The vitamin C:vitamin K3 system - enhancers and inhibitors of the anticancer effect

Altern Med Rev. 2010 Dec;15(4):345-51.


The oxidizing anticancer system of vitamin C and vitamin K₃ (VC:VK₃, producing hydrogen peroxide via superoxide) was combined individually with melatonin, curcumin, quercetin, or cholecalciferol (VD₃) to determine interactions. Substrates were LNCaP and PC-3 prostate cancer cell lines. Three of the tested antioxidants displayed differences in cell line cytotoxicity. Melatonin combined with VC:VK₃ quenched the oxidizing effect, while VC:VK₃ applied 24 hours after melatonin showed no quenching. With increasing curcumin concentrations, an apparent combined effect of VC:VK₃ and curcumin occurred in LNCaP cells, but not PC-3 cells. Quercetin alone was cytotoxic on both cell lines, but demonstrated an additional 50-percent cytotoxicity on PC-3 cells when combined with VC:VK₃. VD₃ was effective against both cell lines, with more effect on PC-3. This effect was negated on LNCaP cells with the addition of VC:VK₃. In conclusion, a natural antioxidant can enhance or decrease the cytotoxicity of an oxidizing anticancer system in vitro, but generalizations about antioxidants cannot be made.

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Antioxidants / pharmacology*
  • Ascorbic Acid / pharmacology*
  • Cell Cycle / drug effects
  • Cholecalciferol / pharmacology
  • Curcumin / pharmacology
  • Cytotoxins / pharmacology*
  • Drug Interactions
  • Drug Therapy, Combination
  • Humans
  • Male
  • Melatonin / pharmacology
  • Oxidative Stress / drug effects
  • Prostatic Neoplasms / drug therapy*
  • Quercetin / pharmacology
  • Tumor Cells, Cultured
  • Vitamin K 3 / pharmacology*


  • Antineoplastic Agents
  • Antioxidants
  • Cytotoxins
  • Cholecalciferol
  • Vitamin K 3
  • Quercetin
  • Curcumin
  • Melatonin
  • Ascorbic Acid