Dihydrobenzofuran Neolignans Isolated from Euonymus alatus Leaves and Twigs Attenuated Inflammatory Responses in the Activated RAW264.7 Macrophage Cells

ABSTRACT

Anti-inflammatory effects of dihydrobenzofuran neolignans isolated from Euonymus alatus leaves and twigs were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. Six neolignans, (+)- simulanol (1), (+)-dehydrodiconiferyl alcohol (2), (-)-simulanol (3), (-)-dehydrodiconiferyl alcohol (4), (+)-dihydrodehyrodiconiferyl alcohol (5), threo-buddlenol B (6) effectively inhibited the production of nitric oxide (NO) induced by LPS, and the activity of iNOS. (-)-dehydrodiconiferyl alcohol (4), which showed the most potent inhibitory activity, attenuated the activity of iNOS enzyme and also the expression of iNOS and COX-2 proteins. The subsequent production of pro-inflammatory cytokines, interleukin-1β, interleukin-6, tumor necrosis factor-α and prostaglandin E2 were also inhibited by the pretreatment of RAW264.7 cells with (-)-dehydrodiconiferyl alcohol (4). These neolignans are thought to contribute to anti-inflammatory effects of E. alatus, and expected to be potential candidates to prevent/treat inflammation-related diseases.