Inhibitory Effects of Pterocarpus santalinus Extract against IgE/Antigen-Sensitized Mast Cells and Atopic Dermatitis-Like Skin Lesions.

Pterocarpus santalinus has been traditionally used as a medicinal plant owing to its anti-inflammatory, anthelmintic, tonic, antihyperglycemic, and diaphoretic properties. We hypothesized that P. santalinus might have therapeutic potential in alleviating allergy and atopic dermatitis. Thus, we investigated the inhibitory effects of P. santalinus extract against allergic responses and 2,4-dinitrochlorobenzene-induced atopic dermatitis-like dorsal skin lesions using immunoglobulin E-sensitized rat basophilic leukemia-2H3 mast cells and NC/Nga mice. Degranulation and enzyme-linked immunosorbent assays were conducted to measure degranulation, proinflammatory cytokine levels, and prostaglandin E₂ concentrations in immunoglobulin E/antigen-sensitized RBL-2H3 mast cells. The therapeutic efficacy of P. santalinus extract in 2,4-dinitrochlorobenzene-induced atopic dermatitis was evaluated through morphological, physiological, and immunological analysis. P. santalinus extract inhibited β-hexosaminidase and histamine release and reduced tumor necrosis factor-α, interleukin-4, and prostaglandin E₂ secretion. Furthermore, P. santalinus extract suppressed atopic dermatitis-like skin lesions by regulating the serum levels of immunoglobulin E and immunoglobulin G2a, and messenger ribonucleic acid expression of T helper cell 1- and T helper cell 2-related mediators in the skin lesions. Histopathological analyses showed a decrease in epidermal thickness and intradermal inflammatory cell infiltration. These results suggested that P. santalinus extract might have beneficial effects in treating allergic and atopic dermatitis-like skin disorders.