New oleanane glycosides from the roots of Gomphrena macrocephala

Abstract

Six new (1-6) and one known (7) oleanane glycosides have been isolated from the roots of Gomphrena macrocephala. On the basis of 1D- and 2D-NMR spectroscopic data and the results of hydrolysis, the structures of 1-6 were determined to be 3β-[(O- β-D-glucuronopyranosyl)oxy]oleana-11,13-dien- 28-oic acid (1), 3β-[(O-β-D-galactopyranosyl-(1→3)-O-[β-D- glucopyranosyl-(1→2)]-β-D-glucuronopyranosyl)oxy]oleana-11, 13-dien-28-oic acid (2), 3β-[(O-β-D-glucuronopyranosyl)oxy]oleana-9, 12-dien-28-oic acid β-D-glucopyranosyl ester (3), 3β-[(O-β-D- galactopyranosyl-(1→3)-O-[β-D-glucopyranosyl-(1→2)] -β-Dglucuronopyranosyl) oxy]oleana-9,12-dien-28-oic acid β-D-glucopyranosyl ester (4), 3β-[(O-β-D-galactopyranosyl- (1→3)-O-[β-D-glucopyranosyl-(1→2)]-β-D-glucuronopyranosyl) oxy]-11-oxo-olean-12-en-28-oic acid β-D-glucopyranosyl ester (5), and 3β-[(O-β-D-galactopyranosyl-(1→3)-O-[β-D-glucopyranosyl- (1→2)]-β-D-glucuronopyranosyl)oxy]-11α-hydroxyolean-12-en- 28-oic acid β-D-glucopyranosyl ester (6), respectively. Although 1-7 did not show apparent cytotoxicity against human oral squamous cell carcinoma (HSC-2) cells and normal human pulp cells (HPC), the aglycones 1a and 3a of 1 and 3 exhibited tumor-specific cytotoxicity against HSC-2 cells, and the IC 50 value of 3a against HSC-2 cells was almost equal to that of etoposide, used as a positive control.