Antibiotic Dixiamycins from a Cold-Seep-Derived Streptomyces olivaceus

Two new (1 and 2) along with six known (3-8) dixiamycins were isolated from the culture broth of a cold-seep-derived actinomycete, Streptomyces olivaceus OUCLQ19-3. Structures of the isolated compounds were elucidated based on extensive MS and NMR spectroscopic analyses together with ECD calculations. In the antibacterial test, compounds 1-8 exhibited notable growth inhibitions against a panel of multi-drug-resistant (MDR) strains with MIC values of 0.78-6.25 μg/mL, among which 1, 2, and 5-7 were more potent than the positive control tetracycline.