Antibacterial Pentacyclic Polyketides from a Soil-Derived Streptomyces.

Nine new pentacyclic polyketides, fasamycins G-K (1-5) and formicamycins N-Q (6-9), along with 10 known analogues (10-19), were isolated from a rhizospheric soil-derived Streptomyces sp. KIB-1414. Their structures and absolute configurations were elucidated by interpretation of NMR and HRMS data and comparisons of CD data. The compounds were active against methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Bacillus subtilis, and Escherichia coli strains, with MIC values ranging from 0.20 to 50.00 μg/mL.