Secondary metabolites from Isodon ternifolius (D. Don) Kudo and their anticancer activity as DNA topoisomerase IB and Tyrosyl-DNA phosphodiesterase 1 inhibitors

Bioorg Med Chem. 2020 Jun 1;28(11):115527. doi: 10.1016/j.bmc.2020.115527. Epub 2020 Apr 22.

Abstract

Based on DNA topoisomerase IB (TOP1) and tyrosyl-DNA phosphodiesterase 1 (TDP1) inhibition of the ethanol extract of the roots of Isodon ternifolius (D. Don) Kudo (Labiatae), its secondary metabolites has been studied. Two new compounds, an ent-abietane diterpenoid isodopene A (1) and a 2,3-seco-triterpene isodopene B (13), along with 25 known compounds were isolated. Their structures were elucidated by spectroscopic analysis and theoretical calculations. The enzyme-based assays indicated that 1 and 13 showed strong (+++) and moderate (++) TOP1 inhibition, respectively. Two chalcone derivatives 11 and 12 were firstly found as dual TDP1 and TOP1 natural inhibitors, and showed synergistic effect with the clinical TOP1 inhibitors topotecan in MCF-7 cells. Compounds 8, 16, and 22 acted as TOP1 catalytic inhibitors with equipotent TOP1 inhibition to camptothecin (++++). Compounds 7 and 8 exhibited significant cytotoxicity against MCF-7, A549, and HCT116 cells with GI50 values in the range of 2.2-4.8 μM. This work would provide valuable information that secondary metabolites from I. ternifolius could be developed as anticancer agents.

Keywords: Cytotoxicity; DNA topoisomerase; Isodon ternifolius; Secondary metabolite; Tyrosyl–DNA phosphodiesterase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Phytogenic / chemistry
  • Antineoplastic Agents, Phytogenic / isolation & purification
  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Cattle
  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • DNA Topoisomerases, Type I / metabolism*
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Humans
  • Isodon / chemistry*
  • Isodon / metabolism
  • Molecular Structure
  • Phosphodiesterase Inhibitors / chemistry
  • Phosphodiesterase Inhibitors / isolation & purification
  • Phosphodiesterase Inhibitors / pharmacology*
  • Phosphoric Diester Hydrolases / metabolism*
  • Structure-Activity Relationship
  • Topoisomerase I Inhibitors / chemistry
  • Topoisomerase I Inhibitors / isolation & purification
  • Topoisomerase I Inhibitors / pharmacology*
  • Tumor Cells, Cultured

Substances

  • Antineoplastic Agents, Phytogenic
  • Phosphodiesterase Inhibitors
  • Topoisomerase I Inhibitors
  • Phosphoric Diester Hydrolases
  • TDP1 protein, human
  • DNA Topoisomerases, Type I