Comparative spasmolytic effect between Cinnamomum tamala and Cinnamomum verum leaf essential oils and eugenol through in vitro and in silico approaches

Cinnamomum tamala and Cinnamomum verum are known for their folk medicinal usage in treating gastrointestinal ailments. The spasmolytic activity of essential oils was studied using isolated rat ileum. The results indicate that C. tamala, despite having a lower content of eugenol (60%), shows a spasmolytic potential of 68.01 ± 2.63% (EC50 = 110.12 ± 13.58 μg/mL) while C. verum with rich eugenol (80%) shows lesser spasmolytic potential (38.96 ± 0.63%) and fails to attain an EC50 value. Upon comparison with standard eugenol’s percentage of spasmolytic (35.68 ± 2.57%), it is evident that the action of these essential oils does not solely rely on the major component but the synergistic role in association with other components of the mixture influences the pharmacological action of the essential oils. In silico docking of phytochemicals of leaf essential oils with M2 (M2AChR) and M3 muscarinic (M3AChR) and nicotinic acetylcholine receptor (nAChR) was carried out to determine the type of receptors through which the essential oils had spasmolytic potential. The binding affinity for eugenol with nAChR shows a better docking score than M2AChR and M3AChR.