The metabolism and activation of butylated-hydroxyanisole (25013165) (BHA) and butylated-hydroxytoluene (128370) (BHT) were compared by two model peroxidase enzymes: horseradish-peroxidase and prostaglandin-H-synthase. Both horseradish-peroxidase and the peroxidase component of prostaglandin-H-synthase were able to oxidize BHA and BHT to reactive intermediates which could covalently bind to protein or form dimeric products. A chemical/chemical interaction was observed between BHA and BHT resulting in a significant stimulation of BHT oxidation and the formation of the potentially toxic butylated-hydroxytoluene-quinone-methide (BHT- quinone-methide). Three dimeric products of BHA were identified from a horseradish-peroxidase catalyzed reaction, whereas with prostaglandin-H-synthase only two dimers were found. Compared with BHA, BHT was a much poorer substrate for peroxidase as was evident from the finding that dimeric products were readily formed from BHA alone but not from BHT alone. BHA markedly stimulated, by 400 percent, the covalent binding of BHT and the formation of BHT- quinone-methide and stilbenequinone. A possible mechanism for the formation of BHT-quinone-methide and stilbenequinone from peroxidative reactions in the presence of both BHA and BHT was presented. In this scheme, when BHA was present in peroxidase incubations in the absence of BHT, BHA was metabolized to a reactive intermediate, phenoxyl radical, which subsequently dimerized or covalently bound to cellular macromolecules. In the presence of BHT, however, BHA was recycled back to the parent compound. Similarly, in the absence of BHA, BHT was metabolized to a reactive intermediate, phenoxyl radical, which was able to covalently bind to cellular macromolecules. A crucial point was the direct interaction of an oxidized metabolite of BHA with BHT.
We take your privacy seriously. You can review and change the way we collect information below.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
Cookies used to make website functionality more relevant to you. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests.
Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data.
Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. These cookies may also be used for advertising purposes by these third parties.