Phytoalexins are antimicrobial compounds produced newly by plants in response to microbial infection and their production is believed to be an important disease resistance mechanism in higher plants. We describe herein the isolation and structure alucidation of antifungal metabolites isolated from mulberry (Morus alba Linne) infected with Fusarium solani f. sp. mori. and qualified as phytoalexins. The diseased cortex and phloem tissues of shoots, xylem tissues of shoots, and leaves were extracted with acetone. The respective extracts were fractionated sequentially by column and preparative thin-layer chromatography over silica gel, polyamide, and/or Sephadex LH-20, resulting in isolation of twelve new metabolites [moracins A〜L (1〜12)], oxyresveratrol (13) and two new metabolites [4'-prenyloxyresveratrol and moracin M (14 and 15)], and one new unidentified metabolite (16) from the afore-mentioned diseased parts of mulberry, respectively. Healthy epidermis of the plant was also examined in the same manner, and three new antifungal compounds (19〜21) were isolated along with known compounds, kuwanon C (17) and morusin (18). The structure of all these new compounds, except 16, was determined as shown in the formulas on the basis of the spectral and chemical data.
