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Helvetica Chimica Acta – Vol. 90 (2007)
0.34. IR(KBr): 3406, 2927, 1740, 1723, 1710, 1636, 1580, 1420. 1H- and 13C-NMR: see Tables 1 and 2.
FAB-MS (neg.): 1073 ([MꢀH]ꢀ), 941 ([MꢀHꢀ132]ꢀ), 779 ([MꢀHꢀ132ꢀ162]ꢀ), 617
([MꢀHꢀ132ꢀ162ꢀ162]ꢀ), 485 ([MꢀHꢀ132ꢀ162ꢀ162ꢀ132]ꢀ). HR-ESI-MS (pos.): 1097.5189
([M+Na]+; calc.1097.5145).
Repensoside C (=(3b)-3-O-(b-D-Xylopyranosyl)gypsogenic Acid 28-{b-D-Glucopyranosyl(1 ! 3)-
[b-D-glucopyranosyl-(1 ! 6)]-b-D-galactopyranosyl} Ester; 3). Colorless, amorphous powder. TLC (A):
Rf 0.35. IR(KBr): 3404, 2927, 1740, 1723, 1710, 1636, 1580, 1500, 1420. 1H- and 13C-NMR: see Tables 1
and 2. FAB-MS (neg.): 1103 ([MꢀH]ꢀ), 941 ([MꢀHꢀ162]ꢀ), 617 ([MꢀHꢀ132ꢀ162ꢀ162]ꢀ), 485
([MꢀHꢀ162ꢀ162ꢀ162ꢀ132]ꢀ). HR-ESI-MS (pos.): 1127.5210 ([M+Na]+; calc.1127.5250).
Repensoside D (=(3b)-3-O-{b-D-Glucopyranosyl-(1 ! 2)-b-D-galactopyranosyl-(1 ! 2)-[b-D-gluco-
pyranosyl-(1 ! 4)]-b-D-galactopyranosyl}gypsogenic Acid; 4). Colorless, amorphous powder. TLC (A):
Rf 0.34. IR(KBr): 3404, 2927, 1723 1740, 1710, 1636, 1580, 1500, 1420. 1H- and 13C-NMR: see Tables 1
and 3. FAB-MS (neg.): 1133 ([MꢀH]ꢀ), 971 ([MꢀHꢀ162]ꢀ), 809 ([MꢀHꢀ162ꢀ162]ꢀ), 485
([MꢀHꢀ162ꢀ162ꢀ162ꢀ162]ꢀ). HR-ESI-MS (pos.): 1157.5321 ([M+Na]+; calc. 1157.5356).
Repensoside
E
(=(3b)-3-O-{b-D-Glucopyranosyl-(1 ! 2)-[b-D-xylopyranosyl-(1 ! 3)]-b-D-gluco-
pyranuronosyl}gypsogenic Acid 28-{a-L-Arabinopyranosyl-(1 ! 4)-a-L-arabinopyranosyl-(1!3)-b-D-
xylopyranosyl-(1!4)-a-L-rhamnopyranosyl-(1!2)-[b-D-quinovopyranosyl-(1!4)]-b-D-fucopyranosyl}
Ester; 5). Colorless, amorphous powder. TLC (A): Rf 0.10. IR(KBr): 3404, 2927, 1740, 1723, 1710, 1636,
1580, 1500, 1420. 1H- and 13C-NMR: see Tables 1 and 4. FAB-MS (neg.): 1789 ([MꢀH]ꢀ). HR-ESI-MS
(pos.): 1813.0178 ([M+Na]+; calc. 1813.0125).
Repensoside F (=(3b)-3-O-{b-D-Galactopyranosyl-(1!2)-[b-D-xylopyranosyl-(1!3)]-b-D-glucopyr-
anuronosyl}gypsogenin 28-{a-L-Arabinopyranosyl-(1!3)-b-D-xylopyranosyl-(1!4)-a-L-rhamnopyrano-
syl-(1!2)-(3-O,4-O-diacetyl-b-D-fucopyranosyl)} Ester; 6). Colorless, amorphous powder. TLC (A): Rf
0.33. IR(KBr): 3404, 2927, 1740, 1723, 1710, 1636, 1580, 1500, 1420. 1H- and 13C-NMR: see Tables 1
and 4. FAB-MS (neg.): 1579 ([MꢀH]ꢀ), 1447 ([MꢀHꢀ132]ꢀ), 1315 ([MꢀHꢀ132ꢀ132]ꢀ), 939
([MꢀHꢀ132ꢀ132ꢀ146ꢀ146ꢀ42ꢀ42]ꢀ),
469
([MꢀHꢀ132ꢀ132ꢀ146ꢀ146ꢀ42ꢀ42ꢀ162ꢀ
132ꢀ176]ꢀ). HR-ESI-MS (pos.): 1603.6802 ([M+Na]+; calc. 1603.6780).
Acid Hydrolysis. A soln. of the isolate (2 mg) in H2O (2 ml) was treated with 2N aq. CF3COOH (5 ml)
and heated at reflux for 3 h. The mixture was extracted with CHCl3 (3ꢂ5 ml) (sapogenin, TLC, solvent
B), the aq. layer was separated, treated with MeOH, and repeatedly evaporated until neutral, and then
analyzed by TLC (solvent C) by comparison with standard sugars.
Alkaline Hydrolysis. The appropriate saponin (2 mg) in 5% aq. KOH soln. (10 ml) was heated at
reflux for 2 h. The mixture was adjusted to pH 6 by adding dil. aq. HCl, and then extracted with H2O-
sat. BuOH (3ꢂ10 ml). The combined BuOH extracts were washed with H2O and evaporated to afford
the corresponding prosapogenin.
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Received November 10, 2006