Isolation and identification of the allelochemicals in Artemisia ordosica aqueous extracts

ObjectiveThe allelochemicals of aqueous extracts from roots, stems, leaves, and seeds of Artemisia ordosica were investigated, and their effects on germination of Agriophyllum squarrosum seeds were also studied, which provided a theoretical basis for better understanding allelopathy in the process of A. ordosica community succession.

MethodThe roots, stems, leaves and seeds of A. ordosica were extracted with ultrapure water for 48 hours at room temperature, centrifugated, and the supernatants were separated into acidic, neutral and alkaline extracts by re-extraction. These extracts were respectively divided into two parts (1/40 for the GC-MS analysis, 39/40 for A. squarrosum seed germination experiment).

ResultThirty-five compounds were identified in the acidic extracts of A. ordosica. Succinic acid (22.42%) and 3,4- dihydroxybenzoic acid (13.13%) were main compounds in roots. Succinic acid (25.81%), caffeic acid (13.53%), 3-hydroxy-4-methoxybenzoic acid (12.12%), and 2-hydroxypropionic acid (11.13%) were main compounds in stems. 3,4-dihydroxybenzoic acid (23.15%), benzoic acid (16.62%), and 3-hydroxy-4-methoxybenzoic acid (15.68%) were main compounds in leaves. 2-hydroxypropionic acid (47.64%) and succinic acid (32.28%) were main compounds in seeds. Twenty compounds were identified in the neutral extracts of A. ordosica. 2-furan propanol was main compound in roots, stems, leaves and seeds, accounting for 62.28%, 33.10%, 47.42%, 85.13% of the detected substances, respectively. Six compounds were identified in the alkaline extracts of A. ordosica. Ethylamine (43.80%) was main compound in roots. 2-hydroxyethylamine was main compound in stems, leaves and seeds, and its relative content was 53.95%, 42.45%, 56.29%, respectively. Acidic, neutral and alkaline extracts of A. ordosica all inhibited the germination of A. squarrosum seeds. Among them, the strongest inhibitory effect was observed for the acidic extract, followed by alkaline extract, and the weakest was neutral extract.

ConclusionThe allelochemicals of A. ordosica are mainly acidic substances, which play an important role in the competition between A. ordosica and other plants. The aqueous extracts of different parts of A. ordosica exhibited different intensity of allelopathic effects, indicating that the allelopathic effect is related to the type and content of allelochemicals.