Isolation, Crystal Structure and Inhibitory Activity against Magnaporthe Grisea of （2R,3R）-3,5,7-trihydroxyflavanone 3-Acetate from Myoporum Bontioides A. Gray

The title compound, (2R,3R)-3,5,7-trihydroxyflavanone 3-acetate, is a flavanonol derivative which was first isolated from Myoporum bontioides A. Gray and characterized by MS, NMR and CD spectra. In addition, the structure was determined by X-ray single-crystal diffraction analysis. It crystallizes in the triclinic lattice, space group P21 with a = 10.686(3), b = 6.862(2), c = 11.267(3) , β = 107.46(1), V = 788.3(4) 3, Z = 2, C17H16O7, Mr = 332.30, Dc = 1.400 g/cm3, μ(MoKα) = 0.110 mm-1, F(000) = 348, the final R = 0.0283 and wR = 0.0826 for 3428 independent reflections (Rint = 0.017) and 1500 observed ones (I > 2σ(I)). The structure consists of one flavone and one water molecule. The flavone molecules form a 1D column by the p…π stacking interactions and C–H…O hydrogen bonds. The weak intermolecular/intermolecular O–H…O hydrogen bonds observed in the crystal give further rise to a complicated network structure. Primary bioassay showed that the title compound has high inhibitory activity against Magnaporthe grisea with the EC50 values of 199.41 μg/mL.