A new sesquiterpenoid from <i>Polyalthia petelotii</i>

<p>A new sesquiterpenoid (‒)-ethyl dihydrophaseate (<b>1</b>) was isolated from the stems and leaves of <i>Polyalthia petelotii</i>, together with two clerodane diterpenoids, 16<i>α</i>-hydroxycleroda-3,13(14)<i>Z</i>-dien-15,16-olide (<b>2</b>), 15-hydroxy-<i>cis</i>-<i>ent</i>-cleroda-3,13(<i>E</i>)-diene (<b>3</b>), a eudesmane sesquiterpenoid, eudesm-4(15)-ene-7<i>α</i>,11-diol (<b>4</b>), an aromatic aldehyde, vanillin (<b>5</b>), a bisisoquinolines alkaloid, spinosine (<b>6</b>) and an aporphine alkaloid, (‒)-oliveroline-<i>β</i>-<i>N</i>-oxide (<b>7</b>). Their structures were established by extensive spectroscopic analysis, including 2D-NMR techniques. Compounds <b>3</b>, <b>4</b> and <b>6</b> were isolated from the genus <i>Polyalthia</i> for the first time and the others obtained originally from <i>P. petelotii</i>. The isolates were assessed for their cytotoxicity against five human tumour lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480), and the result showed that only <b>2</b> displayed weak inhibitory activity.</p