Methylene blue acted as an alternative electron carrier in cultured neurons
Mark Kemp
In cultured neurons, methylene blue accepted electrons from NADH and passed them to cytochrome c, bypassing complexes I and III. A plain summary of Wen et al., J Biol Chem 2011.
In cultured neuronal cells, methylthioninium chloride (methylene blue) accepted electrons from NADH and transferred them to cytochrome c, bypassing complexes I and III of the mitochondrial electron transport chain (Wen et al., J Biol Chem 2011). At low nanomolar concentrations it increased cellular oxygen consumption, reduced anaerobic glycolysis, and protected the cells against several toxic insults; a derivative with its redox centre chemically disabled had no effect on complex activity.
Citation: Wen Y, Li W, Poteet EC, et al. J Biol Chem 2011;286(18):16504–15. PMID 21454572. doi:10.1074/jbc.M110.208447.
What the study did
The authors worked with cultured neuronal cells. They tested whether methylthioninium chloride could move electrons along the mitochondrial electron transport chain when the normal route was blocked, and measured what that did to the cells’ oxygen consumption, their reliance on glycolysis, and their survival under toxic conditions.
The control that makes the paper is a synthesised derivative of methylene blue with the redox centre disabled by N-acetylation — a molecule that looks the same but cannot accept or donate electrons. Whatever the intact molecule did that the disabled one did not could be attributed solely to redox activity.
What it found
Methylene blue accepted electrons from NADH and transferred them to cytochrome c. That route bypasses complexes I and III. When those complexes were blocked, electron flow continued.
Cells treated with methylene blue consumed more oxygen and relied less on anaerobic glycolysis — the signature of mitochondrial respiration running rather than the cell falling back on fermentation.
At low nanomolar concentrations, methylene blue protected the cells against a range of insults in vitro.
The N-acetylated derivative had no effect on mitochondrial complex activities. The authors concluded that methylene blue’s mechanism is fundamentally different from that of conventional antioxidants: it does not scavenge radicals, it changes where electrons go.
| Model | Cultured neuronal cells, in vitro |
| Compound | Methylthioninium chloride; N-acetylated derivative as redox-inactive control |
| Concentration | Low nanomolar |
| Measured | NADH → cytochrome c electron transfer; complex I/III bypass; oxygen consumption; anaerobic glycolysis; cell survival under toxic insult |
| Result | Electron transfer confirmed; oxygen consumption up; glycolysis down; protection at low nanomolar; control derivative inactive |
| Not tested | Humans; oral administration; any dose |
What it means, and what it doesn't
This is a mechanism paper. It shows how the molecule interacts with the electron transport chain in a culture dish, and it does so cleanly — the disabled-derivative control rules out most alternative explanations.
It does not show an effect in a person. Nothing was administered to anyone. The concentrations are bath concentrations in culture medium and do not directly translate to the amount taken by mouth. The paper makes no claim about any product, and neither does this page.
The concentration-dependence of methylene blue — protective at low concentration, pro-oxidant at high — is not the subject of this paper. It is covered in the hub, under “The chemistry, in full”.
Read the paper
Wen Y, Li W, Poteet EC, Xie L, Tan C, Yan LJ, Ju X, Liu R, Qian H, Marvin MA, Goldberg MS, She H, Mao Z, Simpkins JW, Yang SH. Alternative mitochondrial electron transfer as a novel strategy for neuroprotection. Journal of Biological Chemistry 2011;286(18):16504–16515.
- PubMed: https://pubmed.ncbi.nlm.nih.gov/21454572/
- Full text (free): https://pmc.ncbi.nlm.nih.gov/articles/PMC3091255/
- DOI: https://doi.org/10.1074/jbc.M110.208447
This summarises a laboratory study on cultured cells. It is not evidence of an effect in humans and is not a claim about any product.