Herbicidal Quassinoids Isolated from Ailanthus altissima Leaves

Bioassay-guided fractionation of the methanolic extract of Ailanthus altissima leaves led to the isolation of one new quassinoid, named 6--tigloyloxyailanthone (3), and three known quassinoids, ailanthone (1), 13, 18-dehydroglaucarubinone (2), and 6--tigloyloxychaparrinone (4) by a series of chromatographic methods. The structures of the isolates were established by one-dimensional (1D) and 2D-nuclear magnetic resonance (NMR) analysis along with high-resolution time-of-flight mass spectrometry (HRTOFMS) and chemical methods. In addition, herbicidal activity against five grassy weeds and five broad-leaf weeds was evaluated.