Rewiring Receptor Activation: Mechanistic Insights into Toggle Switch Modulation by 25CN-NBx Compounds
ACS Chemical Neuroscience February 18, 2026 Vito F. Palmisano, Micaela Vidal−sánchez, Juan J. Nogueira
Bulky substitutions on the N-benzyl ring of 25CN-NBx compounds cause a significant shift in the position of W336, a key toggle switch residue in the 5-HT2A receptor. This shift influences receptor activation and is thought to play a crucial role in mediating psychedelic signaling. Potential of mean force calculations along the toggle switch's dihedral angle confirm this result. End-state free energy calculations show that 25CN-NB-2-OH-3-Me and 25CN-NB-2-OH-5-MeO have the highest and lowest affinities, respectively, for the receptor. When W336 adopts its negative dihedral state, it establishes stronger van der Waals interactions with residues F332 and I163, key players in receptor activation. This framework can extend to other G protein-coupled receptors where the toggle switch is central to signal activation.