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+ |