Methylene Blue

Methylene blue (methylthioninium chloride) is a phenothiazinium dye with a long history as a histological stain and redox dye. In laboratory research, methylene blue has been studied as an alternative electron carrier that can pass electrons from NADH to cytochrome c in the mitochondrial electron transfer chain, and as an inhibitor of nitric oxide synthase and monoamine oxidase A in enzyme and tissue assays. Cell-culture and rodent studies have examined it in models of cellular senescence and neurodegeneration. Research Market supplies methylene blue as a research reagent with identity data for each lot on its certificate of analysis. It is sold strictly for laboratory research use.

Chemical structure and identification

• Molecular formula: C₁₆H₁₈ClN₃S
• Molecular weight: 319.9 g/mol
• CAS number: 61-73-4
• PubChem CID: 6099
• Synonyms: Methylthioninium chloride
• Form: Physical form and fill are stated on the vial label and batch certificate of analysis
• Analytical methods: HPLC for purity and mass spectrometry for identity, reported on the batch certificate of analysis

Research applications

• Mitochondrial electron transfer: Reviewed for its ability to reroute electrons in the mitochondrial electron transfer chain directly from NADH to cytochrome c, with in-vitro and in-vivo work in animal models of stroke, cerebral ischemia, Alzheimer’s disease, Parkinson’s disease and traumatic brain injury [1]
• Cellular senescence: In human IMR90 fibroblasts in culture, nanomolar methylene blue extended replicative life span by more than 20 population doublings, increased mitochondrial complex IV by 30% and raised cellular oxygen consumption by 37–70% [2]
• Retinal ganglion cells: In primary rat retinal ganglion cells, methylene blue at 1 and 10 µM protected against rotenone, staurosporine and 72 hours of hypoxia, and increased cytochrome c oxidase activity in the presence of hydrogen peroxide [3]
• Nitric oxide synthase: Formation of L-citrulline by purified NO synthase was completely inhibited by 30 µM methylene blue, while soluble guanylyl cyclase was far less sensitive, which the authors read as direct NOS inhibition [4]
• Monoamine oxidase A: Kinetic assays with purified human MAO identified methylene blue as a tight-binding reversible inhibitor of MAO A, with MAO B inhibited only at much higher concentrations [5]

Reference citations

1. Tucker D. et al. (2018). From mitochondrial function to neuroprotection-an emerging role for methylene blue. Mol Neurobiol, 55(6):5137–5153. PMID 28840449 · DOI
2. Atamna H. et al. (2008). Methylene blue delays cellular senescence and enhances key mitochondrial biochemical pathways. FASEB J, 22(3):703–712. PMID 17928358 · DOI
3. Daudt D.R. 3rd et al. (2012). Methylene blue protects primary rat retinal ganglion cells from cellular senescence. Invest Ophthalmol Vis Sci, 53(8):4657–4667. PMID 22661471 · DOI
4. Mayer B. et al. (1993). Inhibition of nitric oxide synthesis by methylene blue. Biochem Pharmacol, 45(2):367–374. PMID 7679577 · DOI
5. Ramsay R.R. et al. (2007). Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction. Br J Pharmacol, 152(6):946–951. PMID 17721552 · DOI

Compound data from PubChem CID 6099. Literature summaries describe published preclinical research and are not claims about this product’s effects in humans or animals.