Pycnogenol® inhibits immunoglobulin E‐mediated allergic response in mast cells

IgE‐dependent mast cell activation is known to be associated with the allergic diseases. Pycnogenol^® (PYC) is a standardized extract of the bark of French maritime pine containing bioflavonoids with a potent antioxidant activity. The antiallergic activity of PYC was evaluated using both in vivo and in vitro experimental models. Oral administration of PYC significantly inhibited anti‐dinitrophenyl (DNP) IgE‐mediated passive cutaneous anaphylaxis in rats. In an in vitro study, PYC dose‐dependently reduced histamine release from rat peritoneal mast cells (RPMC) triggered by anti‐DNP IgE. PYC inhibited the protein expression and secretion of tumor necrosis factor‐α and interleukin‐6 in anti‐DNP IgE‐stimulated RPMC. Moreover, PYC decreased anti‐DNP IgE‐induced calcium uptake into RPMC. Furthermore, PYC suppressed nuclear factor‐kappa B activation. From these results, the clinical use of PYC in the mast cell‐mediated immediate‐type allergic diseases is proposed. Copyright © 2009 John Wiley & Sons, Ltd.