Potent reversible inhibition of myeloperoxidase by aromatic hydroxamates

Area of Science:

• Biochemistry
• Pharmacology
• Enzymology

Background:

• Myeloperoxidase (MPO) is a neutrophil enzyme that generates hypohalous acids, contributing to oxidative stress in inflammatory conditions.
• Controlling MPO activity is a key therapeutic target for managing inflammatory pathologies.
• Previous attempts identified weak reversible inhibitors, necessitating the search for more potent compounds.

Purpose of the Study:

• To identify novel hydroxamate compounds with potent reversible inhibitory activity against MPO.
• To characterize the specificity and binding mechanisms of these inhibitors.
• To explore the potential of these inhibitors in mitigating MPO-driven oxidative stress.

Main Methods:

• Screening of hydroxamate derivatives for MPO inhibitory activity.
• Enzyme kinetics and surface plasmon resonance (SPR) to assess binding affinity and inhibition.
• Crystal structure analysis of MPO complexed with a lead inhibitor (HX1).
• Evaluation of inhibitor specificity against various redox enzymes.

Main Results:

• Three hydroxamates identified as potent reversible MPO inhibitors, with HX1 showing 50% inhibition at 5 nM.
• Inhibitors demonstrated high specificity for MPO in neutrophils and were more potent against MPO than other enzymes.
• SPR confirmed a correlation between hydroxamate binding strength and MPO inhibition.
• Crystal structure revealed HX1 binds in the MPO active site, blocking the substrate channel.

Conclusions:

• Aromatic hydroxamates are potent, reversible inhibitors of MPO, binding tightly to the active site.
• These compounds effectively block MPO's production of hypohalous acids, a key mechanism in oxidative stress.
• This discovery presents a promising pharmacological strategy for controlling MPO activity and limiting inflammation-associated oxidative damage.