Björn Classon

Characterization of a set of HIV-1 protease inhibitors using binding kinetics data from a biosensor-based screen

The interaction between 290 structurally diverse human immunodeficiency virus type 1 (HIV-1) protease inhibitors and the immobilized enzyme was analyzed with an optical biosensor. Although only a single concentration of inhibitor was used, information about the kinetics of the interaction could be obtained by extracting binding signals at discrete time points. The statistical correlation between the biosensor binding data, inhibition of enzyme activity (K;), and viral replication (EC50) revealed that the association and dissociation rates for the interaction could be resolved and that they were characteristic for the compounds. The most potent inhibitors, with respect to K; and EC50 values, including the clinically used drugs, all exhibited fast association and slow dissociation rates. Selective or partially selective binders for HIV-1 protease could be distinguished from compounds that showed a general protein-binding tendency by using three reference target proteins. This biosensor-based direct binding assay revealed a capacity to efficiently provide high-resolution information on the interaction kinetics and specificity of the interaction of a set of compounds with several targets simultaneously.

Synthesis of 2′,3′-dideoxycyclo-2′-pentenyl-3′-C-hydroxymethyl carbocyclic nucleoside analogues as potential anti-viral agents

Abstract The synthesis of optically pure unsaturated carbocyclic nucleoside analogues is described. (3,4 S )-Bis( t -butyldiphenylsilyloxymethyl)-2-cyclopenten-1 R and 1 S -ol were coupled with 6-chloropurine and 2-amino-6-chloropurine respectively, using a modified Mitsunobu reaction. The products were reacted further using standard procedures to give compounds 12, 14, 16 and 18 which were tested for anti-HIV activity.

Synthesis of an artificial antigen that corresponds to a disaccharide repeating unit of the capsular polysaccharide of Haemophilus influenzae type d. A facile synthesis of methyl 2-acetamido-2-deoxy-β-d-mannopyranoside

The synthesis is described of p-nitrophenyl 2-acetamido-3-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-2-deoxy-beta -D- mannopyranosiduronic acid, corresponding to the disaccharide repeating unit of the capsular polysaccharide of Haemophilus influenzae type d, which, after conversion of the p-nitro- into a p-amino-phenyl residue, may be attached to a protein to make an artificial antigen for immunological studies. The synthesis incorporates a facile route to the 2-acetamido-2-deoxy-beta-D-mannopyranosyl unit.

Structural studies of the capsular antigen from Haemophilus influenzae type f.

Abstract The structure of the capsular antigen from Haemophilus influenza type c has been investigated, n.m.r. spectroscopy being the principal method used. It is concluded that the antigen is composed of repeating-units having the following structure: O -Acetyl groups are present in ∼90% of the repeating-units.

Discovery of novel, potent and bioavailable proline-urea based macrocyclic HCV NS3/4A protease inhibitors

A novel series of P3-truncated macrocyclic HCV NS3/4A protease inhibitors containing a P2 proline-urea or carbamate scaffold was synthesized. Very potent inhibitors were obtained through the optimization of the macrocycle size, urea and proline substitution, and bioisosteric replacement of the P1 carboxylic acid moiety. Variation of the lipophilicity by introduction of small lipophilic substituents resulted in improved PK profiles, ultimately leading to compound 13Bh, an extremely potent (K(i)=0.1 nM, EC(50)=4.5 nM) and selective (CC(50) (Huh-7 cells)>50 microM) inhibitor, displaying an excellent PK profile in rats characterized by an oral bioavailability of 54% and a high liver exposure after oral administration.

Synthesis of enantiomerically pure cis and trans 2-aminocyclopentanecarboxylic acids. Use of proline replacements in potential HIV-protease inhibitors

The synthesis of the four diastereomeric 2-aminocyclopentanecarboxylic acids, their use as replacements for proline in potential HIV protease inhibitors containing a hydroxyethylamine dipeptide isostere and the evaluation of the biological activity of these is described.

SYNTHESIS OF 4-SUBSTITUTED CARBOCYCLIC 2,3-DIDEOXY-3-C-HYDROXYMETHYL NUCLEOSIDE ANALOGUES AS POTENTIAL ANTI-VIRAL AGENTS

Abstract The synthesis of two carbocyclic guanosine analogues with an electronegative fluoro or hydroxy substituent in the 4-position is described. The cyclopentanols 17a and 18 were synthesized from enantiomerically pure 3S,4S-bis(hydroxymethyl)cyclopentanone ethylene glycol ketal (7) via a number of key steps involving stereospecific reduction of the keto function and a dihydroxylation of the C-4 methylene. Substitution of the tertiary C-4 hydroxyl. group in 16 with fluorine using bis-(2-methoxyethyl)aminosulfur trifluoride (Deoxo-Fluor™) and coupling of the cyclopentanol-moiety with 2-amino-6-chloropurine using the Mitsunobu procedure gave compounds 3 and 4 which have been evaluated as potential anti-viral agents.

Solid-phase parallel synthesis and SAR of 4-amidofuran-3-one inhibitors of cathepsin S: effect of sulfonamides P3 substituents on potency and selectivity.

Highly potent and selective 4-amidofuran-3-one inhibitors of cathepsin S are described. The synthesis and structure-activity relationship of a series of inhibitors with a sulfonamide moiety in the P3 position is presented. Several members of the series show sub-nanomolar inhibition of the target enzyme as well as an excellent selectivity profile and good cellular potency. Molecular modeling of the most interesting inhibitors describes interactions in the extended S3 pocket and explains the observed selectivity towards cathepsin K.

Synthesis of [4,5-Bis(hydroxymethyl)-1,3-dioxolan-2-yl]nucleosides as Potential Inhibitors of HIV

The synthesis of 1,3-dioxolan-2-ylnucleosides and related chemistry is described. We have shown that 2-methoxy-1,3-dioxolane (6) reacts with silylated thymine and trimethylsilyl triflate to give the acyclic formate ester 1-[2-(formyloxy)ethyl]thymine (8) rather than 1-(1,3-dioxolan-2-yl)thymine (7). A tentative mechanism which could explain this result is discussed. On the other hand, 2-methoxy-1,3-dioxolane 13c reacts with silylated bases to give [4,5-bis(hydroxymethyl)-1,3-dioxolan-2-yl]nucleosides, thus representing the first examples of this novel class of compounds. The nature of the nucleobase and the hydroxyl protecting groups was found to have great influence on the reaction and on the stability of the nucleosides. Compounds 16 and 18 were found to be inactive when tested for anti HIV-1 activity in vitro.

Synthesis of some purine carbocyclic isosteres of 2',3'-dideoxy-3'-C-hydroxymethyl nucleosides as potential inhibitors of HIV

Abstract The synthesis of some enantiomerically pure carbocyclic 2′,3′-dideoxy-3′-C-hydroxymethyl derivatives of adenine, inosine and guanine is described. The Mitsunobu reaction was used in the coupling procedure giving exclusively N9-coupling. The nucleosides were tested for inhibition of HIV multiplication in vitro and were found to be inactive in the assay.