Ortho-dihydroxybenzene oxidation

One of the earliest reports of LO inhibition concerned the effects of ortho-dihydroxybenzene (catechol) derivatives on soybean 15-LO [58]. Lipophilic catechols, notably nordihydroguaiaretic acid (NDGA) (19), were more potent (10 /zM) than pyrocatechol itself. The inactivation was, under some conditions, irreversible, and was accompanied by oxidation of the phenolic compound. The orfAo-dihydroxyphenyl moiety was required for the best potency, and potency also correlated with overall lipophilicity of the inhibitor [61]. NDGA and other phenolic compounds have been shown by electron paramagnetic resonance spectroscopy to reduce the active-site iron from Fe(III) to Fe(II) [62] one-electron oxidation of the phenols occurs to yield detectable free radicals [63]. Electron-poor, less easily oxidized catechols form stable complexes with the active-site iron atom [64]. 

Oxidation of ortho-dihydroxybenzene Fe-assisted PC reaction and its comparison with the unpromoted PC reaction... 

Table 1 Estimated parameters for the unpromoted PC and Fe-assisted PC oxidation of ortho-dihydroxybenzene (20 ppm C in o-DHB)...

Beilstein Handbook Reference) AI3-03995 Benzene, o-dihydroxy- 1,2-Benzenediol BRN 0471401 Catechol, CCRIS 741 Cl 76500 Cl Oxidation Base 26 1,2-Dihydroxybenzene ortho-Dihydroxybenzene Durafur developer C EINECS 204427-5 Fouramine PCH Fourrine 68 HSDB 1436 ... 

Quaternary structure (Section 27 22) Description of the way in which two or more protein chains not connected by chemical bonds are organized in a larger protein Quinone (Section 24 14) The product of oxidation of an ortho or para dihydroxybenzene denvative Examples of quinones include... 

Quinone (Section 24.14) The product of oxidation of an ortho or para dihydroxybenzene derivative. Examples of quinones include... 

The main product of the Elbs reaction is the 1,4-dihydroxybenzene (hydro-quinone). If the para position is already occupied by a substituent, the reaction occurs at an ortho position, leading to a catechol derivative although the yields are not as good as for a hydroquinone. Better yields of catechols 7 can be obtained by a copper-catalyzed oxidation of phenols with molecular oxygen ... 

In this regard, the PC oxidation of phenol produces similar hydroxylated aromatics as reaction intermediates since the oxidation occurs via hydroxyl radical attack. These intermediates might be equally harmful than the parent species. Several authors report that during the oxidation of phenol, they identified various hydroxylated intermediates such as 1,2,3-trihydrox-ybenzene (1,2,3-THB), ortho- and parfl-dihydroxybenzene (o,p-DHB) (Al-Ekabi and Serpone, 1988), 1,2,4-THB and 1,4-benzoquinone (1,4-BQ)... 

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