Gian Maria Bonora

Oligonucleotide Conjugated to Linear and Branched High Molecular Weight Polyethylene Glycol as Substrates for RNase H

Two conjugates of an anti-HIV oligonucleotide (ODN) with different high molecular weight monomethoxy polyethylene glycols (MPEGs) have been tested for their activity as substrate towards RNase H. The MPEG does not impede the formation of the regular hybrid duplex with the target RNA sequence as pointed out by the persistence of the RNase H activity; thus, these derivatives stimulate the hydrolysis of RNA by the enzyme at the same site and with the same extent of cleavage as the native sequence.

Polymer-Conjugated Bioactive Oligonucleotides

This paper presents our most recent investigations on the effect of a soluble, inert polymer as a conjugating agent for synthetic oligonucleotides. In particular, we studied in detail the influence of a high-molecular weight unit of poly(ethylene glycol) (PEG) on both natural and chimeric oligonucleotides acting as antisense andanti-gene effectors. The attachment of a fluorophore at one end of the PEG-oligonucleotideconjugateallowedtrackingofthe intracellular path of these large chemical moieties in order for us to better understand their biological activity. Also evaluated were the substitution of PEG with other chemically and biologically compatible polymer as supporting units. As an extension of these studies, a particular effort was made to prepare orthogonally protected, bifunctional PEG to obtain mixed oligonucleotide PEG-conjugates bearing at the other extremity a peptide as a targeting cellular moiety, or other bioactive molecules able to improve the biological properties of the starting oligonucleotides.

Conformational restriction through C?i ? C?i cyclization: Ac12c, the largest cycloaliphatic C?,?- disubstituted glycine known

Two complete series of N-protected, monodispersed oligopeptide esters to the pentamer level from 1-aminocyclododecane-1-carboxylic acid (Ac(12)c), an alpha-amino acid conformationally constrained through C(alpha)(i) <--> C(alpha)(i) cyclization, and either L-Ala or Aib residues, along with the N-protected Ac(12)c homopeptide alkylamide series from monomer to trimer, have been synthesized by solution methods and fully characterized. The solution-preferred conformations of these peptides have been assessed by Fourier transform ir absorption and (1)H-nmr techniques. Moreover, the molecular structures of one derivative (Z-Ac(12)c-OH) and three peptides [the tripeptide ester Z-L-Ala-Ac(12)c-L-Ala-OMe, the tripeptide alkylamide Z-(Ac(12)c)(3)-NHiPr, and the tetrapeptide ester Z-(Aib)(2)-Ac(12)c-Aib-OtBu (Aib, alpha-aminoisobutyric acid)] have been determined in the crystal state by x-ray diffraction. The results obtained point to the conclusion that beta-bends and 3(10)-helices are preferentially adopted by peptides based on Ac(12)c, the largest cycloaliphatic C-disubstituted glycine known. A comparison with the structural tendencies extracted from published works on peptides from Aib, the prototype of C-disubstituted glycines, and the other extensively studied members of the class of 1-aminocycloalkane-1-carboxylic acids (Ac(n) c, with n = 3-9), is made and the implications for the use of the Ac(12)c residue in the Ac(n) c scan approach of conformationally restricted analogues of bioactive peptides are briefly discussed.

Liquid‐Phase Synthesis and Characterization of a Conjugated Chimeric Oligonucleotide‐PEG‐Peptide

The preparation of a new chimeric conjugate in which a peptide and an oligonucleotide sequence are linked to the same, high-molecular weight poly(ethylene glycol) is reported. First, a new amino function was introduced on PEG selectively protected at the other OH extremity. Then, the peptide was synthesized at the amino-modified end, followed by removal of the OH-protecting group of PEG and synthesis of the oligonucleotide sequence. The final oligonucleotide deprotection was achieved without affecting the integrity of the peptide chain. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Pure, homo-bifunctional poly(ethylene glycol) orthogonally protected: synthesis and characterisation

New orthogonal reversible protections have been introduced on high-molecular weight, di-hydroxy PEGs. The introduction on the reaction intermediates of a removable carboxy group allows an efficient purification from all the undesired polymeric derivatives. A final, pure high-molecular weight DMT-PEG-Fmoc has been obtained.

Reactive PEGs for protein conjugation

Poly(ethylene glycol) (PEG) derivatives are the first choice of the water soluble, biocompatible polymers on hand for conjugation to proteins and polypeptides. This chapter deals with the PEG reagents that are available for the preparation of bioconjugates. The opportunities of different reactive groups on PEG are described and their different activities against the functional moieties of the amino acids are illustrated. Some attention is also given to the modification of the PEG backbone to increase its loading capacity and to eventually modify the stability of the conjugating bonds.

PNA Conjugated to High-Molecular Weight Poly(Ethylene Glycol): Synthesis and Properties

The conjugation of a bioactive, fluorescent PNA sequence to high-molecular weight poly(ethylene glycol) (PEG) is described and the properties of the PEG-PNA conjugate are evaluated.

Poly(ethylene glycol)-supported copper(II) triazacyclononane: an efficient, recoverable, and recyclable catalyst for the cleavage of a phosphodiester

Abstract The triazacyclononane macrocycle has been linked to the soluble polymer monomethoxy poly(ethylene) glycol and its copper(II) complex efficiently catalyzes the hydrolysis of a model phosphodiester. The catalyst, easily recovered from the water solution, shows no appreciable loss of activity when recycled three times.

Pharmacokinetic analysis of multi PEG-theophylline conjugates

In the attempt of prolonging the effect of drugs, a new branched, high-molecular weight multimeric poly(ethylene glycol) (MultiPEG), synthesized with a simple assembling procedure that devised the introduction of functional groups with divergent and selective reactivity, was employed as drug carrier. In particular, the attention was focused on the study of theophylline (THEO) and THEO-MultiPEG conjugates pharmacokinetic after oral administration in rabbit. Pharmacokinetic behavior was studied according to an ad hoc developed mathematical model accounting for THEO-MultiPEG in vivo absorption and decomposition into drug (THEO) and carrier (MultiPEG). The branched high-molecular weight MultiPEG proved to be a reliable drug delivery system able to prolong theophylline staying in the blood after oral administration of a THEO-MultiPEG solution. The analysis of experimental data by means of the developed mathematical model revealed that the prolongation of THEO effect was essentially due to the low THEO-MultiPEG permeability in comparison to that of pure THEO.

Synthesis of a new mPEG-dexamethasone conjugate and preliminary bioavailability studies in rabbits

Poly(ethylene glycol) esters have been proposed as a potential oral-controlled drug delivery system for dexamethasone (DXM). The drug was covalently attached to monomethoxypolyethylene glycol amine (mPEG-NH 2 ) (Mw = 10,000 Da) using a succinate linker. A new PEG-based prodrug system was designed using ester derivatives. The drug-polymer conjugate (mPEG-DXM) was freely water soluble at room temperature. First of all, the adduct hydrolytic stability was assessed at physiological pH. Then, the bioavailability was evaluated by orally administering the mPEG-DXM conjugate in rabbits and comparing to that obtained by the intravenous route. The area under the concentration-time curve (AUC) of PEGylated drug was twice as large as that of the parent drug after oral administration. In conclusion, PEGylated DXM was useful for maintaining the DXM concentration in the blood after oral administration.