A new compound, fusaramin (1), along with three known compounds, sambutoxin (2), N-demethylsambutoxin (3) and (-)-6-deoxyoxysporidinone (4), was isolated from a culture broth of Fusarium sp. FKI-7550 by bioassay-guided fractionation using multidrug-sensitive Saccharomyces cerevisiae 12geneΔ0HSR-iERG6. The chemical structure of 1 was elucidated by NMR studies and electronic circular dichroism spectrum. Compound 1 showed antibacterial activity against some Gram-positive and Gram-negative bacteria and inhibited the growth of S. cerevisiae 12geneΔ0HSR-iERG6 grown on glycerol-containing medium. The MICs of 1 against wild-type and multidrug-sensitive yeasts grown on glycerol-containing medium were >128 μg ml-1 and 0.64 μg ml-1, respectively. However, MICs of 1 against both yeast strains grown on glucose-containing medium were >128 μg ml-1. All compounds showed inhibition of ATP synthesis via oxidative phosphorylation using isolated S. cerevisiae mitochondria.