Angelicin as the principal allelochemical in Heracleum sosnowskyi fruit.
Distribution patterns of furocoumarins in fruits of the invasive species Heracleum sosnowskyi Manden. (Sosnowskyi's hogweed) during a cold stratification period were investigated. Angelicin, bergapten, methoxalen and imperatorin were mainly localized in the fruit coats and their content varied depending on the fruit source. Cold stratification treatment (90 days, 2-3°C) reduced the content of furocoumarins in the fruit coats by more than two times, compared with those before stratification. The specific activity of the detected furocoumarins and total activity of crude extracts were evaluated using Lactuca sativa, as acceptor plant. Crude extracts obtained from fruit coats and seeds of H. sosnowskyi suppressed 50% of radicle and hypocotyl growth of lettuce seedlings at the concentration range of 1.0-1.7 mg/mL. The inhibitory activity of angelicin was proved to be the highest compared with the other tested furocoumarins, and the inhibitory activity of crude extracts could be explained mainly by the presence of angelicin. Both, monocots (Lolium multiflorum, Phleum pratensis, Festuca pratesis, Lolium perenne) and dicots (Tripholium repens, Trifolium pretense) were found to be sensitive to the exudates of whole H. sosnowskyi fruits. Thus, we assume, that high inhibitory potential of furocoumarins, especially angelicin, at high seed productivity of H. sosnowskyi might have an ecological significance in plant-plant interaction.