New Acylated Presenegenin Saponins from Two Species of Muraltia

Six new acylated bisdesmosidic triterpene glycosides 1-6 were isolated from the roots of Muraltia heisteria (L.) DC., as three inseparable mixtures 1/2, 3/4, and 5/6 of the (E)- and (Z)-3,4,5-trimethoxycinnamoyl derivatives. The compound pair 1/2 along with four known saponins were also isolated from the roots of Muraltia satureioides DC. Their structures were elucidated mainly by spectroscopic experiments including 2D-NMR techniques as 3-O-(β -D-glucopyranosyl)presenegenin 28-{O-β-D-apiofuranosyl-(1 → 3)-O-[β-D-xylopyranosyl-(1 → 4)]-O-a-L-rhamnopyranosyl-(1 → 2)-O-[6-O-acetyl-β-D-galactopyranosyl-(1 → 3)]-4-O-[(E)-3,4,5-trimethoxycinnamoyl]-β-D-fucopyranosyl} ester (1) and its (Z)-isomer 2, 3-O-(β-D-glucopyranosyl)presenegenin 28-{O-6-O-acetyl-β-D-galactopyranosyl-(1 → 3)-O-[3-O-acetyl-a-L-rhamnopyranosyl-(1 → 2)]-4-O-[(E)-3,4,5-trimethoxycinnamoyl]-β-D-fucopyranosyl} ester (3) and its (Z)-isomer 4, and 3-O-(β-D-glucopyranosyl)presenegenin 28-{O-3-O-acetyl-a-L-rhamnopyranosyl-(1 → 2)-O-[β-D-xylopyranosyl-(1 → 3)]-4-O-[(E)-3,4,5-trimethoxycinnamoyl]-β-D-fucopyranosyl} ester (5) and its (Z)-isomer 6, respectively.