A new nor-28-oleanane glycoside isolated from Syzygium formosum inhibits nitric oxide production in LPS-stimulated RAW264.7 cells.

One new nor-28-oleanane glycoside (1) and fifteen known compounds (2 - 16) were separated from a methanol extract of Syzygium formosum leaves. Their structures were elucidated via HRESIMS and NMR spectroscopic analyses. The absolute configuration of 1 was determined based on ECD spectra calculated using TD-DFT methods. Among the isolates, syringin (11) exhibited significant inhibitory activity against NO production in LPS-stimulated RAW264.7 cells, with an IC50 value of 18.4 μM. Compounds 1 - 3 displayed moderate inhibitory effects, with IC50 values of 58.4-79.2 μM.