Heptaibin, a Novel Antifungal Peptaibol Antibiotic from Emericellopsis sp. BAUA8289

In the course of our antifungal screening program, a novel antifungal substance, heptaibin (1) was isolated from the culture of Emericellopsis sp. BAUA8289 together with emerimicin IV, a peptaibol antibiotic. The structure of 1 was determined by spectroscopic studies. Compound 1 was an analog of emerimicin IV, in which the isovaline residue is replaced with an alpha -amino-isobutyric acid. In this paper, we report the fermentation, isolation, structure determination and biological activities of 1. Heptaibin is produced by Emericellopsis sp. BAUA8289, a fungus isolated from the root of a rice plant growing in Akita, Japan.