ABSTRACT
Owing to the highly conserved nature of its active site, Influenza B virus neuraminidase (NA) has emerged as a major target for the design of novel anti-influenza drugs. A benzene-ring scaffold has been used in place of the pyranose ring of sialic acid to develop simpler NA inhibitors that contain a minimal number of chiral centers. A new compound belonging to this series, BANA 207, showed significant improvement in inhibitory activity against Influenza B virus NA compared with its parent compound. Here, the structural analysis of a complex of BANA 207 with influenza virus B/Lee/40 NA is reported. The results indicate that BANA 207 forms an unexpected interaction with the crucial active-site residue Glu275 that stabilizes the side chain of this residue in a conformation previously unobserved in NA-inhibitor complexes. This change in the side-chain orientation of Glu275 alters the topology of the triglycerol pocket, which accommodates an additional lipophilic substitution at the benzene ring and may provide an explanation for the increased activity of BANA 207 against Influenza B virus NA.
Subject(s)
Aminobenzoates/pharmacology , Benzoic Acid/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Influenza B virus/enzymology , Neuraminidase/chemistry , Pyrrolidinones/pharmacology , Binding Sites , Carbohydrates/chemistry , Crystallography, X-Ray , Electrons , Glutamic Acid/chemistry , Glycerol/chemistry , Hydrogen Bonding , Inhibitory Concentration 50 , Models, Chemical , Models, Molecular , N-Acetylneuraminic Acid/chemistry , Protein Conformation , Protein Structure, Tertiary , Virion/metabolismABSTRACT
We recently reported the first benzoic acid, 1-[4-carboxy-2-(3-pentylamino)phenyl]-5,5-bis(hydroxymethyl)pyrrolidin-2-one (8), that is a potent inhibitor of avian influenza A neuraminidase (N9) and, unlike other reported potent neuraminidase inhibitors, does not contain a basic aliphatic amine or guanidine nor a simple N-acetyl grouping. However, 8 was a poor inhibitor of influenza B neuraminidase. In the present study we further evaluated 8 as an inhibitor of human influenza A NA isolates, and it was effective against N2NA but found to be 160-fold less active against N1NA. We also synthesized analogues of 8 involving moderate modifications of essential substituents on the pyrrolidinone ring. Specifically, the aminomethyl (9), hydroxyethyl (10), and aminoethyl (11) analogues were prepared. Only the most conservative change (compound 9) resulted in continued effective inhibition of influenza A, in addition to a noteworthy increase in the activity of 9 for N1NA. The effectiveness of 9 against influenza B neuraminidase was furthermore improved 10-fold relative to 8, but this activity remained 50-fold poorer than for type A NA.
