Rapid Discovery of Antifungal α-Pyrone Analogs from Diaporthe kyushuensis ZMU-48-1 via an HSQC-Based DeepSAT Strategy

Endophytic fungi represent an extensive source of chemically diverse and bioactive polyketides. Herein, an HSQC-based DeepSAT-guided strategy was employed for the scaffold-prioritized isolation of metabolites from <i>Diaporthe kyushuensis</i> ZMU-48-1, an endophyte isolated from <i>Acacia confusa</i>. DeepSAT analysis of the semi-purified fractions identified an α-pyrone chemotype, which facilitated the targeted isolation of thirteen pyranone-type polyketides, including eight previously undescribed analogues, diaporthopyranone A-H (<b>1</b>-<b>8</b>). The structures of the new compounds were rigorously elucidated via comprehensive spectroscopic analysis (1D and 2D NMR and HRESIMS), while their absolute configurations were established by comparing experimental and TDDFT-calculated ECD data. All isolates (<b>1</b>-<b>13</b>) were screened for antifungal activity against nine plant pathogens. While most metabolites were inactive at 200 μg/mL, compound 4 inhibited <i>Alternaria alternata</i> and <i>Valsa mali</i> (MICs = 100 and 80 μg/mL, respectively), and compounds <b>6</b> and <b>8</b> exhibited selective inhibition against <i>Colletotrichum musae</i> (MICs = 60 and 80 μg/mL). These results expand the pyranone repertoire of the genus <i>Diaporthe</i> and underscore the utility of the HSQC-DeepSAT platform for the streamlined discovery of specific natural product scaffolds.