The screening of Chinese medicinal herbs for insecticidal principles showed that the essential oil ofEchinops grijsiiHance roots possessed significant larvicidal activity against mosquitoes. The essential oil was extracted via hydrodistillation and its constituents were determined by gas chromatography-mass spectrometry (GC-MS) analysis. GC-MS analyses revealed the presence of 31 components, with 5-(3-buten-1-yn-1-yl)-2,2′-bithiophene (5-BBT, 27.63%), α-terthienyl (α-T, 14.95%), 1,8-cineole (5.56%) andcis-β-ocimene (5.01%) being the four major constituents. Based bioactivity-directed chromatographic separation of the essential oil led to the isolation of 5-BBT, 5-(4-isovaleroyloxybut-1-ynyl)-2,2′-bithiophene (5-IBT) and α-T as active compounds. The essential oil ofE. grijsiiexhibited larvicidal activity against the fourth instar larvae ofAedes albopictus,Anopheles sinensisandCulex pipiens pallenswith LC50values of 2.65 μg/mL, 3.43 μg/mL and 1.47 μg/mL, respectively. The isolated thiophenes, 5-BBT and 5-IBT, possessed strong larvicidal activity against the fourth instar larvae ofAe. albopictus(LC50= 0.34 μg/mL and 0.45 μg/mL, respectively) andAn. sinensis(LC50= 1.36 μg/mL and 5.36 μg/mL, respectively). The two isolated thiophenes also had LC50values against the fourth instar larvae ofC. pipiens pallensof 0.12 μg/mL and 0.33 μg/mL, respectively. The findings indicated that the essential oil ofE. grijsiiroots and the isolated thiophenes have an excellent potential for use in the control ofAe. albopictus,An. sinensisandC. pipiens pallenslarvae and could be used in the search for new, safer and more effective natural compounds as larvicides.Keywords:Echinops grijsii;Aedes albopictus;Anopheles sinensis;Culex pipiens pallens;larvicidal activity
Tingting Liu,Haibo Wu,Hongyun Jiang,Lan Zhang,Yanning Zhang,Liangang Mao
Naturally occurring thiophenes possess excellent nematicidal and fungicidal activities. However, thiophenes often have limited application in soil due to their light-dependent toxicity given the living and reproductive condition of soil-borne pathogens. In this study, six new (1–6) and six known thiophenes (7–12) were isolated from Echinops grijsii. Compounds 1−2, 4–5, 8–9, 11 , and 12 showed stronger nematicidal activity against Meloidogyne incognita than commercial nematicide abamectin. 4–10 were demonstrated as nonphototoxic thiophenes. Among these, 4 and 8 were the most potent thiophenes (LC50 values 2.57 and 0.91 μg/mL in light, 1.80 and 0.86 μg/mL in dark, respectively) against M. incognita. SAR revealed that thiophene skeleton was essential for nematicidal activity, while disubstituted groups were helpful for nonphototoxicity. Although an increased number of acetylenes improved activity, it decreased nonphototoxicity. Acyl groups could suppress the effects of light on activity, with the level of inhibitory effects depending on its number and chain length, while chlorine played important roles in promoting activity. Additionally, compounds 1–2, 4–5, 7, 8, and 10 displayed antifungal activity against six soil-borne fungi in various degrees. The discovery of nonphototoxic thiophenes and elucidation of SAR provide important information for the exploitation and utilization of thiophenes in the integrative management regarding disease complexes caused by the combination of root-knot nematode and soil-borne fungi.
危险品化学品经营许可证（带存储）