Activating human 15-lipoxygenase-1 beyond flatland: discovery of non-aromatic modulators

Modulation of enzyme activity by small molecules is a powerful therapeutic strategy. While human 15-lipoxygenase-1 inhibitors are well-studied, activators have remained elusive. Here, we have successfully identified novel modulators of 15-LOX-1 by focusing on non-aromatic, sp³-rich five-membered ring scaffolds. Through systematic SAR analysis, we found that γ-lactam derivatives act as inhibitors, while butenolide and cyclopentanone derivatives serve as enzyme activators. Structure-activity relationship analysis revealed that the identity of the atom at the β-position and the nature of the substituents at the γ-position, both relative to the ring carbonyl, play a critical role in modulating 15-LOX-1 activity. Selectivity studies demonstrated that the compounds display species- and substrate-specific modulation of lipoxygenase activity. Enzyme kinetic analysis confirmed a competitive mechanism for both inhibition and activation. Molecular modeling provided structural insights, highlighting key interactions with the active site iron and surrounding residues. Overall, our findings expand the chemical space for 15-LOX-1 modulation and offer promising leads for the development of selective enzyme regulators.