Gentiana scabra Bunge roots alleviates skin lesions of contact dermatitis in mice

Ethnopharmacological relevance: The roots and rhizomes of Gentiana scabra Bunge in the family Gentianaceae comprise a major herbal medicine for skin diseases caused by wind-heat or dampness-heat in China, Japan and Korea. This treatment can clear away heat and dry dampness and purge fire from the liver and gallbladder. Aim of the study: This study was designed to investigate the therapeutic potential and anti-inflammatory effects of G. scabra, roots and rhizomes. Materials and methods: Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) revealed the presence of gentiopicrin in the roots and rhizomes of G. scabra. We then investigated the effects of ethanol extract of G. scabra, roots and rhizomes (EEGS) on skin lesions and thickness, erythema and melanin index, histopathological abnormalities, and cytokine and chemokine production in mice with contact dermatitis (CD) induced by 1-fluoro-2,4-dinitrofluorobenzene (DNFB). Moreover, the effects of EEGS on body weights and spleen body weight ratio were evaluated. Results: Topical application of EEGS alleviated skin lesions such as surface roughness, excoriations and scabs on the skin of CD mice, as well as prevented skin enlargement, and lowered the erythema and melanin index. In addition, EEGS prevented hyperkeratosis, epidermal hyperplasia and immune cell infiltration, and inhibited TNF-alpha, IFN-gamma, IL-6 and MCP-1 production in inflamed tissues. EEGS did not affect changes in body weights and spleen body weight ratio in contrast to dexamethasone. Conclusions: These data indicate that the roots and rhizomes of G. scabra can be used as anti-inflammatory agents for CD with relative safety and that its therapeutic mechanisms are related to regulation of pro-inflammatory cytokines such as TNF-alpha and IFN-gamma.