Allomelanins suppress the tumor cell growth in vitro and in vivo. - GreenMedInfo Summary

Allomelanins are nitrogen-free macromolecular polymers of simple phenols produced by higher plants and fungi. In an earlier work we found that allomelanins were effective in suppressing the growth of cultured tumor cells. In the present study we examined the effect of these polymers on the survival curve of Balb/C mice inoculated i.p. with Meth/A cells (3 x 10(4) cells/mouse), which originated from a malignant lymphoma. Allomelanins were extracted from black sesame seeds and black soybeans, and given p.o. via the drinking water. The dose of allomelanins was approximately 3 mg/mouse/day. The percent of survivals was significantly higher in the experimental groups than in the control. Also, when HCT-15 cells were cultured for 2 days in medium containing 400 micrograms/ml of protein-free allomelanins, histograms obtained from flow-cytometry data showed a significant increase in the fraction between the diploid and tetraploid peaks, indicating blockage of the S phase of the cell cycle. These results suggest that allomelanins suppressed the tumor cell growth in vitro and in vivo, and that the effect was cytostatic, mostly by blockage of the S phase.