Inhibitory constituents from the aerial parts of Polygala tenuifolia on LPS-induced NO production in BV2 microglia cells

Five new phenolic glycosides, tenuisides A–E (1?5), and a new megastigmane glycoside, tenuiside F (6), along with seventeen known compounds (7–23) were isolated from the aerial parts of Polygala tenuifolia Willd. Their structures were established by detailed analysis of NMR and HRESIMS spectroscopic data, and the absolute configurations of compounds 5 and 6 were determined by CD spectra and in-NMR-tube Mosher’s method. The inhibitory effects of these compounds were evaluated on NO production in LPS-activated BV-2 microglia cells. Compound 17 showed the strongest activity, with an IC₅₀ value of 7.4 μM, while compounds 1, 8, 14, and 18 showed the moderate activities, with IC₅₀ values of 16.2–38.5 μM. And their primary structure–activity relationships (SARs) of NO inhibitory effects were also briefly discussed.