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 ( 1 H, 1 H‐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 ‐[( E )‐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 ‐[ β ‐ 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 = (2 β ,3 β ,4 α )‐2,3,27‐trihydroxyolean‐12‐ene‐23,28‐dioic acid).