Phenylethylene glycol-derived LpxC inhibitors with diverse Zn2+-binding groups

The Zn²⁺-dependent bacterial deacetylase LpxC is a promising target for the development of novel antibiotics. Most of the known LpxC inhibitors carry a hydroxamate moiety as Zn²⁺-binding group. However, hydroxamic acids generally exhibit poor pharmacokinetic properties. (S)-N-Hydroxy-2-{2-hydroxy-1-[4-(phenylethynyl)phenyl]ethoxy}acetamide (3) is a known phenylethylene glycol derivative potently inhibiting LpxC with a K_i of 66?nM. In vitro experiments have confirmed in silico predictions that the hydroxamate moiety of 3 is indeed metabolically labile. In this study, several strategies were explored to replace the hydroxamate moiety by other Zn²⁺-binding groups while maintaining target activity. In total, 15 phenylethylene glycol derivatives with diverse Zn²⁺-binding groups like carboxylate, hydrazide, carboxamide, sulfonamide, vicinal diol, thiol, thioester, and hydroxypyridinone moieties were prepared in divergent syntheses. However, their biological evaluation revealed that the replacement of the hydroxamate moiety of 3 by any of the investigated Zn²⁺-binding groups is detrimental for LpxC inhibitory and antibacterial activity.