Isolation and Characterization of Lup-20(29)-ene-3, 28-diol (Betulin) from the Stem-Bark of Adenium obesum (Apocynaceae)

Purpose: To isolate and characterize chemical compound(s) of biological importance from the stem-bark of the plant, Adenium obesum. Methods: The stem-bark, after air-drying and powdering, was subjected to sequential hot-continuous extraction using petroleum spirit (60-80 degrees C) and methanol in that order. The petroleum spirit extract was chromatographed using thin layer and column chromatographic techniques. Recrystallization was used to further purify the isolated compound. Characterization of the isolated compound was by melting point, as well as by H-1 and C-13 nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). Results: A triterpenoid (lup-20(29)-ene-3, 28-diol), commonly known as betulin, was isolated from the crude petroleum ether extract of the plant stem-bark. The isolated compound's melting point was 256-257 degrees C. The name, betulin, was assigned to this compound by comparison of its spectroscopic data from H-1-NMR, C-13-NMR and MS analysis with those of authenticated samples reported in the literature. Conclusion: A known compound, betulin (lup-20(29)-ene-3, 28-diol) was isolated from the petroleum ether extract of the stem-bark of Adenium obesum.