IgE receptor on the surface of mast cells with high affinity (3) and induces IgE‐dependent acute hypersensitivity reactions. Furthermore, crosslinking of antigen‐IgE triggers the IgE receptor‐mediated activation of mast cells and induces the degranulation of mast cells through granule membrane

Allergic inflammation is induced by allergens and leads to various allergic diseases, including rhinitis, asthma and conjunctivitis. Histamine is important in the pathogenesis of an immunoglobulin E‐dependent allergic reaction and results in the secretion of cytokines associated with inflammation. Angelica dahurica (A. dahurica) is a medicinal plant widely used in China for the treatment of symptoms related to allergic inflammation. The present study investigated the chemical constituents from A. dahurica and evaluated their reductive effect on allergic inflammation. As a result, 15 compounds including 13 coumarins have been identified as isoimperatorin (1), imperatorin (2), oxypeucedanin (3), oxypeucedanin hydrate (4), bergapten (5), byakangelicin (6), phellopterin (7), byakangelicol (8), isopimpinellin (9), xanthotoxol (10), xanthotoxin (11), pimpinellin (12), scopoletin (13), β‐sitosterol (14) and daucosterol (15). Compounds 1‐13 were able to reduce the release of histamine, with compounds 4‐6 exhibiting the most potent activity. Furthermore, compounds 1‐12 were able to inhibit the secretion of tumor necrosis factor‐α, interleukin (IL)‐1β and IL‐4, with compounds 5 and 7 exhibiting the strongest inhibitory effects. These compounds implemented the inhibitory effects on the expression of inflammatory cytokine genes through the inhibition of nuclear factor‐κB activation. Virtual screening by a docking program indicated that compound 3 is a potent histamine H1 receptor antagonist. Additionally, the calculated physicochemical properties of these compounds support most furanocoumarins to be delivered to binding sites and permeate the cell membrane. The present findings contribute to understanding how A. dahurica attenuates allergic inflammation. Introduction Allergic inflammation is caused by allergens and results in diseases, including rhinitis, asthma and conjunctivitis. It impacts the quality of life and costs large medical expenditures to attenuate the hypersensitive symptoms. In total, 10‐20% of the population worldwide suffers from allergies, and this number annually increases (1). Similarly to effector cells, mast cells are important in allergic inflammation through the production and secretion of allergic mediators, including histamine, chemokines, cytokines and growth factors (2). When exposed to allergens the stimulation leads to the production of immunoglobulin E (IgE) within min, which binds to the IgE receptor on the surface of mast cells with high affinity (3) and induces IgE‐dependent acute hypersensitivity reactions. Furthermore, crosslinking of antigen‐IgE triggers the IgE receptor‐mediated activation of mast cells and induces the degranulation of mast cells through granule membrane fusion (4). This is followed by the release of allergic inflammatory mediators, including histamine, chemokines, cytokines and eicosanoids for the change of membrane permeability (5). As a major allergic mediator, histamine is the most important molecule in acute allergy and acts by binding to the histamine H1 receptor, which manifests edema, warmth and erythema by causing vasodilation, increasing vascular permeability and leukocyte recruitment (6). Additionally, inflammatory cytokines such as tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β and IL‐4, affect the chronic inflammatory phase by enhancing B cell survival or T cell activation (7). Furthermore, nuclear factor (NF)‐κB is an important transcriptional factor in inflammation and activated NF‐κB is able to regulate gene expression of inflammatory cytokine genes, including TNF‐α, IL-1β and IL‐4 (8). Finally, rat basophilic leukemia (RBL)‐2H3 cells are suitable for in vitro studies of mast cell‐mediated allergic inflammation, which involves the degranulation and expression of inflammatory cytokines (9,10). Angelica dahurica (A. dahurica; Fisch. ex Hoffm.) Benth. et Hook. f. ex Franch. et Sav (Umbelliferae) is a plant that belongs to the Angelica genus and is distributed in Northern and Northeastern China. In Traditional Chinese Medicine, the roots of A. dahurica have been used to treat headache, rhinitis, cold and toothache amongst others. Furthermore, pharmacological studies have shown that it has antimicrobial (11), hepatoprotective (12), antioxidative (13) and cholinesterase Coumarins from the roots of Angelica dahurica cause anti‐allergic inflammation