Isolation of two new prenylflavonols from Epimedium brevicornum and their effects on cytokine production in vitro.

In an attempt to search for bioactive natural products, two new prenylflavonols, 2''-hydroxy-3''-en-anhydroicaritin (1) and 2''-hydroxy-beta-anhydroicaritin (2), were isolated from the Chinese medicinal herb Epimedium brevicornum. Their structures were determined by 1D and 2D NMR spectroscopic analysis. The effects of compounds 1 and 2 on cytokine production in vitro were investigated. Compound 1 could significantly downregulate tumor necrosis factor-alpha (TNF-alpha) production and increase interleukin-10 (IL-10) production. These results suggested that compound 1 may have anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated mouse macrophages. In addition, the biogenetic relationships among compounds 1 and 2 are discussed.