Strepoxazine A, a new cytotoxic phenoxazin from the marine sponge-derived bacterium Streptomyces sp. SBT345

Cheng Cheng, Eman M. Othman, Agnes Fekete, Markus Krischke, Helga Stopper, Ru Angelie Edrada-Ebel, Martin J. Mueller, Ute Hentschel, Usama Ramadan Abdelmohsen

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One new phenoxazin analogue, strepoxazine A (1), along with two known antibiotic phenazines phencomycin (2) and tubermycin B (3) were isolated from the solid culture of Streptomyces sp. SBT345 which had previously been recovered from the Mediterranean sponge Agelas oroides. The structures of compounds 1, 2 and 3 were determined by spectroscopic analyses including 1D and 2D NMR, and HR-ESI-MS experiments as well as comparison to the literature. We further investigated the apoptotic effect of the three compounds on the human promyelocytic leukaemia cells HL-60 and human breast adenocarcinoma cells MCF-7. Only strepoxazine A (1) showed cytotoxicity against leukaemia cells HL-60 cells. These results demonstrate that sponge-associated actinomycetes are rich sources for natural products with new pharmacological activities and relevance to drug discovery.

Original languageEnglish
Pages (from-to)4196-4199
Number of pages4
JournalTetrahedron Letters
Issue number37
Early online date3 Aug 2016
Publication statusPublished - 14 Sep 2016



  • actinomycetes
  • cytotoxic
  • phenazine
  • sponges
  • strepoxazine A
  • streptomyces

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