Screening and isolation of a nematicidal sesquiterpene from Magnolia grandiflora L

The ethanolic extracts from 30 plant species were tested for their nematicidal activity against nematodes Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle and Panagrellus redivivus (L.) Goodey. The leaf extract of Magnolia grandiflora L. exhibited the strongest nematicidal activity against both nematodes, causing 73 and 100% mortality respectively within 48 h at 5 mg mL(-1). A new nematicidal sesquiterpene was obtained from the leaves of M. grandiflora. The compound was determined to be 4,5-epoxy-1(10)E,11(13)-germacradien-12,6-olide, based on spectroscopic methods including 2D NMR techniques. The median lethal concentrations (LC50) of the compound against B. xylophilus and P. redivivus were 71 and 46 mg L(-1) respectively at 48 h. This is the first report of Magnoliaceae species with nematicidal activity.