Hydroxycinnamoyl derivatives and secoiridoid glycoside derivatives from Syringa vulgaris flowers and their effects on the pro-inflammatory responses of human neutrophils.

Thirteen new compounds including caffeoyl-glucaric and p-coumaroyl-altraric acid derivatives, one monoterpenoid glucoside, four secoiridoid glycosides, and three hydroxycinnamoyl phenylpropanoid glycosides esterified with an oleoside 11-methyl ester along with fifteen known compounds were isolated from flowers of Syringa vulgaris L. (Oleaceae). Their structures were elucidated by high-resolution spectroscopic methods. The tested compounds were able to decrease the production of reactive oxygen species. Moreover, oleoechinacoside (13), demethylhydroxyoleonuezhenide (14), demethyloleonuezhenide (15), syringaoleoacteoside (25) and oleoacteoside (26) at the concentration of 50µM, moderately suppressed the LPS-stimulated release of pro-inflammatory chemokine IL-8 and TNF-α from human neutrophils. Moreover, oleonuezhenide (12), oleoside 11-methyl ester (16) and oleoacteoside (26) at the concentration of 50µM were able to induce the surface expression of interleukin 10 receptor, which is suppressed by the incubation of monocyte/macrophage cells with LPS.