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Methyl transfer from a hydrophobic vitamin B12 derivative to arsenic trioxide |
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| Authors: | Koichiro Nakamura Yoshio Hisaeda Hiroshi Yamauchi |
| Institution: | a R&D Department, Nippon Sheet Glass Co. Ltd., Chitose-cho 2, Yokkaichi, Mie 510-0051, Japan b Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Moto-oka 744, Nishi-ku, Fukoka 819-0395, Japan c School of Allied Health Sciences, Kitasato University, Kitasato 1-15-1, Sagamihara, Kanagawa, Japan |
| Abstract: | The methylation reaction of arsenic trioxide conducted at 37 °C and pH 7.0 for 24 h using hydrophobic methylated vitamin B12, (methyl) (aquo) heptamethylcobyrinate perchlorate, CH3B12 ester, as a methyl donor in the presence of reduced glutathione (GSH) yielded monomethylarsonous acid (MMA), dimethylarsinic acid (DMA), and trimethylarsine oxide (TMAO) as products with a methylation rate over 95%. In contrast, when methylcobalamin (CH3B12) was used as the methyl donor, only MMA and DMA were produced and the methylation rate dropped to around 20%. Reductive demethylation of a methyl-corrinoid coordination complex mediated by GSH is suggested as a mechanism of methyl transfer to arsenic trioxide. The differences observed for different corrinoid coordination complexes with respect to the reactivity of methyl transfer to arsenic is ascribable to differences inherent in the base-on (CH3B12) and base-off (CH3B12 ester) natures of the compounds. |
| Keywords: | Hydrophobic vitamin B12 derivative Arsenic trioxide Methyl transfer Trimethylarsine oxide Detoxification |
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