Isolation and Phytotoxicity of Apocarotenoids from <i>Chenopodium </i><i>a</i><i>lbum</i>

Two new compounds (<b>1</b>, <b>2</b>) and 16 apocarotenoids (<b>3</b>−<b>18</b>) were isolated from the weed <i>Chenopodium album</i>. The structures of new apocarotenoids were determined to be (3<i>R</i>,6<i>R</i>,7<i>E</i>,9<i>E</i>,11<i>E</i>)-3-hydroxy-13-apo-α-caroten-13-one (<b>1</b>) and (6<i>S</i>,7<i>E</i>,9<i>E</i>,11<i>E</i>)-3-oxo-13-apo-α-caroten-13-one (<b>2</b>) by spectroscopic, NMR, and MS analysis. Five of the known compounds (<b>5</b>, <b>6</b>, <b>13</b>, <b>15</b>, and <b>17</b>) were previously reported only as synthetic compounds. Effects of these compounds on germination and growth of <i>Lactuca</i> <i>sativa </i>(lettuce) were studied in the 10<sup>-4</sup>−10<sup>-7</sup> M concentration range.