Presenegenin Glycosides from Securidaca welwitschii

The five new presenegenin glycosides 1 – 5 were isolated from Securidaca welwitschii , together with one known sucrose diester. Compounds 1 – 4 were obtained as pairs of inseparable ( E )/( Z )‐isomers of a 3,4‐dimethoxycinnamoyl derivative, i.e. , 1 / 2 and 3 / 4 . Their structures were elucidated mainly by 2D‐NMR techniques and mass spectrometry as 3‐ O‐ ( β ‐ D ‐glucopyranosyl)presenegenin 28‐{ O ‐ β ‐ D ‐xylopyranosyl‐(1→4)‐ O ‐ α ‐ L ‐rhamnopyranosyl‐(1→2)‐ O ‐[ β ‐ D ‐glucopyranosyl‐(1→3)]‐4‐ O ‐[( E )‐3,4‐dimethoxycinnamoyl]‐ β ‐ D ‐fucopyranosyl} ester ( 1 ) and its ( Z )‐isomer 2 , 3‐ O‐ ( β ‐ D ‐glucopyranosyl)presenegenin 28 ‐ { O ‐ β ‐ D ‐galactopyranosyl‐(1→4)‐ O ‐ β ‐ D ‐xylopyranosyl‐(1→4)‐ O ‐3‐ O ‐acetyl‐ α ‐ L ‐rhamnopyranosyl‐(1→2)‐ O ‐[ β ‐ D ‐glucopyranosyl‐(1→3)]‐4‐ O ‐[( E )‐3,4‐dimethoxycinnamoyl]‐ β ‐ D ‐fucopyranosyl} ester ( 3 ) and its ( Z )‐isomer 4 , and 3‐ O‐ ( β ‐ D ‐glucopyranosyl)presenegenin 28‐[ O ‐ β ‐ D ‐galactopyranosyl‐(1→3)‐ O ‐ β ‐ D ‐xylopyranosyl‐(1→4)‐ O ‐ α ‐ L ‐rhamnopyranosyl‐(1→2)‐ β ‐ D ‐fucopyranosyl] ester ( 5 ) (presenegenin=(2 β ,3 β ,4 α )‐2,3,27‐trihydroxyolean‐12‐ene‐23,28‐dioic acid).