Antifungal Indole Diketopiperazines From <i>Aspergillus fumigatus</i>

Chemical investigation of the desert soil-derived fungus Aspergillus fumigatus J3-4-1 led to the isolation of two new indole diketopiperazines, fumines A (1) and B (2), along with seven known analogues (3-9). Their structures were elucidated through comprehensive analysis of NMR and HRESIMS data and were further confirmed by electronic circular dichroism (ECD) calculations. All isolated compounds exhibited broad-spectrum antifungal activity against five phytopathogenic fungi at a concentration of 50 µg/mL, with inhibition rates ranging from 12.51% to 88.08%. Notably, compounds 2 and 3 displayed superior activity against A. alternata and A. solani, with IC₅₀ values as low as 7.22 µg/mL, outperforming the commercial fungicide hymexazol. These results highlight the potential of these compounds as promising candidates for the development of new antifungal agents.