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Dischidia imbricata (Blume) Steud. is a herbaceous plant belonging to the Apocynaceae family. This plant has been reported to possess various pharmacological properties, however, there has been no report related to its allelopathic properties. Therefore, the aqueous methanol extracts of D. imbricata were examined for possible allelopathic activity against the seedling growth of dicotyledonous plants; lettuce (Lactuca sativa L.), cress (Lepidium sativum L.), and alfalfa (Medicago sativa L.), and monocotyledonous plants; barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), Italian ryegrass (Lolium multiflorum Lam.), and timothy (Phleum pratense L.). D. imbricata extracts exhibited a significant inhibition on the seedling growth of all the test plant species at the concentration ≥ 0.01 g dry weight equivalent extract mL-1. The seedling growth of lettuce showed the highest inhibition with D. imbricata extracts followed by alfalfa and cress, whereas the least inhibition was found on the seedling growth of timothy. Concentrations required for 50% inhibition (I50 values) of all the test plant species were in the range of 0.003 to 0.067 g D.W. equivalent extract mL-1 for shoot growth, and 0.018 to 0.026 g D.W. equivalent extract mL-1 for root growth. In addition considering the I50 values, the root growth of the test plant species was more sensitive to D. imbricata extracts than their shoot growth, except cress seedling. These results indicated that D. imbricata may possess allelopathic activity and may contain allelopathic substances.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Aqueous methanol extracts of Acmella oleracea inhibited the growth of roots and shoots of cress (Lepidum sativum), lettuce (Lactuca sativa), Italian ryegrass (Lolium multiflorum), and barnyard grass (Echinochloa crus-galli) with the extract concentration-dependent manner. The extracts were then purified and 2 growth inhibitory substances were isolated and identified by spectral data as (E,E)-2,4-undecadien-8,10-diynoic acid isobutylamide (compound 1) and nona-(2Z)-en-6,8-diynoic acid 2-phenylethylamide (compound 2). Compound 1 inhibited the growth of cress roots and shoots at concentrations greater than 0.3 mM and that of barnyard grass root at concentrations greater than 0.03 mM. Compound 2 inhibited the growth of cress shoots and barnyard grass roots at concentrations greater than 1 mM. The inhibition on the seedling growth indicates that both compounds had growth inhibitory activity and may contribute to the inhibitory effect of A. oleracea extracts. This is the first report of having growth inhibitory activity of compounds 1 and 2 on plants.

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