Constituents of the Roots of Dichapetalum pallidum and Their Anti-Proliferative Activity

Abstract

As part of our search for bioactive compounds from the Dichapetalaceae, repeated chromatographic purification of the roots of a hitherto unexamined species, <i>Dichapetalum pallidum</i>, led to the isolation of the newly occurring 7-hydroxydichapetalin P (<b>1</b>) and the known dichapetalins A (<b>2</b>) and X (<b>3</b>). Also isolated were the known compounds friedelin-2,3-lactone (<b>4</b>), friedelan-3-one (<b>6</b>), friedelan-3β-ol (<b>7</b>) and pomolic (<b>8</b>), as well as the dipeptide aurantiamide acetate (<b>5</b>). The compounds were characterized by direct interpretation of their IR, 1D NMR and 2D NMR spectral data and by comparison of their physico-chemical data, including their chromatographic profiles, with the literature and authentic samples in our compound library for the genus <i>Dichapetalum</i>. The compounds were assayed for their anti-proliferative activities against the human T-lymphocytic leukemia (Jurkat), acute promyelocytic leukemia (HL-60) and T-lymphoblast-like leukemia (CEM) cell lines. Overall, dichapetalin X showed the strongest (3.14 μM) and broadest cytotoxic activities against all the leukemic cell lines tested, exhibiting even stronger activities than the standard compound, curcumin.