Synthesis, activity and mechanism for double-ring conjugated enones

Area of Science:

• Medicinal Chemistry
• Immunology
• Molecular Biology

Background:

• Toll-like receptor 4 (TLR4) and its associated TLR4/NF-κB signaling pathway are crucial in mediating inflammatory responses and are implicated in various inflammation-related diseases.
• The intricate interplay between pro-inflammatory factors, chemokines, adhesion molecules, TLR4, and its ligands drives disease pathogenesis.

Purpose of the Study:

• To synthesize and evaluate novel double-ring conjugated enones for their in vitro inhibitory activity against TLR4.
• To investigate the anti-inflammatory effects and underlying mechanisms of promising compounds using an LPS-induced rat synovial cell inflammation model.

Main Methods:

• Synthesis of eight target compounds and in vitro screening for TLR4 inhibitory activity.
• Assessment of anti-inflammatory effects using lipopolysaccharide (LPS)-induced rat synovial cell inflammation models.
• Mechanism studies involving apoptosis assays, inflammatory cytokine level analysis (TNF-α, IL-1β, IL-6), and Western blot analysis of key proteins in the TLR4/NF-κB pathway (TLR4, MyD88, NF-κB, IκB).

Main Results:

• Double-ring conjugated enones demonstrated significant TLR4 inhibitory activity in vitro, with compound 4f exhibiting a potent IC50 value of 0.56 ± 0.10 μM, outperforming the positive control methotrexate.
• Compound 4f effectively promoted apoptosis in rat synovial cells, potentially via up-regulation of Caspase-3 expression.
• Compound 4f significantly suppressed LPS-induced increases in pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and modulated the expression of key proteins within the TLR4/NF-κB signaling pathway, including TLR4, MyD88, NF-κB, and IκB.

Conclusions:

• The synthesized double-ring conjugated enones, particularly compound 4f, possess significant TLR4 inhibitory and anti-inflammatory properties.
• Compound 4f demonstrates therapeutic potential by inhibiting inflammation, promoting apoptosis, and regulating the TLR4/NF-κB pathway in a cellular model of inflammation.