Novel Polyketides with Agricultural Bioactivity Produced by Phomopsis sp. HDSJ-28, an Endophytic Fungus Derived from Taxus yunnanensis

Phomopsisols A and B (1 and 2), possessing an unprecedented highly oxygenated isobenzofuran dimer core, along with one new tenellone derivative (3), and two new polyketides (13 and 14), as well as 11 known compounds, were isolated from the endophytic Phomopsis sp. associated with Taxus yunnanensis. The structures were determined mainly by the NMR, MS, ECD, and optical rotation calculations and single-crystal X-ray diffraction analyses. Most compounds demonstrated selective antifungal activity against the phytopathogens Colletotrichum karsti and Colletotrichum gloeosporioides, rather than against the biocontrol fungus Clonostachys rosea. Compounds 1-6 and 9-12 exhibited attractive feeding activities toward silkworms with attraction rates of 33-65%. Compounds 1, 9, 10, 15, and 16 promoted the growth of Oryza sativa seedlings. In contrast, compounds 3-6 completely inhibited both shoot and root growths of rice at a concentration of 20 μg/mL. Notably, compound 3 demonstrated significant multiple agricultural activities, including antifungal activity, feeding attraction, and phytotoxicity.