author(s)
Xin Chao Liu, Ligang Zhou and Zhi Long Liu

abstract
Ethanol extracts of 20 plant species (Euphorbiaceae) were assessed for nematicidal activity against the root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood. Out of these, four extracts: Croton tiglium, Euphorbia fischeriana, Leptopus chinensis and Ricinus communis caused 100​% mortalities of the root-knot nematode at 1000 μg/ml for 72 h. The ethanol extract of E. fischeriana exhibited nematicidal activity against M. incognita with a 72-h LC50 value of 69.0 μg/ml. Six nematicidal constituents were isolated from E. fischeriana as 1-(2, 4-dihydroxy-6-methoxy-3-methylphenyl)-ethanone (1), jolkinolide A (2), jolkinolide B (3), 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate (4), 17-hydroxyjolkinolide A (5), and 17-hydroxyjolkinolide B (6). Compound 4 and 1 exhibited strong toxicity against M. incognita with 72-h LC50 values of 48.6 μg/ml and 87.8 μg/ml, respectively. The other four compounds, compound 5 (LC50 = 354.6 μg/ml), 6 (LC50 = 539.4 μg/ml), 2 (LC50 = 627.7 μg/ml) and 3 (LC50 = 825.2 μg/ml), also possessed toxicity against M. incognita. The above findings suggested that the four ethanol extractsand constituents of E. fischeriana especially compound 4 and 1 may be explored as natural potential nematicides.