Donghaecyclinones A–C: New Cytotoxic Rearranged Angucyclinones from a Volcanic Island-Derived Marine Streptomyces sp.

Abstract

Chemical profiling of the <i>Streptomyces</i> sp. strain SUD119, which was isolated from a marine sediment sample collected from a volcanic island in Korea, led to the discovery of three new metabolites: donghaecyclinones A-C (<b>1</b>-<b>3</b>). The structures of <b>1</b>-<b>3</b> were found to be rearranged, multicyclic, angucyclinone-class compounds according to nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyses. The configurations of their stereogenic centers were successfully assigned using a combination of quantum mechanics-based computational methods for calculating the NMR shielding tensor (DP4 and CP3) as well as electronic circular dichroism (ECD) along with a modified version of Mosher's method. Donghaecyclinones A-C (<b>1</b>-<b>3</b>) displayed cytotoxicity against diverse human cancer cell lines (IC₅₀: 6.7-9.6 μM for <b>3</b>).