| Abstract: | Angucyclinones are aromatic polyketides produced by type II polyketide synthases (PKS) and are mainly found in terrestrial actinomycetes. To discover more angucyclinones from marine actinomycetes, a genomic DNA-based PCR assay targeting type II polyketide synthases was performed. Among the 167 marine actinomycetes strains screened, twelve strains were identified as the “positive” strains possessing type II PKS-encoding genes based on the sequencing of PCR products. One of the 12 “positive” strains, Streptomyces sp. PKU-MA00218 was selected for the large-scale fermentation based on the HPLC and TLC analysis. Four angucyclinones, 6-deoxy-8-O-methylrabelomycin (1), 8-O-methylrabelomycin (2), 8-O-methyltetrangulol (3), C-ring cleavage product of angucyclinone C (4), were isolated and their structures were elucidated based on spectroscopic analyses. The isolation of angucyclinones 1–4 highlights the power of genome mining technologies based on biosynthetic knowledge in natural products discovery. |
