Triterpene saponins from Billia rosea

Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isolated from the seeds of Billia rosea (Planch. & Linden) C. Ulloa & P. Jorg. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments (H-1, C-13, DEPT, COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC) and mass spectrometry as (3 beta,21 beta,22 alpha)-3-[(2-O-beta-D-glucopyranosyl-O-[alpha-L-arabinopyranosyl-(1 -> 4)]-beta-D-glucopyranosyl)oxy]-21-[((2E,6S)-2,6-dimethyl-6-hydroxyocta -2,7-dienoyl)oxy]-22-(acetyloxy)-24-hydroxyolean-12-en-28-oic acid, (3 beta,21 beta,22 alpha)-3-[(2-O-beta-D-galactopyranosyl-beta-D-glucopyranosyl)oxy]-21,2 2-dihydroxyolean-12-en-28-yl O-alpha-L-arabinopyranosyl-(1 -> 4)-beta-D-glucopyranoside, (3 beta,21 beta,22 alpha)-3-[(2-O-beta-D-galactopyranosyl-O-[alpha-L-arabinopyranosyl-( 1 -> 4)]-beta-D-xylopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-beta-D-glucopyranoside, (3 beta,21 beta,22 alpha)-3-[(2-O-beta-D-galactopyranosyl-O-[alpha-L-arabinopyranosyl-( 1 -> 4)]-beta-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-beta-D-glucopyranoside, (3 beta,21 beta,22 alpha)-3-[(2-O-beta-D-galactopyranosyl-O-[alpha-L-arabinopyranosyl-( 1 -> 4)]-beta-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranoside, and dipteroside A. Billiosides B and C exhibited moderate effects when tested as hepatic glucose-6-phosphatase inhibitors and as glucose intestinal absorption inhibitors, using in situ rat intestinal segments.