Two new chemical constituents from Lonicera japonica.

Two new chemical constituents, japopenoid D (1), and japopenoid E (2), were isolated and identified from the flower buds of Lonicera japonica Thunb. The structures of these compounds were elucidated based on spectroscopic analysis (HR-ESI-MS, NMR), and the absolute configurations of 1 and 2 were determined by comparison of their electronic circular dichroism (ECD) spectra with literature and theoretical calculation. The anti-inflammatory activities of the isolates were evaluated by measuring their inhibitory effects on PGE2 and IL-6 production in LPS stimulated RAW 264.7 macrophages. As a result, compound 1 could reduce PGE2 and IL-6 levels in LPS-activated RAW 264.7 macrophages with IC50 values of 6.78 and 42.07 μM, respectively.