Synergistic cytotoxic action of vitamin C and vitamin K3

We investigated the combination effect of sodium ascorbate (vitamin Q and menadione (vitamin K-3) on the viability of various cultured cells. Human oral squamous cell carcinoma (HSC-2, HSC-3) and human promyelocytic leukemia (HL-60) cells were more sensitive to these vitamins as compared to normal cells (human gingival fibroblast HGF, human periodontal ligament fibroblast HPLF, human pulp cell HPC). The combination of vitamin C and vitamin K-3 produced synergistic cytotoxicity against all these 6 cell lines. Treatment with vitamin C or vitamin K-3, or their combination, induced internucleosomal DNA fragmentation only in HL-60 cells, but not in the oral tumor cell lines (HSC-2, HSC-3, HSG). ESR spectroscopy showed that vitamins C and K-3 produce radicals under alkaline conditions and that the combination of these two vitamins synergistically enhanced their respective radical intensities.