Relaxant Effect of Bioactive Component Compatibility of San-ao Decoction on In vitro Guinea Pig Airway Smooth Muscle:A Dose-Response Relationship Study

Background:Component compatibility is important to the modernization of traditional Chinese medicine.Studies have shown that San-ao decoction(SAD)can treat respiratory diseases by relaxing airway smooth muscle(ASM)and reducing airway hyper-responsiveness.However,whether its bioactive components and compatibility also present with similar relaxant effects remains unknown.This study aims to explore the potential relaxant property,dose-response relationship,and underlying mechanisms of the bioactive component compatibility in SAD.Methods:Network pharmacology was primarily used to identify the bioactive components of SAD and uncover its underlying mechanisms.ASM tension force measuring technique was utilized to verify the relaxant and dose-response effects on in vitro guinea pig ASM.Results:We postulated pseudoephedrine hydrochloride(PH),amygdalin(AM),and diammonium glycyrrhizate(DG)to be the bioactive components of SAD,which could effectively relax ASM in a dose-dependent manner on both acetylcholine-induced and spontaneous contraction.Both PH and AM could lead to DG dose–response curve shift.The regression equation of these three bioactive components was Y=-2.048×X_(1)+0.411×X_(2)+14.052×X_(3)(X_(1),X_(2),X_(3)representing PH,AM,and DG,respectively).The underlying mechanisms of these components might be associated with the regulation of smooth muscle contraction.Conclusions:PH,AM,and DG are the bioactive components of SAD,which can relax ASM in a dose–response manner and exert a synergistic effect.Clinically,compatibility of these three bioactive components may serve as a new complementary and alternative treatment for respiratory diseases.