Compound III (pyrazolopyrimidine analog)

Compound III is a novel pyrazolopyrimidine-based small molecule that functions as a potent antagonist of the androgen receptor (AR), specifically investigated for the treatment of prostate cancer. Identified through a combination of structure-based and ligand-based virtual screening, this research compound possesses a chemical skeleton distinct from existing nonsteroidal antiandrogens such as bicalutamide and enzalutamide. Its mechanism of action involves binding to the AR ligand-binding domain and preventing the structural repositioning of helix 12. This action blocks the formation of the activation function 2 (AF2) site, which is essential for recruiting co-activators and initiating gene transcription. In vitro studies have shown that Compound III inhibits the proliferation of LNCaP prostate cancer cells in a dose-dependent manner with higher potency than bicalutamide. As of its publication in *Frontiers in Pharmacology* in 2018, it remains a preclinical research compound and has not transitioned to clinical development.