Triterpenoid saponins with antifeedant activities from stem bark of Catunaregam spinosa (Rubiaceae) against Plutella xylostella (Plutellidae)

Seven triterpenoid saponins, including four new compounds, catunarosides A–D (1–4), and three known compounds, swartziatrioside (5), aralia-saponin V (6), araliasaponin IV (7) were isolated from the stem bark of Catunaregam spinosa, a Chinese mangrove associate. Their structures were elucidated on the basis of their spectral data and hydrolysis experiments. The antifeedant activities of compounds 1–7 against Plutella xylostella were also evaluated.

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► Seven oleanane-type saponins were isolated from stem bark of C. spinosa.
► Four new compounds were determined as catunaroside A–D by spectral and chemical methods.
► Three known compounds were obtained firstly from Catunaregam.
► All compounds exhibited moderate antifeedant activities against Plutella xylostella.