MPP+

MPP+
IUPAC name	1-Methyl-4-phenylpyridin-1-ium
Other names	Cyperquat
Identifiers
CAS number	39794-99-5
PubChem	39484
EINECS number	248-939-7
MeSH	1-Methyl-4-phenylpyridinium
SMILES	C[n+]1=cc=c(c=c1)c2=cc=cc=c2
Properties
Molecular formula	C12H12N]]+
Molar mass	173.25 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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MPP+ (1-methyl-4-phenylpyridinium) is a positively charged molecule with chemical formula C₁₂H₁₂N⁺. It is toxic and acts by interfering with oxidative phosphorylation in mitochondria, causing depletion of ATP and cell death. It also inhibits the synthesis of catecholamines, reduces levels of dopamine and cardiac norepinephrine, and inactivates tyrosine hydroxylase.

The neurotoxin MPTP is converted in the brain into MPP+ by the enzyme MAO-B, causing parkinsonism in primates by killing certain dopamine-producing neurons in the substantia nigra.

The chloride of MPP+ has been used as a herbicide under the trade name cyperquat and is structurally similar to the herbicide paraquat.