Iridoids from the Roots of Patrinia scabra and Their Inhibitory Potential on LPS-Induced Nitric Oxide Production

An activity-guided fractionation procedure of the 70% aqueous EtOH extract from the roots of Patrinia scabra led to the isolation and characterization of five new iridoids, patriscabrins A-E (1-5), along with 13 known compounds. The structures of 1-5 were determined by interpretation of spectroscopic data, particularly by 1D and 2D NMR, ECD, and VCD studies. Thereafter, isolates were evaluated for their inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells. Of these, the new iridoids 2 and 5 and the known lignan patrineolignan B (6) exhibited IC₅₀ values of 14.7 to 17.8 μM.