Related Experiment Video
Updated: Jun 25, 2026

Methods for Detecting Cough and Airway Inflammation in Mice
Published on: August 2, 2024
Structural insights into TRPA1 and TRPV1 modulation by flavonoid glycosides from licorice for cough relief
Yang Yi1, Guifang Duan2, Zonglin Dai3
1State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; Yunnan Baiyao International Medical Research Centre, Peking University, Beijing 100191, China.
Background:
Transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) are two nociceptive TRP channel subtypes that play central roles in cough hypersensitivity.
Purpose:
This study evaluated the antitussive efficacy of liquiritin apioside (LIQA) and liquiritin (LIQ), two major flavonoid glycosides from licorice, in acute chemically induced cough models, and investigated their modulations of TRPA1 and TRPV1.
Methods:
In guinea pig models, cough was induced by capsaicin (a TRPV1 agonist) and cinnamaldehyde (a TRPA1 agonist), respectively. The inhibitory effects of LIQA and LIQ against TRPA1 and TRPV1 were assessed using electrophysiological profiling and fluorescence-based calcium assays. To elucidate the underlying mechanisms, high-resolution cryo-electron microscopy (cryo-EM) structural analysis, and molecular simulations were conducted.
Results:
LIQA and LIQ significantly reduced cough frequency in the guinea pig models. Electrophysiological profiling revealed that LIQA suppressed human TRPA1 (hTRPA1) channel activity, while LIQ blocked human TRPV1 (hTRPV1) activation. High-resolution cryo-EM structures of hTRPA1/LIQA (2.59 Å) and hTRPV1/LIQ (3.05 Å) complexes were obtained. Structural analysis indicates that LIQA stabilizes hTRPA1 in a closed conformation with T624 at the coupling region site, whereas LIQ interacts with S512 through hydrogen bonding in the deep S4-S5 site of hTRPV1, thereby inhibiting pore opening.
Conclusion:
This study establishes LIQA and LIQ as lead compounds with acute antitussive activities mediated by TRPA1/TRPV1 modulation.
Related Concept Videos
The Physiology of Taste
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Analgesia and Pain Management
Thermosensation
Upper Respiratory Drugs: Antitussives, Expectorants, and Mucolytics
Antitussives include codeine, dextromethorphan (Robitussin), and benzonatate (Tessalon). Codeine and dextromethorphan exert their effects centrally by suppressing the cough reflex center in the medulla. Benzonatate operates peripherally within the respiratory tract by anesthetizing...
