BackgroundAnaphylaxis is a type of potentially fatal hypersensitivity reaction resulting from the activation of mast cell mediators, especially histamine and lipid mediators. Non-IgE-mediated anaphylaxis can occur because of the direct activation of mast cells. Hydroxysafflor yellow A (HSYA) is the main chemical component of safflower (Carthamus tinctorius) and has been reported to have pharmacological activities. However, the anti-anaphylactoid effect of HSYA has not yet been investigated. PurposeThe aims of this study were to evaluate the anti-anaphylactoid activity of HSYA in vivo and to investigate the underlying mechanism in vitro. MethodsThe anti-anaphylactoid activity of HSYA was evaluated in a mouse model of hindpaw extravasation. Calcium imaging was used to assess intracellular Ca2+ mobilization. The levels of cytokines and chemokines released by stimulated mast cells were measured using enzyme immunoassay kits. Western blotting was used to explore the related molecular signaling pathways. ResultsHSYA markedly inhibited mast cell degranulation by suppressing the activation of intracellular Ca2+ mobilization and preventing the release of cytokines and chemokines from mast cells in a dose-dependent manner via the PKC-PLCγ-IP3R signaling pathway. ConclusionIn summary, HSYA has anti-anaphylactoid pharmacological activity, which makes it a potential candidate for the development of a novel agent to suppress drug-induced anaphylactoid reactions.