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In the course of screening for yeast squalene synthase inhibitors, bisabosqual A was isolated from the culture broth of Stachybotrys sp. RF-7260. The related compounds bisabosquals B, C and D were also isolated from Stachybotrys ruwenzoriensis RF-6853. Bisabosquals inhibited squalene synthases. IC50 values of bisabosqual A against the microsomal squalene synthases from Saccharomyces cerevisiae, Candida albicans, HepG2cell and rat liver were 0.43, 0.25, 0.95 and 2.5^ug/ml, respectively. Bisabosqual C exhibited inhibitory activities similar to bisabosqual A. Bisabosqual A showed broad spectrum antifungal activity in vitro.

A novel lipopeptide antibiotic, stalobacin I (1), was discovered from a culture broth of an unidentified Gram-negative bacterium. Stalobacin I (1) had a unique chemical architecture composed of an upper and a lower half peptide sequence, which were linked via a hemiaminal methylene moiety. The sequence of 1 contained an unusual amino acid, carnosadine, 3,4dihydroxyariginine, 3-hydroxyisoleucine, and 3-hydroxyaspartic acid, and a novel cyclopropyl fatty acid. The antibacterial activity of 1 against a broad range of drug-resistant Gram-positive bacteria was much stronger than those of "last resort" antibiotics such as vancomycin, linezolid, and telavancin (MIC 0.004−0.016 μg/mL). Furthermore, compound 1 induced a characteristic morphological change in Gram-positive and Gram-negative strains by inflating the bacterial cell body. The absolute configuration of a cyclopropyl amino acid, carnosadine, was determined by the synthetic study of its stereoisomers, which was an essential component for the strong activity of 1.