Molecular Networking-Driven Discovery of Antifungal Azaphilone Dimers from the Marine-Derived Fungus Humicola sp. HK1‑8

A novel azaphilone dimer, humilone A (1), along with its related monomer, humilone B (2), was isolated from cultures of the marine-derived fungus Humicola sp. HK1-8 using a molecular networking-guided discovery approach. Further investigation of the molecular family of azaphilone dimers led to the putative identification of four analogues, humilones C–F (3–6), based on systematic analysis of their characteristic MS/MS fragmentation patterns. Detailed fragmentation studies of the dimers revealed that the predominant cleavage fragments originated from C–C bond scission at the dimeric methylene bridge. Compound 1 displayed antifungal activity against Rhizoctonia solani.