Inhibitory effects of Solidago chilensis Meyen hydroalcoholic extract on acute inflammation

Alcoholic or hydroalcoholic preparations of the plant Solidago chilensis Meyen (Asteraceae) are employed in popular medicines to treat inflammation. The anti-inflammatory effects of the hydroalcoholic extract of aerial parts of the plant (93% ethanol) were investigated and the main components of the extract were identified. Ear oedema was induced in male Wistar rats by topical application of the chloroform fraction of latex-extract from Euphorbia milii. Leukocyte mobilisation was quantified after air-pouch inflammation evoked by oyster glycogen. Leukocyte–endothelial interactions and mast cell degranulation were quantified by intravital microscopy. The extract itself was characterised via HPLC–DAD–MS and HPLC–MS/MS. Topical (12.5–50 mg/kg) or intraperitoneal (25 or 50 mg/kg) administrations of the extract reduced ear oedema formation (>25% reduction). Intraperitoneal applications of 25 mg/kg of extract inhibited the migration of polymorphonuclear cells into the inflamed cavity (about 50%). In addition, the rolling behaviour and adherence of circulating leukocytes to postcapillary venules of the mesentery network was diminished (50%), but the mast cell degranulation in the perivascular area was not affected. The major components of the extract were identified as caffeoylquinic acid derivatives and the flavonoid rutin. The data presented herein show local and systemic anti-inflammatory effects of the hydroalcoholic extract of aerial parts of Solidago chilensis, and implicate the inhibition of leukocyte–endothelial interactions as an important mechanism of the extract's action.