Interactions between β2-Adrenoceptor Ligands and Membrane: Atomic-Level Insights from Magic-Angle Spinning NMR

Area of Science:

• Pharmacology
• Biophysics
• Medicinal Chemistry

Background:

• Understanding drug-membrane interactions is key for optimizing drug efficacy and delivery.
• The β2-adrenoceptor agonists are important for treating respiratory diseases.
• Previous studies have not fully elucidated the atomic-level interactions of these agonists with membrane lipids.

Purpose of the Study:

• To investigate the relationship between the structural properties of β2-adrenoceptor ligands and their membrane interactions.
• To determine the location and distribution of five distinct β2 agonists within model membranes.
• To elucidate the role of hydrophobicity and substitution geometry in these compound-lipid interactions.

Main Methods:

• Utilized magic angle spinning Nuclear Magnetic Resonance (NMR) spectroscopy.
• Employed ¹H nuclear Overhauser enhancement (NOE) and paramagnetic relaxation enhancement (PRE) techniques.
• Studied interactions in monounsaturated model membranes with five β2 agonists: indacaterol, two indacaterol analogues, salmeterol, and formoterol.

Main Results:

• All five β2 agonists exhibited hydrophilic aromatic groups primarily at the lipid/water interface.
• Distinct location and dynamic behaviors were observed for the lipophilic aromatic rings of the agonists.
• Hydrophobicity and the geometry of lipophilic group substitutions significantly influence compound-lipid interactions.

Conclusions:

• The study provides atomic-level insights into β2 agonist-membrane interactions.
• Lipid interactions are governed by the specific structural features of the agonists, particularly their lipophilic components.
• Findings are critical for the rational design of β2 agonists with improved pharmacokinetic and pharmacodynamic profiles.