Halobacin, a herbicidal acyloin derivative from a marine bacterium of the genus Halobacillus

Halobacin (1), a new glycosylated acyloin derivative, was isolated from the fermentation broth of a coral-associated bacterium Halobacillus sp. DUNA-S15. The structure of 1 was determined based on NMR and MS analyses and the absolute configuration of the sugar moiety was determined by diastereomeric HPLC separation using chiral derivatization. Compound 1 was inactive in antimicrobial and cytotoxicity assays but suppressed the root growth of germinated seeds of lettuce and barnyard millet to ca 30% at 1 µg ml^-1 and ca 70% at 10 µg ml^-1 compared to the nontreated seeds.