Targeting botulinum A cellular toxicity: a prodrug approach

J Med Chem. 2013 Oct 24;56(20):7870-9. doi: 10.1021/jm400873n. Epub 2013 Oct 15.

Abstract

The botulinum neurotoxin light chain (LC) protease has become an important therapeutic target for postexposure treatment of botulism. Hydroxamic acid based small molecules have proven to be potent inhibitors of LC/A with nanomolar Ki values, yet they lack cellular activity conceivably due to low membrane permeability. To overcome this potential liability, we investigated two prodrug strategies, 1,4,2-dioxazole and carbamate, based on our 1-adamantylacetohydroxamic acid scaffold. The 1,4,2-dioxazole prodrug did not demonstrate cellular activity, however, carbamates exhibited cellular potency with the most active compound displaying an EC50 value of 20 μM. Cellular trafficking studies were conducted using a "fluorescently silent" prodrug that remained in this state until cellular uptake was complete, which allowed for visualization of the drug's release inside neuronal cells. In sum, this research sets the stage for future studies leveraging the specific targeting and delivery of these prodrugs, as well as other antibotulinum agents, into neuronal cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anti-Bacterial Agents / chemical synthesis
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / pharmacology*
  • Azoles / chemical synthesis
  • Azoles / pharmacokinetics
  • Azoles / pharmacology
  • Botulinum Toxins, Type A / antagonists & inhibitors*
  • Botulinum Toxins, Type A / metabolism
  • Carbamates / chemical synthesis
  • Carbamates / pharmacokinetics
  • Carbamates / pharmacology
  • Cell Survival / drug effects
  • Cells, Cultured
  • Clostridium botulinum / drug effects
  • Clostridium botulinum / metabolism
  • Drug Stability
  • Half-Life
  • Humans
  • Hydroxamic Acids / chemistry
  • Microscopy, Confocal
  • Models, Chemical
  • Molecular Structure
  • Neurons / cytology
  • Neurons / drug effects*
  • Neurons / metabolism
  • Prodrugs / chemical synthesis
  • Prodrugs / pharmacokinetics
  • Prodrugs / pharmacology*

Substances

  • Anti-Bacterial Agents
  • Azoles
  • Carbamates
  • Hydroxamic Acids
  • Prodrugs
  • Botulinum Toxins, Type A