Effect of extract from laquer tree ( Rhus verniciflua Stokes) on DNCB-induced atopic dermatitis in NC/Nga mouse

Laquer tree (Rhus verniciflua Stokes; Anacardiaceae, RVS) has been used in oriental medicines. This study examined whether the extract of RVS free of urushiol (detoxified RVS extract, DRE) exerting antiinflammation could alleviate the symptoms of atopic dermatitis (AD) induced with 2,4-dinitrochlorobenzene (DNCB) in NC/Nga mice. DRE contained flavonoids like fustin (153 mg/g), fisetin (14.6 mg/g), sulfuretin (13.3 mg/g), and quercetin (0.95 mg/g). DRE (10 μg/mL) decreased the production of nitric oxide activated by lipopolysaccharide. Oral administration of DRE (200 mg/kg weight/day) decreased scratching frequencies, the epidermal thickness on dorsal skin, and the number of degranulated mast cell. DRE significantly lowered the levels of IgE in sera (p<0.01), which were elevated by DNCB. DNCB reciprocally raised IL-4 and lowered IFN-γ in media of spleenocyte. DRE reversely raised IFN-γ and lowered IL-4. Contrastively, dexamethasone suppressed the overall immune reactions. In conclusion, DRE inhibited Th2-mediated IgE overproduction through modulation of Th1/2 balance, which was in part attributed to anti-inflammatory activity.