[Studies on the thymidine-triphosphate synthesis in malignant tumors. II. Effect of hyperthermia, Vitamin K and Cytotoxic agents (author's transl)]

Menadione: spectrum of anticancer activity and effects on nucleotide metabolism in human neoplastic cell lines

The spectrum of cytotoxicity of menadione (MD) was examined in a panel of human cancer cell lines. MD was equipotent against multidrug-resistant and parental leukemia cell lines with IC50 values of 13.5 +/- 3.6 and 18 +/- 2.4 microM respectively. A cervical carcinoma cell line resistant to the antimetabolite, methotrexate (MTX), was as sensitive to MD as its parental cell line. The interactions of fifteen clinically utilized anticancer drugs with MD were examined in vitro and the majority were found to be additive, with four agents exhibiting synergism and one agent exhibiting antagonism. MD inhibited the incorporation of radioactive thymidine, uridine and amino acids into DNA, RNA and protein, respectively, in three human cancer cell lines. Some possible reasons for the inhibition of DNA synthesis including effects of MD on intracellular deoxyribonucleoside triphosphate pools were examined and ruled out. Although results from previous studies using rat hepatocytes suggested that mitochondria may be a target of MD, no significant effect of this compound on total intracellular adenosine triphosphate (ATP) pools in human cancer cell lines was observed. Collectively, these in vitro results demonstrate that MD possesses a broad spectrum of anticancer activity and suggest the potential utility of this agent in cancer therapy. Future studies directed at elucidation of the mechanism of MD action in human cancer cells are warranted and are under study.

High-performance liquid chromatographic assay of vitamin K in human serum

A sensitive combined adsorption and reversed-phase high-performance liquid chromatographic procedure is described that permits the determination of endogenous vitamin K1 levels in serum. The separation of vitamin K1 (cis- + trans-isomers), vitamin K1 epoxide and the menaquinones MK-2, MK-4 and MK-9 by adsorption, reversed-phase and cyano-bonded phase chromatography is discussed. The methodology was further developed for the quantitative measurement of vitamin K1 in human serum. Concentrations as low as 500 pg/ml in serum could be detected. The identity of the vitamin K1 peak was confirmed by UV absorption spectrophotometry and re-chromatography. The method has been applied to the determination of serum levels in normal healthy individuals and patients treated with vitamin K1.