Tandocyclinones A and B, Ether Bridged C-Glycosyl Benz[a]anthracenes from an Intertidal Zone Streptomyces sp.

Thanh Hau Huynh, Eun Seo Bae, Bo Eun Heo, Jayho Lee, Joon Soo An, Yun Kwon, Sang Jip Nam, Ki Bong Oh, Jichan Jang, Sang Kook Lee, Dong Chan Oh

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Two new proton-deficient metabolites, tandocyclinones A and B (1 and 2), were discovered via the chemical profiling of the Streptomyces sp. strain TDH03, which was isolated from a marine sediment sample collected from the intertidal mudflat in Tando Port, the Republic of Korea. The structures of 1 and 2 were elucidated as new ether-bridged C-glycosyl benz[a]anthracenes by using a combination of spectroscopic analyses of ultraviolet (UV) and mass spectrometry (MS) data, along with nuclear magnetic resonance (NMR) spectra, which were acquired in tetrahydrofuran (THF)-d8 selected after an extensive search for a solvent, resulting in mostly observable exchangeable protons in the 1H NMR spectrum. Their configurations were successfully assigned by applying a J-based configuration analysis, rotating-frame Overhauser enhancement spectroscopy (ROESY) NMR correlations, chemical derivatization methods based on NMR (a modified version of Mosher’s method) and circular dichroism (CD) (Snatzke’s method using Mo2(OAc)4-induced CD), as well as quantum-mechanics-based computational methods, to calculate the electronic circular dichroism (ECD). Tandocyclinones A and B (1 and 2) were found to have weak antifungal activity against Trichophyton mentagrophytes IFM40996 with an MIC value of 128 μg/mL (244 and 265 μM for 1 and 2, respectively). A further biological evaluation revealed that tandocyclinone A (1) displayed inhibitory activity against Mycobacterium avium (MIC50 = 40.8 μM) and antiproliferative activity against SNU638 and HCT116 cancer cells, with IC50 values of 31.9 µM and 49.4 µM, respectively.

Original languageEnglish
Article number500
JournalMarine Drugs
Issue number9
StatePublished - Sep 2023

Bibliographical note

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© 2023 by the authors.


  • Crews’ rule
  • Mosher’s method
  • Mycobacterium avium
  • Snatzke’s method
  • Streptomycessp
  • antiproliferative activity
  • structure elucidation


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