Hydroquinone

Hydroquinone, also known as benzene-1,4-diol, is an aromatic organic compound which is a type of phenol, having the chemical formula C6H4(OH)2. Its chemical structure has two hydroxyl groups bonded to a benzene ring in a para position. Hydroquinone is commonly used as a biomarker for benzene exposure. The presence of hydroquinone in normal individuals stems mainly from direct dietary ingestion, catabolism of tyrosine and other substrates by gut bacteria, ingestion of arbutin-containing foods, cigarette smoking, and the use of some over-the-counter medicines. Hydroquinone is a white granular solid at room temperature and pressure. The hydroxyl groups of hydroquinone are quite weakly acidic. Hydroquinone can lose an H+ from one of the hydroxyls to form a monophenolate ion or lose an H+ from both to form a diphenolate ion. Hydroquinone has a variety of uses principally associated with its action as a reducing agent which is soluble in water. It is a major component of most photographic developers where, with the compound Metol, it reduces silver halides to elemental silver.

ID EC Number Name
KEGG:R01297 1.14.13.64 4-hydroxybenzoate,NADH:oxygen oxidoreductase (1-hydroxylating, decarboxylating)
KEGG:R01299 1.14.13.64 4-hydroxybenzoate,NADPH:oxygen oxidoreductase (1-hydroxylating, decarboxylating)
KEGG:R02363 1.14.18.1 hydroquinone:oxygen oxidoreductase
KEGG:R02489 4.1.1.62 gentisate carboxy-lyase
KEGG:R05133 3.2.1.86 arbutin 6-phosphate glucohydrolase
KEGG:R05244 1.6.5.6 NADPH:p-benzoquinone oxidoreductase
KEGG:R05246 1.13.11.66 C00530 + C00007<=>C06603
KEGG:R05267 2.5.1.- C01327 + C00530 + C00127<=>C06601 + 2 C00051
KEGG:R05482 C00530 + C00088 + 7 C00080 + 6 C05359<=>C02372 + 3 C00001
KEGG:R05769 2.4.1.218 UDP-glucose:hydroquinone-O-b-D-glucosyltransferase
KEGG:R06851 1.14.13.- C00530 + C00005 + C00080 + C00007<=>C02814 + C00006 + C00001
KEGG:R06893 3.1.1.2 aryl-ester hydrolase
KEGG:R09105 3.1.1.- C18216 + C00001<=>C00156 + C00530
KEGG:R11659 1.8.5.7 2-(glutathione-S-yl)-hydroquinone:glutathione oxidoreductase
KEGG:R13227 1.8.5.10 hydrogen sulfide:[DsrC protein]-dithiol oxidoreductase (trisulfide-forming)
KEGG:R13388 1.97.1.14 quinone:selenite oxidoreductase
BioCyc:RXN0-5295 3.2.1.- CPD-1162 + WATER --> GLC-6-P + HYDROQUINONE
BioCyc:RXN-19775 1.11.1.- HYDROQUINONE + HYDROGEN-PEROXIDE<=>P-BENZOQUINONE + 2 WATER
BioCyc:TRANS-RXN0-529 HYDROQUINONE --> HYDROQUINONE
Rhea:RHEA:11277 1.10.3.2 4 hydroquinone + O2 => 4 benzosemiquinone + 2 H2O
Rhea:RHEA:11278 1.10.3.2 4 benzosemiquinone + 2 H2O => 4 hydroquinone + O2
Rhea:RHEA:11279 1.10.3.2 4 hydroquinone + O2 <=> 4 benzosemiquinone + 2 H2O
Rhea:RHEA:12561 2.4.1.218 hydroquinone + UDP-α-D-glucose => hydroquinone O-β-D-glucopyranoside + UDP + H+
Rhea:RHEA:12562 2.4.1.218 hydroquinone O-β-D-glucopyranoside + UDP + H+ => hydroquinone + UDP-α-D-glucose
Rhea:RHEA:12563 2.4.1.218 hydroquinone + UDP-α-D-glucose <=> hydroquinone O-β-D-glucopyranoside + UDP + H+
Rhea:RHEA:16386 1.14.13.64 4-hydroxybenzoate + NADPH + O2 + 2 H+ => hydroquinone + CO2 + NADP+ + H2O
Rhea:RHEA:16387 1.14.13.64 hydroquinone + CO2 + NADP+ + H2O => 4-hydroxybenzoate + NADPH + O2 + 2 H+
Rhea:RHEA:16388 1.14.13.64 4-hydroxybenzoate + NADPH + O2 + 2 H+ <=> hydroquinone + CO2 + NADP+ + H2O
Rhea:RHEA:16390 1.14.13.64 4-hydroxybenzoate + NADH + O2 + 2 H+ => hydroquinone + CO2 + NAD+ + H2O
Rhea:RHEA:16391 1.14.13.64 hydroquinone + CO2 + NAD+ + H2O => 4-hydroxybenzoate + NADH + O2 + 2 H+