Lorenzo Napoli | Università degli Studi di Napoli "Federico II" (original) (raw)

Papers by Lorenzo Napoli

Research paper thumbnail of Degradation of some representative polycyclic aromatic hydrocarbons by the water-soluble protein extracts from Zea mays L. cv PR32-B10

The ability of the water-soluble protein extracts from Zea mais L. cv. PR32-B10 to degrade some r... more The ability of the water-soluble protein extracts from Zea mais L. cv. PR32-B10 to degrade some representative
polycyclic aromatic hydrocarbons (PAHs), has been evaluated. Surface sterilized seeds of corn
(Zea mais L. Pioneer cv. PR32-B10) were hydroponically cultivated in a growth chamber under nostressful
conditions. The water-soluble protein extracts isolated from maize tissues showed peroxidase,
polyphenol oxidase and catalase activities. Incubation of the extracts with naphthalene, fluorene,
phenanthrene and pyrene, led to formation of oxidized and/or degradation products. GC-MS and TLC
monitoring of the processes showed that naphthalene, phenanthrene, fluorene and pyrene underwent
100%, 78%, 92% and 65% oxidative degradation, respectively, after 120 min. The chemical structure of the
degradation products were determined by 1H NMR and ESI-MS spectrometry.

Research paper thumbnail of Design, Synthesis and Characterisation of a Fluorescently Labelled CyPLOS Ionophore

Chemistry - A European Journal, 2010

Scheme 1. General scheme for the synthesis and applications of the glucoside 8.

Research paper thumbnail of Synthesis of 4-Substituted Pyrimidine 2′,3′-Dideoxynucleosides

Nucleosides and Nucleotides, 1991

Rea"ti", of 5 ' -O-( 4,4'-dimethoxytriphenylmethyl )-3 '-deoxythymidine wlth triphenylphosphine/c... more Rea"ti", of 5 ' -O-( 4,4'-dimethoxytriphenylmethyl )-3 '-deoxythymidine wlth triphenylphosphine/carbon tetrachloride, fo11owed by deprotection of the 5'-hydroxyl group, afforded the 4-chloro derivative 3 from which some 4-substituted pyrimldin-2( 1 H )one-2' , J'-dideoxyribosides were obtained by nucleo-ph11ic substitution under very mild conditions.

Research paper thumbnail of Synthetic studies on the glycosylation of the base residues of inosine and uridine

Journal of the Chemical Society, Perkin Transactions 1, 1999

Ribosylation and glucosylation of the base residues of inosine and uridine have been efficiently ... more Ribosylation and glucosylation of the base residues of inosine and uridine have been efficiently achieved using Mitsunobu reaction, leading to the N-1 and 6-O-glycosylinosine and N-3-glycosyluridine derivatives, all with β configuration at the glycosidic carbon. The unprecedented 5-amino-1-(β--ribofuranosyl)imidazole-4-[N-(β--glucopyranosyl)carboxamide] has also been synthesised.

Research paper thumbnail of Reactions of Pd(PPh3)4 with 3′,5′-Di-O- acetylthymidine: Oxidative addition of Pd(PPh3)4 on thymidine N3 and C4 atoms

Organometallics, 2005

Oxidative addition reactions of Pd(PPh 3 ) 4 on the pyrimidine nucleosides 3′,5′-di-Oacetylthymid... more Oxidative addition reactions of Pd(PPh 3 ) 4 on the pyrimidine nucleosides 3′,5′-di-Oacetylthymidine and 3′,5′-di-O-acetyl-4-chlorothymidine and on the nucleobase 1-methylthymine have been investigated. N3 and C4 metal coordinated complexes 3 and 7 were isolated and characterized by spectroscopic techniques. Moreover, the crystal structure of the trans-[PdCl(1-methyl thymine)(PPh 3 ) 2 ]‚H 2 O (4) is reported.

Research paper thumbnail of Use of controlled pore glass in solid phase oligosaccharide synthesis. Application to the semiautomated synthesis of a glyconucleotide conjugate

Tetrahedron Letters, 1998

Three polymeric supports (polystyrene, Tentagel and controlled pore glass) have been tested far s... more Three polymeric supports (polystyrene, Tentagel and controlled pore glass) have been tested far solid phase synthesis of oligosaccharides based on the trichloroacetimidate methodology. Controlled pore glass has been found to yield satisfactory results with TMSOTf as the glycosylation promoter. An application to the on-line preparation of a glyconucleotide is also reported.

Research paper thumbnail of Solid phase synthesis of oligosaccharides

Tetrahedron Letters, 1996

... PII: S00404039(96)010209 00404039 96 15.00 + 0.00 Solid Phase Synthesis of Oligosaccharides M... more ... PII: S00404039(96)010209 00404039 96 15.00 + 0.00 Solid Phase Synthesis of Oligosaccharides Matteo Adinolfi, Gaspare Barone, Lorenzo De Napoli*, Alfonso Iadonisi and Gennaro Piceialli Dipartimento di Chimica Organica e Biologic, a, Universi di Napoli "Federico II" via ...

Research paper thumbnail of Reaction of 3?,5?-di-O-acetyl-2?-deoxyinosine with the chlorinating agent PPh3?CCl4: synthesis of the 6-chloroderivative and of a new base linked dimer, useful intermediate to 15N-1-labelled 2?-deoxyinosine

Journal of The Chemical Society-perkin Transactions 1, 1994

Abstract Treatment of 3′, 5′-di-O-acetyl-2′-deoxyinosine 1 with PPh 3–CCl 4 in the presence of ca... more Abstract Treatment of 3′, 5′-di-O-acetyl-2′-deoxyinosine 1 with PPh 3–CCl 4 in the presence of catalytic 1, 8-diazabicyclo [5.4. 0] undec-7-ene (DBU) afforded 6-chloro-9-(2′-deoxy-3′, 5′ di-O-acetyl-β-D-ribofuranosyl) purine 3. Use of an excess of DBU gave the ...

Research paper thumbnail of Improved synthesis of isoguanosine and 6-substituted xanthosine derivatives

Journal of The Chemical Society-perkin Transactions 1, 1995

Abstract Isoguanosine 1 was obtained in 76% overall yield starting from 2′, 3′, 5′-tri-O-acetylxa... more Abstract Isoguanosine 1 was obtained in 76% overall yield starting from 2′, 3′, 5′-tri-O-acetylxanthosine 3 in a reaction involving the chloro derivative 4 and the N-(purin-6-yl) pyridinium salt derivative 8 which also proved to be new and valuable synthetic ...

Research paper thumbnail of β-amino acid residues: Conformational characterization of an N- and C-protectedhomo-β-(S)-leucine

Letters in Peptide Science, 1997

An N-and C-protected derivative of homo-~J-leucine, Fmoc-homo-~-(S)-leucine methyl ester, synthes... more An N-and C-protected derivative of homo-~J-leucine, Fmoc-homo-~-(S)-leucine methyl ester, synthesized from the corresponding proteinogenic parent c~-amino acid in enantiopure form has been fully characterized in the solid state by X-ray diffraction analysis. The crystal conformation of this new residue indicates an extended conformation for this homo-~-residue, with the q0 torsion angle being more constrained than the g and ~ angles.

Research paper thumbnail of A new synthesis of oxanosine and 2′-deoxyoxanosine

Tetrahedron Letters, 1998

An easy and more efficient synthesis of oxanosine and 2'-deoxyoxanosine has been developed, a key... more An easy and more efficient synthesis of oxanosine and 2'-deoxyoxanosine has been developed, a key step in the reported synthesis is a new photochemical transformation by UV irradiation of 1-hydroxy derivatives of inosine.

Research paper thumbnail of The absolute configuration of the axane sesquiterpenes from the sponge axinella cannabina

Tetrahedron Letters, 1977

Research paper thumbnail of 13C-NMR spectrum and absolute stereochemistry of furoscalarol

Tetrahedron Letters, 1978

Research paper thumbnail of Solid phase glycosidation of oligonucleotides

Tetrahedron Letters, 1999

CPG-bound nucleosides (deoxyguanosine excepted) can be stereoselectively glycosylated in high yie... more CPG-bound nucleosides (deoxyguanosine excepted) can be stereoselectively glycosylated in high yield at their 5'-hydroxyl by a "disarmed" trichioroacetimidate donor in the presence of stoichiometric amounts of TMSOTf (5 eq.) and in short reaction times. These results allowed the solid-phase synthesis of an oligonucleotide functionalized at both ends with sugar residues.

Research paper thumbnail of A new ferrocenemethyl-thymidine nucleoside: Synthesis, incorporation into oligonucleotides and optical spectroscopic studies on the resulting single strand, duplex and triplex structures

Tetrahedron, 1999

A new thymidine analogue, bearing a ferrocenemethyl residue at the N-3 position of the base, was ... more A new thymidine analogue, bearing a ferrocenemethyl residue at the N-3 position of the base, was synthesized in high yields via Mitsunobu reaction of ferrocenemethanol with sugar protected thymidine, converted into the corresponding 3'-phosphoramidite and incorporated into oligonucleotides. Duplex and triplex formation experiments, evaluated by UV and CD spectroscopy, showed a dramatic decrease of the affinity towards complementary single strands, while for triplexes, the introduction of a ferrocene residue in the third strand resulted in higher melting temperatures, associated with a reduced content of triplex structure.

Research paper thumbnail of Synthesis and characterization of new 3′-3′ linked oligodeoxyribonucleotides for alternate strand triple helix formation

Tetrahedron, 1999

Protected forms of 1,2,3-propanetriol and cis, cis-l,3,5-cyclohexanetriol were incorporated onto ... more Protected forms of 1,2,3-propanetriol and cis, cis-l,3,5-cyclohexanetriol were incorporated onto solid supports which were exploited in the solid phase synthesis of 3'-3' linked oligodeoxyribonucleotides (ODNs), involving only nucleoside 3'-phosphoramidites as building blocks. UV thermal denaturation analysis showed the ability of ODNs with this inversion of polarity motif to cooperatively hybridize with duplexes of the type 5'-(Pu)m(PY)n-3' in an alternate strand recognition approach.

Research paper thumbnail of Solid phase synthesis of oligonucleotides tethered to oligo-glucose phosphate tails

Tetrahedron, 2002

Oligonucleotides conjugated at both 3 0 and 5 0 -ends with glucose residues, 4,6-linked through a... more Oligonucleotides conjugated at both 3 0 and 5 0 -ends with glucose residues, 4,6-linked through a phosphodiester bridge, have been synthesized by sequential addition of a 6-O-DMT-glucose-4-phosphoramidite building block following a standard automated ODN assembly procedure. Two 3 0 ,5 0 -bis-glycoconjugated 18-mers, designed for antisense experiments, have been prepared and their hybridization properties with a complementary DNA fragment evaluated by UV thermal analysis. q

Research paper thumbnail of Solid phase synthesis of DNA-3′-PNA chimeras by using Bhoc/Fmoc PNA monomers

Tetrahedron, 2001

AbstractÐOligonucleotides carrying a peptide nucleic acid (PNA) tail at the 3 0 -end have been ef... more AbstractÐOligonucleotides carrying a peptide nucleic acid (PNA) tail at the 3 0 -end have been ef®ciently prepared by an on-line automated synthetic protocol exploiting commercially available Bhoc/Fmoc PNA monomers for the assembly of the PNA tract, followed by a deprotection/reprotection of the base protecting groups. The syntheses of the ODN domain in the chimeras have then been performed by standard methods. The hybridization properties of the synthesized chimeras with complementary DNA fragments have been investigated by thermal denaturation experiments. q

Research paper thumbnail of A Rapid and Simple Chromatographic Separation of Diastereomers of Silibinin and Their Oxidation to Produce 2,3-Dehydrosilybin Enantiomers in an Optically Pure Form

Planta Medica, 2013

Silybin A and B were separated from commercial silibinin using the preparative HPLC method. The d... more Silybin A and B were separated from commercial silibinin using the preparative HPLC method. The described method is rapid and effective in obtaining gram-scale amounts of two diastereoisomers with minimal effort. In our approach, silibinin was dissolved in THF (solubility greater than 100 mg/mL), an alternative solvent to H 2 O or MeOH in which silibinin has a very low solubility (ca 0.05-1.5 mg/mL), and then separated into its two components using preparative RP-HPLC. By starting with purified diastereoisomers, it was possible to obtain the two enantiomers of 2,3-dehydrosilybin in good yields and optically pure using an efficient oxidation procedure. All of the purified products were fully characterised using NMR ( 1 H, 13 C), CD, [α] D , and ESI MS analyses. The purities of the products, which were evaluated using analytical HPLC, were greater than 98 % in all cases.

Research paper thumbnail of Modulating the activity of oligonucleotides by carbohydrate conjugation: solid phase synthesis of sucrose-oligonucleotide hybrids

Organic & Biomolecular Chemistry, 2004

In order to expand the repertoire of available oligosaccharide-oligonucleotide hybrids, the on-li... more In order to expand the repertoire of available oligosaccharide-oligonucleotide hybrids, the on-line solid phase synthesis of oligonucleotides conjugated at the 3'-and/or 5'-end with a preformed disaccharide unit has been performed. The key compound in the synthetic scheme described here is an appropriate phosphoramidite derivative of fully protected sucrose, used in association with a solid support functionalized with DMT-protected sucrose. The sucrose units at both ends of selected oligonucleotide sequences were shown to increase their chemical and enzymatic stability, while not interfering with duplex formation and with the ability of G-rich sequences to adopt a quadruplex structure.

Research paper thumbnail of Degradation of some representative polycyclic aromatic hydrocarbons by the water-soluble protein extracts from Zea mays L. cv PR32-B10

The ability of the water-soluble protein extracts from Zea mais L. cv. PR32-B10 to degrade some r... more The ability of the water-soluble protein extracts from Zea mais L. cv. PR32-B10 to degrade some representative
polycyclic aromatic hydrocarbons (PAHs), has been evaluated. Surface sterilized seeds of corn
(Zea mais L. Pioneer cv. PR32-B10) were hydroponically cultivated in a growth chamber under nostressful
conditions. The water-soluble protein extracts isolated from maize tissues showed peroxidase,
polyphenol oxidase and catalase activities. Incubation of the extracts with naphthalene, fluorene,
phenanthrene and pyrene, led to formation of oxidized and/or degradation products. GC-MS and TLC
monitoring of the processes showed that naphthalene, phenanthrene, fluorene and pyrene underwent
100%, 78%, 92% and 65% oxidative degradation, respectively, after 120 min. The chemical structure of the
degradation products were determined by 1H NMR and ESI-MS spectrometry.

Research paper thumbnail of Design, Synthesis and Characterisation of a Fluorescently Labelled CyPLOS Ionophore

Chemistry - A European Journal, 2010

Scheme 1. General scheme for the synthesis and applications of the glucoside 8.

Research paper thumbnail of Synthesis of 4-Substituted Pyrimidine 2′,3′-Dideoxynucleosides

Nucleosides and Nucleotides, 1991

Rea"ti", of 5 ' -O-( 4,4'-dimethoxytriphenylmethyl )-3 '-deoxythymidine wlth triphenylphosphine/c... more Rea"ti", of 5 ' -O-( 4,4'-dimethoxytriphenylmethyl )-3 '-deoxythymidine wlth triphenylphosphine/carbon tetrachloride, fo11owed by deprotection of the 5'-hydroxyl group, afforded the 4-chloro derivative 3 from which some 4-substituted pyrimldin-2( 1 H )one-2' , J'-dideoxyribosides were obtained by nucleo-ph11ic substitution under very mild conditions.

Research paper thumbnail of Synthetic studies on the glycosylation of the base residues of inosine and uridine

Journal of the Chemical Society, Perkin Transactions 1, 1999

Ribosylation and glucosylation of the base residues of inosine and uridine have been efficiently ... more Ribosylation and glucosylation of the base residues of inosine and uridine have been efficiently achieved using Mitsunobu reaction, leading to the N-1 and 6-O-glycosylinosine and N-3-glycosyluridine derivatives, all with β configuration at the glycosidic carbon. The unprecedented 5-amino-1-(β--ribofuranosyl)imidazole-4-[N-(β--glucopyranosyl)carboxamide] has also been synthesised.

Research paper thumbnail of Reactions of Pd(PPh3)4 with 3′,5′-Di-O- acetylthymidine: Oxidative addition of Pd(PPh3)4 on thymidine N3 and C4 atoms

Organometallics, 2005

Oxidative addition reactions of Pd(PPh 3 ) 4 on the pyrimidine nucleosides 3′,5′-di-Oacetylthymid... more Oxidative addition reactions of Pd(PPh 3 ) 4 on the pyrimidine nucleosides 3′,5′-di-Oacetylthymidine and 3′,5′-di-O-acetyl-4-chlorothymidine and on the nucleobase 1-methylthymine have been investigated. N3 and C4 metal coordinated complexes 3 and 7 were isolated and characterized by spectroscopic techniques. Moreover, the crystal structure of the trans-[PdCl(1-methyl thymine)(PPh 3 ) 2 ]‚H 2 O (4) is reported.

Research paper thumbnail of Use of controlled pore glass in solid phase oligosaccharide synthesis. Application to the semiautomated synthesis of a glyconucleotide conjugate

Tetrahedron Letters, 1998

Three polymeric supports (polystyrene, Tentagel and controlled pore glass) have been tested far s... more Three polymeric supports (polystyrene, Tentagel and controlled pore glass) have been tested far solid phase synthesis of oligosaccharides based on the trichloroacetimidate methodology. Controlled pore glass has been found to yield satisfactory results with TMSOTf as the glycosylation promoter. An application to the on-line preparation of a glyconucleotide is also reported.

Research paper thumbnail of Solid phase synthesis of oligosaccharides

Tetrahedron Letters, 1996

... PII: S00404039(96)010209 00404039 96 15.00 + 0.00 Solid Phase Synthesis of Oligosaccharides M... more ... PII: S00404039(96)010209 00404039 96 15.00 + 0.00 Solid Phase Synthesis of Oligosaccharides Matteo Adinolfi, Gaspare Barone, Lorenzo De Napoli*, Alfonso Iadonisi and Gennaro Piceialli Dipartimento di Chimica Organica e Biologic, a, Universi di Napoli "Federico II" via ...

Research paper thumbnail of Reaction of 3?,5?-di-O-acetyl-2?-deoxyinosine with the chlorinating agent PPh3?CCl4: synthesis of the 6-chloroderivative and of a new base linked dimer, useful intermediate to 15N-1-labelled 2?-deoxyinosine

Journal of The Chemical Society-perkin Transactions 1, 1994

Abstract Treatment of 3′, 5′-di-O-acetyl-2′-deoxyinosine 1 with PPh 3–CCl 4 in the presence of ca... more Abstract Treatment of 3′, 5′-di-O-acetyl-2′-deoxyinosine 1 with PPh 3–CCl 4 in the presence of catalytic 1, 8-diazabicyclo [5.4. 0] undec-7-ene (DBU) afforded 6-chloro-9-(2′-deoxy-3′, 5′ di-O-acetyl-β-D-ribofuranosyl) purine 3. Use of an excess of DBU gave the ...

Research paper thumbnail of Improved synthesis of isoguanosine and 6-substituted xanthosine derivatives

Journal of The Chemical Society-perkin Transactions 1, 1995

Abstract Isoguanosine 1 was obtained in 76% overall yield starting from 2′, 3′, 5′-tri-O-acetylxa... more Abstract Isoguanosine 1 was obtained in 76% overall yield starting from 2′, 3′, 5′-tri-O-acetylxanthosine 3 in a reaction involving the chloro derivative 4 and the N-(purin-6-yl) pyridinium salt derivative 8 which also proved to be new and valuable synthetic ...

Research paper thumbnail of β-amino acid residues: Conformational characterization of an N- and C-protectedhomo-β-(S)-leucine

Letters in Peptide Science, 1997

An N-and C-protected derivative of homo-~J-leucine, Fmoc-homo-~-(S)-leucine methyl ester, synthes... more An N-and C-protected derivative of homo-~J-leucine, Fmoc-homo-~-(S)-leucine methyl ester, synthesized from the corresponding proteinogenic parent c~-amino acid in enantiopure form has been fully characterized in the solid state by X-ray diffraction analysis. The crystal conformation of this new residue indicates an extended conformation for this homo-~-residue, with the q0 torsion angle being more constrained than the g and ~ angles.

Research paper thumbnail of A new synthesis of oxanosine and 2′-deoxyoxanosine

Tetrahedron Letters, 1998

An easy and more efficient synthesis of oxanosine and 2'-deoxyoxanosine has been developed, a key... more An easy and more efficient synthesis of oxanosine and 2'-deoxyoxanosine has been developed, a key step in the reported synthesis is a new photochemical transformation by UV irradiation of 1-hydroxy derivatives of inosine.

Research paper thumbnail of The absolute configuration of the axane sesquiterpenes from the sponge axinella cannabina

Tetrahedron Letters, 1977

Research paper thumbnail of 13C-NMR spectrum and absolute stereochemistry of furoscalarol

Tetrahedron Letters, 1978

Research paper thumbnail of Solid phase glycosidation of oligonucleotides

Tetrahedron Letters, 1999

CPG-bound nucleosides (deoxyguanosine excepted) can be stereoselectively glycosylated in high yie... more CPG-bound nucleosides (deoxyguanosine excepted) can be stereoselectively glycosylated in high yield at their 5'-hydroxyl by a "disarmed" trichioroacetimidate donor in the presence of stoichiometric amounts of TMSOTf (5 eq.) and in short reaction times. These results allowed the solid-phase synthesis of an oligonucleotide functionalized at both ends with sugar residues.

Research paper thumbnail of A new ferrocenemethyl-thymidine nucleoside: Synthesis, incorporation into oligonucleotides and optical spectroscopic studies on the resulting single strand, duplex and triplex structures

Tetrahedron, 1999

A new thymidine analogue, bearing a ferrocenemethyl residue at the N-3 position of the base, was ... more A new thymidine analogue, bearing a ferrocenemethyl residue at the N-3 position of the base, was synthesized in high yields via Mitsunobu reaction of ferrocenemethanol with sugar protected thymidine, converted into the corresponding 3'-phosphoramidite and incorporated into oligonucleotides. Duplex and triplex formation experiments, evaluated by UV and CD spectroscopy, showed a dramatic decrease of the affinity towards complementary single strands, while for triplexes, the introduction of a ferrocene residue in the third strand resulted in higher melting temperatures, associated with a reduced content of triplex structure.

Research paper thumbnail of Synthesis and characterization of new 3′-3′ linked oligodeoxyribonucleotides for alternate strand triple helix formation

Tetrahedron, 1999

Protected forms of 1,2,3-propanetriol and cis, cis-l,3,5-cyclohexanetriol were incorporated onto ... more Protected forms of 1,2,3-propanetriol and cis, cis-l,3,5-cyclohexanetriol were incorporated onto solid supports which were exploited in the solid phase synthesis of 3'-3' linked oligodeoxyribonucleotides (ODNs), involving only nucleoside 3'-phosphoramidites as building blocks. UV thermal denaturation analysis showed the ability of ODNs with this inversion of polarity motif to cooperatively hybridize with duplexes of the type 5'-(Pu)m(PY)n-3' in an alternate strand recognition approach.

Research paper thumbnail of Solid phase synthesis of oligonucleotides tethered to oligo-glucose phosphate tails

Tetrahedron, 2002

Oligonucleotides conjugated at both 3 0 and 5 0 -ends with glucose residues, 4,6-linked through a... more Oligonucleotides conjugated at both 3 0 and 5 0 -ends with glucose residues, 4,6-linked through a phosphodiester bridge, have been synthesized by sequential addition of a 6-O-DMT-glucose-4-phosphoramidite building block following a standard automated ODN assembly procedure. Two 3 0 ,5 0 -bis-glycoconjugated 18-mers, designed for antisense experiments, have been prepared and their hybridization properties with a complementary DNA fragment evaluated by UV thermal analysis. q

Research paper thumbnail of Solid phase synthesis of DNA-3′-PNA chimeras by using Bhoc/Fmoc PNA monomers

Tetrahedron, 2001

AbstractÐOligonucleotides carrying a peptide nucleic acid (PNA) tail at the 3 0 -end have been ef... more AbstractÐOligonucleotides carrying a peptide nucleic acid (PNA) tail at the 3 0 -end have been ef®ciently prepared by an on-line automated synthetic protocol exploiting commercially available Bhoc/Fmoc PNA monomers for the assembly of the PNA tract, followed by a deprotection/reprotection of the base protecting groups. The syntheses of the ODN domain in the chimeras have then been performed by standard methods. The hybridization properties of the synthesized chimeras with complementary DNA fragments have been investigated by thermal denaturation experiments. q

Research paper thumbnail of A Rapid and Simple Chromatographic Separation of Diastereomers of Silibinin and Their Oxidation to Produce 2,3-Dehydrosilybin Enantiomers in an Optically Pure Form

Planta Medica, 2013

Silybin A and B were separated from commercial silibinin using the preparative HPLC method. The d... more Silybin A and B were separated from commercial silibinin using the preparative HPLC method. The described method is rapid and effective in obtaining gram-scale amounts of two diastereoisomers with minimal effort. In our approach, silibinin was dissolved in THF (solubility greater than 100 mg/mL), an alternative solvent to H 2 O or MeOH in which silibinin has a very low solubility (ca 0.05-1.5 mg/mL), and then separated into its two components using preparative RP-HPLC. By starting with purified diastereoisomers, it was possible to obtain the two enantiomers of 2,3-dehydrosilybin in good yields and optically pure using an efficient oxidation procedure. All of the purified products were fully characterised using NMR ( 1 H, 13 C), CD, [α] D , and ESI MS analyses. The purities of the products, which were evaluated using analytical HPLC, were greater than 98 % in all cases.

Research paper thumbnail of Modulating the activity of oligonucleotides by carbohydrate conjugation: solid phase synthesis of sucrose-oligonucleotide hybrids

Organic & Biomolecular Chemistry, 2004

In order to expand the repertoire of available oligosaccharide-oligonucleotide hybrids, the on-li... more In order to expand the repertoire of available oligosaccharide-oligonucleotide hybrids, the on-line solid phase synthesis of oligonucleotides conjugated at the 3'-and/or 5'-end with a preformed disaccharide unit has been performed. The key compound in the synthetic scheme described here is an appropriate phosphoramidite derivative of fully protected sucrose, used in association with a solid support functionalized with DMT-protected sucrose. The sucrose units at both ends of selected oligonucleotide sequences were shown to increase their chemical and enzymatic stability, while not interfering with duplex formation and with the ability of G-rich sequences to adopt a quadruplex structure.