RESUMEN
Four new isocoumarins, alternariethers A-C (1-3) and alternariester (4) were separated from the fermentation of the fungus Alternaria malorum FL39, purified from Myoporum bontioides. Their structures were ascertained using NMR and HR-ESI-MS spectroscopy. For compoundâ 4, the absolute configuration was solved with the help of ECD calculation and the DP4+ method. Compared with the positive control triadimefon, compoundâ 1 showed more potent antifungal effects on Colletotrichum musae. The antifungal effects of compoundsâ 1, 2, and 3 on Fusarium oxysporum and Fusarium graminearum, of compoundâ 4 on F. oxysporum, were equal to those of triadimefon. Except for compoundâ 4 which was inactive against Escherichia coli with O78 serotype, all compounds showed moderate or weak antibacterial activity against Staphylococcus aureus ATCC 6538 and E. coli with O6 or O78 serotype.