# Evaluation of molecular mechanisms of (Z)-3-(pentadec-10′-enyl)-catechol (litreol) and synthetic derivatives as inhibitors of human leukotriene biosynthesis

## TL;DR

This study explores how a natural compound and its derivatives inhibit the production of inflammatory molecules in human cells, identifying one as a potent anti-inflammatory agent.

## Contribution

The study reveals the molecular mechanisms and binding modes of litreol and its derivatives as 5-LO inhibitors, highlighting their anti-inflammatory potential.

## Key findings

- CI and CS are potent 5-LO inhibitors with IC50 values as low as 0.06 μM in cell-free assays.
- CI prevents 5-LO/FLAP interaction and blocks ERK-1/2 and p38 MAP kinase pathways.
- The free catechol group is essential for activity, as its acetylation leads to loss of function.

## Abstract

5-Lipoxygenase (5-LO) catalyzes the early steps of leukotriene (LT) biosynthesis, making it an attractive target for anti-inflammatory drug development. This study provides a more detailed evaluation of the molecular mechanisms and pharmacological effects of litreol (CI), a natural compound from the Anacardiaceae family, along with its synthetic derivatives (CS, AS, and AI). The synthesis and biological evaluation of litreol analogs have already been previously published. Therefore, the aim of this article is to further explore their mechanisms of action, providing a more thorough investigation into their effects on 5-LO. Using both isolated human recombinant 5-LO in cell-free systems and cell-based assays, we evaluated the impact of the synthesized compounds on 5-LO product formation. Among them, CI and CS emerged as potent inhibitors, exhibiting IC50 values of 0.26 μM and 0.80 μM in neutrophils, and 0.06 μM and 0.15 μM in cell-free assays, respectively. Notably, CI exhibited 2.5- to 3-fold greater potency compared to its hydrogenated analogue, CS. Both compounds also showed inhibitory activity against 12-lipoxygenase (12-LO) with IC50 of 3.15 and 5.10 μM, respectively. Moreover, CI prevented the 5-LO/FLAP protein interaction and blocked both ERK-1/2 and p38 MAP kinase-dependent pathways required for 5-LO activation. Conversely, AS and AI derivatives did not show significant 5-LO inhibitory effects. Computational studies revealed that the differing binding modes and stability of CI and CS at the allosteric site of 5-LO explain their varying inhibitory effects. CI forms a stronger interaction network, supporting its higher potency, while CS shows greater flexibility and weaker interactions, correlating with lower activity. Additionally, the free catechol group is essential for activity, as its acetylation leads to loss of function. Overall, our findings highlight CI as a promising 5-LO inhibitor, in intact human leukocytes accounting for a novel potent anti-inflammatory compound.