Solid-phase methods for the preparation of hydantoins are reviewed. Furthermore, an optimized met... more Solid-phase methods for the preparation of hydantoins are reviewed. Furthermore, an optimized method based on the concourse of 1,1'-carbonyldiimidazole allows the preparation of hydantoins without loss of chiral integrity.
Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) substrates show in... more Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) substrates show insulin-mimetic effects and are therefore potentially valuable molecules for the treatment of diabetes mellitus. Herein we review several structural and electronic aspects of SSAO arylalkylamine-based substrates. Two main modifications directly affect amine oxidase (AO) activity: 1) variation in ring substitution modulates the biological activity of the arylalkylamine ligand by converting a substrate into a substrate-like inhibitor, and 2) variation in the number of methylene units between the aromatic ring and the ammonium groups of the arylalkylamine substrates dramatically alters the oxidation rate between species. Furthermore, we review relevant information about mammalian SSAO/VAP-1 substrate selectivity and specificity over monoamine oxidases (MAOs).
Diketopiperazines, which are cyclic dipeptides, are often formed by a side reaction of solid-phas... more Diketopiperazines, which are cyclic dipeptides, are often formed by a side reaction of solid-phase peptide synthesis. Using the new “Backbone Amide Linker,” this chemistry can be conveniently harnessed for the intentional preparation of diketopiperazines. These products will be useful scaffolds for combinatorial chemistry, since they incorporate three different points of diversity: both amino acid side-chains and one (of the two)
We report the solid-phase synthesis of two different families, containing either diketopiperazine... more We report the solid-phase synthesis of two different families, containing either diketopiperazine or hydantoin structures, of rigidified RGD mimetics and their binding affinity to the αvβ3 receptor.
In solid-phase peptide synthesis, a side-reaction consisting of the premature and undesired remov... more In solid-phase peptide synthesis, a side-reaction consisting of the premature and undesired removal of the Fmoc group has been detected. This can be caused by a primary amine of sufficient basicity, such as the ε-amino of the Lys, present in the peptide resin. This side-reaction, which is not promoted by either the β-amino side-chain of the Dapa residue or the
An effective solid-phase preparation of anilides from supported carboxylic acids is described by ... more An effective solid-phase preparation of anilides from supported carboxylic acids is described by their activation as the corresponding acid chlorides with TMUCl Cl.
The combinatorial parallel synthesis of peptide-biphenyl hybrids on solid support using state of ... more The combinatorial parallel synthesis of peptide-biphenyl hybrids on solid support using state of the art of peptide synthesis is reported. Key steps were the N to C addition of an amino moiety, hydrolysis of the methyl ester, and the absence of cross-linked compounds when the 2,2′-diamino-1,1′-biphenyl was incorporated. When tested for activity as calpain inhibitors, some of the compounds exhibited IC 50 values in the nanomolar range.
European journal of medicinal chemistry, Jan 9, 2014
Here we synthesized carbosilane, generation 1 to 3, and PEG-based dendrons functionalized at the ... more Here we synthesized carbosilane, generation 1 to 3, and PEG-based dendrons functionalized at the periphery with NHBoc groups and at the focal point with azide and alkyne moieties, respectively. The coupling of these two types of dendrons via click chemistry led to the formation of new hybrid dendrimers with two distinct moieties, the hydrophobic carbosilane and the hydrophilic PEG-based dendron. The protected dendrimers were transformed into cationic ammonium dendrimers. These unique amphiphilic dendrimers were studied as vectors for gene therapy against HIV in peripheral blood mononuclear cells (PBMC) and their performance was compared with that of a PEG-free carbosilane dendrimer. The presence of the PEG moiety afforded lower toxicities and evidenced a weaker interaction between dendrimers and siRNA when compared to the homodendrimer analogous. Both features, lower toxicity and lower dendriplex strength, are key properties for use of these vectors as carriers of nucleic material.
The controlled presentation of biofunctionality is of key importance for hydrogel applications in... more The controlled presentation of biofunctionality is of key importance for hydrogel applications in cell-based regenerative medicine. Here, a versatile approach was demonstrated to present clustered binding epitopes in an injectable, thermoresponsive hydrogel. Well-defined multivalent dendrimers bearing four integrin binding sequences and an azido moiety were covalently grafted to propargylamine-derived hyaluronic acid (Hyal-pa) using copper-catalyzed alkyne-azide cycloaddition (CuAAC), and then combined with pN-modified hyaluronan (Hyal-pN). The dendrimers were prepared by synthesizing a bifunctional diethylenetriamine pentaacetic acid core with azido and NHBoc oligo(ethylene glycol) aminoethyl branches, then further conjugated with solid-phase synthesized RGDS and DGRS peptides. Azido terminated pN was synthesized by reversible addition-fragmentation chain transfer polymerization and reacted to Hyal-pa via CuAAC. Nuclear magnetic resonance (NMR), high performance liquid chromatograp...
A novel method for the synthesis of parasubstituted phenylalanine containing cyclic peptides is d... more A novel method for the synthesis of parasubstituted phenylalanine containing cyclic peptides is described. The main features of this strategy are the coupling of phenylalanine to the solid support through its side chain via a triazene linkage, on-resin cyclization of the peptide chain, cleavage of the cyclic peptide from the resin under mild acidic conditions and further transformation of the resulting diazonium salt. The usefulness of this approach is exemplified by the solid-phase synthesis of some derivatives of the naturally occurring cyclic depsipeptide zygosporamide.
European Journal of Pharmaceutics and Biopharmaceutics, 2015
The aim of the present study was to develop a novel strategy to deliver intracellularly the pepti... more The aim of the present study was to develop a novel strategy to deliver intracellularly the peptide GSE24.2 for the treatment of Dyskeratosis congenita (DC) and other defective telomerase disorders. For this purpose, biodegradable polymeric nanoparticles using poly (lactic-co-glycolic acid) (PLGA NPs) or poly (lactic-co-glycolic acid)-poly ethylene glycol (PLGA-PEG NPs) attached to either polycations or cell-penetrating peptides (CPPs) were prepared in order to increase their cellular uptake. The particles exhibited an adequate size and zeta potential, with good peptide loading and a biphasic pattern obtained in the in vitro release assay, showing an initial burst release and a later sustained release. GSE24.2 structural integrity after encapsulation was assessed using SDS-PAGE, revealing an unaltered peptide after the NPs elaboration. According to the cytotoxicity results, cell viability was not affected by uncoated polymeric NPs, but the incorporation of surface modifiers slightly decreased the viability of cells. The intracellular uptake exhibited a remarkable improvement of the internalization, when the NPs were conjugated to the CPPs. Finally, the bioactivity, addressed by measuring DNA damage rescue and telomerase reactivation, showed that some formulations had the lowest cytotoxicity and highest biological activity. These results proved that GSE24.2-loaded NPs could be delivered to cells, and therefore, become an effective approach for the treatment of DC and other defective telomerase syndromes.
A suitable combination of soluble and polymeric protecting groups and coupling reagents has allow... more A suitable combination of soluble and polymeric protecting groups and coupling reagents has allowed the first synthesis of the natural cyclodepsipeptide of marine origin Kahalalide B to be carried out.
A four-dimensional orthogonal protecting scheme that involves the acid-labile BAL linker in conju... more A four-dimensional orthogonal protecting scheme that involves the acid-labile BAL linker in conjunction with Fmoc, Alloc and pNb protecting groups, which can be removed by b-elimination, allyl transfer, and reductive hydrolysis, respectively, allows the solid-phase preparation of scaffolds based on a cyclic tetra-b-peptide with free amino side chains ready for further elaboration. acid. Amino acid symbols denote L-configuration unless otherwise noted.
Journal of the Chemical Society, Perkin Transactions 1, 1995
J. CHEM. SOC. PERKIN TRANS. I 1995 ... S-Phenylacetamidomethyl (Phacm): an orthogonal cysteine pr... more J. CHEM. SOC. PERKIN TRANS. I 1995 ... S-Phenylacetamidomethyl (Phacm): an orthogonal cysteine protecting ... Miriam Royo," Jordi Alsina," Ernest Giralt," Urszula Slomcyznska * 9S9a9b and Fernando Albericio *@ a Department of Organic Chemistry, University of Barcelona, ...
The design and synthesis of Lamellarin D conjugates with a nuclear localization signal peptide an... more The design and synthesis of Lamellarin D conjugates with a nuclear localization signal peptide and a poly(ethylene glycol)-based dendrimer are described. Conjugates 1-4 were obtained in 8-84% overall yields from the corresponding protected Lamellarin D. Conjugates 1 and 4 are 1.4- to 3.3-fold more cytotoxic than the parent compound against three human tumor cell lines (MDA-MB-231 breast, A-549 lung, and HT-29 colon). Besides, conjugates 3 and 4 showed a decrease in activity potency in BJ skin fibroblasts, a normal cell culture. Cellular internalization was analyzed, and a nuclear distribution pattern was observed for 4, which contains a nuclear localization signaling sequence.
The aim of this study was to assess the diagnostic accuracy of the proportion of prostate-specifi... more The aim of this study was to assess the diagnostic accuracy of the proportion of prostate-specific antigen (PSA) complexed to alpha(1)-antichymotrypsin (PSA-alpha(1)ACT:PSA ratio) in the differential diagnosis of prostate cancer (CaP) and benign prostatic hyperplasia (BPH) in men with total PSA of 10-30 microg/L. We used our immunoassays (ELISAs) for total PSA and PSA-alpha(1)ACT complex to study 146 men. In 123, total PSA was between 10 and 20 microg/L; 66 of these had CaP and 57 BPH. In 23 men, total PSA was between 20 and 30 microg/L; 14 of these had CaP and 9 BPH. We calculated the area under the ROC curves (AUC) for total PSA, PSA-alpha(1)ACT complex, and PSA-alpha(1)ACT:PSA ratio, and determined the cutoff points that gave sensitivities approaching 100%. In the total PSA range between 10 and 20 microg/L, the AUC was significantly higher for the PSA-alpha(1)ACT:PSA ratio (0.850) than for total PSA (0.507) and PSA-alpha(1)ACT complex (0.710; P <0.0001). A cutoff ratio of 0.62...
International Journal of Peptide Research and Therapeutics, 2011
The multifunctional character of tryptophan has made it a target for the development of new molec... more The multifunctional character of tryptophan has made it a target for the development of new molecules with therapeutic applications. In this sense the design of alternative solid phase routes would allow the widening of synthetic possibilities to access these molecules through conventional or combinatorial strategies. The present work describes a new strategy for side-chain anchoring of tryptophan to dihydropyranyl-functionalized polystyrene resins and its application to the synthesis of the natural diketopiperazine Brevianamide F. For this study a new handle (4-[(3,4-dihydro-2H-pyran-2-yl)methoxy]benzoic acid) was prepared in order to functionalize aminomethyl or methylbenzhydrylamine resins. A preliminary study in solution using Fmoc-Trp-OR (R = Allyl or Me) and suitable resin models showed that the formation of an hemiaminal linkage with the indole system could be brought about by either conventional or microwave heating in 1,2-dichloroethane and in the presence of pyridine p-toluenesulfonate in yields of 70-95% practically without the formation of subproducts. On the other hand the amino acid could be liberated from the resin at room temperature in yields of up to 90% using trifluoroacetic acid in dichloromethane in the presence of 1,3-dimethoxybenzene as a cation scavenger. The conditions found in solution for the reversible formation of the hemiaminal were only reproducible in solid-phase work using conventional heating. These conditions were used in the synthesis of Brevianamide F, furnishing the diketopiperazine in an overall yield of 56%. These results demonstrate the potential of this strategy for the preparation of new molecules based upon tryptophan as a synthetic precursor.
Solid-phase methods for the preparation of hydantoins are reviewed. Furthermore, an optimized met... more Solid-phase methods for the preparation of hydantoins are reviewed. Furthermore, an optimized method based on the concourse of 1,1'-carbonyldiimidazole allows the preparation of hydantoins without loss of chiral integrity.
Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) substrates show in... more Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) substrates show insulin-mimetic effects and are therefore potentially valuable molecules for the treatment of diabetes mellitus. Herein we review several structural and electronic aspects of SSAO arylalkylamine-based substrates. Two main modifications directly affect amine oxidase (AO) activity: 1) variation in ring substitution modulates the biological activity of the arylalkylamine ligand by converting a substrate into a substrate-like inhibitor, and 2) variation in the number of methylene units between the aromatic ring and the ammonium groups of the arylalkylamine substrates dramatically alters the oxidation rate between species. Furthermore, we review relevant information about mammalian SSAO/VAP-1 substrate selectivity and specificity over monoamine oxidases (MAOs).
Diketopiperazines, which are cyclic dipeptides, are often formed by a side reaction of solid-phas... more Diketopiperazines, which are cyclic dipeptides, are often formed by a side reaction of solid-phase peptide synthesis. Using the new “Backbone Amide Linker,” this chemistry can be conveniently harnessed for the intentional preparation of diketopiperazines. These products will be useful scaffolds for combinatorial chemistry, since they incorporate three different points of diversity: both amino acid side-chains and one (of the two)
We report the solid-phase synthesis of two different families, containing either diketopiperazine... more We report the solid-phase synthesis of two different families, containing either diketopiperazine or hydantoin structures, of rigidified RGD mimetics and their binding affinity to the αvβ3 receptor.
In solid-phase peptide synthesis, a side-reaction consisting of the premature and undesired remov... more In solid-phase peptide synthesis, a side-reaction consisting of the premature and undesired removal of the Fmoc group has been detected. This can be caused by a primary amine of sufficient basicity, such as the ε-amino of the Lys, present in the peptide resin. This side-reaction, which is not promoted by either the β-amino side-chain of the Dapa residue or the
An effective solid-phase preparation of anilides from supported carboxylic acids is described by ... more An effective solid-phase preparation of anilides from supported carboxylic acids is described by their activation as the corresponding acid chlorides with TMUCl Cl.
The combinatorial parallel synthesis of peptide-biphenyl hybrids on solid support using state of ... more The combinatorial parallel synthesis of peptide-biphenyl hybrids on solid support using state of the art of peptide synthesis is reported. Key steps were the N to C addition of an amino moiety, hydrolysis of the methyl ester, and the absence of cross-linked compounds when the 2,2′-diamino-1,1′-biphenyl was incorporated. When tested for activity as calpain inhibitors, some of the compounds exhibited IC 50 values in the nanomolar range.
European journal of medicinal chemistry, Jan 9, 2014
Here we synthesized carbosilane, generation 1 to 3, and PEG-based dendrons functionalized at the ... more Here we synthesized carbosilane, generation 1 to 3, and PEG-based dendrons functionalized at the periphery with NHBoc groups and at the focal point with azide and alkyne moieties, respectively. The coupling of these two types of dendrons via click chemistry led to the formation of new hybrid dendrimers with two distinct moieties, the hydrophobic carbosilane and the hydrophilic PEG-based dendron. The protected dendrimers were transformed into cationic ammonium dendrimers. These unique amphiphilic dendrimers were studied as vectors for gene therapy against HIV in peripheral blood mononuclear cells (PBMC) and their performance was compared with that of a PEG-free carbosilane dendrimer. The presence of the PEG moiety afforded lower toxicities and evidenced a weaker interaction between dendrimers and siRNA when compared to the homodendrimer analogous. Both features, lower toxicity and lower dendriplex strength, are key properties for use of these vectors as carriers of nucleic material.
The controlled presentation of biofunctionality is of key importance for hydrogel applications in... more The controlled presentation of biofunctionality is of key importance for hydrogel applications in cell-based regenerative medicine. Here, a versatile approach was demonstrated to present clustered binding epitopes in an injectable, thermoresponsive hydrogel. Well-defined multivalent dendrimers bearing four integrin binding sequences and an azido moiety were covalently grafted to propargylamine-derived hyaluronic acid (Hyal-pa) using copper-catalyzed alkyne-azide cycloaddition (CuAAC), and then combined with pN-modified hyaluronan (Hyal-pN). The dendrimers were prepared by synthesizing a bifunctional diethylenetriamine pentaacetic acid core with azido and NHBoc oligo(ethylene glycol) aminoethyl branches, then further conjugated with solid-phase synthesized RGDS and DGRS peptides. Azido terminated pN was synthesized by reversible addition-fragmentation chain transfer polymerization and reacted to Hyal-pa via CuAAC. Nuclear magnetic resonance (NMR), high performance liquid chromatograp...
A novel method for the synthesis of parasubstituted phenylalanine containing cyclic peptides is d... more A novel method for the synthesis of parasubstituted phenylalanine containing cyclic peptides is described. The main features of this strategy are the coupling of phenylalanine to the solid support through its side chain via a triazene linkage, on-resin cyclization of the peptide chain, cleavage of the cyclic peptide from the resin under mild acidic conditions and further transformation of the resulting diazonium salt. The usefulness of this approach is exemplified by the solid-phase synthesis of some derivatives of the naturally occurring cyclic depsipeptide zygosporamide.
European Journal of Pharmaceutics and Biopharmaceutics, 2015
The aim of the present study was to develop a novel strategy to deliver intracellularly the pepti... more The aim of the present study was to develop a novel strategy to deliver intracellularly the peptide GSE24.2 for the treatment of Dyskeratosis congenita (DC) and other defective telomerase disorders. For this purpose, biodegradable polymeric nanoparticles using poly (lactic-co-glycolic acid) (PLGA NPs) or poly (lactic-co-glycolic acid)-poly ethylene glycol (PLGA-PEG NPs) attached to either polycations or cell-penetrating peptides (CPPs) were prepared in order to increase their cellular uptake. The particles exhibited an adequate size and zeta potential, with good peptide loading and a biphasic pattern obtained in the in vitro release assay, showing an initial burst release and a later sustained release. GSE24.2 structural integrity after encapsulation was assessed using SDS-PAGE, revealing an unaltered peptide after the NPs elaboration. According to the cytotoxicity results, cell viability was not affected by uncoated polymeric NPs, but the incorporation of surface modifiers slightly decreased the viability of cells. The intracellular uptake exhibited a remarkable improvement of the internalization, when the NPs were conjugated to the CPPs. Finally, the bioactivity, addressed by measuring DNA damage rescue and telomerase reactivation, showed that some formulations had the lowest cytotoxicity and highest biological activity. These results proved that GSE24.2-loaded NPs could be delivered to cells, and therefore, become an effective approach for the treatment of DC and other defective telomerase syndromes.
A suitable combination of soluble and polymeric protecting groups and coupling reagents has allow... more A suitable combination of soluble and polymeric protecting groups and coupling reagents has allowed the first synthesis of the natural cyclodepsipeptide of marine origin Kahalalide B to be carried out.
A four-dimensional orthogonal protecting scheme that involves the acid-labile BAL linker in conju... more A four-dimensional orthogonal protecting scheme that involves the acid-labile BAL linker in conjunction with Fmoc, Alloc and pNb protecting groups, which can be removed by b-elimination, allyl transfer, and reductive hydrolysis, respectively, allows the solid-phase preparation of scaffolds based on a cyclic tetra-b-peptide with free amino side chains ready for further elaboration. acid. Amino acid symbols denote L-configuration unless otherwise noted.
Journal of the Chemical Society, Perkin Transactions 1, 1995
J. CHEM. SOC. PERKIN TRANS. I 1995 ... S-Phenylacetamidomethyl (Phacm): an orthogonal cysteine pr... more J. CHEM. SOC. PERKIN TRANS. I 1995 ... S-Phenylacetamidomethyl (Phacm): an orthogonal cysteine protecting ... Miriam Royo,&amp;amp;quot; Jordi Alsina,&amp;amp;quot; Ernest Giralt,&amp;amp;quot; Urszula Slomcyznska * 9S9a9b and Fernando Albericio *@ a Department of Organic Chemistry, University of Barcelona, ...
The design and synthesis of Lamellarin D conjugates with a nuclear localization signal peptide an... more The design and synthesis of Lamellarin D conjugates with a nuclear localization signal peptide and a poly(ethylene glycol)-based dendrimer are described. Conjugates 1-4 were obtained in 8-84% overall yields from the corresponding protected Lamellarin D. Conjugates 1 and 4 are 1.4- to 3.3-fold more cytotoxic than the parent compound against three human tumor cell lines (MDA-MB-231 breast, A-549 lung, and HT-29 colon). Besides, conjugates 3 and 4 showed a decrease in activity potency in BJ skin fibroblasts, a normal cell culture. Cellular internalization was analyzed, and a nuclear distribution pattern was observed for 4, which contains a nuclear localization signaling sequence.
The aim of this study was to assess the diagnostic accuracy of the proportion of prostate-specifi... more The aim of this study was to assess the diagnostic accuracy of the proportion of prostate-specific antigen (PSA) complexed to alpha(1)-antichymotrypsin (PSA-alpha(1)ACT:PSA ratio) in the differential diagnosis of prostate cancer (CaP) and benign prostatic hyperplasia (BPH) in men with total PSA of 10-30 microg/L. We used our immunoassays (ELISAs) for total PSA and PSA-alpha(1)ACT complex to study 146 men. In 123, total PSA was between 10 and 20 microg/L; 66 of these had CaP and 57 BPH. In 23 men, total PSA was between 20 and 30 microg/L; 14 of these had CaP and 9 BPH. We calculated the area under the ROC curves (AUC) for total PSA, PSA-alpha(1)ACT complex, and PSA-alpha(1)ACT:PSA ratio, and determined the cutoff points that gave sensitivities approaching 100%. In the total PSA range between 10 and 20 microg/L, the AUC was significantly higher for the PSA-alpha(1)ACT:PSA ratio (0.850) than for total PSA (0.507) and PSA-alpha(1)ACT complex (0.710; P <0.0001). A cutoff ratio of 0.62...
International Journal of Peptide Research and Therapeutics, 2011
The multifunctional character of tryptophan has made it a target for the development of new molec... more The multifunctional character of tryptophan has made it a target for the development of new molecules with therapeutic applications. In this sense the design of alternative solid phase routes would allow the widening of synthetic possibilities to access these molecules through conventional or combinatorial strategies. The present work describes a new strategy for side-chain anchoring of tryptophan to dihydropyranyl-functionalized polystyrene resins and its application to the synthesis of the natural diketopiperazine Brevianamide F. For this study a new handle (4-[(3,4-dihydro-2H-pyran-2-yl)methoxy]benzoic acid) was prepared in order to functionalize aminomethyl or methylbenzhydrylamine resins. A preliminary study in solution using Fmoc-Trp-OR (R = Allyl or Me) and suitable resin models showed that the formation of an hemiaminal linkage with the indole system could be brought about by either conventional or microwave heating in 1,2-dichloroethane and in the presence of pyridine p-toluenesulfonate in yields of 70-95% practically without the formation of subproducts. On the other hand the amino acid could be liberated from the resin at room temperature in yields of up to 90% using trifluoroacetic acid in dichloromethane in the presence of 1,3-dimethoxybenzene as a cation scavenger. The conditions found in solution for the reversible formation of the hemiaminal were only reproducible in solid-phase work using conventional heating. These conditions were used in the synthesis of Brevianamide F, furnishing the diketopiperazine in an overall yield of 56%. These results demonstrate the potential of this strategy for the preparation of new molecules based upon tryptophan as a synthetic precursor.
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Papers by Miriam Royo