Abnormal cell morphology and cytotoxic effect are induced by 6-0-palmitol-ascorbate-2-0-phosphate, but not by ascorbic acid or hyperthermia alone.

A new derivative of ascorbic acid (AsA), 6-0-palmitoyl-ascorbate 2-0-phosphate (Asc2P6Pal) was developed to enhance the antitumor activity of AsA. When Ehrlich ascites tumor cells were treated with 50 microM Asc2P6Pal at 37 degrees C or 42 degrees C for 1 h and then cultured for 20 h, most of cells exhibited some morphological abnormalities, including exudation of intracellular granules together with other contents on the cell membrane surface, resulting in cell fragmentation. The abnormal features were further enhanced by a long term culture for 96 h and heat treatment at 42 degrees C. In contrast, no abnormality was detected for untreated cells or cells treated with AsA (free acid) at 37 degrees C or 42 degrees C. Cells cultured for 96 h after the treatment suffered from inhibition of DNA synthesis and proliferation. This inhibition was markedly enhanced by combination with the hyperthermic treatment at 42 degrees C, but not for a short-term culture of 20 h after the treatment. No effects were seen upon similar treatment with AsA. The abnormal cells produced during culture for 20 h after the treatment were evaluated to be viable, because they failed to be stained with trypan blue and retained most of the DNA synthesizing ability of Asc2P6Pal-untreated cells. However, they appeared and died after a continuous 76 h of culture (96 h).