adopted to synthesize a series of new molecules containing the pyrazolo[3,4-d]pyrimidine (PP) scaffold, which have been evaluated as promising human adenosine receptor (AR) antagonists. The effect of substitutions at the N(2), C(4) and C(6) positions of PPs on the affinity and selectivity towards the adenosine receptors were explored. Most of the pyrazolo[3,4-d]pyrimidine-4-carboxylates displayed from moderate to good affinity at the human A3AR (hA3AR), as indicated by the low micromolar range of Ki values (Ki hA3AR = 0.7-34 μM). In particular, compounds 60 and 62 displayed good affinity at the hA3AR (60, Ki hA3AR = 2.2 μM and 62, Ki hA3AR = 2.9 μM) and selectivity towards the other AR subtypes (60, >46-fold selective and 62, >34-fold selective, respectively). In view of these results, these novel PP analogues were docked both in the crystallographic structure of the hA2AAR and in a homology model of the hA3AR in order to support the struct...
International Journal of Medicinal Chemistry, 2011
In the past few decades, medicinal chemistry research towards potent and selective antagonists of... more In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A 1 , A 2A , A 2B , and A 3 ) has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR) profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4triazolo- [1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists.
Bioorganic & Medicinal Chemistry - BIOORGAN MED CHEM, 2010
A new series of triazolotriazines variously substituted at the C5 and N7 (5–25) positions was syn... more A new series of triazolotriazines variously substituted at the C5 and N7 (5–25) positions was synthesized and fully characterized at the four adenosine receptor (AR) subtypes. In particular, arylacetyl or arylcarbamoyl moieties were introduced at the N7 position, which enhanced affinity at the hA2B and hA3 ARs, respectively, when utilized on the pyrazolo-triazolopyrimidine nucleus as we reported in the past. In general, compounds with a free amino group at the 7 position (5, 6), showed good affinity at the rat (r) A2A AR (range 18.3–96.5nM), while the introduction of a phenylcarbamoyl moiety at the N7 position (12, 19, 24) slightly increased the affinity at the hA3 AR (range 311–633nM) with respect to the unsubstituted derivatives. The binding profiles of the synthesized analogues seemed to correlate with the substitutions at the C5 and N7 positions. At the hA2B AR, derivative 5, which contained a free amino group at the 7 position, was the most potent (EC50 3.42μM) and could repres...
Molecular Pharmaceutics, 2012
We propose a potential antiparkinsonian prodrug DP-L-A(2A)ANT (2) obtained by amidic conjugation ... more We propose a potential antiparkinsonian prodrug DP-L-A(2A)ANT (2) obtained by amidic conjugation of dopamine (1) via a succinic spacer to a new triazolo-triazine A(2A) adenosine receptor (AR) antagonist A(2A)ANT (3). The affinity of 2 and its hydrolysis products-1, 3, dopamine-linker DP-L (4) and A(2A)ANT-linker L-A(2A)ANT (5)-was evaluated for hA(1), hA(2A), hA(2B) and hA(3) ARs and rat striatum A(2A)ARs or D(2) receptors. The hydrolysis patterns of 2, 4 and 5 and the stabilities of 1 and 3 were evaluated by HPLC analysis in human whole blood and rat brain homogenates. High hA(2A) affinity was shown by compounds 2 (K(i) = 7.32 ± 0.65 nM), 3 (K(i) = 35 ± 3 nM) and 5 (K(i) = 72 ± 5 nM), whose affinity values were similar in rat striatum. These compounds were not able to change dopamine affinity for D(2) receptors but counteracted the CGS 21680-induced reduction of dopamine affinity. DP-L (4) was inactive on adenosine and dopaminergic receptors. As for stability studies, compounds 4 and 5 were not degraded in incubation media. In human blood, the prodrug 2 was hydrolyzed (half-life = 2.73 ± 0.23 h) mainly on the amidic bound coupling the A(2A)ANT (3), whereas in rat brain homogenates the prodrug 2 was hydrolyzed (half-life > eight hours) exclusively on the amidic bound coupling dopamine, allowing its controlled release and increasing its poor stability as characterized by half-life = 22.5 ± 1.5 min.