For laboratory research use only.
Methylene blue (methylthioninium chloride) is a synthetic thiazine dye. PubChem lists it under CID 6099 as a cationic phenothiazinium compound used as a stain and redox-active chromophore (PubChem CID 6099).
Chemical behavior
In water the oxidized form absorbs strongly in the visible range and appears deep blue. Reduction yields a colorless leuko form. That reversible redox couple is why the dye appears in histology staining and in chemical or biochemical systems that need a visible redox mediator. Photometric work often accounts for light sensitivity because the chromophore is photochemically active.
Laboratory research context
Beyond classical staining, recent experimental papers have used methylene blue in specialized models—for example metabolic readouts in tendon tissue models (PMID 42058931) and tumor-growth models in mice (PMID 38254843). Related phenothiazine dyes are not automatically interchangeable; a bioenergetics study of new methylene blue reported mitochondrial effects that caution against treating every blue thiazine as equivalent (PMID 40846101). Model-specific findings should stay attached to those papers rather than generalized as broad biological benefit.
Sources
- PubChem Compound Summary: Methylene Blue (CID 6099)
- Methylene blue restores NAD(+)/NADH homeostasis to attenuate Achilles tendinopathy via activating AIF/Mitochondrial respiratory chain complex I. (J Orthop Translat, PMID 42058931)
- Methylene Blue Metabolic Therapy Restrains In Vivo Ovarian Tumor Growth. (Cancers, 2024, PMID 38254843)
- Beyond phototoxicity: The dark side of new methylene blue on mitochondrial and cellular bioenergetics. (Free Radic Biol Med, PMID 40846101)