Antifungal meroterpenes and dioxolanone derivatives from plant-associated endophytic fungus Phyllosticta sp. WGHL2

Four new meroterpenes named as guignardones U-X (1–4), along with eleven known meroterpenes (5–15) and three known dioxolanone derivatives (16–18), were obtained from the endophytic fungus Phyllosticta sp. WGHL2. The structural elucidation was conducted by HRESIMS, NMR, single crystal X-ray diffraction, along with ECD calculations and comparison. In antifungal tests, compound 16 possessed broad-spectrum antifungal activities against Rhizoctonia solani, Fusarium graminearum and Botrytis cinerea with inhibition ratio of 48.43%, 40.98%, and 49.53% at 50 μg/mL, respectively. Moreover, compound 16 showed moderate protective effect against B. cinerea in vivo at 200 μg/mL and exhibited effective inhibition on the spore germination of B. cinerea.