Modifying effects of the environmental contaminant catechol, and its isomers resorcinol and hydroquinone, on methyl-N-amylnitrosamine (MNAN)-induced carcinogenesis were studied in male F344 rats. Groups of 15 rats were given three i.p. injections of 25 mg/kg of body weight of MNAN within the initial 2-wk period, and commencing 1 wk thereafter they were administered 0.8% catechol, 0.8% resorcino...

The mitomycin C-resistance gene, mcrA, of Streptomyces lavendulae produces MCRA, a protein that protects this microorganism from its own antibiotic, the antitumor drug mitomycin C. Expression of the bacterial mcrA gene in mammalian Chinese hamster ovary cells causes profound resistance to mitomycin C and to its structurally related analog porfiromycin under aerobic conditions but produces littl...

In agriculture high urease activity during urea fertilization causes substantial environmental and economical problems by releasing abnormally large amount of ammonia into the atmosphere which leads to plant damage as well as ammonia toxicity. All over the world, urea is the most widely applied nitrogen fertilizer. Due to the action of enzyme urease; urea nitrogen is lost as volatile ammonia. F...

In the area of photoyellowing of mechanical pulps, recently obtained experimental evidence has shown that hydroquinone/p-quinone redox couple is present in lignin-rich mechanical pulps. It was also noted that compared to a control pulp the concentration of pquinones was significantly higher in a photoyellowed pulp. Under ambient conditions, upon exposure to light, the existent pulp hydroquinone...

A novel flow-injection chemiluminescence(CL)method has been developed for the determination of hydroquinone (HQ) and catechol (CT), based on their inhibition of the chemiluminescence reaction of luminol–KMnO4–β-cyclodextrin (β-CD). It was found that β-cyclodextrin could effectively enhance the chemiluminescence produced from the reaction of luminol with KMnO4 in basic media. The proposed method...

Although various treatment methods for melasma have developed, substantial improvement of the condition is sometimes difficult. We have experientially found that some of refractory melasma caused by daily friction can easily be treated by using a combination of a peeling agent (20% glycolic acid) and a depigmenting agent (5% hydroquinone) twice daily at home. And here, by performing skin biopsi...

In the preceding paper the oxidation of substrates by “indophenol oxidase” was demonstrated to be a joint action of cytochrome and cytochrome oxidase. It was further shown that with a given amount of oxidase the velocity of hydroquinone oxidation reached a maximum as the amount of added cytochrome was increased. The latter fact immediately suggested the probability that the rapid aerobic oxidat...