On-line screening and identification of polyphenolic antioxidant compounds of <i>Convolvulus trabutianus</i>

<p><i>Convolvulus trabutianus</i> Schweinf. & Muschl. is an endemic plant from northern Sahara used in folk medicine. Herein we report, the isolation, characterization and evaluation of the radical scavenging properties of twenty three compounds from different extracts of this species by on-line HPLC-ABTS<sup>•+</sup> screening. These compounds include nine phenolic acids: <b>2</b>, <b>6</b>, <b>10–16</b>, two phytosterols: <b>3–4</b>, four coumarins: <b>5</b>, <b>7–9</b>, two quinic acids: <b>21</b> and <b>22</b> and six flavonoids: <b>1</b>, <b>17–20</b> and <b>23</b> among which the most active were: <b>10</b>, <b>16</b>, <b>21</b> and <b>22</b>. All the extracts showed a significant antioxidant activity on-line. These results were validated off-line by ORAC and TEAC assays. Four compounds: <b>1</b>, <b>5</b>, <b>18</b> and <b>19</b> were described for the first time from the Convolvulaceae family, whereas compounds <b>2</b>, <b>6</b>, <b>8</b>, <b>10</b>, <b>13</b> and <b>21</b> were new for the genus <i>Convolvulus</i>.</p>