Triterpene saponins from four species of the polygalaceae family

Twelve triterpene saponins were isolated by successive MPLC over silica gel from four species of Polygalaceae: From Polygala ruwenzoriensis, five new saponins 1-5 of which 1-4 as two pairs of (E)/(Z)-isomers, together with the four known compounds tenuifoline, (E)- and (Z)-senegasaponin b, (E)- and (Z)-senegin II, and polygalasaponin XXVIII, from the genus Carpolobia, one new saponin 6 from C. alba and the known arilloside (11) from C. lutea, and another new triterpene glycoside 7 from Polygala arenaria. Their structures were established mainly by 600-MHz 2D-NMR techniques (¹H, ¹H-COSY, TOCSY, NOESY, HSQC, HMBC) as 3-O-(β-D-glucopyranosyl) presenegenin 28-{O-α-L-arabinopyranosyl-(1 → 4)-O-β-D- xylopyranosyl-(1 → 4)-O-α-L-rhamnopyranosyl-(1 → 2)-4-O-[(E)-4-methoxycinnamoyl]-β-D-fucopyranosyl} ester (1) and its (Z)-isomer 2, 3-O-(β-D-glucopyranosyl)presenegenin 28-{O-α-L- arabinopyranosyl-(1 → 4)-O-β-D-xylopyranosyl-(1 → 4)-O-α-L-rhamnopyranosyl-(1 → 2)-4-O-[(£)-3,4- dimethoxycinnamoyl]-β-D-fucopyranosyl} ester (3) and its (Z)-isomer 4, 3-O-(β-D-glucopyranosyl)presenegenin 28-[O-β-D-galactopyranosyl-(1 → 4)-O-β-D-xylopyranosyl-(1 → 4)-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranosyl] ester (5), 3-O-(β-D-glucopyranosyl) presenegenin 28-{O-α-L-arabinopyranosyl-(1 → 3)-O-[β3-D- galactopyranosyl-(1 → 4)]-O-β-D-xylopyranosyl-(1 → 4)-O-α-L-rhamnopyranosyl-(1 → 2)-O-[β-D-apiofuranosyl-(1 → 3)]-4-O-acetyl-β-D-fucopyranosyl} ester (6), and 3-O-(β-D- glucopyranosyl)presenegenin 28-{O-β-D-galactopyranosyl-(1 → 4)-O-[β-D-glucopyranosyl-(1 → 3)]-O-β-D-xylopyranosyl-(1 → 4)-O-α-L-rhamnopyranosyl-(1 → 2)-β-D-fucopyranosyl} ester (7) (presenegenin = (2β,3β,4α)-2,3,27-trihydroxyolean-12-ene-23,28- dioic acid).