Structure-based optimization of non-peptidic Cathepsin D inhibitors

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Osteoarthritis Research

Background:

• Cathepsin D (CatD) is implicated in osteoarthritis pathogenesis.
• Developing effective CatD inhibitors is a therapeutic goal for osteoarthritis.
• Non-peptidic scaffolds offer potential advantages over peptidomimetics.

Purpose of the Study:

• To discover and optimize novel non-peptidic acylguanidine inhibitors of Cathepsin D.
• To evaluate the in vitro and ex vivo efficacy of these inhibitors.
• To identify a starting point for developing new osteoarthritis therapeutics.

Main Methods:

• High-throughput screening (HTS) to identify initial hits.
• Structure-based drug design utilizing CatD X-ray crystallography.
• Biochemical assays to determine enzyme inhibition potency.
• Ex vivo glycosaminoglycan (GAG) release assays in bovine cartilage.
• Assessment of cellular permeability and microsomal stability.

Main Results:

• Identification of a novel series of non-peptidic acylguanidine inhibitors.
• Optimization yielded compounds with single-digit nanomolar potency in biochemical CatD assays.
• Most potent analogues exhibited only micromolar activity in ex vivo GAG release assays.
• Compounds demonstrated low cellular permeability and suboptimal microsomal stability.

Conclusions:

• The novel acylguanidine scaffold shows promise as a starting point for Cathepsin D inhibitors.
• Further optimization is required to improve pharmacokinetic properties for in vivo efficacy.
• This research provides a foundation for developing new osteoarthritis treatments targeting Cathepsin D.