Antibiotic Dixiamycins from a Cold-Seep-Derived Streptomyces olivaceus

Two new (1and 2) along with six known (3–8) dixiamycins were isolated from the culture broth of a cold-seep-derived actinomycete, Streptomyces olivaceusOUCLQ19-3. Structures of the isolated compounds were elucidated based on extensive MS and NMR spectroscopic analyses together with ECD calculations. In the antibacterial test, compounds 1–8exhibited 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 5–7were more potent than the positive control tetracycline.