Structure-Activity Relationship Study of Antimalarial Asparagine-Derived Proteasome Inhibitors

Area of Science:

• Medicinal Chemistry
• Parasitology
• Structural Biology

Background:

• Malaria is a major global health issue caused by drug-resistant Plasmodium parasites.
• The Plasmodium 20S proteasome core (Pf20S) is a validated antimalarial target, crucial for parasite survival.
• Existing antimalarial drugs face widespread resistance, necessitating novel therapeutic strategies.

Purpose of the Study:

• To further optimize a novel class of Pf20S inhibitors with improved pharmacokinetic properties.
• To gain structural insights into Pf20S-inhibitor interactions to guide future drug design.
• To develop next-generation antimalarial compounds targeting Pf20S.

Main Methods:

• Iterative chemical optimization of lead Pf20S inhibitors.
• Cryo-electron microscopy (Cryo-EM) to determine structural complexes of Pf20S and inhibitors.
• Structure-activity relationship (SAR) analysis to correlate structural features with inhibitory activity.

Main Results:

• Optimized inhibitors demonstrated enhanced potency and selectivity against Pf20S over human proteasomes.
• Cryo-EM revealed a novel binding pose of the inhibitor at the Pf20S β5 active site.
• An N-cap sulfonamide modification showed enhanced activity compared to an N-cap amide, explained by the novel binding pose.

Conclusions:

• Further optimization of Pf20S inhibitors can yield compounds with improved drug-like properties.
• Structural insights are critical for understanding inhibitor binding and designing more effective antimalarials.
• This work provides a foundation for developing novel Pf20S-targeting antimalarial drugs.