Ambazone as a membrane active antitumor drug

Area of Science:

• Pharmacology and Biophysics
• Cancer Research
• Immunology

Background:

• Ambazone (1,4-benzoquinone guanylhydrazone thiosemicarbazone) is an antineoplastic agent with activity against transplantable tumors in rodents.
• Its therapeutic effects are suggested to be partly mediated by the immune system.

Purpose of the Study:

• To characterize the biophysical and physicochemical properties of ambazone.
• To elucidate the molecular mechanisms underlying its antineoplastic and immunological activities.
• To investigate its absorption, distribution, and interaction with biological targets.

Main Methods:

• Thin-layer chromatography, absorption spectroscopy, polarography, n-octanol/water partitioning.
• Spectrophotometric and fluorescence measurements using liposomes and ANS probe.
• DNA melting experiments, pharmacokinetic studies in rodents, mutagenicity assays.

Main Results:

• Ambazone has low hydrophobicity and undergoes three protonation reactions (pK values 10.69, 7.39, 6.22).
• It interacts non-specifically with phospholipid bilayers, increasing cellular cAMP in leukemia cells and macrophages.
• Ambazone stabilizes DNA at neutral/singly positive charge, but destabilizes it when doubly positive; absorption is 35-50%, with strong red blood cell binding.

Conclusions:

• Membrane interaction provides a molecular basis for ambazone's immunological and antineoplastic effects.
• Ambazone's interaction with DNA and its incomplete absorption influence its efficacy and toxicity.
• Its affinity for cellular targets like membranes, nucleic acids, and proteins contributes to its antibacterial effects.