Novel-Type GABAB PAMs: Structure–Activity Relationship in Light of the Protein Structure

• Published in: ACS medicinal chemistry letters Vol. 15; no. 3; pp. 396 - 405
• Main Authors: Krámos, Balázs, Hadady, Zsuzsa, Makó, Attila, Szántó, Gábor, Felföldi, Nóra, Magdó, Ildikó, Bobok, Amrita Ágnes, Bata, Imre, Román, Viktor, Visegrády, András, Keserű, György M., Greiner, István, Éles, János
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 14.03.2024; Amer Chemical Soc
• Subjects: Chemistry, Medicinal; Life Sciences & Biomedicine; Pharmacology & Pharmacy; Science & Technology; Lipophilic ligand efficiency; GABAB receptor; Structure-based drug design; LLE; LipE; Positive allosteric modulator; SBDD; PAM; RESPONSES; ACTIVATION; Structure-based drugdesign; POSITIVE ALLOSTERIC MODULATORS
• ISSN: 1948-5875; 1948-5875
• DOI: 10.1021/acsmedchemlett.3c00560

Selecting a known HTS hit with the pyrazolo­[1,5-a]­pyrimidine core, our project was started from CMPPE, and its optimization was driven by a ligand-based pharmacophore model developed on the basis of published GABAB positive allosteric modulators (PAMs). Our primary goal was to improve the potency by finding new enthalpic interactions. Therefore, we included the lipophilic ligand efficiency (LLE or LipE) as an objective function in the optimization that led to a carboxylic acid derivative (34). This lead candidate offers the possibility to improve potency without drastically inflating the physicochemical properties. Although the discovery of the novel carboxyl feature was surprising, it turned out to be an important element of the GABAB PAM pharmacophore that can be perfectly explained based on the new protein structures. Rationalizing the binding mode of 34, we analyzed the intersubunit PAM binding site of GABAB receptor using the publicly available experimental structures.