New triterpenoid saponins from bulbs of Bolbostemma paniculatum

Nine new triterpenoid saponins were isolated from the bulbs of Bolbostemma paniculatum (Maxim.) Franquet (Cucurbitaceae): 7beta18,20,26-tetrahydroxy-(20S)-dammar-24E-en-3-O-alpha-L-(3-acetyl)arabinopyranosyl-(1-->2)-beta-D-glucopyrinoside, 7beta8,20,26-tryhydroxy-(20S)-dammar-24E-en-3-O-alpha-L-(4-acetyl)arabinopyranosyl-(1-->2)-beta-D-glucopyranoside, 7beta18,20,26-tetrahydroxy-(20S)dammar-24E-en-3-O-alpha-L-arabinopyranosyl-(1 -->2)-beta-D-(6-acetyl)glucopyranoside, 7beta20,26-trihydroxy-(20S)-dammar-24E-en-3-O-alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranoside, 7beta20,26-trihydroxy-(20S)-dammar-24E-en-3-O-alpha-L-(3-acetyl)arabinopyranosyl-(1-->2)-beta-D-glucopyranoside, 7beta,20,26-trihydroxy-(20S)dammar-24E-en-3-O-alpha-L-(4-acetyl)arabinopyranosyl-(1-->2)-beta-D-glucopyranoside, 7beta20,26-trihydroxy-8-formyl-(20S)-dammar-24E-en-3-O-alpha-L-(3-acetyl)arabinopyranosyl-(1 -->2)-beta-D-glucopyranoside, 7beta20,26-trihydroxy-8-formyl-(20S)-dammar-24E-en-3-O-alpha-L-(4-acetyl)arabinopyranosyl-(1 -->2)-beta-D-glucopyranoside and 6 -O-palmitoyltubeimoside I. In addition, four known triterpenoid saponins: tubeimoside I, tubeimoside II, tubeimoside III and tubeimoside IV were isolated. The structures of the above compounds were elucidated based on spectroscopic studies, and the configuration of C-20 of tubeimoside IV was revised as S rather than R as reported in previous literature. The compounds were tested for their antiviral activity.