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

Abstract

<i>Pterocarpus santalinus</i> has been traditionally used as a medicinal plant owing to its anti-inflammatory, anthelmintic, tonic, antihyperglycemic, and diaphoretic properties. We hypothesized that <i>P. santalinus</i> might have therapeutic potential in alleviating allergy and atopic dermatitis. Thus, we investigated the inhibitory effects of <i>P. santalinus</i> 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 <i>P. santalinus</i> extract in 2,4-dinitrochlorobenzene-induced atopic dermatitis was evaluated through morphological, physiological, and immunological analysis. <i>P. santalinus</i> extract inhibited <i>β</i>-hexosaminidase and histamine release and reduced tumor necrosis factor-<i>α</i>, interleukin-4, and prostaglandin E₂ secretion. Furthermore, <i>P. santalinus</i> 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 <i>P. santalinus</i> extract might have beneficial effects in treating allergic and atopic dermatitis-like skin disorders.