Quambalarine B, a Secondary Metabolite from Quambalaria cyanescens with Potential Anticancer Properties

J Nat Prod. 2016 Sep 23;79(9):2304-14. doi: 10.1021/acs.jnatprod.6b00362. Epub 2016 Aug 29.


Quambalarine B (QB) is a secondary metabolite produced by the basidiomycete Quambalaria cyanescens with potential anticancer activity. Here we report that QB at low micromolar concentration inhibits proliferation of several model leukemic cell lines (Jurkat, NALM6, and REH), whereas higher concentrations induce cell death. By contrast, the effect of QB on primary leukocytes (peripheral blood mononuclear cells) is significantly milder with lower toxicity and cytostatic activity. Moreover, QB inhibited expression of the C-MYC oncoprotein and mRNA expression of its target genes, LDHA, PKM2, and GLS. Finally, QB blocked the phosphorylation of P70S6K, a downstream effector kinase in mTOR signaling that regulates translation of C-MYC. This observation could explain the molecular mechanism behind the antiproliferative and cytotoxic effects of QB on leukemic cells. Altogether, our results establish QB as a promising molecule in anticancer treatment.

MeSH terms

  • Antineoplastic Agents / blood
  • Antineoplastic Agents / chemistry*
  • Antineoplastic Agents / isolation & purification
  • Antineoplastic Agents / pharmacology*
  • Basidiomycota / chemistry*
  • Cell Proliferation / drug effects
  • Drug Screening Assays, Antitumor
  • Humans
  • Jurkat Cells / drug effects
  • Leukocytes, Mononuclear / drug effects
  • Molecular Structure
  • Naphthoquinones / blood
  • Naphthoquinones / chemical synthesis
  • Naphthoquinones / chemistry*
  • Naphthoquinones / isolation & purification
  • Naphthoquinones / pharmacology*
  • Phosphorylation
  • Ribosomal Protein S6 Kinases, 70-kDa
  • Signal Transduction / physiology
  • TOR Serine-Threonine Kinases


  • 3-hexanoyl-2,5,7,8-tetrahydroxy-1,4-naphthoquinone
  • Antineoplastic Agents
  • Naphthoquinones
  • MTOR protein, human
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases