Dimeric antioxidant and cytotoxic triterpenoid saponins from Terminalia ivorensis A Chev

Three saponins including two dimeric triterpenoid glucosides possessing an unusual skeleton ivorenosides A and B and a monomeric triterpenoid saponin (ivorenoside C) together with the known sericoside were Isolated from the bark of Terminalia ivorensis Their structures were established on the basis of 1D and 2D NMR data chemical methods and tandem MS-MS spectrometry as a dimer of beta-D-glucopyranosyl-18 19-seco-2 alpha 3 beta 19 19 24-pentahydroxyolean-12-en-28-oate and beta-D-glucopyranosyl-2 alpha,3 beta 19 alpha 24-tetrahydroxyolean-12-en-28-oate (ivorenoside A 1) a dimer of beta-D-glucopyranosyl-18 19-seco-24-carboxyl-2 alpha,3 beta 19 19-tetrahydroxyolean-12-en-28-oate and beta-D-glucopyranosyl-2 alpha 3 beta 19 alpha,24-tetrahydroxyolean-12-en-28-oate (ivorenoside B 2) and beta-D-glucopyranosyl-2 alpha,3 beta 19 beta 24-tetrahydroxyolean-11oxo-olean-12-en-28-oate (ivorenoside C 3) Ivorenosides A and B are the first examples in nature of dimeric triterpenoid saponins with a 18 19-seco E ring of one of the two units These isolated compounds were evaluated for their antioxidant properties and further for their cytotoxic activity against four human cancer cell lines Ivorenoside B and C exhibited scavenging activity against DPPH and ABTS(+) radicals with IC50 values comparable with that of the standard drug Trolox and ivorenoside A showed antiproliferative activity against MDA-MB-231 and HCT116 human cancer cell lines with IC50 values of 3 96 and 343 mu M respectively (C) 2010 Elsevier Ltd All rights reserved