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A phytochemical investigation of the roots of <i>Aspilia pluriseta</i> led to the isolation of <i>ent</i>-kaurane-type diterpenoids and additional phytochemicals (<b>1</b>&#8315;<b>23</b>). The structures of the isolated compounds were elucidated based on Nuclear Magnetic Resonance (NMR) spectroscopic and mass spectrometric analyses. The absolute configurations of seven of the <i>ent</i>-kaurane-type diterpenoids (<b>3</b>&#8315;<b>6</b>, <b>6b, 7</b> and <b>8</b>) were determined by single crystal X-ray diffraction studies. Eleven of the compounds were also isolated from the roots and the aerial parts of <i>Aspilia mossambicensis</i>. The literature NMR assignments for compounds <b>1</b> and <b>5</b> were revised. In a cytotoxicity assay, 12&#945;-methoxy-<i>ent</i>-kaur-9(11),16-dien-19-oic acid (<b>1</b>) (IC₅₀ = 27.3 &#177; 1.9 &#181;M) and 9&#946;-hydroxy-15&#945;-angeloyloxy-<i>ent</i>-kaur-16-en-19-oic acid (<b>3</b>) (IC₅₀ = 24.7 &#177; 2.8 &#181;M) were the most cytotoxic against the hepatocellular carcinoma (Hep-G2) cell line, while 15&#945;-angeloyloxy-16&#946;,17-epoxy-<i>ent</i>-kauran-19-oic acid (<b>5</b>) (IC₅₀ = 30.7 &#177; 1.7 &#181;M) was the most cytotoxic against adenocarcinomic human alveolar basal epithelial (A549) cells.