Study of in vitro cytotoxicity of a water soluble organic arsenic compound, arsenosugar, in seaweed.

In the present study, we demonstrated the cytotoxic effect of a dimethylarsenic compound in seaweed, (R)-(2',3'-dihydroxypropyl) 5- deoxy-5-dimethylarsinoyl-beta-D-riboside, namely arsenosugar (AsSug), on mammalian cells, murine macrophages, in comparison with that of an inorganic arsenical, arsenite, in vitro. More than 99.5% pure AsSug was synthesized. Arsenite was strongly and equally toxic to both peritoneal macrophages (PMs) and alveolar macrophages (AMs), and the concentration of arsenite that inhibited the viability of cells by 50% compared to the viability of control cells (50% inhibitory concentration; IC50) was 5 microM. In contrast, AsSug showed no cytotoxicity to both PMs and AMs at the microM concentration level; however, it induced different and interesting cellular responses in both macrophages at high concentrations, 1-10 mM. AsSug enhanced the viability of PMs at an optimal dose of 5 mM; conversely, it showed weak but significant cytotoxicity to AMs (IC50 = 8 mM).