ABSTRACT
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. Jørg. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments (1H, 13C, DEPT, COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC) and mass spectrometry as (3ß,21ß,22α)-3-[(2-O-ß-D-glucopyranosyl-O-[α-L-arabinopyranosyl-(1 â 4)]-ß-D-glucopyranosyl)oxy]-21-[((2E,6S)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl)oxy]-22-(acetyloxy)-24-hydroxyolean-12-en-28-oic acid, (3ß,21ß,22α)-3-[(2-O-ß-D-galactopyranosyl-ß-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-α-L-arabinopyranosyl-(1 â 4)-ß-D-glucopyranoside, (3ß,21ß,22α)-3-[(2-O-ß-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 â 4)]-ß-D-xylopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-ß-D-glucopyranoside, (3ß,21ß,22α)-3-[(2-O-ß-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 â 4)]-ß-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-ß-D-glucopyranoside, (3ß,21ß,22α)-3-[(2-O-ß-D-galactopyranosyl-O-[α-L-arabinopyranosyl-(1 â 4)]-ß-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O-ß-D-glucopyranosyl-(1 â 6)-ß-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.
