Bioassay-guided isolation of constituents of Piper sarmentosum using a mitochondrial transmembrane potential assay

J Nat Prod. 2011 Oct 28;74(10):2193-9. doi: 10.1021/np200557e. Epub 2011 Oct 5.


Bioassay-guided fractionation was conducted on a chloroform-soluble extract of the aerial parts of Piper sarmentosum collected in Vietnam, monitored by a mitochondrial transmembrane potential assay using HT-29 human colon cancer cells. This led to the isolation of four new C-benzylated dihydroflavones, sarmentosumins A-D (1-4), as well as 14 known compounds. The structures of the new compounds were elucidated on the basis of spectroscopic data interpretation. Among these compounds, 1-4 as well as five known C-benzylated dihydroflavones (5-9) and a piperamide, pipercallosine (11), were found to induce apoptosis in HT-29 cells by moderately reducing the mitochondrial transmembrane potential (ΔΨm), with ED50 values ranging from 1.6 to 13.6 μM. Furthermore, 7-methoxydichamanetin (8) and pinocembrin (10) exhibited proteasome inhibitory activities in a human 20S proteasome bioassay with IC50 values of 3.45±0.18 and 2.87±0.26 μM, respectively. This is the first time that C-benzylated dihydroflavones have been reported to demonstrate an apoptotic effect associated with disruption of the mitochondrial transmembrane potential.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / isolation & purification*
  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Drug Screening Assays, Antitumor
  • Flavones / chemistry
  • Flavones / isolation & purification*
  • Flavones / pharmacology
  • HL-60 Cells
  • HT29 Cells
  • Humans
  • Inhibitory Concentration 50
  • Membrane Potentials / drug effects*
  • Mitochondria / drug effects*
  • Piper / chemistry*
  • Vietnam


  • Antineoplastic Agents
  • Flavones