Novel Triterpene Saponins from Zizyphus joazeiro (original) (raw)

2000, Helvetica Chimica Acta

Two dammarane-type saponins with a novel aglycone derived from the parent 16,22-epoxy-24methylidenedammarane and lotoside A, a new lotogenin derivative, were isolated from the MeOH extract of the stem bark of the Brazilian medicinal plant Zizyphus joazeiro, in addition to the known saponin 3b-{{O-[O-[a-l-arabinofuranosyl-(1 3 2)]-O-[b-d-glucopyranosyl-(1 3 3)]]-a-l-arabinopyranosyl}oxy}jujubogenin (1). The structures of the new compounds were determined as 16,22-epoxy-3b-[(b-d-glucopyranosyl)oxy]-24methylidenedammarane-15a,16a,20b-triol (2), 16,22-epoxy-3b-{{O-[O-[b-d-glucopyranosyl-(1 3 2)]-O-[b-dapiofuranosyl-(1 3 3)]]-b-d-glucopyranosyl-(1 3 2)-a-l-arabinopyranosyl}oxy}-24-methylidenedammarane-15a,16a,20b-triol (3), and 3b-{{O-[O-[b-d-glucopyranosyl-(1 3 2)]-O-[b-d-apiofuranosyl-(1 3 3)]]-b-d-glucopyranosyl-(1 3 2)-a-l-arabinopyranosyl}oxy}lotogenin (4) by means of 1D-and 2D-NMR spectroscopy, as well as FAB mass spectrometry. For the novel aglycone, we propose the name joazeirogenin and, for the new saponins, joazeiroside A (2) and B (3). Joazeirogenin was found to be 16,22-epoxy-24-methylidenedammarane-3b,15a,16a,20b-tetrol.