Effect of cleistanthin A and B on adrenergic and cholinergic receptors

Objective: The aim was to study the in vitro and in silico interactions of cleistanthin A and B on the adrenergic and cholinergic receptors using isolated animal tissues and bioinformatics tools. Materials and Methods: The alpha adrenergic receptor activities of cleistanthin A and B were studied in vitro using a guinea pig vas deferens preparation. The beta adrenergic receptor activities of cleistanthin A and B on an isolated rat heart were studied in vitro using a modified Langendorff apparatus. The effects of cleistanthin A and B on the nicotinic and muscarinic cholinergic receptors were studied in vitro using rabbit vas deferens and rabbit jejunum, respectively. All the drug responses were recorded using a data acquisition system through a variable force transducer. The receptor-ligand interactions of cleistanthin A and B with adrenergic and cholinergic receptor proteins were determined using the ArgusLab molecular modeling and drug docking program. Results: Cleistanthin A and B significantly inhibited the actions of the alpha adrenergic receptor and the nicotinic cholinergic receptor. Cleistanthin A and B shifted the dose-response curve to the right with an increased EC₅₀ value of phenylephrine and acetylcholine. Both cleistanthin A and B did not have any significant effect on the beta adrenergic and muscarinic cholinergic receptors. Conclusion: Cleistanthin A and B block the alpha adrenergic and nicotinic cholinergic receptors, but these compounds do not interact at all with the beta adrenergic and muscarinic cholinergic receptors.