The methanol extract of O. rigidum was subjected to Sephadex LH-20 gel permeation chromatography followed by flash reversed-phase C18 chromatography. A 1H NMR spectrum of the major fraction that was obtained from the C18 flash chromatography column (20% H2O in MeOH) identified resonances associated with aromatic, anomeric, alcoholic, and acetate protons. This fraction was further purified using bonded-phase NH2 HPLC to give two resolved peaks. The 1H NMR spectra of these two peaks both contained signals observed for the initial fraction, but had subtle differences in the anomeric region of their spectra. Further, there were a series of sharp singlets between 1.96 and 2.05 ppm, which were attributed to acetate protons. Although these fractions appeared as single peaks in their chromatograms, the 1H NMR spectra indicated that they were not pure compounds. The two fractions were subjected to an LC-MSTOF experiment to