Dirk B. Mendel

Mechanism by Which Mutations at His274 Alter Sensitivity of Influenza A Virus N1 Neuraminidase to Oseltamivir Carboxylate and Zanamivir

ABSTRACT Oseltamivir carboxylate is a potent and specific inhibitor of influenza neuraminidase (NA). An influenza A/H1N1 variant selected in vitro with reduced susceptibility to oseltamivir carboxylate contains a His274Tyr mutation. To understand the mechanism by which a His274Tyr mutation gives rise to drug resistance, we studied a series of NA variant proteins containing various substitutions at position 274. Replacement of His274 with larger side chain residues (Tyr or Phe) reduced the NA sensitivity to oseltamivir carboxylate. In contrast, replacement of His274 with smaller side chain residues (Gly, Asn, Ser, and Gln) resulted in enhanced or unchanged sensitivity to oseltamivir carboxylate. Previous studies have suggested that the slow-binding inhibition of NA by oseltamivir carboxylate is a result of the reorientation of Glu276. Loss of this slow-binding inhibition in the His274Tyr and His274Phe mutant NA but not in His274Asn, His274Gly, His274Ser, or His274Gln supports the conclusion that the conformational change of Glu276 is restricted in the His274Tyr and His274Phe mutant NA upon oseltamivir carboxylate binding. Interestingly, His274Asn, as well as His274Gly, His274Ser, and His274Gln, also displayed reduced sensitivity to zanamivir and its analogue, 4-amino-Neu5Ac2en. Substitution of His274 with Tyr in influenza A/Tokyo/3/67 (H3N2) recombinant NA did not affect the susceptibility to oseltamivir carboxylate. These data indicate that the volume occupied by the amino acid side chain at position 274 can influence the sensitivities of influenza N1 NA but not of N2 NA to both oseltamivir carboxylate and zanamivir.

Neuraminidase Inhibitors as Anti-Influenza Virus Agents

Influenza virus neuraminidase (NA) catalyses the cleavage of sialic acid residues terminally linked to glycoproteins and glycolipids and plays an important role in the replication of the virus. Recently, several potent NA inhibitors have been synthesized based on the rational design of mimicking the transition state of the sialic acid cleavage. Zanamivir and oseltamivir (GS 4104, the prodrug of GS 4071) have emerged as promising influenza NA inhibitors for the treatment and prophylaxis of human influenza virus infection. This review describes the recent work toward the discovery and development of influenza NA inhibitors.

A new series of C3-aza carbocyclic influenza neuraminidase inhibitors: synthesis and inhibitory activity☆

The synthesis and influenza neuraminidase inhibitory activity of a new series of C3-aza carbocyclic neuraminidase inhibitors are described. Analogues 3c and 3j, bearing a 3-pentyl group, exhibit influenza A inhibitory activities comparable to that of 1.

Structure-activity relationships of carbocyclic influenza neuraminidase inhibitors

Abstract The structure-activity relationships (SAR) for a new class of potent inhibitors (1) of influenza neuraminidase are described. Systematic modifications of substituents at the C-3, C-4, and C-5 positions of the carbocyclic ring were performed to establish fundamental SAR to assist in the design of potent inhibitors with activity against both of influenza A and B viruses.

Carbocyclic influenza neuraminidase inhibitors possessing a C3-Cyclic amine side chain : Synthesis and inhibitory activity

As part of our continuing work in the area of influenza neuraminidase inhibitors, a series of C3-aza inhibitors possessing a cyclic amine side chain was synthesized and evaluated for influenza neuraminidase inhibitory activity. Analogues possessing a six-, seven- and eight-membered ring, 4c-e, respectively, at the C3 position exhibited excellent influenza B neuraminidase inhibition.

Synthesis and evaluation of 1,4,5,6-tetrahydropyridazine derivatives as influenza neuraminidase inhibitors

1,4,5,6-Tetrahydropyridazine derivative 15 and its C-5 epimer 19, which possessed side chains similar to GS4071, were synthesized via a hetero Diels-Alder reaction, and evaluated as influenza neuraminidase inhibitors. Compounds 15 and 19 exhibited a microM range of influenza neuraminidase inhibitory activity.

C3-Thia and C3-carba isosteres of a carbocyclic influenza neuraminidase inhibitor, (3R,4R,5S)-4-acetamido-5-amino-3-propoxyl-1-cyclohexene-1-carboxylic acid

The importance of the oxygen atom in the C3 ether side chain of a carbocyclic influenza neuraminidase inhibitor 3 was investigated by replacement of the C3 ether oxygen atom of 3 with either a sulfur atom (compound 4) or a carbon atom (compound 5). The regio- and stereospecific syntheses of both isoteres are described starting from (−)-quinic acid.

Synthesis and activity of C2-substituted analogs of influenza neuraminidase inhibitor GS 4071

The influence of C2-substitution of GS 4071 on the influenza neuraminidase inhibitory activity was investigated. The introduction of lipophilic substituents (chloro, methyl, and methylthio) at the C2 position resulted in a significant decrease of the activity. This result indicates that at the enzyme active site there is limited hydrophobic pocket for group at the C2 position of GS 4071.

Stereospecific synthesis of a GS 4104 metabolite: Determination of absolute sterochemistry and influenza neuraminidase inhibitory activity

The total synthesis for the determination of the absolute stereochemistry of a GS 4104 metabolite 3 is described. In addition, the influenza neuraminidase inhibitory activity of 3 and related intermediates are reported.