Cytotoxic and antioxidant triterpene saponins from Butyrospermum parkii (Sapotaceae)

Abstract

Three new triterpenoid saponins, elucidated as 3-O-β-D-glucopyranosyloleanolic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranoside (parkioside A, 1), 3-O-[β-D-apifuranosyl-(1→3)-β-D-glucopyranosyl]oleanolic acid 28-O-[β-D-apifuranosyl-(1→3)-β-D-xylopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→3)]-α-L-rhamnopyranosyl-(1→2)β-D-xylopyranoside (parkioside B, 2) and 3-O-β-D-glucuronopyranosyl-16α-hydroxyprotobassic acid 28-O-α-L-rhamnopyranosyl-(1→3)-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranoside (parkioside C, 3), were isolated from the n-BuOH extract of the root bark of Butyrospermum parkii, along with the known 3-O-β-D-glucopyranosyloleanolic acid (androseptoside A). The structures of the isolated compounds were established on the basis of chemical and spectroscopic methods, mainly 1D and 2D NMR data and mass spectrometry. The new compounds were tested for both radical scavenging and cytotoxic activities. Compound 2 showed cytotoxic activity against A375 and T98G cell lines, with IC(50) values of 2.74 and 2.93 μM, respectively. Furthermore, it showed an antioxidant activity comparable to that of Trolox or butylated hydroxytoluene (BHT), used as controls, against 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), oxygen and nitric oxide radicals.