Ruthenium red
Chemical compound
From Wikipedia, the free encyclopedia
Ruthenium red (RR), also known as ammoniated ruthenium oxychloride, is an inorganic compound used as a dye in histology to stain aldehyde fixed mucopolysaccharides.
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| ECHA InfoCard | 100.228.922 |
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| Properties | |
| Cl6H42N14O2Ru3 | |
| Molar mass | 786.34 g·mol−1 |
| Appearance | Brownish-red solid[1] |
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| GHS labelling:[1] | |
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| Warning | |
| H302, H315, H319 | |
| P264, P264+P265, P270, P280, P301+P317, P302+P352, P305+P351+P338, P321, P330, P332+P317, P337+P317, P362+P364, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure
The chloride has the chemical formula [Ru3O2(NH3)14]Cl6·4H2O.[2] A thiosulfate been characterized with the formula [Ru3O2(NH3)14](S2O3)3·4H2O.[3] The cation is composed of a linear [(NH3)5-RuIII-O-(NH3)4RuIV-O-RuIII-(NH3)5]6+ backbone formed from three ruthenium coordination octahedra.[3][4]
The inhibition of mitochondrial Ca2+ uptake is attributed to an impurity with the formula μ-O-[(HCO2)(NH3)4Ru]2Cl3.[4] This compound crystallizes in the orthorhombic system (space group Pnn2 (No. 34), a = 8.588 Å, b = 13.335 Å, c = 7.602 Å, cell volume = 870.6 Å3, Z = 2 units per cell).[4]
Preparation
The chloride is prepared by the aerial oxidation of ruthenium(III) chloride in aqueous ammonia solution.[3] The thiosulfate is prepared by treating an aqueous solution of the chloride with sodium thiosulfate.[3]
Uses
Ruthenium red has been used as a pharmacological tool to study specific cellular mechanisms. Selectivity is a significant issue in such studies as RR is known to interact with many proteins.[5] These include mammalian ion channels (CatSper1, TASK, RyR1, RyR2, RyR3, TRPM6, TRPM8, TRPV1, TRPV2, TRPV3, TRPV4, TRPV5, TRPV6, TRPA1, mCa1, mCa2, CALHM1[6][7]) TRPP3,[8] a plant ion channel, Ca2+-ATPase, mitochondrial Ca2+ uniporter,[9] tubulin, myosin light-chain phosphatase, and Ca2+ binding proteins such as calmodulin. Ruthenium red displays nanomolar potency against several of its binding partners (e.g. TRPV4, ryanodine receptors,...). For example, it is a potent inhibitor of intracellular calcium release by ryanodine receptors (Kd ~20 nM).[10] As a TRPA1 blocker, it assists in reducing the airway inflammation caused by pepper spray.
RR has been used on plant material since 1890 for staining pectins, mucilages, and gums. RR is a stereoselective stain for pectic acid, insofar as the staining site occurs between each monomer unit and the next adjacent neighbor.[11]