A new iridoid glycoside, namely 8-O-(threo-2, 3-dihydroxyl-3-phenyl-propionoyl)-harpagide (1), along with a new cinnamoyl glycoside named as cis-sibirioside A (2), were isolated from Scrophularia ningpoensis Hemsl. Their chemical structures were completely established by spectroscopic methods and comparison with related literatures. Compound 1 exhibited moderate antifouling effect against the settlement of Balanus amphitrite larvae with IC50 being 13.5 μg/mL and LC50 > 25 μg/mL.
Keywords: Scrophularia ningpoensis Hemsl; antifouling; cinnamoyl glycoside; iridoid glycoside.