A new medermycin derivative, MDN-0171 (1), and two known structurally related compounds, medermycin (2) and antibiotic G15-F (3) were isolated from the acetone extract of culture broths of the marine-derived Streptomyces albolongus strain CA-186053. Their structures were determined using a combination of spectroscopic techniques, including 1D and 2D NMR and electrospray-time of flight mass spectrometry (ESI-TOF MS). Compounds 2 and 3 accounted for the antimicrobial activity (against methicillin-resistant Staphylococcus aureus and Escherichia coli) previously detected in the crude extract of this actinomycete.
Keywords: Medermycin; marine natural products; pyranonaphthoquinone; structural elucidation.