Nitricquinomycins A-C, uncommon naphthopyrrolediones from the Streptomyces sp. ZS-A45

Nitricquinomycins A-C (1 similar to 3), three uncommon naphthopyrrolediones, together with one new compound (4), were isolated from the modified rice solid fermentation of the marine-derived Streptomyces sp. ZS-A45, an actinobacterium isolated from the marine sediments collected from Zhoushan island. Their structures were elucidated on the basis of MS, NMR spectroscopic and quantum chemical calculations of the electronic circular dichroism (ECD) spectra. Compounds 3 and 4 exhibited significant cytotoxicity against A2780 cell lines with IC50 values of 4.77 and 2.92 mu M, respectively; on the other hand, compound 3 exhibited moderate antibacterial activities against Escherichia coli, Staphylococcus aureus and Candida albicans with MIC values of 20.0 40.0 and 40.0 mu M, respectively. (C) 2019 Published by Elsevier Ltd.