Friday, May 26, 2006

Auto-Oxidation of Catechol

There has been a comment on this blog about the stability of the catechol compounds with respect to the formation of ortho-quinones.

Oxidation of Catechol to o-benzoqiunone is free radical mediated, passing through a semiquinone radical.

"The equilibrium potential for the one-electron transfer between catechol and the semiquinone radical (cat.) is 100 mV at pH 7 (Eberson, 1985). For the second electron transfer between the semiquinone radical and the catechol dianion (cat2-), an equilibrium potential of 530 mV, 139 mV and 43 mV for pH 7, pH 11 and pH 13.5 respectively was reported (Steenken and Neta, 1979). As a consequence, under physiological conditions catechol is not auto-oxidized (IronsandSawahata,1985), except in the presence of heavy metals (e.g. copper). Several enzymes in plants, animals and bacteria are able to catalyze oxidation of catechol to benzoqiunone. "

The passage has been extracted from an aricle " Chemical properties of catechols and their modes of toxic action in cells, from microorrganisms to mammals." Environmental Microbiology (2001)3 (2), 81-91

2 Comments:

At 2:28 PM, Blogger katbears92 said...

can you explain to me how tyrosinase is being inhibited by egcg???

 
At 2:29 PM, Blogger katbears92 said...

can you show me the complete pathway how melanin production is reduced by EGCG??? THANK YOU VERY MUCH.

 

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