Enzymic synthesis hydroquinone

One of the most exciting discoveries related to quinone/hydroquinone chemistry is thek synthesis by biosynthetic routes (12,13). Using bacterial enzymes to convert D-glucose [50-99-7] (7) to either 1,2- or l,4-ben2enediol allows the use of renewable raw material to replace traditional petrochemicals. The promise of reduced dependence on caustic solutions and the use of transition-metal catalysts for thek synthesis are attractive in spite of the scientific and economic problems still to be solved. 

This enzyme exhibits no hydroxylase activity and is involved in the final synthesis of many naturally occurring /t-quinoncs. e.g. the naphthaquinone juglone in walnut (1.58) and the benzoquinone arbutin (hydroquinone-(3-D-glucopyranoside 2.46). Arbutin is a plant cryo-protectant that stabilizes membranes (Hincha et al., 1999). This compound has medicinal properties and has, for example, been used to treat urinary tract infections in humans. It is also used to lighten skin color, because it inhibits tyrosinase and hence the formation of melanin. The derivative deoxyarbutin (2.47 note the difference in the sugar molecule) was recently reported to be considerably more effective as a skin-lightening compound (Boissy et al., 2005). 

Vitamin K cycle—metabolic interconversions of vitamin K associated with the synthesis of vitamin K-dependent clotting factors. Vitamin K1 or K2 is activated by reduction to the hydroquinone form (KH2). Stepwise oxidation to vitamin K epoxide (KO) is coupled to prothrombin carboxylation by the enzyme carboxylase. The reactivation of vitamin K epoxide is the warfarin-sensitive step (warfarin). The R on the vitamin K molecule represents a 20-carbon phytyl side chain in vitamin Ki and a 30- to 65-carbon polyprenyl side chain in vitamin K2. 

The formation of aryl D-glucosides is characteristic of insects as well as of plants. An enzyme has been prepared from the fat body of the locust which will catalyze the synthesis of arbutin from hydroquinone and uridine 5-(a-D-glucopyranosyl pyrophosphate),and homogenates of cockroach hepatic coecum have been shown to catalyze the formation of o-aminophenyl, S-D-glucopyranoside from the same glycosyl nucleotide and o-aminophenol. ... 

Bearberry Arctostaphylos uva-ursi (L.) Spreng is a small shrub, whose leaves contain arbutin, a hydroquinone heteroside, that yields hydroquinone after degradation by a j3-glucosidase enzyme. Hydroquinone acts by inhibiting the tyrosinase enzyme, which initiates the biochemical synthesis of melanin. At present, the use of this hydroquinone glucoside is becoming less and less frequent because of the restrictions on the use of synthetic hydroquinones for cosmetic applications and because of its well-known irritant effects on the skin (Maeda and Fukuda, 1991, 1996). 

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