<p>In addition to known constituents of <i>Telekia speciosa</i>, an acetone extract from ray florets of the plant yielded: 5,5ʹ-dibutoxy-2,2ʹ-bifuran (<b>1</b>), 5,5ʹ-diisobutoxy-2,2ʹ-bifuran (<b>2</b>), α-tocopherol (<b>3</b>), β-tocopherol (<b>4</b>), loliolide palmitate (<b>5</b>), a mixture of calenduladiol esters - 16β-hydroxylupeol-3-O-palmitate (<b>7</b>) and 16β-hydroxylupeol-3-O-myristate (<b>8</b>), 1-epiinuviscolide (<b>12</b>), inuviscolide (<b>13</b>), 3-epiisotelekin (<b>16</b>), 4α-hydroxy-9β,10β-epoxy-1β(H)-11(13)-guaien-8α,12-olide (<b>17</b>), 4α-hydroxy-1β(H)-9(10),11(13)-guaiadien-8α,12-olide (<b>18</b>), loliolide (<b>19</b>) and 4β,10β-dihydroxy-1α(H),5α(H)-11(13)-guaien-8α,12-olide (<b>20</b>). Calenduladiol esters and asperilin (<b>14</b>) were the major constituents of the extract. Their cytotoxic effect on human normal prostate epithelial cells (PNT-2), human prostate carcinoma cell lines, human skin fibroblasts (HSF) and human melanoma cell lines was examined <i>in vitro</i>. Triterpene esters showed no cytotoxicity against nearly all cell lines tested, except for Du145 prostate carcinoma cells (IC<sub>50</sub> – 62.0 μΜ). Asperilin displayed activity against the cell lines under study, especially against three tested lines of melanomas (A375, IC<sub>50</sub> – 17.6 μΜ, WM793, IC<sub>50</sub> – 28.2 μΜ and Hs 294T, IC<sub>50</sub> – 29.5 μΜ).</p
