In Silico Studies on the Interaction Between Allergic Inflammatory Receptors/Cytokines and Phytochemicals of <i>Acorus calamus</i>

Allergic diseases have been increasing significantly with increasing level of pollution besides the natural causes, affecting more than 20% of the global population. First-line treatment using antiallergic drugs include topical corticosteroids, as well as adjuvant treatment of antihistamine drugs, that have adverse side effects including development of drug resistance when used for long term, thus necessitating alternative strategies. Acorus calamus rhizome (ACR) is known to be used in traditional medicines. The present study intends to assess the antiallergic potential of secondary metabolites reported to be present ACR. Molecular docking studies could evaluate the binding affinity of the curated secondary metabolites with four key allergy-associated proteins, viz., histamine H1 receptor (H1R), interleukin-4 (IL-4), IL-13, and IL-5. Based on molecular docking and absorption, distribution, metabolism, excretion, and toxicity analyses, best two inhibitory phytochemicals appear to be δ-cadinene and β-caryophyllene for H1R; acoronene and espatulenol for IL-4; lepidozene and δ-cadinene for IL-13; and curcumin and pinostilbene for IL-5, respectively. Molecular dynamics simulation studies further confirm that these compounds can form stable complexes with the aforementioned proteins. Such set of comprehensive studies are considered to emerge as baseline for further in vitro and in vivo studies to validate their antiallergic potentials.