Wormwood (Artemisia absinthium L.) as a promising nematicidal and antifungal agent: Chemical composition, comparison of extraction techniques and bioassay-guided isolation

Abstract

The ethyl acetate, ethanol and water extracts of different organs (flowers, leaves, stems and roots) of wormwood (Artemisia absinthium L.) were investigated to examine nematicidal and antifungal activities in an effort to promote future agricultural applications of the wormwood and its potential as an industrial crop. The results showed that highest concentration of total thiophene content (TTC), as well as nematicidal and antifungal activities were found in ethyl acetate extract of roots. TTC and biological activities were highly correlated, indicating that thiophenes played an important role in nematicidal and antifungal activities. Furthermore, four extraction techniques (Maceration, Soxhlet extraction, Supercritical fluid extraction and Ultrasound-assisted extraction) were compared by evaluating the yield of thiophenes. Supercritical fluid extraction (SFE) appeared to be the best method for extracting thiophenes with the highest TTC and superior activities. In addition, eight thiophenes (1–8) including two new compounds (1 and 2) were isolated from the SFE extract by the bioassay-guided method. All thiophenes showed potent nematicidal activities. In particular, 1–4 (50% lethal concentration (LC50) values of 2.69, 4.17, 6.13 and 7.65 mg/L, respectively) were more effective than commercial nematicide abamectin (LC50, 9.47 mg/L). Also, these thiophenes showed antifungal activities against four soil-borne fungi at different degrees, especially for compounds 1 and 2 which exhibited noticeable antifungal effects (minimum inhibitory concentration (MIC) values ranging from 8–16 mg/L). Findings of this work suggest that wormwood root and its thiophenes could be used in nematicide and fungicide agent industry.