Meanings
nounmethylthioninium (uncountable)
- uncountablechemistryThe heterocyclic cation 3,7-bis(dimethylamino)-phenothiazin-5-ium, which is the basis of methylene blue
Methylene blue (MB, methylthioninium chloride) is a phenothiazine that crosses the blood brain barrier and acts as a redox cycler.
2014 February 20, Cliona Stack et al., “Methylene blue upregulates Nrf2/ARE genes and prevents tau-related neurotoxicity”, in Human Molecular Genetics, volume 23, →DOI
Origin
From methyl + thionine + -ium (“quaternary ammonium compound”).
Full word history & related roots →Cite this entry
APA
methylthioninium. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/methylthioninium
MLA
“methylthioninium.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/methylthioninium. Accessed November 4, 2026.
Chicago
WatkinsX Dictionary, s.v. “methylthioninium,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/methylthioninium.
Source: methylthioninium on Wiktionary, CC BY-SA 4.0.