Decoction of Dictamnus Dasycarpus Turcz. Root Bark Ameliorates Skin Lesions and Inhibits Inflammatory Reactions in Mice with Contact Dermatitis

BACKGROUND: The root bark of Dictamnus dasycarpus Turcz. (Dictamni Radicis Cortex) has been widely used to treat skin diseases in Korea, and its anti-inflammatory efficacies were recently reported. OBJECTIVE: The paper aims to investigate the inhibitory effects of decoction of Dictamni Radicis Cortex (DDRC) in mice with contact dermatitis (CD). MATERIALS AND METHODS: We investigated the effects of DDRC on skin lesion characteristics such as crust, scales, incrustation and petechiae, the erythema and melanin indexes, skin thickness, histopathologic changes, and cytokine production in 1-fluoro-2,4-dinitrofluorobenzene (DNFB)-induced CD mice. RESULTS: Topical application of DDRC ameliorated crust, scales, incrustation, and induced by DNFB. In addition, DDRC lowered the erythema index significantly (P < 0.05). DDRC effectively inhibited enlargement of skin thickness (P < 0.05). Histopathologic observation showed that DDRC inhibited epidermal hyperplasia, hyperkeratosis, and spongiotic changes. Finally, DDRC decreased production levels of IFN-γ, TNF-α and IL-6 induced by repeated application of DNFB (P < 0.05). CONCLUSION: These data suggest that DDRC can be used in the treatment of inflammatory skin diseases including CD. Moreover, these results are closely related to the decreasing production of TNF-α IFN-γ and IL-6 in inflamed tissues. SUMMARY: DDRC ameliorated skin lesions such as crust, scales, incrustation and petechiae, and lowered erythema index on skin surface in CD mice. DDRC inhibited enlargement of dorsal skin and prevented epidermal hyperplasia, hyperkeratosis, and spongiotic changes in inflamed tissues. DDRC reduced the levels of TNF-α, IFN-γ, and IL-6 in inflamed tissues of CD mice. DDRC did not affect spleen/body weight ratio in CD mice. Abbreviations used: DDRC: decoction of Dictamni Radicis Cortex, CD: contact dermatitis, DNFB: 1-fluoro-2,4-dinitrofluorobenzene, AOO: acetone and olive oil, DEX: dexamethasone, CBA: cytometric bead array